THE UNIVERSITY OF CHICAGO
AH ECOLOGICAL SURVEY OF THE PORCUPINE MOUNTAINS
A DISSERTATION
SUBMITTED TO THE FACULTY
OF TEE OGDEN GRADUATE SCHOOL OF SCIEHCE
IH CANDIDACY FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
DEPARTMENT OF BOTANY
CHICAGO .ILLINOIS
NOVEMBER. 1923
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Knpy 1968
INTRODUCTION
1
EARL IER INVESTIGATIONS III THE PORCUPINE MOUNTAINS - 3
LOCATION AND PHYSIOGRAPHY - - - 5
CLIMaTE OP THE REGION - 7
THE CLIMAX FORMATIONS - 11
I. THE HEMLOCK CLIMAX - 12
A. Aspect of the forest - -- -- -- -- -- -12
B. Composition and dynamics of the forest - - - 16
1. Consideration of individual species - - 17
2. Quadrat studies ------------22
3. Initial physical factors and
competition ------------25
4* Equilibrium at any point --------28
C« Successions leading to the hemlock climax - - 29
1. Primary successions ----------29
a. Physiographic influences ----- 29
b* The shore successions -------31
Types of shore - - '- - v- ----- 34
2* Secondary successions in the Hemlock
climax - -----------
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II. THE MAPLE CLIMAX - 38
A. General physiographic features ------- 39
B. Successions relations - -- -- -- — - - 41
I. Xeruroh successions on the first range - 41
(1) Summit of the range -------42
fa) Ecological factors ----- 42
(b) The plant associations - - - 43
fc) Quadrat studies -------47
(2) The escarpment and its asso¬
ciations ----------50
(3) The talus slope ---------53
f4) Forest below the talus ------ 58
II. Hydrarch successions in the valley
of Carp River -----------61
a. Carp River ------------64
b • Carp Lake ------------66
o. Flood plain -----------69
SUMMARY - 71
REFERENCES - 77,78,79,80
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Map showing general position of the Porcupine Moun¬
tains in Ontonagon County, Michigan.
INTRODUCTION
In his classic article on the climax forest of
Isle Royale, Lake Superior, Cooper (5) refers to the trans-
itional zone between the two great phytogeographic regions -
the northeastern conifer forest and the eastern deciduous
forest. Certain features of both regions, he says, are
found in the southwestern portion of the island; but he
did not carry out his first intention of tracing the relat¬
ions between them. On the mainland of Michigan to the south,
the maple forest is well developed, especially at certain
inland points. Areas near the coast, however, may show
many transitional features, such as occur in the Porcupine
Mountains, which are about 125 km. south southwest of Isle
Royale. These so-called mountains, which are really
prominent hills or hilly ridges, represent the highest points
of land reached in the Upper Peninsula. As Leverett (20)
points out, they are "the most conspicuous features in this
entire area, for they rise on their north slope very abruptly
from the shore of Lake Superior to a height of 1400 feet
above the lake".
The purpose of this ecological survey was to make
a careful study of the climax formation of the region, in
eluding their relations to each other, and to correlate,
if possible, the various plant associations occurring within
them.
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The Porcupine Mountains consist roughly of three
ranges of hills, paralleling the coast (fig. 1), that nearest
the shore b&ing the most rugged. Back of these lies a table¬
land stretching south to the Gogebic Range.
It was not found possible to examine all of this
territory; nor does it seem essential to an understanding of
the vegeta tional development of the region. Practically all
the detail studies were made in connection with the first
range, and the valley of Carp River behind it. It must be
admitted that this near-shore region received most attention
because of its greater accessibility, yet aside from this it
seemed of major importance for the following reasons: (1) on
account of the pioneer conditions found on the first range,
where the summit still remains unclaimed by vegetational
development, (2) on account of the proximity of Lake Superior,
permitting the observation of various stages of succession
along the shore, (3) the proximity of a comparatively high
altitude (for the region) to the wind-swept surface of Lake
Superior, giving a definiteness to the larger problems of
vegetation, (4) a forest covering which gives it unusual
value for a study of the relation between two climax formations,
(5) opportunity for observing praotically primeval forest
conditions.
Field work was carried out in the sunnier of 1922.
Headquarters were first established at a point on Union
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Map showing a portion of the Porcupine Mountains.
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Bay (Sec. 16, T. 51 H» H 42 W«). This was found to be the
most convenient location for the examination of the shore
line and the hemlock forest of the north slope. Later, head¬
quarters were located on the site of an old mining property
near Carp Lake. All the work in connection with Carp River
valley and the summit of the range was done from this point.
I wish to express my appreciation of the encourage¬
ment and co-operation of Dr. H. C. Cowles of the University
of Chicago, under whose direction the work was undertaken.
I also wish to thank Dr. Geo. D. Puller of the same institution
for suggestions in regard to the method of work. To the follow
ing gentlemen, I desire likewise to extend my thanks. Dr. A. J.
Grout of New Brighton, II. Y. , for the determination of about
45 species of moss. Dr. Bruce Pink of Miami University, Ohio,
for the determination of about 60 species of lichens, and Dr.
E. A. Bessey of the Michigan Agricultural College, for assist¬
ance in various ways. The nomenclature used in connection with
the pteridophytea and spermatophytes is that of GRAY'S MANUAL,
seventh edition.
EARLIER INVESTIGATIONS IN THE PORCUPINE MOUNTAINS-
The early interest attaching to an exploration of
the mountains was based on the prospect of finding copper.
Indications of this interest are shown in the abandoned
shafts and wordings in various parts of the region. In 1848
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Pig. 1. - Carp Lake from top of fir at range, looking
southwest: second and third ranges in the distance: escarp
ment of first range extending H. S. W. (extreme right);
outlet of lake at far end.
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the mountains were visited by W. D. Whitney (11) acting as
botanist on a government expedition in charge of J. W. Foster.
The following year, several places on the south shore of Lake
Superior were visited - as far west - Whitney says, as the
Ontonagon Valley and Carp River, both being in the vicinity
of the Porcupines. In the second report on the region (IP) ,
which was published in 1851, Whitney gives a list of plants
seen in the Upper Peninsula, including some from Isle Royale.
This list, being very general, gives no clue as to what
species were observed in the Porcupine Mountains. In
JACKSON'S LAKE SUPERIORS), published in 1849, Bela Hubbard,
a geologist, in discussing the origin and character of the
soil in the Porcupines, points out that the sugar maple pre¬
dominates throughout the elevated portions, 'while hemlock is
the prevailing tree upon the lower lands.
During the next fifty years, apparently little was
done in the way of botanical investigation in this region.
In the summer of 1903, F. E. Wright (£8), Assistant State
Geologist, continued the work, earlier begun under the
direction of Dr. L. L. Hubbard, of preparing data for an
accurate geological report and map of the mountains. During
a part of this time he was accompanied by Dr. A. G. Ruthven
of the University of Michigan, who became interested in the
biological aspects of the country. In 1904 and 1905, the
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University Museum sent purties to northern Michigan to make
biological studies in the Porcupine Mountains and in Isle
Royale. One party, led by ])r. Ruthven, spent one month in
the Porcupines and the remainder of the season on Isle Royale.
The report of this expedition fl) came out in 1905* It covers
both regions, listing 91 species of plants, and notes the
ecological distribution of the more important species.
A list of over 600 plants found in the neighboring
county of Gogebic should be mentioned. It was based on work
done by Dr. £• ii. Bessey and the writer (10) during portions
of the summers of 1919 and 1920.
LOCATION AND PHYSIOGRAPHY.
The Porcupine Mountains are in Ontonagon County in
the Northern Peninsula of Michigan, in lat. 47 0., long. 90 w.
(see map). Thoir unique position, close to the south shore of
Lake Superior, has already been pointod out. Thoy reach a maxi -
mum altitude of 616 m. above sea level or 435 tn. above the level
of the lake. The top of the first range or ridge comes within 2
km. of tho shore. Its north slope is rather gentle, but becomes
increasingly stoop as one approaches the summit, finally
reaching a height of 275 m. abovo the lake in sec. 14, T. 51 B.
R. 43 W. There is then a sudden descent of about 120 m. to
the valley Of Carp River, half of this descent bOfcng, in
places, vertical rock face, at tho base of the cliff there
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Pig. 2. - Geological map of a portion of the
Porcupine Mountains, showing their relation to the
Keweenaw Series to the south. (After Irving).
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i8 a talus slope extending in places several hundred meters
down the side of the valley. This great cliff extends for
a distance of about 10 km. across T. hi U. R. 43 W. It is
interesting to note Poster’s impressions on first seeing
this great outcropping of rock in 1848. He says "Suddenly
the traveler finds himself on the brink of a precipice five
hundred feet deep, at the base of which lies a small laice,
so sheltered and hemmed in by the surrounding mountains that
the wind rarely ripples its surface. Gloomy evergreens skirt
its shores, whose long and pendant branches are so faithfully
reflected on the surface that the eye can with difficulty
determine where the water ends and the shore begins. Prom
this lake flows the Carp River, and the beholder occasionally
catches a glimpse of its waters as they wind through the
narrow valley towards the great reservoir".
Geologioally , the mountains form a crescent-shaped
off -shoot or spur from the main range to the south (fig. 2).
This latter extends from Keweenaw Point southwest to Wisconsin,
including the well-known iron and copper ranges of the Keweenaw
Series. The ranges of the Porcupines consist largely of
eruptive rocks with interbedded sandstones and conglomerates,
the strata tilted from 30° - 40° . They represent part of a
pre-Cambrian upheaval, probably during early Proterozoic time.
The present system of hills forms a comparatively small
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Geological sections illustrating the struc
ure of the Porcupine Mountains, (/if tor Irving)
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portion ( fig. 3) of the original land mass, the rest having
been removed by erosion during a very long period of time.
At the beginning of the glacial period, the general
topography was probably much the same as at present. The
mountains were laid bare at a relatively early date, mating a
cusp in the ice front, presumably between the Warren and Algon¬
quin stages. According to Lane (19) the water was ponded on
the north side of the mountains to a depth of 171 m. above the
present surface of Late Superior and on the south side at least
49 m. higher than this, the drainage being toward the Mississippi.
Old beach lines on the north slopes show successive stages in
the height of the late, where the late level was more or less
stationary.
From what has been said, it is evident that the
highest level lies bact of the first range, though the latter
is much the most rugged. The rough topography is, in general,
conditioned by the geologic structure of the region. The main
drainage lines are occupied by the Carp and Little Carp rivers,
which flow roughly southwest. These parallel the general
direction of the ridges, and finally turn northwest, emptying
into Lake Superior. A portion of the drainage is also east and
southeast into the valley of Iron Eivor.
CLIMATE OF THE HBOIOH.
The following data were obtained through the
courtesy of the U. 3. Weather Bureau at East Lansing; see also
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report by Seeley (£4). It is believed that tables I and II
taken together give a fair index of the olimatio conditions.
Ber gland, representing inland conditions, is about £7 km.
south southeast of Carp Lake; it has an elevation of £15 m.
above the surface of Lake Superior. Ontonagon is situated
at the mouth of the Ontonagon River, 3£ km. east of Bergland.
The tables show that the mean temperature for the year is
very nearly the same for both places.
-TABLE I-
MEAH TEMPERATURE AT BERGLAHD FOR 11 YEARS
°C — Jan.
Feb.
Mar.
Apr.
May
June
-1£.9
-11.4
-4.1
4.1
10.5
16.3
°C — July
Aug.
Sept •
Oct.
Uov •
Dec. Yr.
18.6
16.9
1£.7
6.8
-0.£
-7.7 4.1
-TABLE II-
MEaH TEMPERATURE AT Oil TO 1J AG OH
FOR 7
YEARS
°C — Jan.
Feb.
Mar.
Apr.
May
June
-9.3
-10.8
-3.5
3.8
9 .£
13.5
*C — July
AUg.
Sept .
Oct.
Hov.
Dec. Yr.
17.8
17.4
14.0
9.4
0.7
-5.8 4.£
di eroriees in "the average monthly temperatures
0f the tm) P^cea indicate the probable moderating influence
Ox ^Lq J.arge body of water* ^he average maximum temperature
for 5 years at Ontonagon was 34.6° C. and the average minimum
-^‘•7 C. The mean monthly temperature at Bergland for 11
ye&iii was above 0 C. for 7 months of the year, beginning with
April, and the mean monthly minimum above this for 6 months,
beginning with Hay. Tables prepared by the U. 3. Weather
Bureau show that the average date of the last killing frost
in spring is June 9, while that of the first Killing frost in
the fall is 3opt ember 16, giving 89 days as the average length
Ox uhe growing season. In this region the isotherms parallel
the shore line, and the average temperature of points along
the coat is several degrees warmer than inland points a few
miles further back. During the hot summer months, however,
the isotherms move back from the shore, so that the discrepancy
between shore and inland conditions is not so great.
-TABLJ5 III-
AViSRAGiS MONTHLY PRJSC IPITATIOU AT B3RGLABD FOE 11 Y&ARS
— Jan.
Feb.
Mar.
Apr.
May
June
cm 4.05
3.26
4.27
4.70
7.86
8.87
July
Aug.
Sopt.
Oct.
Ilov.
Dec. Yr.
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AV ERASE MONTHLY PRECIPITATION AT ONTONAGON FOR 6 YEARS
_ Jan-
Feb.
liar.
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May
June
cm -- 6.96
4-66
3.89
2.61
6.72
6.25
— July
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Sept.
Oot.
Nov.
Be o. Yr.
cm — 11.37
8.42
9.27
4.37
5.86
7.02 74.57
1.&0 above data, while not extending over as groat a
period of time as might be deuxrublo, would seem to indicate
that the average yearly rainfall for the region is about 76
cm* The figures show that the average precipitation along
the coast during the months from November to February is 305?
greater than the precipitation at Bergland 26 ion. bacic from
the coast- This may help tc explain certain striking differ¬
ences between the vegetation near the shore and that further
inland- Slightly more than one-half the average rainfall
occurs during the 5 months of the growing season (from May
to September), apparently coming earlier in the season at
inland points- The greatest average precipitation was in
July.
The average number of cloudy days per month for 5
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Fig* 4. - iSxfJorior view of hemlock climax along a
"forty” lino where the timber hue been cut: two eugar
maples to the right, largo hemlock in the background,
salmon berry and three email hemlocks in the fore¬
ground; elevation about 100 m. above Lake Superior.
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years at Ontonagon was 14, and partly cloudy 5, leaving
an average of 137 clear days for the year. The prevailing
direction of the wind at the same station is from the
northwest, often veering around from the west.
The extent and ruggednesa of the Porcupines allow
for much local variation. The above climatic data axe not
meant to be more than general. Their character accords with
the general mesophytic character of the vegetation in its
larger aspects.
THE CLIMAX FORMATIONS.
There are two climax plant formations covering
the ranges of the Porcupine Mountains. On the north slope
of the first range occurs a typical hemlock: forest. This
gradually merges into a maple forest near the top of the
slope. From this point maple forms the climax formation
on the ranges to the south, though scattered patches of
hemlock: occur on the lower slopes. Any interpretation
of the vegetation of the region must take into account
the relation between these two formations, their relative
position with respect to the larger physiographic features
and the successions leading up to them. In this paper
the hemlock climax will be considered first.
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I. Tim HJ&ILOCiC CL mAX
This is apparently the most mesophytic formation
of the region. Its most typical development is on the lower
half of the north slope of the first range. It is composed
largely of three tree species: Tsuga canadonsi s (L.) Carr,
(hemlock) , Acer ^accharum Harsh, (sugar maple) and Betula
lutea Michx. f. (yellow birch). At the lower levels near
the lake shore, the forest is almost entirely hemlock:, while
near the top of the ridge it mergest into the less mosophytic
maple forest.
Intensive studies were made at various points in
the forest with a view to determining the relations between
the three principal species. The life habits of each, from
the seedling stage up, were studied as closely as time
permitted. Interrelations of the species were also studied
by means of quadrats and windfall areas.
A. Aspect of the Forest.
At first sight the forest appears to be almost
a pure stand of hemlock. The boles are conspicuous below,
but the upper portions of the trees, which are 25-30 m. or
mere tall, form a dense mass of interlaced foliage, with a
ragged skyline. Here and there are occasional trees of
yellow birch, with more open tops; also a few tall spindling
maples, devoid of foliage, excepting near the summit, and
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Pig. 5. - Showa distribution of yellow
birch and maple, the conifers being r amoved;
trees in the foreground are mostly maples;
looking northeast toward Lake Superior; edge
of forest to left; note abundant growth of
aalmon berry aa a ground cover.
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often indicating by the presence of dead twigg, the com¬
petition to which they are subjected.
In section 16, T* 51 K* R. 42 W. , the hemlock: had
been removed from certain "forties", making it possible to
obtain a view of the general composition of the forest from
the outside. This is shown in fig* 4. The three species
mentioned are practically the only ones in evidence from
an exterior view of a soction made in this part of the
forest. Other large tree species, of less common occurrence,
will be considered later.
In the area cut over, referred to above, only the
conifers had been removed, leaving the two principal deciduous
species standing, as shown in fig* 5* This gave an opportunity
to estimate the relative distribution and character of the
latter. An estimate was also made of the comparative number
of species in the forest having a diameter not less than
1.5 dm. This was done by listing the individuals in a belt
transect 220 m. long and 10 m. wide. It resulted In the
following data so far as the principal species is concerned:
hemlock, 80.5$; maple, 13.6$; yellow birch, 4.5$; basswood,
1 . 5$*
On entering tho forest, one is impressed with the
apparent age and maturity of the trees (fig* 6). The light
is much reduced by the dense canopy above, formed principally
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Fig. 6. - Interior view of Liosophytio
forest (see. 16, T. 61 K* R. 42 W#): trees
mostly hemlook; a largo yellow biroh in
foreground at left; a portion of the orown
of a maple at the right; looking north to¬
ward Lake Superior; note gentlo slope.
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by the fine spray of the hemlocks. An examination over a
large area shows considerable diversity in regard to light
conditions, the differences boing due to more or less open
areas caused by windfalls of varying ages. In reality the
forest may be considered as a patchwork of these windfalls,
which are ever appearing, maturing their growth and con¬
sequently producing a general shift in the position of the
better lighted areas.
The forest floor is rather uneven and on the whole
well drained, the general direction of the gullies being
north (towards Lake Superior). A few of these gullies are
occupied by small streams, even during the summer months,
while others contain no running water* but are very moist,
so that the moisture content of the soil is quite variable
for different portions of the forest. This seems to be the
controlling factor in causing certain departures from the
ordinary composition of the forest (fig. 7).
There is comparatively little shrubby vegetation
in the dense hemlock forest. Of the few shrubs found,
probably Lonicera canadensis Harsh, (bush honeysuckle) is
the most shade tolerant. The most important ecologically
is Rub us parvlflorus Ifutt. (salmon berry), which is very
quick to appear where an opening admits even a little more
light to the forest floor. The bottoms of shallow draws
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Pig* V. - Shows a *78 1 tor, more open por¬
tion of the forest, in which tho predominant
large tree is arbor vitae: in the foreground,
salmon borry, and 30 idlings of maple, balsam,
and white spruce; other tree seedlings ob¬
served vjere yellow birch, basswood, and whito
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are sometimes covered with it, evon when partially shaded.
Large numbers of woody sugar maple seedlings from 2-6 dm.
tall often form a shrubby growth of considerable ecological
importance. Other shrubs and shrubby trees found more or
lees frequently in or near the border of windfall areas are:
Acer spicatum Lem. (mountain maple) , Amelanchier canadensis (L. )
lledie. (June berry), Salix rostrata Richards (Bebbfs 7,/illow) ,
Prunus Virginians L. (choke cherry), Cornus alternifolia L. f.
(alternate -leaved dogwood) , and Corylus rostrata Ait. (beaked
hazelnut ) .
In general, tfte herbaceous vegetation forms a closer
index to the moisture content of the surface soil than the
woody vegetation. . The most widely spread and shade-tolerant
species of the hemlock forest is Aral la nudicaulis L. (wild
sarsaoarilla) • Others of rather general distribution are:
Galium triflorum Kichx. (bed straw) , Aster macro phyll us L.
(large-leaved aster), Clintonia borealis (Ait) Raf . , Pitched! a
repens L. (partridge-berry) , Ox alia Acotosolla L. (wood sorrel^,
Trientalis americana (Pers.) Pursh. ( star-f lower ) , Lycop odium
ennotinum L. (stiff club moss) and Aspidium spinulosum (0. F.
Mtlller) Sw- var. intermedium (Muhl.) P. C. Eaton. The follow¬
ing list is not so characteristic, but it includes some which
are frequently found along water courses or low ground:
Asplenium Pilix-f emina (L.) Bernh. (lady fern), Onocloa
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?%. Q. - Stand of sugar muplo, approximately 7a m.
north of the summit of the ridgo in see. 14. hi n. H.
43 tho trees here aro somewhat larger than is typioal;
note comparatively dear forest floor; maple seedlings
in tho foreground.
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Struthiopteris (L. ) Hoff, (ostrich fern), Phegopteris poly-
podioidea Fee (beech fern), Circaoa alp in a L. (enchanter's
nightshade), Solidago latifolia L. (broad-loaved goldenrod),
Mitella nuda L. (bishop's cap), Stroptopus roseus Itichx.
(twisted-stalk), Cornua canadensis L. (dwarf cornel),
>
Chinaphlla uribellata (L. ) Hutt. (pipsiosowa) , Pronanthea alba
L. (rattlesnake-root). Aster paniculatus Lam., Kununculua
recurvatus Poir. (rough cinquefoil).
Several species of moss and lichens lend color to
the general aspect of the forest. One of the most conspicuous
is Ileokera pennata (L.) Hedw. , forming green mats on the sides
of the trees and oft on extending several meters up. On rotting
logs in windfalls and along small crooks occur such moss species
as Brachy thee ium salebrosum (Hof fin.) Bryol., Plagiothecium
turfaceura lindb., Kypnum Crist a-Custrensis L. , and the lichen
3ticta pulmonariu (L.) Schaer.
B. Composition and dynamics of the forest.
As before indicated, one of the major problems in
connection with the forest of the north slope, is to account
for its composition, especially as regards the relation be¬
tween the hemlock and maple. As one ascends the slope the
maple contingent becomes greater and the hemlock less, so that
finally there appears to be at first sight an almost pure stand
T .1)
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. *
.
i . . •
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•
-
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■17-
of maple (fig* 8).
The fact that the most conspicuous stand of almost
pure hemlock forest is to be found on the north slope of the
first range within about 10G0 m- of the shore is probably
to be accounted for by climatic conditions, rather than by
differences in character of soil. The present composition
of the hemlock climax has undoubtedly existed for centuries.
In other words, the forest as a whole is in equilibrium as
regards the relative numbers of the component tree species
at a given altitude. A casual observation of the stages of
succession in a windfall area, might lead one to think that
maple should be the predominant tree (fig. 9). For this
reason it seemed necessary to consider carefully such
questions as the rate of growth, habit, shade tolerance, etc.
of the more important species, and the relationship of their
development, as shown by quadrat studies.
1. COlf SID .SHAT ION OF INDIVIDUAL SPSCIiiS.
T3UGA CANADi&NSIS (hemlock).- This species continues
to grow in diameter many years after its top has leached the
crown of the forest, the result being that the stand consists
of individuals with great diversity in their ages. Sapling
stages are quite common, though their growth is often vory
slow. The tolerance of all stages for weak light explains
«
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-
Pig* 9. - Seedlings of sugar maple in
hemlock forest: thooo pioturod ara 1*5 • S.O
dm* high, there being approximately 40 in¬
dividuals per square meter*
.
.
.
-1C
the dominance of the species over maple, its nearest com-
petltor in the forest. On account of this tolerance,
suppression at eome stage of its earlier growth is the rule
rather than the exception.
The tree usually seeds at intervals of every & or
3 years, and in spite of reduced fertility, many more seedlings
start than are able to mature, even though they are not notice¬
ably abundant, us in the case of the maple. The production
of seeds and seedlings is therefore not the critical fuetor
in the regeneration of either species.
The species is extremely sensitive to sudden changes
in the density of the forest, and seedlings respond quickly
in rate of growth to alight increases in the amount of light
admitted, but they are killed by too much light, and therefore
the tree will not take a central position in an open vyiridfall
unless it is sheltered by fast'er growing species. On account
of its shallow root system, it is very susceptible to surface
fires.
ACKR SACCHaKUM (sugar maple). - This species, as it
occurs in the hemlock climaK, is tall and slim and free of
limbs except near the top. The trees are apparently healthy,
though all of them have undoubtedly suffered more or lees
suppression. As al ready noted, the seedlings occur in such
numbers that a superficial observation might lead one to
• • ■ . ; 1. y.
9
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Pig. 10. - View along an old wood
road, which here acta ae an artificial
•windfall: on each aide of the road there
ie a donee growth of young maplee, E - 6
ra« high; ualmon berry in the foreground.
—
'
19-
conelude that the forest would, in a few generations, be¬
come a pure stand of maple. Closer observation soon shows
that a very small percentage of these ever mature* Accord¬
ing to Fro thingham (13) the trees seed every 3-5 years
under forest conditions; and oven-aged groups of very close-
standing seedlings are of common occurrence* They prefer
mapia leaf -mold and avoid areas covered with hemlock needles*
The close and abundant growth of the seedlings results in
such severe competition that the individuals are weakened and
most of them succumb to suppresion or disease. However, the
seedlings are very tolerant of shade conditions, arid a few
here and there are able to persist, and take advantage of the
increased light occasioned by a windfall* Indeed, the relative
stand of maple and other hardwoods in the hemlock climax seems
mainly to be conditioned by the number of windfall areas. In
such areas. Hub us parviflorus often forms a ground cover,
affording more or less protection to young seedlings which are
exposed to strong sunlight.
BKTULA LUSHA (yellow birch). - This tree, coming
next to maple in its distribution, is an important element
in the climax formation. In the forest it becomes slim and
tall with a clean bole, having limbs only near the top. A
specimen was observed along a woods road about 30 m. tall,
ivith a broad crown, occupying half the height; this tree was
. r • . • ■ . • - - : ' ; •
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-20-
5*6 d m* in diameter and was fruiting heavily. It grows more
rapidly than the maple end in its earlier stages requires
muoh nore light* Seedlings are comparatively rare in the
hemlock forest; when found, they are apt to occur in well-
lighted windfalls* Sometimes they arc; very numerous on a
email area in full sunlight • They occur also on rotting logs
with hemlock and other seedlings, and are apparently free from
disease. The natural point of regeneration for the apscics
is in vindfall ureas* Where an area has been slightly burned
over, the seedlings are sometimes very numerous* At one point,
where the forest had been cut away, the mature specimens cf
birch seemed nore prone to rot than the maple, apparently
suffering from a sudden influx of bright sunlight; in other
words, maple seems to be u less critical tree in most cf its
stages, than the birch* The latter is a much less aggressive
reproducer than the maple, in spite of the fact that it seeds
mere often* It may and often does become extensive in its
habit (Prothingham 13), producing largo stands of even-aged
trees, which shows that its seed production has a high enough
"factor of safety" to be vvell within the limits reouired by
nature* Besides reproduction by seeds, this species readily
sprouts from the stump* It seems clear that its relative
distribution in the hemlock: climax is net based cn the perform¬
ance of its seeds, but on its less tolerance for shade con-
.
' •• ■
• •
- ; *
' :: . •
. <y- x
.
21-
ditions than the maple and hemlock*
omm SPiiCIKS OF TRKi$8 III TKK IDmOCK: FOREST. - Several
other tree species occur, hut they are of less Importance eco¬
logically than those mentioned. One of those of occasional occur¬
rence is basswood (Tilia amor lean a L«). It gets to be a large tree,
with a clear hole nearly up to the forest crown. Seedlings were
frequently found, having a distinctly prostrate habit, the leaves
becoming very large in the shade. (Thuja occidental is L. (arbor
vitas) occurs in low spots but is not a tree of general die-
%
tribution. As a forest tree it often becomes very large. Its
presence along the shore line will be discussed litter. Pinus
St rob us L. (white pine) is occasionally found as a very large
tree, towering above the rest of the forest. My observations
seamed to indicate that where one was found, several others were
likely to occur in the some neighborhood. Abies bal Samoa (L. )
Mill, (balsam) is not common. It is rarely found as a mature
tree in the hemlock forest, though seedlings are often frequent
in windfall openings, and occasionally colonies of young trees
are found in like situations. Whether this species will mature
in competition with others evidently depends on the size of the
forest opening; in most cases it is suppressed by the more shade-
tclerant trees, \7hen it occurs as a mature tree in the forest,
it is safe to infer that the opening was well lighted for a
considerable length of time. Its beha\rior in this respect bears
. ■ t v' • ' • •
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out the findings of Cooper (Z>) on Isle Royal 0, where he showed
that the birth-rate of this species Is balanced by a high rate
of mortality when in competition with certain other species.
>
Other tree species occasionally found in the hemlook
climax are 2i eea canadensis (Mill.) BSP (white spruce), Quorcus
rubra L. (red oak) , Fraxinua amerlcana L. (white ash) , and
0 atrya virgin 1 ana (Mill.) K. Jfoch (hop hornbeam).
B . QUADRAT STUD IBS .
%
This method was found useful in connection with the
study of forest regeneration, and the distribution of the
principal species. 7/hare it became necessary to determine the
average ages of the trees, this v?us done by means of tables
prepared by Frothinghan (IS). The trees were too large to maxe
felling practicable for this work. Besides the quadrat studies
every other means that suggested itself was used for gaining
a knowledge of the dynamics of the forest. The quadrats were
10 ns. square.
QUADRAT 1 (fig. II). - This quadrat shows
the distribution of trees in the typical hemlock climax shown
in fig. 6. It represents a condi tion of mature growth. Most
of the trees here stand at w average distance of from £ to 3
m. It is noticeable, hovievur, that practically half of this
quadrat is occupied by a giant hemlock 300 years old, -whose
■
Fig. 11. - Quadrat 1 (see fig.
6 for locution): the numerals indi¬
cate the approximate ages of the
treos: the quadrat is 10 m* square.
- -
-
-23-
sjajiere of influence lias undoubtedly extended much further
than the younger trees. The f or oat floor here was free of
large shrubs; of small woody plants, 60 specimens of Rubus
Parvlflorus wore counted, 14 of Lonlcera canadensis and at
least 30u seedlings of Acer saccharum. The most conspicuous
herbaceous plant was Aralia nudicaulis. Other herbaceous
plants noted were Pliego p tor is Dryopteris, Cllntonia boreal is,
Galium trifloruia, Mitch el la repons. I it ell a nuda. Cornus
canadenai s. and Dyco podium annotlnun. In fact, both the woody
and herbaceous vegetation were typical of a well-drained
portion of the dense hemlock forest.
QUADRAT 2 (fig* 12). - This was taken in
a windfall. It consists of comparatively young growth. The
oldest standing specimens consist of a hemlock 130 years old,
a white spruce 110, and a sugar maple 90 years old; and none
of these had reached their full growth. The dominating
influence of this hamlocK is clearly shown in the diagram.
Its dense spray is more effective in causing suppression than
that of the maple or even of the white spruce. The best-
lighted area of the quadrat is occupied by the younger growth,
nearly one-third of which consists of balsam. The maple,
100 years old, shown near the top of the quadrat, was broken
off several feet above the base by a secondary windfall, and
in falling apparently leveled four other trees as shown.
*
.
'
Fsaga. cATiJL de n s/ s t-C Acer- Jdcc/idrum as
Abies baj s a.mea. &b Picea. ca.na.den & is pc.
Jietula. hjtea. bl Popu) us gran di dentata. pg
Fa.! ten tree. •—
Fig* 12. - Quadrat 2: taken In a
windfall area in the hemlock climax
-
►
: i. . .
24 —
consisting of two balsams, a yellow-birch, and a specimen
of large-toothed aspen (Populua grand id entata ) . The last
three species named are all faeter-grcwing than hemlock or
maple. Of the 14 trees which are standing, 5 are balsams,
a hemlocks, Z maples and 1 shite aprftco. The oldest balsam
is 50 years, and it is certain the other balsams will be
suppressed, probably before any one of them reaches loO.
White spruce (l3icea canadensis ) is very rare in the hemlock
forest, and it is likely that this single specimen will
eventually disappear before the maturing hemlocks. This
leaves the struggle between the 5 hemlocks and the 2 maples,
and typifies the final stage in any windfall. It is vory
suggestive as to the light it sheds on the ultimate com¬
position of the forest at this point.
Salmonberry and largo seedlings of mountain maple
and sugar maple formed a low woody growth that acted as a
screen for the usual herbaceous vegetation. The quadrat
contained several hundred sugar maple seedlings, the oldest
being about 5 years. These latter were very much affected
by anthracnose leaf spot and by an insect disease. Ninety
hemlock seedlings were counted, mostly growing on rotting
logs in the shadier part of the quadrat. Large-toothed
aspen was represented by 15 seedlings; the largest in¬
dividuals, though only 3 years old, were twice as tall as
•• •
,
.
■
■
26
tho 5-ycur seedlings of sugar maple* Balsam seedlings wore
found in the suimier parts of the quadrat, Zb individuals
being counted* Several species of moss, already mentioned,
were found on rotting logs in or near this quadrat* They are
often of considerable ecological importance in the formation
of seod beds*
In tho quadrat studies above described, certain
conclusions in regard to shade tolerance and its effect in
the distribution of the species, seem inevitable* This will
bo considered in what follows*
3. IUITIiiL PHYSICAL FACTORS AND COMPETITION.
I<; is evident that a great many factors enter in
to the dynamics of the forest* a few of those have been
pointed out as thoy affect the life history and occurrence
of the dominant species of troes* In a consideration of the
composition of the hemlock climax on the north slopo, two
questions arise* First, what cutises tho variation in com¬
position from tho base of tho elope to tho top of the ridgo,
a difference in elevation of approximately 300 m.? Second,
what is the most effective factor governing tho composition at
any one point? Frothingham has pointed out that there are
two sets of factors influencing the distribution and dominance
of trees in tho natural forest, namely, physical, including
soil, humidity, li^ht, etc. and physiological (biotic) including
-
-
.
V
** * -
. ■ " • -• . '•
. •
.
,
::
. .
/
.
-26-
aggressiveness in reproduction, tolerance of shade, rate
of growth, form, size, longevity, and resistance to injury
and disease. The first question seems to he answered hy a
consideration of the physical factors of moisture and light.
Soil evidently has little to do with it; if all the hem¬
locks were removed from the north slope, maple oould easily
take possession, as is evident from its regeneration in
windfalls, and its prominence in the ranges further south.
Hemlock, rather than maple, is thus the critical tree on the
north side of the first range. This species is known to
prefer cool, moist slopes, where the drainage is f&ir. Good
drainage, however, may he left out of consideration here,
as it occurs on the ranges farther south where hemlock is
not prominent. The greatest humidity lies low along the lake
shore. Here dense fogs are frequent even in the earlier part
of the growing season. The smaller ratio of humidity at
the higher elevations allows a corresponding increase in the
intensity of the light near the top of the ridge. As before
noted, hemlock is known to he very sensitive in its response
to light; it is also known to he more shade tolerant than
maple. Thus it seems clear that the dominance of hemlock
at lower elevations on the north slope, and its absence as
a dense stand on higher elevations and on the ranges further
south, is correlated with the physical factors of moisture
,
.
-
. ... . ... 1
.
.
-27-
and light.
The answer to the second question involves
the consideration of the relative physiological response
of other species, especially maple and yellow birch, to the
conditions imposed by the dominant hemlock. Hemlock and
sugar maple, are the most conspicuous examples in the lake
Region of what Fro thing ham calls intensive reproducers,
i.e., species which are more aggressive inside than outside
the forest. The effective aggressiveness of each species
i3 due to a oonbination of factors. Both species, when
growing under forest conditions, are likely to have a
suppressed period of growth for at least the first 50 years.
Quadrat studies show a great variation in age of individ¬
uals, even among the adult trees forming the forest crown,
mature trees varying from 100 to 300 years or more. One
hemlock, measuring about 1 m. in diameter, was estimated
at over 400 years. The greatest tolerance of maple, how¬
ever, seems to be in the seedling stage, quadrat studies
often showing hundreds of seedlings in the dense shade of
the hemlocks. On the other hand, the seedlings of hemlock
are rather critical in their light requirements, being
killed by too much or too little shade. In general, they
grow more abundantly in the more open part of the forest,
but not necessarily in a windfall.
-
.
.
• . - : t '
-
- >>v : .. .
• l
«
,
■ ; ... ; . .
• l • ' - ai
■
. . .
* . . • ; 'l
♦ ’
4. EQUILIBRIUM AT ARY POINT.
Though the different tree species vary widely
as to their relative production of seeds and seedlings, it
seems certain that all are productive enough to be well
within the limits required by nature. It has been pointed
out by various observers that the "factor of safety” in
seed and seedling production is very large and that there
is an enormous wastage In all cases. While this larger seed
production may be important on denuded areas, it seems clear
that it has little to do with the relative number of in¬
dividuals of different species, where the dominant species
are intensive, and where a balance has long been reached
and maintained. This balance is changed little if any by
excessive seed production of any species. It is conditioned
by something more invariable than seed production. The true
explanation seems to be the relative tolerance of the species
for each other under the conditions imposed by the physical
factors at that point. For example, the population of the
yellow birch, which forms approximately 5^ of the total
tree population half way up the north slope, is a measure
of its relative response to the conditions imposed by
the hemlock and maple. Since the equilibrium of the
forest represents the result of the effective response of
each species, the balance may be shown diagrammatically as
.
.
.
♦ » . .<
. .
,
*
.
hemlock
magpie
yellow birch
a.11 other tree species
Fig* 13.*- Vector diagrams, illustrating
approximate equilibrium (in number of individ¬
uals) at two points on the north slope of the
first range: the uppor figure illustrates the
conditions halfway up tho slope; the lower
figure shows conditions of balance near the
top; hemlock has been nearly replaced by maple;
CD is represented largely by busBv/ood and iron-
wood
.
^ ^ x r
in fig. 13* The vectors DA, AB, and BC# (upper figure) ,
illustrate the effective response of the three principal
species somewhere up the north slope. Evidently the
magnitude of the vectors does not correspond to the number
of individuals of each species; in other words, while
population may indicate response, it is not a measure of
it. The vector CD indicates the effective control of all
other species. The lower figure illustrates the conditions
of balance near the top of the ridge. If any one species
were eliminated from the forest, it would soon come back
in approximately the some proportion at any point.
C. Successions leading to the hemlock climax.
1. Primary successions.
The primary successions leading to the
hemlock climax may be seen along the shore of Lake Superior,
at the foot of the first range. The pioneer stages are
present in most cases, but the transition is often rather
abrupt. Lack of well marked zonation is probably due to
the severe conditions along the shore.
a. Physiographic influences.
The development of the shore line is
correlated with the post-glacial history of the Lake Superior
region. On account of the gradual withdrawal of the lake.
*
.
*
.
* '
• ; *
Ki*
-
L - - - - J
Fig* 14* - Kooky shore a few miles west of Union Buy;
shows sandstone beds dipping toward the north; the edges
of the tilted strata off shore form a rocky terrace, break¬
ing more or less the foroo of tho waves; vegetation roudily
establishes itsolf in tho joint und bedding pianos, as
shown; white coating on the rock surface is Farneliu luctoa»
.
. X.. .
*
-30-
more and more of the north slope of the first range has
been uncovered, This has probably been counterbal anoed
by erosion, and by the sinking of the ooast in this region,
which is believed to be taking place (l).
The rock shore is the predominant type. Where it is
gravelly or sandy, a little investigation shows that the
rook is not far underneath. The exposed rock is largely
red sandstone, dipping everywhere at an angle, as shown
in fig. 14. In places conglomerate is exposed and loose
boulders along the shore are frequent. The ?/idth of the
rock beach varies from 15 to 45 m. Sandy or gravelly
beaches in more or less protected places may be narrower
than this, so that the forest comes comparatively close to
the water, as shown in fig. 15, which shows a narrow gravel
beach.
There is such a variation in the slope and character
of the rocky shore that it is difficult to divide it into
any definite zones in accordance with the ecological faotors
influencing plant life. Its lower portion, being always
subject to wave action, during both summer and winter, is
devoid of plant life, exoept in sheltered corners of the
rooks, which escape the direct pounding of the water. The
lower limit of plant life is marked, roughly, by the maxi¬
mum height of the waves in summer. The winter waves and
*
.
*
.
.
- • ; ■ ■ ■ . . . ' .
. .
.
■*
...
► •
t ...
'
* -
Fig. 15. - A narrow shingle beaoh, in which the forest
comes unusually close to the water’s edge, being protected
from the winter storms by the lodge of rod, off shore; note
zo no of white birch and arbor vitae lining the shore at this
point, bordered by salmon berry and Cornus al torn! foil- ;
Bcmisetum arvonse growing in tho shingle.
.
*
*©i" « it " f )
-31-
ioo usual ly roach much higher than this, and thus mark out
the upper limits of u zone in which only tho hardiest per¬
ennials are able to survive.
b* The shoro successions.
Since the surface of tho lake has
boon at tho present level for a long period of time, the
distribution of the pioneer associations at any point along
tho shoro has reached a balance which will remain practically
the same so long as the climatic, ecological and historical
factors remain unchanged* In other words, it is probably
incorrect to say that active invasion or retrogression is
taking place at the present time, even admitting the slight
changes in coast line, due to subsidence or erosion.
The pioneer associations along the shore are composed
of crevice plants, of lichens and of mosses. On account of
the frugraontal nature of the rooks, crevice plants appear
to be tho moot important pioneers; most of them are per¬
ennials. The seeds lodge in the moist cracks of joint and
bedding planes, and germinate even where little or no soil
is present. Gradually the seedling intercepts enough soil
for tho establishment of a firm root system, and then is
able to persist for many years, and spread by means of
offshoots. Two of the commonest and hardiest species in
tliio connection are Juncus Dudley! W iegand and Dos champ si a
«
. " ' r ■ ■ ' • •
■
. ■
Fig. 16. - Shows a wall of conglomerate paralleling the
shore, and forming a protective barrier to the forest be¬
hind it: oonifers and aspens growing under the xerophytlc
conditions at the top; the conifers include a small white
pino fin the background j , small specimens of white spruce,
balsam, ana arbor vitao, all growing in the crevices of
tiio rod..
Fig. 17. - Shows Deooharapsia oaespltosa and ^stor
Faxoni growing in a typioul situation along the shore:
note dip of the strata, and fragmental character of the
rock*
-32-
oaespitosa (L. ) Beauv. (huirgrass). The former was found
growing within 3 dm. of the water; the latter is undoubtedly
the commonest grass growing in the crevioes of the shore
rooks.
Pig. 14 represents a typical situation for crevice
vegetation. Such a habitat enables even woody plants to
come in very early. In the foreground is shown a large
specimen of ninebark (Physooarpus opulifolius ) and in the
background a small speciman of mountain ash ( :pyr us sitchensis j ♦
The former has assumed more or less of the krummholz form of
growth, especially on the lake or windward side; its habit
of growth thus makes it more efficient as a conserver of
soil and moisture.
The rate of succession along the outer shore is evi¬
dently not to be measured by the character of the plant life,
the highest forms being found with the lowest. As before
indicated, this rate is exceedingly slow, due to the severity
of the situation. In spite of this, a large number of species
are found. One group may be olassod as typical crevice plants.
Among these, besides those mentioned, are Campanula rotund! -
folia L. (bluebell), Aster Faxoni Porter, Soneoio Balsamitae
Muhl. (groundsel), Fragaria virgin! ana Duchesne (strawberry),
Achillea Millefolium L. (yarrow), Bquisetum arvense L. (horse¬
tail ) .
-
..... -■
- • J
.
... • - - ;J ■ ■' •
■
- ■ . -■ ■ • 1 - • ■■ ■ "
• . ■
, - ■ : • "
,
-
. . - **
.
■ M ■ : - ’ .
. .U -1
Fig. 18. - Hocii surface well above the wash of the waves:
the cruatose lichen is Parnel ia lactea; the mose (dar£ patches)
Grirsnlu qpocarpa; Polypodium vulgar e in crevices near the top
of the boulder
"
* u i
In the outer portion of the shore line, at least, shrubs
often occupy the most exposed situations. The typioal species
nre Physooarpus opulifolius (L.) Maxim, (ninebark), Rosa
acicularis Lindl. var. Bourgeauiana Crepin (wild rose), Salix
petiolaris Sm., and Cornus stolonifera Michx. f. f red -osier
dogwood). The seedlings of Populus tremuloides often accompany
the willows. Along the inner portion of the shore, tree seed¬
lings are frequent, the commonest being those of Thuja occi¬
dental is L. Here the usual successions occur, with lichens
and mosses as pioneers. With a few exceptions, they are well
above the wash of the winter wavos. The wash of the higher
water can often be very accurately traced on large isolated
boulders of conglomerate. This material, on account of its
differential weathering, supports a richer flora of lichens
and mosses than the sandstone, and the transition from washed
to unwashed surface often appears rather abrupt.
Several species of lichen and moss occur in the severest
situations. The pioneer crustose lichen appears to be Rhizo-
oarpon petraeum (Wulf • ) Koerb. This form persists often under
the lash of the winter waves. Other crustose forms common on
the rooks further back are Plao odium aurellium (Hoffm. ) Tuck,
and Lecanora oineraafL. ) Sommerf. A few species of moss,
such as Ceratodon purpureus (L.) Brid., Leptobryum pyri forme
(L.) Wils. and Funaria hygrometrioa (1. ) Sibth., occur in
. ' .
• • : . : • ... . . ‘ 1
.. . ■ . . • - • ’ .... J ....
......
*
. . ' - • : * -
- 0 . ' :
. . . - - • -
■ ‘ •
< . X i : v '*.'?■ ■- ■ ' ■
■■ '> : ••
■ . . \ . . . : . '
• • • . • ■ •• •• • : ■-
*
;
,iv; o"' / • ?■*'■ % l . . -
.
1 - .V.
. • ‘
: . . ; .
1
u
■rJ
Pig* ly* - Shows the roots of vihite pine running for
several meters along the surface and finally acting as an
agent of rock displacement: the roots on the far side of
the tree are covered hy a mat of Arctoataphylos Uvu-ursi ;
small red pine and aspens bordering the shore in the back¬
ground.
_J
Pig* 20- - A broad type of ehingle beach, devoid of
vegetation on account of the wash of the winter waves*
exposed crevices* In some cases they undoubtedly Jiave the
way for higher plants. Further Inshore various foliose and
fruticose lichens and mat-forming mosses form a definite
stage of the rock succession. Among these may be mentioned
Grimmia apocarpa (I.) Hedw., Amblystegium varium (Kedw.)
Lindb., Btiota amplissima (Scop.) Mass*, Panne li a conspersa
(Ehrh. ) Ach., StereE7caul on paschale (L.) Hoffta. and various,
species of Cladonia,
Following the mosses and lichens one often finds the
bearberry (arotostaphylos Uva-ursi fL*) Spreng, ) as a pioneer
mat former. With the accumulation of more soil, shrubby
species become more abundant. Besides those mentioned, the
following occur:- Diorvilla Ionic era Mill, (bush honeysuckle),
Amelanohier canadensis fL.) Medic, (shad bush), Oornus alter-
nifolia L. f. and Rub us parviflorus IJutt. (salmon berry).
In the development of this succession finally come
the trees, their roots sometime spreading 3 - 10 m. before
finding.a suitable crevice for anchorage (fig. 19). Roots
of this kind. form an important barrier for holding back soil
washed from above. The fallen trunks also assist in the same
manner, as well as finally furnishing additional humus by
their decay.
-Types of she re -
The character of the shore vegetation is largely in-
f *. .. ;t _ ‘ X ■: l.* ■ i' • :0
- . V .• J . ■' *
: -v. . *:.l
.
V . . ... . • ^ ' .... - - —
, . * _ • • :
- - • * '
.
..I- * .... • v :C 1
• »• ' - • T‘ I
. ■ . i ~ ■ 1 * • ° *
• i t 1 '
. ' , . _ • * ... .
.
.
c
Pig. 21. - Types of shore line; see text.
' - ; * i .
-35-
fluencQd by variations in physiography. This includes sub¬
merged ledges of rook, shore, cliff 3, coves and the accumula-r
tion of shingle barriers. Submerged ledges, breaking the
effect of the waves, and coves affording protected areas, are
both factors in extending the forested area closer to the
water's edge. The effect of these two influences may be
seen in fig. 15.
It seemed possible to classify the shore into
three general types, as shown in fig. 21. Fig* A shows a
type in which the surface immediately back of the shore line
is low. It often represents the mouth of a gully, and possibly
of a drowned river (see Ruthven (23) p. 25). The area is
swampy, usually being occupied by large specimens of Thuja
ocoidentalis and Fraxinus nigra. It is sometimes separated
from the immediate shore line by a narrow zone of shingle
and driftwood. Back of the area, there is often an abrupt
rise of from 6 to 10 m. to the typical hemlock forest.
In Bf the hemlock forest extends practically
up to th3 shore line, though there is always a fringe of other
species on the iimiedi ate outskirts, the commonest being arbor
vitae and white biroh. Other species occurring are Abies
balsam ea, Acer saooharum and Acer spioatum. Stages inter¬
mediate between A and B occur.
C represents the conditions whene the shore line
. , • • i - ■ 1
.
, . ’ V .
*• •
■
- ’ • • . ’ , .
-
. ‘
l . ;
' • . . - ' ■ ‘ . . - \ _
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> • ' • . •: .. ; ;
V ' ... ,
• ‘ - • > - ■ . . . j . •
-36-
is bordered by a rocky cliff. In this case the area above
is often forested to the very edge of the cliff. On account
of the dip of the strata, such areas are so well drained that
the vegetation becomes xerophytic in character. This was
found to bo true even where the soil was 3 dra. deep as was
observed at one point. At this point the ridge had once been
covered by a growth of pine, which had been blown dawn, and
was being followed by a growth of white birch, aspen and
balsam, the two formwr being on the lake side, being better
able to adapt themselves to the unusually severe wind con-
f
ditions.
2. Secondary successions in the hemlock climax.
In the latter part of the summer of 1919,
an extensive fire swept over a portion of the north range,
destroying several square miles of virgin hemlock forest.
This fire extended as far east as the range line between town¬
ships 42 and 43. The conffers were killed outright, though
many dead trunks were left standing (fig. 22). It was very
evident that the deciduous trees, including the sugar maple
and especially basswood, were more resi stant to the effects
of the fire than the conifers. This was especially trtioeable
in the zone between the burned and unburned areas, where the
trees were singed. Fig. 22 shows how thoroughly the humus
. i ; .
i
* -
. . , • t • ; * ;■:* •• " v r.
• ' ‘ ■ *
• r -
-
i
• .*•
; . • V ~ -
• '• -
- .
. - - • .
e - ;
t ' • . v . -
. . : ... . j * . -
. . -
Pig. 22 « - A "bum” in the hemlock forest three year a
after the fire: note angular character of the sandstone
fragments underlying the forest floor, the humus being com¬
pletely destroyed; north slope of first range looking west.
. . . ■
37-
w&e burned off, exposing what appears to be ordinary talus
material , composed of angular* unwashed fragments of sand¬
stone, mostly 1-3 dm. in diameter.
"Burn" associations had started over the entire area,
being further advanced at some points than at others. She
commonest herbaceous pioneers consisted of Krigoron canadensis
L. (horseweod), JBpiloblum angustlfollun L. fprroat willow-herb ,
Aster raacrophyllus 1., .uraliu hispid a Vent, (bristly sarsa-
\
parilla), and Holygonun Pour-la si 1 Greene. Amongst the shrubby
species coming in next tho following were noted:- Hub us purvi-
florus (s-lmon berry J, hunbueus racemose L. (red-borried eldor),
Piervillu henio era Mill* (bush honeysuckle ) , Rhus typhina L.
(staghorn sumac), and Kuhns ldaous X,. vur* aouleutlsslmua ( C.
a. Mey. ) Hegel & Tiling. Tliese are followed by ? run as p pansy 1-
vanica I». f., (wild red cherry), ^ cor spicatun Lam. (mountain
maple), seedling aspens and occasional seedlings of sugar
rauplo (iicer Bacoharum ) . Hemlock seedlings undoubtedly come in
at a later stage, finally displacing the maple. One of the
most noticeable elements of this secondary succession is Rubus
parviflorus. The plant spreads rapidly over large areas by
stems just below the surface, these stems sometimes being
several meters long. The foliage forme a "leaf mosaic n which
reduces the light to such an extent thut shade-tolerant speci os
are able to make on early start, thus probably hastening the
• ' . , •
l ■ .
-
.
-.-I.- - • ■
■ 4 i-
\ l ’ - •:
*
*
?i£. 23 • - Quadrat 3. This quadrat
represents a stand of trees in a foroat of
almost pure maple; it was taicen in sqc»14,
about 1U0 m* from the summit of the ridge
(see fig* 7)*
- .• .T.
'''I
• - *
-38-
climax stage.
II. THE MaPLE CLIML.
This is the formation associated with vegetation-
al development at the top of tho first range and over the
ranges further south. Its mature form may be seen 100 m. south
of the summit of the range (fig. 8). Here a 10 m. quadrat
was laid out (fig. £3). It represents a stand of almost pure
maple. The larger trees averaged about 4 m. apart, the forest
canopy being rather dense for maple. The uniformity in the
ages of several of the younger trees marked them out as the
survivors of a single generation of seedlings. In fact, the
presence of several dead saplings varying from 30 to 40 years
suggested that these trees had already reached a critical
period in their development. Thrifty specimens of Tilia
and Ostrya were found just outside the limits of the quadrat.
The soil at this point was a rich leaf mold of medium acidity.
It was not deep, as indicated by the root systems of fallen
trees, exposing the bare rock. Though the forest floor was
comparatively open, immature shrubby vegetation was repre¬
sented by specimens of Kubus parviflorus and Sanbuous race-
mo sa. The latter species gets to bo vayy large and rampant
in maple windfalls, dominating the ground cover. The follow¬
ing are typical herbaceous species:- ^spidium spinulosum
- v ^ ..
... ..
- . • • -• . . ■ . . - ;
• V. J
. •
- • • • • z -.j ; .
' •• •'< • • \ • :
t
.
■ ;
\ }i - i „ - v .- i
’ • ' • - • ; - 1 :.v; ; . ' •
<- $ ' . • •; s r
' * •
. N ■ v *
• • • - J - ‘ • i
. ■ •- j\: j •_ *. •;
-39-
(0. F. Mtillar ) Sw. vur. intermedium (Muhl.) D. C. Eaton,
Phogopteris Dryopteris (L. ) Pee (oak fern), Afliantum pe datum
L. (maidenhair), Botrychium vigfginianum (L.) Sw. (rattle¬
snake fern), Hystrix pa tula Moenoh. (ho ttle -Brush grass).
Hi lium effusum L. (millet grass), Solidago latl folia L.
(broad-leaved golderirod ) , Kibes Gynosbatl L. (wild goosfebrryy),
Smilaoina raoemosa (L.) Desf. (false spikenard), Actaea alba
(I*) Mill, (white baneberry), Viola canadensis, L., Sanguinaria
canadensis L. (bloodroot), Aral i a nudicaulis L. (wild sarsa¬
parilla), P olygonatum biflorum (Walt.) Ell* (true Soloman *s
seal), and Galium triflorurn Miohx. (bedstraw). The last-named
species is one of the commonest of the smaller groxmd covers*
The maple climax, as above described, occupies
a comparatively narrow zone on the north side of the first
range. As will be shown later its development on the south
side is as yet in the early stages, this development being
closely related to the physiographic foatures of the range
and the adjoining valley of Carp River.
A. General physiographic features.
That the top of the first range still holds out
against the mesophytic forest is undoubtedly due to the
peculiar topography of this range. As is evident from fig. 3,
this topography is associated with the geological formation
,• . . . .
' - .
, - • . .
. . , .
. - ' • _ . ■ _
: . . .
...
• - , . .
J.-si ox .... - _ _ . ' .
- ■ • : . “ . .
/ , ,
: . ' . : . :
•• ■ .. .
. . . ■■
■
• • ■ l ; : : ’ ■ .
►
. . .. Xu-..
- ; • ' '• • . ■ - , ; *v ■ .
Gi . . i . . 'X' • . ;
Pig* 24* - Cliff and talus slope, first range: view
from a point just east of Carp Lake, looking north; the
cliff at this point is about 130 m. abovo the floor of
Carp River Valley and 240 m* abovo Lake Superior; the
face of the escarpment is approximately 65 m* high at this
point; note fringe of forest between talus slope and river
valley*
3 1 f , .-4 »• Z'.ti , l
*
.
Pig. 25. - View of cliff in section 15f T. 51 K . R. 43 W. ,
looicing east: in the foreground are shown tho last stages of
the cliff, preceding the formation of a B&&dle; in places the
soil has accumulated on the bare roc£; note xerophytic char¬
acter of the vegetation.
.
.
. . • •
•40
Of Carp Lake, which was once much larger than at present.
frha dip oT the strata toward the north has created a great
cliff or escarpment, which is continually weathering away,
producing a talus slope at its foot (fig. 24). This cliff
extends west and west-southwest across T* 51 B. H. 43 V/.,
a distance of about 10 km. I*c varies from point to point
alo r the range as to elevation of summit, height of escarp¬
ment and width of talus slope. At. one point opposite Carp
lake the talus descends into the luko; hut at most points
there is a fringe of forest between the foot of the talus
and flood plain of the river, as shown in fig. 24. In sec.
14, there is a depression in the cliff where the escarpment
has entirely disappeared leaving a saddle across the range.
The same thing, though less marked, occurs about a mile
west in sec. 15, and in varying degrees at other points along
the range, making it possible at such places to descend into
the valley without difficulty. Where a saddle i3 sufficiently
low, as in sec. 14, the talus is almost entirely covered by
soil washed from above, and the fringe of forest, from below
may extend clear across the depression. In sec. 15. (fig.
25} this process has not gone so far. There is still a rock
faco varying from 3 to 5 m. high. The relation between the
various physiographic features as thoy appear at different
points along the range is shown in fig. 26.
.
.
.
[**4|j I . . is
r; ; #» "fc . .
I '
-J
Pig. h6. - Typical cross-sections at various points
through the auranit of tho first range
-41
A represents a stage of the cliff found opposite
Carp Lake in sec* 22. Here the escarpment is high and the
talus slope dips into the lake. At this point the trap and
sandstone portions of the cliff can readily ho di stinguished.
The trap is superimposed upon the sandstone, and has under¬
gone a greater disintegration, forming a ledge as shown.
B and 0 typify ordinary conditions whore the escarpment is
high and the talus slope from £00 - 300 m. wide, bordered by
a more or less mesophytic forest at the foot. At 3) is shown
a stage where the top has been rounded off to such an extent
that xerophytic tree species, such as red and white pine,
are able to gain a footing. The former is usually more
abundant under the brow of the cliff, where it is more or
less sheltered. The latter is found in the more exposed
situations, being the first to creep over the top when
the conditions become favorable. Stages B, C, and D may
all be seen in section 14. IS and F represent stages at a
low point in the range, such as is shown in fig. 25, preced¬
ing the formation of a saddle. Here tho talus slope is
much reduced, the forest pushing well up toward the summit,
even though the latter may still remain xerophytic.
0
B- Successional relations
I. Xeraroh successions on the first range.
m ecological survey of the vegetation
' 3 -
; •
- '
; , : . ; '• . " ‘ ’
t : • ■- < ■■■-'" ’■
# ■ - . _ - . : •; ‘ 1 - - - ' • ■
- 5 : • -
; ; . ■ . . -- •
• • .. , • - • - * " '
. ' ' ‘ T • ' * .
■ . • : •
•- :: : • - * ■
Pig. £7. - Limit of forotst growth on summit of ridge,
looking oast. The prevailing direction of the wind is from
the southwest; this is more or less evident from the general
direction of the branches in the small pines shown; clump
of small red pines in background (to left); basrberry mat
on rock in foreground.
-42
involves an examination of the environmental factors and
plant successions (1) at the summit (2) along the escarp¬
ment (3) on the talus slope (4) below the talus slope*
(l) Summit of the range.
fa) Ecological factors. In general,
the forested area of the north slope may fall short of
reaching the crest of the ridge, as shown in fig. 26, E,
or may reach slightly over the summit, as at F. From
this point to the brink of the precipitous cliff, which
averages from 20 - 40 m., there is usually a large amount
of bare rock surface. Where the soil has accumulated, it
is of very slight depth. There seem to be two principal
reasons for this condition, both being due to the presence
of the escarpment; fl) the soil due to rock disintegration
is washed over the south side of the crest nearly as fast
as it is formed, (2) the escarpment itself forms an effectual
barrier to the encroachment of the mesophytic forest below.
This zone of bare or nearly bare rock surface therefore re¬
mains unprotected. Its exposed situation makes it especially
susceptible to the dynamics of weathering, including the
frost of winter, the heat of summer, full exposure to rain
and to all winds from the south. A portion of the soil
wafefced over the crest accumulates in a narrow strip along
the top of the talus slope. The rest is gradually washed
.
. t
.
.
■
■ .
*
.
.
Fig. 28- - A portion of tho summit, looking oust: Carp
River in the valley below fat right); small red pines and
stunted aspens to tho left, back of which a transition zone
occurs as shown in fig- 32, leading to the maple climax of
tho north slope; note pines growing from crevices in face
of escarpment.
.
.
, ■ . : . ✓
down through the talus, finally reaching the forested area
at its foot. On the other hand, soil found on the north
crest is soon cheeked in its descent by the forest. A certain
amount of it collects in depressions and irregularities of the
rock surface and along the edges of joint planes, affording
a foothold for crevice plants and matted vegetation.
(b) The plant associations.
The pioneer stages at the summit
consist of lichens and mosses on the bare rock surface, and
on the ground. Among the commoner crustose lichens appear
such forms as Lecanora cinerea, Rhizocarpon petraeum and
PI ac odium aurellium. Following these come foliose species,
Parmel ia conspersa (Khrh. ) Ach. being the most conspicuous
and covering a large proportion of the rock surface; Physcia
obscura ( Schaer. ) Hyl. , Lecanora garovaglii and Gyrophora
hyperborea Ach. are less common. Where a slight amount of
soil has accumulated on the rock surfaces, fruticose types
appear, common species being Cladonia rangiferina (L. ) Web.,
Claddmia sylvatica (L.) Hoffm. , and Stereocaulon paschale
(L.) Hoffm.
Associated with the lichens in the pioneer rock suc¬
cessions are moss species, such as Grimmia apooarpa, Poly-
trichum piliferum Schreb. and Tortella tortuosa (L. ) Limpr. ,
the two latter being the commonest. One of the early mat
.
...
, ■ : -
.
»
*
• *
, M i .
.
Fig. 2^* - Cioae-up of rock eurface, crest of ridgo:
in the foreground, Juniperua communis var. deprea8a,Danthonla
aplcata. Antennuria noodiolca, Potontillu trldentata. Poly¬
gonum Dougiaeii (lower right) , and Parmelia conapersa, the
dominant lichen; Solid ago randii var. nentlcola in the back¬
ground.
formers is Solaginalla rpuestris (L.) Spring., often Cover¬
ing large areas on the rook surface. It is not uncommon
to find superposed upon this mat the two common mosses
already mentioned. The Selaginella mat becomes nearly 1
dm. thick in plaoes, living plants growing on the dead
mat of former generations. This paves the way for her^
baceous plants, such as Danthonia 3picata (L.) Beauv. (wild
oat grass), Potenti 11a tridentata Ait. ( three -too tiled
cinquefoil), and even for woody species, such as the bear-
berry (Arctostaphylos Uva-ursi (L.) Sp r eng. ) and stunted
specimens, (2 - 4 dm. high), of staghorn sumac (Khus typhina
L.). The roots of the latter creep over the rock surface
for several decimeters until finally they may become anchored
in a crevice, arctostaphylos is especially well adapted
to the severe conditions found on these rock surfaces. Often
it occurs in large patches, thus aiding in the retention of
more soil and the conservation of soil moisture. Large
angular depressions in the rook surface may occasionally
be found where enough moisture is retained to support even
shrubby growth without being definitely anchored in a crevice.
Such a case was illustrated by a low specimen ( 2 - 3 dm.
high) of Hew Jersey tea (Oeanothus am eric anus L. ) which had
adapted itself completely to the shape of the depression,
but could be pulled out bodily as a dense mat.
■: 0 , . • f :l ... .... - '
. .. 1 •
.
• - . . .
t . . - . . ■
S . i:i ■( * *' - ' ,r‘'
. , at ■» —
*
» ■ ..
•' «
-45-
Muoh of the rook at the bare summit is more or less
porous in texture; rook fragments are numerous but irregular.
Joint and bedding planes are not as distinctly marked as
on the face of the escarpment. Whenever a orevice occurs,
however, soil readily collects, and a number of plants gain
a footing. The summer flora is practically a xerophytic
one; the occurrence of certain vernal species, however,
indicates that during the spring there is a comparatively
large amount of moisture on the ridge, due in part, pro¬
bably, to the melting snow. Of the orevice plants, Danthonia
spioata, already mentioned, is one of the most important,
on account of it3 abundance and its densely tufted habit
of growth. Other noteworthy crevice plants are Soli dago
randii Britton var. montioola Porter, Potentilla tridentata.
artemisia candata Michx., Woodsia ilvensi s (L.) R. Br.,
Campanula rotundifolia L. (harebell), Viola arenaria DC.
(sand violet), Aquilegia canadensis L. (wild columbine),
Panicum denauperatum Muhl. and Panicum meridionale Ashe.
Where a small amount of dry soil has accumulated, the
following occur: Antennaria neodioica Greene (everlasting ) ,
Lechea striota Leggett (pinweed), Panicum xanthophysum
Gray, Satureja vulgaris (L.) Fritsch. (basil), Aralia
hispida Vent, (bristly sarsaparilla), Apocynum androesi-
mi folium L. (spreading dog bane ). Bpigaea repeps L. (trailing
-
, ;
.
. • • •
’ c ?• * •
I •- it ©tfftalQ ^olvc'ic *»ri^O • -~T ' r'—' •* -:-
* ■ J „ i. ,l$e£olir $jaa«)
. _ . ... . ' _
,
. '. -- L •
’ . .
• . - • • ; ,
-46-
arbutus), Hieraciuri soabrnii Iliohx* (huwkweed), lip il obi pis
angnstifoliun L*, ^.ster macro hyllus L., Corydalls semper-
vlrons (L • } Pers. , Oerastlun arvonso L«, Fragaria vosc->
L. var. a nor io ana Porter, apd Our ox adust., Boott.
It will be noted that the above are porronnial species*
A few annuals occur, such as Silono antlrrhlna L*, (sleepy
catchfly), Kr Igor on canadensis L. (horse-weed), and Poly¬
gonum Pouglasll Greene. These annuals lead a precarious
existence, as their seeds must, in tho main, bo washed
over the cliff each year* The distribution of the above
herbaooous species varies considerably from one point of
the ridge to another. Their presence results in the
accumulation of humus, especially in depressions or in
connection with dead mats of Solaginella*
Accompanying the herbaceous vegetation are a few
speoies of low shrubs, the commonest being species of
blueberry (Yaceiniun p onnsylvani oura Lam. var. angustl-
folium (idt«) Gray and Vaooiniuci nigrum Britton). These
often form largo patches slightly bach of the summit,
where more soil has accumulated. Other spocios found
along the summit are:- Juniporus oonmunis L. var. non tana
A it., Bosa aclcularis Lindl., Sails humulls Marsh., Dior-
villa Lonicora Hill*, Shepherd la canadensis fL.) IJutt.,
and stunted specimens of Juneborry (iimolanohier oana-
.
.
-
, 1 I
■
Fig. 30. -
(laaplo oliiaax) t
14, T. 51 ft. ft.
Transition to mosophytic forest
top of ridge, at a point in sec.
43 17.; soo description of quadrat
4 and 5
-47-
densis (L.) Medic.
A few dwarfed specimens of white pine (Pinus Strobus )
are scattered along the summit, but the species is much
more common over the crest of the ridge (fig. 24), where
it receives more shelter and moisture. The gray pine (Pinus
Ban Asians Lamb.) was noticed at only one point.
The limit of forest growth is bordered by a very dis¬
tinct transitional zone all along the summit. The general
character of this is shown in fig. 28, but it varies a great
deal in composition at different points of the ridge, ap¬
proaching more mesophytic conditions at lower elevations.
Gnarled and stunted specimens of red oak ( Quercus rubra L.)
are mingled with aspen (Populus tremuloides Michx. ) and
white birch (Betula alba L. var. papyrif era (Marsh.) Spach. ) ,
the latter sometimes appearing in almost pure stands.
(c) Quadrat studies.
A detailed study of the transitional zone was made
at a point in sec. 14, just west of the saddle (see map).
This is typical of most of the ridgo. Beginning at the
area of bare rock surface shown in fig. 29, situated
approximately 25 ra. bacA from the face of the cliff, a
series of four quadrats was taken in succession, the last
being in the mesophytic forest (fig. 50). These quadrats
were 10 ra. square, making the total width of the transitional
f . t
;'j i ■ rt •• 1 :
• ; ItJt c t
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. . . *
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, . . .
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.
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• - 'i*v
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as
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as
•
<Jr
r
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as
•
•
?r
as
•
as
•
•
as
as
•
•
•
a_5
as
as
?r
•
dS
•
as
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as
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ov
•
cLS
bi
•
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as
as
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•
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pr
l°r
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pr
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ca
Pr
•
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pr
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pr
-p*
Pr
ca.
. *sp
•
ca. .
Pr
•
Pr
•
Pr
•
• asp
ca- .
•r
Pr
•
•
ca
•
Pr
Pr
Pr
" **
ca
•
ca
rock surface
_ _
_ —
Acer sa.ccha.rurn as
Qoercua rubra. <^r
Bctu I <a_ |utea_ bl
Ostry*- virgin I a.n <t ov
Populut t. remu lo '• ole*
Pinos resjnoja. pr
Cca.nothuj imcricanos ca.
Arne ld.ncbi'e.r sp a. sp
5 a. \ ■ x homilis S h
Pig. 31.
Quadrat a 4 and 3; see
fig.
2U and toxt
.
zone 40 in. at this point.
QUADRAT 4 (fig. 21) was taken to include a portion
oi the rock surface (fig. 29 )f as well as the marginal tree
growth. Here the soil was thin and dry, the ground sloping
gently toward the south. Several small red pines (Pinus
resinosa ) represented the typical tree growth. They stood
comparatively close, with small dead ones intermingled,
amongst the red pines were a few small white pines and
balsams. Aster macrophyllus L. formed a large proportion
of the ground cover. Besides this were several other
speoies already mentioned as typical of exposed portions
of the ridge, such as Salix humulis, Vacoinium spp., Artemisia
cauda ta. etc.
QUADRAT 5 typified the zone of scrubby red oaks
(fig. 32), a characteristic belt very often following the
conifers. The oak growth consisted mostly of sprouts (up
to 3 m. high) coming from old root crowns in very shallow
soil. This quadrat came Just north of the crest, so that
the surface sloped gently towards the north. The conditions,
however, were still xerophytic, as indicated by the presence
of such plants as Aral ia hispida, Danthonia spioata, and
large patches of ffunaria hygrometrica. There were also a
few scattered seedlings of aspen, white birch and sugar
maple. There were some evidences of burning on this
. ■ • : ; ■ J
I
.
. j, . : r.’i' ,
....... t .
*
.
.
.
-
*
,
' ■ ■- y ' 'i r, ti
«
Pig. 32* - Zone of transitional tree growth at quadrat
5: note red pines, email red oaks, and aspens; bare rock
surface in places; the conspicuous grass is Danthonla spieata.
\
49
quadrat, so that conditions might not have heon entirely
typical, Funaria hygr ometri oa was found to be very common
in burned areas over various parts of the region. In
general the oak sprouts soern to be the ecological equivalent
of young rod pine. The ground cover was much the sane as
the preceding quadrat, with the exception of Polygonum dume-
torum, a very common species along- the edge of the meso-
phytic forest,
QUADRAT 6 represents a transitional stage from
quadrat number 5, in which the oak constituent has reached
a higher 3tage of development, the individuals attaining
a height of from 7 - 10 m., with much less sprouting, though
still indicating somewhat unfavorable conditions. The pre¬
sence of red maple and numerous sugar maple in the northern
half of the quadrat indicated the transition to the meso-
phytic maple forest.
QUADRAT 7, The striking feature of this quadrat
I
v/ as the dominance (in numbers) of sugar maple saplings
5-10 cm. in diameter. Intermingled with these were well
developed specimens of red oak (up to 15 m. or more high),
hop hornbeam (Ostrya virginiana ) and yellow birch (Be tula
lutea ) .
Following quadrat 7, the maples gradually in¬
crease in size, of ton accompanied by basswood and a thick
.
. ... ' ' • - ‘
...
... 0: J
aoo :5*0 »dt flair. it .« xtulauia
■
j I : . . • ■ '
.
,
- *•
grcwth of red-berried elder ( Sambucus racemosa ) t the
latter disappearing or becoming less frequent in the
denser shade of the mesophytic forest further down the
slope. Along the upper limit of the maple forest, it
is not uncommon to see the flat, upturned root systems
of trees, especially maples, which have adapted themselves
to a layer of soil not over 1 dm. thick over the rock
surface. This area is more or less subject to windfalls,
apparently not because the velocity of the wind is greater
here than nearer the summit, but because it forms a
critical line between the low types of trees which spread
their roots out through the shallow soil, with crevice
connections in many oases, and the taller types which owe
their increased size to a deeper, richer soil, but which
offer a greater leverage to the force of the wind.
The above description of the transition from
rocky summit to mesophytic forest applies in general to
the higher portions of the range. Variations naturally
occur, depdnding op the elevation, exposure, local topo¬
graphy and depth of soil.
(2) The escarpment and its associations.
The height of the rock face or escarp¬
ment varies at different points along the range, as shown
in fig. 24. The upper portion may be vertical or nearly
-
s. r> «; ■ 0 > *
■
.
, •
Pig. 33. - Overhanging ledge of
cliff shown in fig. 25* £z shows dip of
the strata (sandstone); various plants
gain a foothold in the moist crevices
(see text p.5l ) .
—
so. The lower portion curves around to meet the talus
slope, which is very steep at the top; or there may "be a
series of lower escarpments wi th shorter talus slopes be¬
tween as shown at the left (fig. 24). Owing to the dip
of the strata, the face of the cliff is alv;ays very uneven,
and the seams of the rock, on account of the direction of
dip, often retain a sufficient degree of moisture to
support the more xerophytic tree types. The unusual sever¬
ity of the situation so far as vegetation is concerned, is
due to the continual splitting off of rook fragments from
the parent rock.
The cliff is often "broken by ledges, due to
different resistances of the various kind of rock to
weathering; these may vary in width from a few decimeters
to several meters, with corresponding accumulations of
soil. On the vertical rook faces, a few species of lichens
may be found, such as Locidoa lucida A oh., Gyrophora vellea
(L.) ach. and Ainphlloma lanuginosum (Hoffm. ) Uyl. The
vortical face of sandstone represented in A, fig. 26, is
marked by bands of the yellow lichen, Placodium elegans.
Where ledges overhang, as shown in fig. 33, the conditions
are more moist on account of the shade. Amphiloma lanupin-
osum and the leafy liverwort, Radula complanata, aro usually
abundant; also various foliose and frutiooso lichens, such
.
- •
. ■
; , ' - '
■
. ■
1
’ - '
. . . ' _
... . - »■ f
j . • C*
Vig* 34* - Hock ledge on face of escarpment .look¬
ing east: in the foreground, two snail white pines and
small specimens of Prurtua pennsylvanlca. Phus typhlna.
and Corn us clrcinata; also Arctostuphylos Uva-ural ,
Artemisia caudata. and Danthonla spicata; in the back-
ground, a snail red pine, and loaves of oak (Ouorcus
rubra) showing below; Parmelia conspersa on rock sur¬
face above and below; V/ocdsla llvensis and Campanula
rotundifolla growing from rock crovices fin foreground)*
such as Physcia obscura (Schaer.) Hyl. , Parmelia caperata
5 Ach. , Puiaullna calicaris (L. ) Fr. , and Qyrophora vallea
(L.) Ach* In the crevices of such ledges occur two character¬
istic fern species, namely. Poly podium vulgare L* and Woodsia
ilvensls (L.) R. Br.
The flora of the exposed ledges is very variable*
On the smaller, newer lodges, a few lichen epecioa, such as
Lecidea lactea (Plot.) Sohaer. and Parmolia conspersa (rlhrh.}
Ach* nay gain a footing* On larger ledges, the higher plants
are usually well represented, from small herbaceous species
to trees whose roots are anchored in some of the bigger cre¬
vices (fig. 34)* Typical species are shown in the figure*
Among others nay be mentioned Potentilla tridentata. Pan i cue;
xanthophyaum. CeanOthus oner ic anus , ??ubus parviflorus. Amel-
anchier canadensis. Polystichum Lone hit is , Thuja occidental is .
and Juniperus co; munfta L* vur. mentana Ait*
When there is a marked difference in rate of
weathering between the sandstone and trap, a bread ledge 10 -
16 m* aoross mey be formed (fig* 26A). On account of the greater
deposit of soil and consequent storage of moisture, the con¬
ditions here are much moro stable* Such an area may develop
a comparatively thicx stand of pine, thriving under the pro¬
tection of the cliff.
The destiny of the escarpment is the condition seen
.
. ' ■ Qi , ' . MiSM i
*
Lt-
Fig. 36. - View of first range, looking
14: Carp Kiver and valley to the right; shows
reduction of escarpment and advance of forest
east, in sec.
stage in
up the slope*
■
-63-
where at present saddles cross the range. Gutting will
continue at the top and face, and filling will continue
at the bottom until the lines of cut and fill meet. In¬
vasion of mesophytio types will principally be from below,
the summit holding out longest against the final meso-
X
phytic forest. Fig. 35 shows a stage approaching such a
condition.
(3) Talus slope.
In general the width of the talus
slope depends on the height of the escarpment, especially
where the latter is not broken by large ledges. When the
face of the cliff is low, the band of talus is comparative
ly narrow, for here the rock fragments from above do not
come in sufficient numbers to prevent invasion of the
forest below. Where the cliff is high, many of the larger
, *•
fsagments may roll 200 or 300 m.,* effectively checking the
growth of the forest beyond this point. The resulting
area is desolate in appearance ffig.36), very little
vegetation gaining a foothold except near the top and
bottom.
Where the cliff is principally sandstone, the rock
fragments are smaller and more flattened than where trap
predominates. In the former case soil apparently collects
more quickly and vegetation makes a more rapid invasion.
.
' *
.
.
: - :
,
• .
‘
.
.
Fig- 36. - Bottom of talus immediately west of saddle
in seo. 14, looking east: angle of slope here is about 30°;
note line of forest as it creeps over the saddle across the
low point of the range; the cliff at this point is very high
and the talus field 200 m- or more in width; shows character¬
istic clumping habit of white birch when growing in talus-
.
-64-
As pointed out bofor \ there are two points on the talus
where soil first begins to accumulate, namely, the bottom
of the slope along tho margin of tho forest and the very
top - at the foot of the asoarprient • Host of that at the
top is due to fine material v/hioh is washed over from the
summit and hold in place. This finer soil, coupled with
the shadier conditions directly under the cliff, gives
rise to a narrow strip of vegetation composed of a complex
of spool os, some pioneer and some more or less mosophytic
in char actor, -among the more important of these are Plnus
atrobus . Plnus re si no Sc .Quercus rubra t Prunus pennsylvonica.
fop ulus trenuloidos, Coanothus am eri conns, ? sod ora quinque-
folia, Rhus Toxicodendron, Oornus circinata. Khus typhina .
Oolastrus sc and e ns, Ostrya virgin! ana, Arctostaphylos Uva-
ursi, and Symphorioarpos racomosus Miohx. var. pauciflorus
Robbins. This plant assemblage, especially as regards the
more mesophytic species, is only temporary, for as tho cliff
recedes, the vegetation must recode with it. As tho height
of the cliff becomes less, tho increased light and lessened
degree of moisture make conditions intolerant for the more
mesophytic si)ecies. Finally, with the disappearance of the
escarpment, only xerophytic species are able to endure ,
such as occur on the more exposed portions of the smaller
talus slopes. The border of tho forest forms a tension
’
J e , . [ k.
• ■
-
i.J*
f
Pig* 37* - Lichens and moosoa on the talus slope (see
fig* 35); the conspicuous foliose lichen is Parmelia conspersa;
the throe Cladonius (lower right) are rangif erina. C. eyl -
vatica and pyxldatu; Hedwigia ciliata ( extreme left ) •
line at the bottom of the talus. Conditions for growth
here are more favorable, not only on account of soil
accumulation, but on account of the partial shade, -again,
the pioneer species consist of lichens, which become more
abundant here than higher up on the more exposed portions
of the slope. By far the most conspicuous is Parmelia
oonspersa. which covers the top of nearly every fragment
of rook (fig. 37). The humus derived from this speoies
paves the way for fruticose forms, such as Cladonla rangi-
ferina (L. ) Hoffm., Cladonia sylvatioa (L.) Rabenh. and
Cladonia pyxidata (L.) Hofffti. Following the lichens or
sometimes closely associated with them are three species
of moss, namely, Thuidium abietinum (L.) Br. & Sch., Hed-
wigia oiliata iShrh. and Ceratodon purpureus (L.) Bride.
The two fern species already mentioned, Po'lypodium vulgare
and Woodsia ilvensis, follow the lichens and mosses. They
are very common along the bottom of the talus slope, send¬
ing their roots down between the slabs, an early stage
of the me sophy tic forest may then follow directly as shown
in fig. 36, where the talus is fringed by white birch. The
conspicuous ommission of the usual mat stage here is due
to the ability of the white birch to invade tho talus be¬
fore almost any other woody form. Clumping specimens with
several stems often occur on the bare talus, sending thoir
.
.
■ : • *
'
, . -
.
.
-i * - :w I ’•
Fig. 30. - An advanced stage in the in¬
vasion of the talus slope: note small size
of rocK fragments (sandstone); pioneer tree
species consist of Populua grandidentata.
snail oaks (Quercus rubra) , and small white
pines (Plnus -3 1 rob us ) .
- .as .>j'
-56
roots far down between the fragments. In such cases they
form nuclei for other pioneer speoies. Populus tremuloides
and Populus grand! dontata are the pioneers along 3ome parts
of the forest front.
as the cliff wears down and the talus elope becomes
proportionately narrower, invasi on from both the bottom and
top is accelerated (fig. 38). This is partially due to
the fact that less new talus is put down, allowing the forces
of weathering to establish a residual soil in which many
speoies soon anchor themselves. One of the most efficient
of these is Panic urn linear! foil urn Scribn. Evidence seems
to show that it starts almost entirely by seeds from above.
The warm nature of the talus soil, coupled with its moist
condition during the early part of the season, must produce
favorable conditions for germination of the many seeds which
undoubtedly find lodgment there. Probably a very small
percentage of tho seedlings are able to endure the very dry
conditions which obtain during the summer. Other species
of grass, such as Danthonia spioata, Qryzopsis June ea, and
Oryzopsis asperifolia also come in early. Arotostaphylos
Uva-ursl and Aster maorophyllus L. form mats over the bare
fragments, the latter plant being more prominent as con¬
ditions become shadier. Its large leaves form a very effect-
.
. ■ '
• ‘ . _ . ' . -
.
: .. . ' ‘ - . . ;
.
. ‘
.
: *
y- -
: cii -
-
.
-57-
ive mosaic 1-2 dm, above the surface, enabling more
aesophytio species to start# .associated with these in
varying proportions are tho brake (uteris aoqullina h. ),
the sulmonberry (Rub us parvifloruo Butt.) and the bush
honeyoucklo (Mervilla Lonicora rill#), the latter often
being very common on the upper, dryer portions of the
slope.
The pioneer tree growth consists of small soattered
individuals# If white birch be the pioneer spool os, which
seems not always to be the oase, it is soon followed by the
poplar spocios alroady mentioned and by scrubby specimens
of red oak# Besides many seedlings of the above, several
other woody species appear more or less during the early
stages of invasion such as hop hornbeam (Ostryi virgin! an a
frill# ) k# k och# ) , arrow-wood (Viburnum dent -turn L« ) » choke-
cherry (krunus virglnlana L»). buffalo-berry ( Shepherd! a
canadensis (L.) Butt.), Rubus procumbens lluhl. , Rosa acicul-
aris Lindl#, and seedlings of basswood, white ash and sugar
mapla#
Burly herbaceous species, as such, hardly form a
definite stage in the succession in the sense of paving the
way for woody growth# They may precede or accompany tfco
latter, but are lator controlled by reaction# among the
oonmoner species may bo mentioned Brigoron canadonsis L.
’
-
-58-
(horseweed ) , Silene antirrhina L. (sleepy catolifly), Satur-
oj a vulgaris (L.) Fritch. (basil), iiralia hispida Vent*
(bristly sarsaparilla), Convolvulus spithamaeus L. (ereot
bindweed), Carey adusta Boott., Antennaria neodioiea Greene
(everlasting). Frag aria vasca L. var. amerioana Porter (wild
strawberry), Bpilobiuro angustifolium L, (fireweed), Adlumia
fungosa (ait.) Greene (climbing fumitory), Apocynum androesimi-
folium L. (spreading dogbane) and Campanula rotundifolia L.
(harebell ).
The sequence of the invading associations varies greatly
at different points along the range. While Be tula alba var.
papyri f era is the dominant pioneer tree species at some points,
at others it is Populuo tremuloides or Pop ulus grandidentata.
The exact ecologioal relationship between these three speoies
is an interesting problem, but it was not worked out. Even¬
tually the invading forest merges with the permanent fringe
of forest below the talus. The latter is often dominated
by sugar maple and red oak, but here again considerable var¬
iation occurs, which will be considered later.
(4) Forest below talus slope.
This extends in general from the flood
plain of the valley below to the bottom of the talus slope
above, pushing up tov?ard the summit or even reaching it at
low points in the range. It may vary in width from a mere
' . • . t i . . .
; . ? r . .
.
.
. .:
.
.
.
.
••
,
,
Pig* 39* - View of escarpment, looking north: vertical
rock face about 70 m. high at tliia point; below this £00 -
300 m* of talus material, being invadod by pines and aspens;
below the talua elope iu the front of the advancing forest,
which slopes to the valley of Carp River bolow*
.
»«
-59
fringe of trees us ut A, fig. £6, to several hundred meters
at P. While the trees species are mainly deciduous, espe¬
cially above, oonifers often occur near the bottom. These
include white and red pine, balsam, arbor vitae, white spruce
and hemlock. In fact, tlie last named speoies sometimes forms
groves of large treos, similar to the climax forest of the
north slope.
A transect of the forested area was made at a point
just east of the saddle in sec. 14. Hear the top, the
talus slope was being rapidly invaded by small oaks and
«»
aspens, as shown in fig. 33, Populus grandidentata being the
dominant species, intermingled with scattering white birch
and maple saplings. A little further down, the open spaces
became fewer, the trees taller (up to 15 m. ), gradually form¬
ing a canopy above, giving perceptibly shadier conditions.
The soil contained more humus, derived largoly from the
leaves of the aspens. Here patches of Aster maorophyllus and
Aralia nudi caul is formed a large proportion of the ground
cover. Occasional small specimens of white ash, balsam,
hop hornbeam, and basswood were noted as invaders at this
stage. The unfavorable conditions for anchorage produce
remarkable clumping of the stems in certain speoies, espec¬
ially in the sapling stage of the hop hornbeam, sugar maple
and red oak. Wine stems were counted in one specimen of
i ' • “°-
■
-
: . ■ ; ' "• '
.
: •• • '
.
Pig* 60* - Lower odge of foreot, border ing flood plain:
the large tree in foreground io blade aeh; in the bacicground,
Botula alba var* papyrifora. Bopulua tremuloidoa, Ac or rub rum.
Cornua atolonif era. .hi! lx rootrata ana oalix petiolarie*
■ *
••
hop hornbeam. Basswood overcomes the difficulty by ex¬
cessive sprouting. Approximately half way down the slope,
a bench occurred, 15 - 20 m. wide, and nearly level. A
striking feature hero was the appearance of rather large
conifers, including specimens of white pine (up to 5 dm.
dia. } balsam, white spruce, and arbor vitae. Poplar as
the dominant species was replaced by red oak and white
birch, ilore mesophytic oondi tions were indioatod by the
presence of such species as Smilacina racomosa (L.) Desf.
(false spikenard), Galium triflorum Iliohx. (sweet-scented
bed straw ) , Hepatioa triloba Chair (liver-leaf), liaianthamum
oanadense Pesf. (false lily-of-the-valley ) , Strootopus
roseus Michx. ( tv/is ted -stalk ) and Mitohella re pens L. (part¬
ridge-berry). Gradually the oaks were replaced by the sugar
maple, which became the dominant species to the edge of the
flood plain, with white pine still frequent as a subdominant.
At the edgo of the forest bordering the flood plain, the
increased light and moisture conditions produce a marked
change in tho ground cover, with a great diversity of species
coming in. Seedlings of aspen (Pop ulus tremuloides ) and
hazel ( Oorylus rostra ta ) seem to be responses to tho in¬
creased light. Tho frequent occurrence of wild black cherry
(Prunus aorotina ) along the margin of the forest is undoubted
ly a response to tho same conditions. Groves of aspon
J.
.
, • . • •
r
i ;
- - .
«
.
i
fi/fc
Fig. 41. - Gullying on south aide of first rung©,
about halfway down the slope: white birch and aspen in
the background; in the foreground, snail specimens of
sugar maple and yellow birch; shoviu clumping specimens
of hop hornbeam (upper right); ground cover mainly com¬
posed of Aral la nudicaulls.
' '
61-
saplings mixed with white hi rah aro not uncommon (fig .40).
The appearance of many other woody species is due more to
the itncreased moisture along the margin of the flood plain.
Among these may he mentioned ffraxinus nigra Marsh. (black
ash), Sal lx di pooler Kuhl • (glaucous willow). Viburnum
Opulus L. ( cranberry- tree ) , nlmus inoana (L.) Moench.
(speokled alder), .acer rub rum L. (red maple), Spiraea salici -
folia L. (meadow-sweet) and Cornus stolon! for a Llichx. (red-
osier dogwood).
l'he complex of ibrost and flood plain species is very
variable in its composition. This may be explained partly
by the very unstable conditions in the valley and partly
by ohanges in the edaphio conditions produced by gullying
down the side of the rungo, with the consequent deposition
of new soil near the bottom of the slope. A noteworthy
instance of the latter occurs opposite the saddle in sec.
14 (fig. 41). Gullying in this case is due to the in¬
creased drainage over the saddle, resulting mainly from
the melting snow in the spring. In the summer, its upper
portion at least may be dry.
II. Hydraroh successions in the valley of Carp River.
As before indicated, the mesophytic forest be¬
low the talus slope is bordorod by Carp River or its flood
plain. This flood plain is comparatively broad in the
V
-
t
__ . ... _ - _ .
• -
_ _ :
.
: : . . : : . ■ -
J *■
k . . ; v - -
• '
L . i *
, I' • •
,
Fig* 42* - "Cedar swamp" # north edge of Carp Kivor
valley: the lurge trees near the center are arbor vitae
(Thuja occidentalia) ; the shrubs in the background are
Alnus Inc ana, arid Cornua etolonifera*
'
.
-62-
vicinity of the lake, due to the flat nature of the valley.
At this point the river is a sluggish, meandering stream
20 - 40 m. wide, doing very little vertical cutting, but
shifting its course from time to time. Carp Lake is merely
a broadened part of the river. According to Wright (28 )
the valley resulted not from the erosive action of a former
river but to the pounding action of the waves on the shores
of a vanished lake which covered the area. The present
floor of the valley is subject to periodical flooding, in
which a certain amount of sediment and debris from higher
levels is laid down. There is thus a lack of stabilization
in the edaphic conditions which prevents the encroachment
of the mesophytic forest. The lino of demarcation between
forest and flood plain is usually very abrupt, as shown in
fig. 40. Flooding has the effect of producing irregularities
and telescoping in the hydraroh successions paralleling the
river, so that these successions are evidently not playing
a prominent part in the formation of the forest. There are
a few points along the range, however, where transitional
bog forests may be found. One occurs between secs. 13
and 18, T. 51 H. (fig. 42). This is near the mouth of a
drainage system coming directly from the ridge. This
forest is quite limited in extent. Its interest lies in
the suggestion it gives as to the character of the bog
,
-
• * ... ,
...
• ■ ' •
*
.
* . . -L‘
'' :t " ' ■
forest which will eventually procode the meso phytic
forest as the latter claims the entire valley. The typical
tree species are arbor vitae, white spruce, balsam, tamar-
aoli and black ash. The forest floor is rough and often
covered with a mass of shrubs, fallen logs and herbaceous
grow tli. The soil is typical muck, having a fine texture.
In July the water table was approximately 3 dm. below the
surface. Characteristic herbaceous plants are Aral! a
nud i oaul i n . as tor naorophyllus . Galium asprollum Ilichx. ,
Aspiflium crista tun (L.) Sw., Clintonia borealis fiJLt. ) Raf • ,
Clrcaou alpinu L., Carox loptaloa .ahlerib. , and Habenaria
hyperboreu fL.) Rydb.
The hydraroh successions of the river a nX flood plain
contain many of the eloments of typical peat bog areas
suoh us described by Davis flOa) for the Upper Peninsula.
On the other hand, there is a lack of definitoness in the
sequenoo of the associations; and the sphagnum element,
with its accompanying vegetation, is not at all common.
The latter condition is duo to the influx of fresh water
during at least a portion of the year. A year of unusually
high flood may destroy the continuity of vegetational
development along cortain linos. This is well attested
near the intake of Carp Lake by the dead und dying trunks
of small black ash treos. Periods of exoessivo flooding
'
■
.
Pig* 43* - Carp Kivor from the summit of the first
range, looking i»* 3* i£*: the river flows west, emptying
into Carp Lake; flood plain in the distance covered by
an alder swamp*
■
-
-64-
may approximately be measured by the oldest of these.
After such periods of high water, pioneer species again
come in, initiating a new course of succession. A patch-
work results, which is especially evident in the shrubby
vegetation. This patchwork is further modified by the
varying ability of the different species to withstand the
presence of excessive water about their roots. The
shorter -lived herbaceous forms often show more definite
zonation, especially along such restricted areas as mud
flats or sandy beaches bordering the river or lake. They
are able to adapt themselves more readily to changing con¬
ditions.
In order to illustrate the tendency of the hydraroh
successions in the valley, the associations found in the
river, lake and flood plain, will be briefly described.
a. Carp River (fig. 42;.
Where this stream flov^s through the
flood plain it is comparatively shallow with a muddy
bottom. The slow-moving current makes the ecological
conditions very similar to those found along the margins
of many of the smaller lakes in the Upper Peninsula. Among
the immersed aquatics may be mentioned, Potamogeton pusillus
L., Potamogeton heterophyllus Schreb., Potamogeton zosteri-
folius Schumacher, Potamogeton amplifolius Tuckerm.,
£ . ( ti l y err j *.
.
. .
, .• . ::
.
,
• ...
■ •- .
-
*
Fig* 44* - Carp Kiver near north edge of flood plain:
the a3i rub lining the bank at this point is principally Ainu a
inoana: the aquatics are Spar gan iron euryoarpua and Mynphaoa
advena; top of first range just visible in tho background
(upper right)*
65-
Potamogeton natans L., Myriophyllum Farwellii Morong. ,
Ranunc ulus aquatilis L • var. oapillaoeue PC • , Hippuris
vulgaris L.
The commonest large aquatic is Nymphaea
advena Ait. (yellow pond lily); it sometimes forms patches
extending half way across the stream. Castalia tuberosa
(Paine) Creene (white pond lily) is much less common,
though it occasionally occurs in large patches; the same
may he said of the water-shield (Brasenia Schg&beri Gmel.).
In many places the stream is fringed with overhanging shrubs
as shown in fig. 44. Mud banks often occur at the bends,
supporting various aquatic or amphibious species, such as
Potentilla palustris (L.) Scop, (marsh cinque-foil),
Sparganium eyryoarpum Engelm. (bur-reed)., Bleocharis
aoicularis (L.) R. & S.t Carex filiformis Good, (bog sedge)
and Car ex striota Lam. The last two species form clumps
at various points along the bank, thus enabling other species
to obtain a footing.
The shrubby growth along the banks
consists principally of the following:- ALmus incana (L.)
Moench. (hoary alder). Hex verticillata (L.) A. Gray (win¬
ter-berry), Cornus stolonifera Miohx. (red-osior dogwood),
Chamaedaphne calyculata (L.) Moench. (leather-leaf).
Spiraea salioifolia Roi (meadow-sweet), Salix petiolaris
... ••
. •
.
• . - -
.... - -• — ■
_ 2 ♦ •
’ -• - * . .I' _ •••
*
.
. : - ' . . .. ■ • -
,1 : J.... ... •
.
66-
Sol lx pedicellarls ?ursh (bog willow) and
lucida iiuhi. (shining willow)* Two fern species,
namely Osmund a regalia L. and Aopidium Tholypterls (L. )
Sw* » often occur at the margin of the water, more or lees
shaded by the shrubs. Ciianaodaphno calvculata. though
not the commonest shrub lining the river bank, is pro¬
bably the moat important in the formation of floating
mats, these often starting from sedge hummocks. One
effect of the mats is to cut off quieter bodies of water
where various aquatic and amphibious specios are more success
ful in establishing themselves.
One thing seems clear in connection with the
successions along the margin of the river, namely their
instability. Kven when Carp Lake as such, is gone, the
river will still continue, though not in its present bed,
as the bottom of the valley will have been raised through
sedimentation.
b. Carp Lake (fig. 1) •
The lake lies parallel to the main ridges,
covering the floor of the valley for a distance of about
2 km. Its broadest portion is near the east end, where
it has u width of approximately 0.5 km. Excepting at
this end, the nesophytic foest oxtends nearly to the
water* s edge. At the east end a broad delta has been
'
'
« • .... I
N
Pig. 45. - Delta, east end of Carp Luke, looking east:
in the foreground, aclrpus occidentulis t aquisetura fluviatlle,
and flypphaoa ad vena; narrow channel of tho river shown in the
background; first range in the distance, showing saddle in
section 14
-67-
forraed, where Carp River enters the lake (fig# 45). The
submerged part of the delta extends well out into the lake,
being several hundred meters broad at its widest portion
(fig. 46). Hero the water is shallow, varying from 3-10
dm. in depth. The west end of the lake is also shallow,
and ohoked with aquatic growth and debris, especially near
the outlet. In general the beaches are very narrow. Most
of those on the north side are of the shingle type. In
places they are entirely lacking, the shore line being
directly bordered by a fringe of shrubs similar to those
along the bank of the river. Sandy beaches occur on the
south side and near the west end on the north side. They
are broader than the gravel beaches and show more clearly
the zonal development of vegetation. The edaphic con¬
ditions are naturally more stable around the margin of
the lake than along the river. Especially is this true
on the south side where deposition is occurring more rapidly
than on the north.
The free-floating aquatic vegetation of the
lake, being very similar to that of the river, need not be
mentioned. The best evidences of plant succession are seen
on the flat sandy beaches and on muddy flats near the
delta. At the delta there is a zone of rushes extending
from 50 - 100 m. out into the lake. Its outer part consists
■
...
.
e.. . ■ ■ ■ • '
' *- ’
*
Fig* 46* - iSast end of lake, looking south toward second
range: the zone of rushes ( Sclrpua cceidentulis) marks the
shallow water over the submerged portion of the delta; the
group of balsams along the opposite shore indicates the pres¬
ence of a small stream flowing into the lake*
-u8-
of the bulrush (Scirpu3 occldentalis (Wats.) Chase; then
comes a zone of Equisetum fluviatlle L. (pipes) covering
a large area. The inner portion of the zone consists of
a mixture of Glyoeria borealis (Nash ) Batohelder (northern
manna grass), Leersia oryzoides (L.) Sw. (rice cutgrass),
and along the muddy shore El eo char is palustris (L.) R. &
S., Ac or us Calamus L. (sweet flag), Dulichium arundinaceum
(L.) Britton, Polygonum amphibium L. (water smartweed),
Glyoeria canadensis (Miohx. ) Trin. (rattlesnake grass),
Solypus atrovirens Muhl., Eleooharis obtusa (Willd.) Schultes
(blunt spike -rush) and Saglttaria latifolia L. form& Gracilis
(Pursh) Robinson, apparently the common form in northern
Michigan. The immediate shore is fringed with clumps of
Salix lucida, interspersed with open areas covered with
Oalamagrostis canadensis (Miclix.) Beauv. (blue joint). Logs
lying almost concealed tell the story of flooding at this
point; this is also shown by standing specimens of Alnus
inoana and Salix petiolaris, dead above, but making vigor¬
ous gew growths at the base.
In the shallow water bordering the sandy
beaches, the rushes are often accompanied by areas of pipe-
wort (Eriocaulon artioulaturn (Huds.) Morong. This may
produce unusually long stems when growing with Soirpus
occidentalism Among the commoner species occurring on the
.
* • .
. . . . . ■ .
' . . . < •• .
.
- — - . - — - - ~ -
.
. J V
. ' « ’
'
... . . . ■ . . ...
*
,
.
.
-69-
sandy beaches are the following:- Juncus brevicaudatus
(iSnglem*) Pernold, Hypericum elliptlcum Hook* (pale St*
John's wort), Cladiun nariscoidos Terr* (twig-rush) ,
Ranunculus Plemcmla L. (smaller spearwort) , Him ulus r ingens
L* (nonkey flower), Slum clout aef ollnm Schrank (water
parsnip), Agr ostia hy emails (Walt.) BSP* (hair grass). Car ex
erinita Lam*, Car ex rostrata Stokes, and Carex Ooderi Betz.
Both the sandy and gravelly beaches are very often backed
by a shrubby association composed of 6hamaedaphne cal you -
lata. Ilex verticlllata. and nlnua Inc ana* With these often
occur Spiraea salicifolia and Praxinus nigra, fringing tho
me so phytic forest.
It is evident from tho above description
that tho transition from lake to me so phytic forest is rather
abrupt; this is especially true on the north side of tho
lake, where the angle of slope is greatest* The few asso¬
ciations notod along the narrow beaches consist of plants
which are able to endure submergence for brief periods. The
shrubby growth backing the beaches, though only a little
above the mean level of the lake, is high enough to escape
mostly the destructive influences of high water.
c. Blood plain.
On account of tho varying influence to
which the flood-plain is subjected, the successions are not
..
'
* i
-70-
in general , well marked. In the broader portions of the
valley, as in ooo. 24. ?. 61 H. R. 43 W. . there is a dense
growth of Alnua Inc ana . intermingled with occasional in¬
dividuals of tamarack. In the northwest corner of the above
section there is a small "tamaracK swamp", forming a typical
stage in the filling up of a peat bog. The ecological stages
of such a bog have been well described by Transeau (25),
Cooper (5), and others and will not be treated here. In
sections 23 and 14, immediately east of the lake, the flood-
plain is covered by a grassy marsh (fig. 40), with a shrubby
zone lining the river, as already described. The flora of
this area is very composite in character. Portions of it
are dominated by a dense growth of blue joint (Calamagrostls
canadensis ) . The list of specios observed here includes
the following: - Ascloplas incarnata L. , Verbena hast at a L. ,
Aster punlc eus L. , iSupatorlum purpureum L. , Sclrpus Cyperlnus
(L. ) Aunth. , Osmund a regal is L. , Onoclea aenslbillfe L. ,
Solidago aerctlna Ait • , Anemone canadensis L . , Chelono glabra
L. , Aapldium Thelyptorlo (L. ) Sw. , Pteris aquillna L. ,
Glyceria canadonsi s (Hichx. ) Trin. , Lysimachla torrestria
N
(L. ) BSP. , Iris versicolor L. 9 Cicuta bulbif era I. , Suutel-
laria lateriflora L. , Thai ict rum dasycarpum Fisch. & Lall.,
Galium asprollum Hichx. , Conn strictum Ait. , Impatlens bi¬
flora Valt. , Hum ex vertic Hiatus L. , Hypericum vlrglnloum I. ,
.
■
. ■
.
.
.
*
• . 1
-71
Campanula ullginosa Rydb • f Phalarls arundi nacea L . , Clematis
virgin! ana L . , Leersla oryeoldes ( L • ) Sw • , Kumulus Lnpulus
I<« , Ranunculus Pennsylvania us L. f., Gal ium Clayton! Miohx.,
Radioula palustris (L.) Moench., Garex filiformis L., and
Oarex tribuloides Wahl*
The grassy marsh described above un¬
doubtedly oocupies the position of a former delta. It
thus represents a stage in the gradual filling up of the
valley with sediment and organic remains.
STOIMAHI
The ranges of the Porcupine Mountains are
entirely surrounded by a low plain, so that the mountains
were islands for some time after the final retreat of the
ice sheet. As the water subsided, the higher ranges to
the south were first uncovered. Pioneer invasion probably
took place where the wash of the waves was not too severe,
following stages analagous to those found in the present
shore line. At the present time, these southern ranges or
hills, including Government Peak, the highest point, are
clothed with a mesophytio forest to the very top (fig. !)•
This mesophytio forest was possibly preceded by a zero-
phytic coniferous forest dominated by pine species, as
T'
••P
. ' ‘
.
; • *
\ , . : •
; .. ,
-■ »
v ’ - .
•
....
•
r ^
•' i 01 1 •.
s. i . ■■
r
•
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• * .
■
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•
W V V
' - . . ... «, ,» 1
t
. * . *. * * ••
,
, ....
•
. * *
•
-
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•
«■ « • .
.* .
t
* /* r
72-
suggested by Ruthven fl,p. 27). In this ease the pines
began their invasion near the water's edge, following the
heath mat stags# They made their last stand at the top
of the mountains, being followed up and replaced by a
mesophytio fbrest, the successions being correlated with
the greater accumulation of soil near the base of the
slope.
The top of the first range is unique in still
holding out against the mesophytio forest. This is un¬
doubtedly due to the peculiar topography of this range.
As is evident from fig. 3, this topography is associated
with the presenoe of Carp Lake, which once covered a much
greater area than at present. The ddp of the strata to¬
ward the north, coupled with the subsidence of Carp Lake,
has created a great cliff or escarpment, which is con¬
tinually wearing away, producing a talus slope at its foot.
The development of vegetation over the region
has led to two climax formations, namely the hemlock climax
and the maple climax.
The presence of the hemlock climax on the north
elope of the first range seems to be conditioned by the
physical factors of temperature, moisture and light. Great¬
er humidity and more uniformity in temperature noar the
shore is due to the presenoe of a largo body of water. The
;
.p
'
. . t
. t " 5 .%•».
*
: i Lj. i
f •
- •
•
s. *
*
L 0
•
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• ■ • :
l< i
.
cl' ■ '2
i : ■ no ' ' ! '■ :
.f i I • •. : • J '
-- •• • . . ■ •• *-r ••
*. o
- ' i > * • ■
X ■ ■
V .
, • :
* *'
- -
- : - . : H S
,
• :• • ... V- ~v;:
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■- J .
.
. . . j.
.. / .. •- -* <*• * „-v * *
J . '• ; • : i
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1 ■ J * v
average temperature of points along the coast is several
degrees warmer than inland points a few miles bach, and
the average precipitation during the winter months is
30/ii more than at Bergland, 26 km* hack from the shore*
Keduced light intensity at the lower, more humid elevations
on the north slope is probably more favorable to hemlock as
compared with maple.
The maple climax occurs on the higher portions
of the first range (excepting the summit) and on the ranges
further south. As compared with hemlock, maple seems to be
more tolerant of extremes of temperature and light.
The principal succession leading to the hemlock
climax is along the shore. The pioneers in the more exposed
situations are erevioe plants. In the severer situations
tliese can initiate only very short or incomplete lines of
succession. Where conditions are less severe, which may
be only a few meters further inshore, the pioneers consist
of lichens, mosses and crevice plants, which lead to more
definite lines of advance; but the irregularities of the
shore line produce such varied conditions that there is
often a lack of any gradual transition from lower to higher
ecological forms. At practically all points along the shore,
the climax forest has pushed do wn to the limit of its
possible extension undor present conditions; and this has
.■ - ■ :■ • -
>:
. . . . . . ■ . .
.
. ■ f *
• i ' : -l
. - : •
. -V ... _. v.. • . i : . .... -o . ... ; • -
. • •
,
r . •. . • v.. :• :• ;
.
; •, .
, * .
• • i - . . : • .i ' • ' • >
• * •
it L li - \ ' . * • •'.!
L -i . , i „ O ' ■ X .. •
• . • . . . '
74-
resulted in a telescoping of the ordinary transitional
stages •
Lines of succession leading to the maple climax
may be seen at the summit of the first range and in the
valley of Carp River. In the first case the climax is
reached through xerarch series, beginning with crustose
lichens and xerophytic mosses on the exposed rock surface
of the summit. One of the principal pioneers is Selaginella
rupestris « which often forma a layer of humus 1-2 dm.
thick. This together with various low-growing species, in¬
cluding crevice plants such as Danthonia spicata and Panic urn
depauperatum. paves the way for the heath mat, which is
composed largely of two species of Vaccinium (see text). A
zone of scrubby conifers and oaks then leads gradually to the
maple climax on the north side of the summit.
On the south side the presence of the cliff
forms a direct barrier to invasion from below, except where
the escarpment has been worn down so as to produce a saddle
aoross the range. Below the escarpment there is a talus
slope of varying width, fringed by a mesophytic forest ex¬
tending below to the flood plain of Carp Hiver. In general
this mesophytic forest is young and heterogeneous in char¬
acter, but it is approaching the maple climax. Its upper
border is irregular, but forms a more or less sinuous
'
.
.
-75-
curve representing a line of invasion on the talus. Since
the width of the talus depends on the height of the escarp¬
ment, the line of invasion extends high at low points in
the range.
Suocessional continuity on the talus is more
or less broken, at least in the earlier stages. Lichens
and certain moss species are undoubtedly important, but
Betula alba var. papyrifera is one of the noteworthy pioneers
adapting itself to unuaually severe conditions. This is
followed sooner or later by aspens, after which there is a
gradual transition toward the mesophytic climax.
As the cliff wears down the summit of the range
will eventually be claimed by the mesophytic forest. At
present the xerarch series forms a connecting link between
the maple climax in the valley and on the north side of the
summit.
The lower edge~ of the mesophytic forest below
the talus forms an abrupt border to the flood plain of
Carp River. This is due to periodical flooding, which
produces irregularities and telescoping throughout the
hydrarch series on the comparatively flat floor of the
valley. Any marked building up of the mesophytic climax
from this source must therefore await a change in physio¬
graphic conditions along the river valley. This will
. | . *' *r
.
.
mesophytic forest
(m^-ple cl/md.X )
Fig# 47. - Diagram shewing linos of vogatational
development leading to the maple climax on the first
range.
.
.
-76-
oome with the gradual filling up of the valley through
sedimentation, thus changing* the conditions under which
flooding now ocours. The present successions along the
valley of Carp River and Carp Lake aro of comparatively
little moment; however they indicate the character of a
portion of the hydruroh series which will eventually lead
to a mesophytic climax covering the entire floor of the
valley*
The principal * ones of vegetation in connect¬
ion with the development of the maple climax on tho first
range are shown in the diagram (fig* 47). The letters
a, b, £, d, indicate the lines of succession. The line £
begins with lichens, mosses, and crevice plants at the bare
summit, and culminates in the maple forest on the north
elope; b originates largely from seeds washing over the N
summit; £ represents a line of invasion on the talus slope
from Ihe forest below; d is a broken line representing the
discontinuous nature of the hydrarch succession from the
valley of Carp River. Part of this succession leads to the
mesophytic forest on the second range.
; . .
.
I :
* .
. 2 ’ V '• ; v
.
; , ■ • -
. ;? * ' ' " . - . . . v -1 1
.* •: . : ' '• i-
.
77-
-RKFERENCE8-
1. ADAMS, C. C. , An ecological survey in northern Michigan.
A report from the University Museum, University
of Michigan, published, by the State Board of Geo¬
logical Survey as a part of the report for 1905.
Lansing, Mich. 1906. Part I, pp. 17 - 47, written
by Dr. A. 0. Ruthven, deals with the general
ecological relations of the Porcupine Mountains,
and pp. 75 - 92 contain notes on the flora of
these mountains. 1905.
2. BEAL, W. J., Observations on successions of forests in
northern Michigan. Rep. Mich. Forestry Comm.
1:25 - 29. 1888.
3. BURT, W. A., Catalogue of the plants collected in the
primitive region south of Lake Superior in 1846.
D. Cooley, Jackson’s Lake Superior, pp. 875 -
882. Washington, D. C.
4. CLEMENTS, F. E. , Plant Succession, An Analysis of the
Development of Vegetation. Publ. 242, Carnegie
Inst. Wash. 1916.
5. COOPER, W. S. , The climax forest of Isle Royale, Lake
Superior, and its development. BOT. GAZ. 55:1 -
44, 115 - 140, 189 - 235. 1913.
6. COWLES, E. C., The physiographic ecology of Chicago
and vicinity. BOT. GaZ. 31:73 - 108, 145 - 182,
1001
, r. . ; .Wx
, # • •
:
f
.
; - , . i- ‘
-78-
'• _ _ » The influence of underlying rooks on
the character of the vegetation. Bull. Amer.
Bur. Geog. 2:1 - 26. 1901.
8* _ , The causes of vegetative cycles. BOT.
GAZ. 51:161 - 185. 1911.
The physiographic ecology of northern
Michigan. Science 12:708 - 709. 1900.
10. DaRLILGTOL, H. T., Contributions to the flora of
Gogebic County, Michigan. 22nd Rep. Mich. Acad.
Soi. 1920, pp. 147 - 176; Mich. Aoad. Sci., Arts
and Letters, Vol. 1, pp. 74 - 82.
10a. DAVIS, C. A., The formation, character and distribution
of peat bogs in the northern peninsula of Michigan.
Mioh. Geol. Survey. 1906.
11. FOSTER, J. W., and WHITLEY, J. D., Report on the geology
and topography of a portion of the Lake Superior
land district, in the state of Michigan. Exec.
Doc., 1st Sess., 31st Co#g. Vol. 9, part 1. 1850.
12. _ , Report on the geology of the Lake Superior
land district. Part II, the iron region. Sen. Doc.,
Spec. Sess., 32d Cong. Vol. 3, 1851. Contains a
list of plants from the Upper Peninsula, including
some from the Porcupine Mountains.
.
, « ,
: ' * . ‘
*
. «
.
-79-
13* FROTHIHGHAM, E. H. , The northern hardwood forest; its
composition, growth and management* Bull. 285,
Contrib. For. Serv. , U. S. D. A* 1915.
14. _ , The eastern hemlock. Dept. Bull.
152, U. S. D. A. 1915.
15. FULLER , G. D. , Evaporation and soil moisture in relation
to the succession of plant associations. BOT. GAZ
58:193 - 234. 1914.
16. GLEASON, H. A., The structure and development of the
plant association. Bull. Torr. Bot. Club, 44:463
481. 1917.
17. GRAVES, H. S. , The study of natural reproduction of
forests. Forestry Quart. 6:115 - 137. 1908.
18. ENECHTEL, A., Natural reproduction in the Adirondack
forests. Forestry Quart. 1:50 - 55. 1903.
19. LANE, A. C. , The Keweenaw Series of Michigan. Mich.
Geol. and Biolog. Survey. 1911.
20. LEVERETT, Frank, and TAYLOR, Frank B., The pleistocene
of Indiana and Michigan and the History of the
Great Lakes. U. S. Geol. Survey. Monograph 53.
1915.
21. MOORE, B. , Reproduction in coniferous forests of
northern New England. B0T« GAZ. 64:149 - 158.
1917
. -
. . . . * .
*
.
*
l ■
- . - : ,
‘
.
. . :
..... •
-
*
.
,
. < ' . . ...
.
./
• •
-80-
22. ROBINSON, B. L. , and FERNALD, M. L. , Gray* s Manual
of Botany. Ed. VII. New York. 1908.
23. RUTHVEN , A. G. , Notes on the plants of tho Porcupine
Mountains and Isle Royale, Michigan. In ADAMS
(1).
24. SEELEY, D. A., The Climate of Michigan. State Dept.
Agr. , Lansing, Mich. 1922.
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