A conclusion was thai light, rather than root competition or moist lire. i> ;ui a I l-ini port ;mt factor. (!ra- 30Vsky I L6), working with white pine stand- in the Yale Forest mar Keene, New Hampshire, concluded that the light which reaches the fores! floor beneath a fully stocked stand is of sufficient intensity and quality to 3upport reproduction. Light, therefore, wa- not considered :i determining factor in the establishment of white pine reproduction. Selection of Soils and Tree Species 109 The weakened growth and absence of reproduction was believed due to other factors of environment. Craib (10), working in the same forest, demonstrated that root competition with older trees may be the deciding factor in the survival of the reproduction. Stevens (34) measured the rate of growth in the length of lateral roots of white pine, 4 to & years old, planted in open fields. He did not establish a correlation between root growth and weather or soil condition. Finding root growth more rapid on sandy soil, he con- cluded that, with four-year-old white pines set 6 feet apart on sandy soil, root competition may be expected to start within 5 years after planting. In clayey soil the growth made annually was much smaller and competition was delayed until about the tenth year. SELECTION OF SOILS AND TREE SPECIES FOR INVESTIGATION Establishment of the Plantations Selection of the planting sites and establishment of the planta- tions were carried out in the spring of 1933 by Raymond Kienholz and H. A. Lunt. In 1940, when the writer joined the staff of the Station, it was felt that the two plantations had advanced in growth sufficiently to permit the study of the spread and penetration of the root systems of the trees. The two soils selected for planting were Merrimac loamy sand and Charlton fine sandy loam. The plot on the Merrimac soil was in Peoples State Forest in the town of Barkhamsted, Litchfield Coun- ty, about five miles east of the city of Winsted. It was located on the east side of the West Branch of the Farming-ton Eiver, on a river terrace without perceptible slope, about 450 feet above sea level. The river valley is surrounded by forested hills rising from 400 to 600 feet above it. The land was 'formerly cultivated for a number of years, then abandoned. By the time planting was undertaken a thick grass cover with heavy sod had formed. The Charlton soil plot was located near Bantam Lake on land belonging to the White Memorial Foundation. The general location is about one mile south from the village of Bantam, Connecticut, and about 500 yards north of Bantam Lake. The elevation of this plot is about 900 feet above sea level. The general appearance of the country shows quite unmistakably signs of glaciation, with drumlins forming prominent features. The plot is in a glaciated valley on land with a gentle slope. A conspicuous hill rises to the east of the plot. The land was formerly cultivated and then abandoned. By the time planting was undertaken a thick grass cover with heavy sod was present. The two plots had been planted by four men between April 20 and April 25, 1933. The planting was at 6 x 6-feet spacing, carefully measured. Where individual trees were planted, the sod was removed for a radius of about 1.5 feet. A hole was dug to accommodate the roots without crowding and, after the roots were inserted, they were carefully covered with soil and well tamped. The planting followed 110 Connecticut Eo'periment Station Bulletin 454 a certain pattern of pure and mixed rows, and the mixed rows in themselves followed a definite plan. However, the original design of planting, made up with rigid regularity, was altered somewhat to meet the supply of planting stock and the shape of the field plots. An exact record of the source and kind of planting stock is not available. After making several inquiries and examining the trees themselves, the writer has concluded, from the evidence at hand, that the conifers were 2-1 stock, and the hardwoods 1-0 stock. The coni- fers came from local nurseries. They were grown for one year as transplanted stock at the Connecticut Agricultural Experiment Station Nursery at Windsor, Connecticut, before they were planted in the Figure 1. General view of the seven-year-old plantation utilized for root study in this investigation. Plantation on Charlton fine sandy loam, Bantam Lake, Bantam, Connecticut. field. The hardwoods came from the Forest Nursery Company in Tennessee. Since this nursery in all probability secured the seed locally and grew the seedlings, the change of climate involved in transferring the seedlings from Tennessee to Connecticut may account to a huge extent for the poor survival of the hardwood trees. In Angus! of 1934 an examination was made of the two plots and a record was made of the mortality and survival of the individual trees. After this examination the two plots received no more atten- tion until the initiation of this investigation. Condition of the Plantations at the Initiation of the Study In June, L940, the two plantations were examined by the writer and, after a preliminary inspection, plans were made to conduct the root investigations presented in this paper. The two plantations at this time were seven years old and afforded view- as in Figures 1 and 2. In certain part- of these plantation-., where survival was ^nnl and treeg grew rapidly, the crowns of the trees were about ready to close. Selection of Soils and -Tree Species 111 a « CM < H a 0 P > rf K> ' ' r/i o U3 o "43 ^ e H m H •a o o 3 1 a o Ph H _g "a v. O OfOfONfOO\00'OK^O 1— 1 ON <^> CV] t^. 10 r ar'J rtMfMtO 1— < CM "^ CM 10 t-h 1— 1 CM 3-D-" §15 •^ z ~ ^NO-HOcOTtK^OWaMcOHrHVOK i— I T-H CM r-tOO\"HlOM i—l CM ON i—l 3X3 5 — iiOCMCMNfOi-KMtOrHit 1-1 CO CM T-H T-H 3 <*- - > o « J? e S s ?i v> J3 *» "* Cj (V, 3 5 ?.2 I ^ CSS Is? g Os-S ^ ] tt, cl, a, o o <4h 9* . A 1. 2. 3 4 . a • » a. .: .. 3 0 B: C, cz I i I Figure 4. (Continued.) 118 Conn e die u t Exp e rime n t St a t io n Bulletin 451 Figure 5. Horizon features and rool distribution in Merrimac loamy sand. Patchy appearance of the atypical profile is shown. This set of transects was made around a red pine tree 7.7 [eel in height. (Continued on page 1 1('. j Methods of Procedure 119 2 . i_! . Figure 5. (Continued.) 1-20 Connecticut Experiment Station Bulletin 454 ^a^&L "•• &t~ 2 3 . , 1 'rs*r~ o "4 © & _ . *•■ ?■■ 6- ■•* _JfeL_— SI © ^JBj Figure 6. Horizon features and rool distribution in Charlton fine san£ .,,„. This set of transects was made around a Norway spruce tree 7. loam andy 4 feei in heifiltt. ( < 'ii pa.uc 121.) Methods of Procedure 121 ■-*. - -id ° - •• o ° "o o •■ b ,2 flSfib, .<*> jo ©° . B — *""•» — °e o * © ■**•. 1 . 2. 3. i i , Figure 6. (Continued.) 122 Connecticut Experiment Station Bulletin 454 daries are indicated by lines, horizons are lettered, and large rocks, which were mapped to scale, are cross-hatched. Roots of trees were mapped according to five size classes with the following symbols in- dicating; root sizes. Roots ; of trees Roots of trees other Diameter of root under investigation than those investigated up to 0.05 inch • X 0.05 to 0.1 inch 0 a 0.1 to 0.2 inch ® 0 0.2 to 0.5 inch e 0 0.5 to 1.0 inch © . is In order that mapping could be done accurately a frame 3.5 feet long and 2 feet wide was constructed. This frame and its application is essentially the same as that described by Ely (12). Thin wire was used in preference to string for subdividing the frame into smaller squares because wire gave rigidity to the frame and kept the lines from saging. Wires 6 inches apart were sufficient for orientation in mapping. With the aid of an ordinary foot ruler the mapping could be done with accuracy. The frame, fitted against the exposed pro- file, was used as a guide in mapping the roots to scale, as illustrated in Figure 7. As the work on root charting proceeded, the exposed horizons were studied and described. The succession of horizons on the two areas followed a certain general pattern but all deviations and varia- tions from the usual pattern were noted for each tree. Collection of Soil Samples Immediately following the mapping of roots two main series of soil samples were taken. One set was collected by horizons for. the entire plot. On Merrimac loamy sand two patterns of soil horizon succession appeared to be evident, one of which was more general and far more widespread than the other. As the work progressed it be- came apparent that, except for one modification occurring only in patches, the two patterns were essentially the same. On Charlton fine sandy loam one common type of horizon pattern prevailed throughout. The general soil samples collected for the two areas consisted of one set for Charlton fine sandy loam and two sets for Merrimac loamy sand, one from the typical and one from the atypical profile pattern. These sets were taken in paper bags in" small lots as the work .progressed to give a good representation of the entire area. The resulting composite soil samples were accumulated from not less than 40 different places. All samples were thoroughly mixed before any laboratory analysis was begun. The other set was collected by soil horizons also, but in pairs rather than by individual samples. One sample of the pair was taken from or near areas where roots showed particularly heavy concentra- tion. The other taken from areas in the same horizon, at about the Field Observations 123 same level, where there were no roots at all or where they were very scarce. Soil samples collected from typical profiles of both soils were kept separate for each tree species. An exception was made in the case of the atypical profile on Merrimac loamy sand. Due to the fact that areas of atypical profiles occurred irregularly and were rather limited in extent, it was decided to maintain root concentration divisions irrespective of species. Soil was taken in small lots and was mixed to form composite samples. Such composite samples were made up from not less than five separate lots and as a rule represented at least twenty individual portions. In addition to the above, three special sets of soil samples were collected from each area. One set was taken from the A and Bi horizons, at four random places on each area. These were put into air-tight glass fruit jars. This set was used for the aggregate analy- sis. The second set consisted of soil samples taken from the middle of the A and Bi horizons in each area at six random places by means of 250 cc. soil cylinders. These cylinders were of the same type as described by Coile (8). The technique of taking the soil samples was also according to Coile's suggestions. These soil samples repre- sented undisturbed soil and were used for physical analyses. The third set of special samples consisted of three specimens taken one under the other at specified depths below the surface of the soil, from five random places in each area. Undisturbed core samples repre- senting a volume of one liter were drawn with steel cylinders, follow- ing1 the technique of Lutz (24). These samples also were used for the physical analyses of the two soils. Photographing the Roots After the mapping of roots and collection of soil samples, each tree was left standing on a square block of soil measuring 2 feet on a side (Figures 8 and 9). At this stage the trees were removed from the soil, care being taken not to disturb the roots as the soil was dug away. A white board with lines 6 inches apart was used as a back- ground in photographing the exposed roots. The central root mass of each tree of the different species in the two soils was then photo- graphed against this board. FIELD OBSERVATIONS In this investigation very young forest stands were utilized in which top layers of the forest floor had not yet accumulated. Humus layers were absent except for very limited areas around the trunks of the largest trees. Soil horizons were uncovered in the transects down to the Ci or C2 layers. The two soils and soil horizons were described in great detail in field notes included in the author's dissertation.1 Consistent outstand- ing differences between the two soils were observed. Merrimac loamy sand was developed from water-deposited material of coarse texture; the parent rocks were granites, some gneisses and schists. Gravel 1 Tale University, Graduate School and School of Forestry, Doctor's thesis. 179 pp. 124 Connecticut Experiment Station Hull, tin 454 vras found in the Ck horizon in the majority of cases. Coarse sand. often white in color, was also encountered in the C* horizon. Charl- ton line sandy loam, on the other hand, was derived from parent ma- terial consisting; of a heavy, well-disintegrated mass of glacial till Figure 7. View of the frame used for field mapping. The frame is fitted against the _' \ J fool block of soil- Note cross wires, 0.5 fool apart, which were used as lin< . I- posure of i.\ pii al pn »file in * )hai Iton fine sand) loam, Bantam Lake, Bantam, Connecticut. in which -<-liis! fragments were predominant sional large boulders were round in this soil. Erratics up t<> occa- Field Observations 125 Another conspicuous difference between the two soils was the dif- ference in drainage. Merrimac loamy sand, owing to the texture of its subsoil, allowed excellent drainage and the water table was ap- proximately 10 feet below the surface. Yellow- and brown color pre- vailed throughout the B and Ci horizons and indicated good aeration. Charlton fine sandy loam offered good drainage only as deep as the Bi horizon but, below that, due to the compact glacial till in the Ci horizon, drainage was slow and the water table was only 3 to 5 feet below the surface. An olive color in the Bs horizon was common, and blue or green colors indicating poor drainage were often found in the Ci horizon. The roots of trees did not reach into this horizon in Charlton soil while only a very few penetrated into the Ci horizon in Merrimac soil. The A horizons in the two soils were similar in color, being very dark brown, approaching a blackish brown. The color of the A hori- zon was slightly lighter in Merrimac loamy sand and this horizon was thicker, with coarser and more friable soil than in Charlton fine sandy loam. Certain similarities existed in the Bi horizons of the two soils. These horizons were light yellow to yellowish brown in color, being somewhat lighter in Charlton fine sandy loam. In Merrimac loamy sand the Bi horizon was thicker, having coarser and more friable soil. The differences in the B2 horizons between the two soils were very pronounced. The B2 horizon in Merrimac soil was similar to the Bi horizon. It was brownish yellow, and the soil was coarse in texture and very friable. In Charlton soil the B2 horizon was quite different from the overlying Bi horizon but similar to the Ci horizon. It was of a yellowish olive color and was slightly compact. In this soil the boundary between the B2 and Ci horizons was gradual and very ir- regular, while the boundary between the Bi and B2 horizon was abrupt and wavy. In Merrimac soil the boundary between the Bi and B2 and the B2 and Ci horizons was gradual and wavy. There was practically no catastrophic deformation of profiles in Charlton fine sandy loam. Occasionally in Merrimac loamy sand deformations were encountered that perhaps were clue to man's activ- ity. In this soil, in addition to these few cases, a quite common and uniform type of deformity was often encountered during the excava- tion. In more or less extensive areas of the transects the Bi horizon was subdivided into two parts which were designated as Bi and Bid. The Bi layer which constituted the upper portion was similar to the usual Bi horizon. The only differences noted in the field were that it was somewhat reddish in color and of finer texture than the usual Bi horizon. The Bid horizon was distinctly different from any other layer of the profile. Occurring only in spots, it was very dark black- ish brown in color and more compact than any other horizon in this soil. It is difficult to explain this irregularity but, considering that charcoal was found in the Bi-f soil the central rool mass was removed and photographed. Exposure of typical profile in Merrimac loam) sand, Peoples Forest, Pleasanl Valley, Connecticut, Statistical Analysis 127 The method used for aggregate analysis was a modification of the one described by Dittrich (11) and by Russell and Tamhane (31). This analysis was done on duplicate samples of 50 grams each. Net aggregate fractions were expressed in percentage of oven dry weight of the soil sample used. The two sets of soil samples taken for inves- tigating physical properties -of the two soils were soil-in-place samples and were treated and analyzed in the laboratory in the same manner ; i. e., by the method described by Lutz (24). Chemical analyses of the general soil samples collected by hori- zons were all done in duplicate, for only the most important chemical elements in the soil. Total calcium, potassium and magnesium were determined by the official methods of the Association of Official Ag- ricultural Chemists (5). Other methods used were as follows: total phosphorus by the perchloric acid method of Volk and Jones (44) ; exchangeable calcium and replaceable potassium by the modified Wil- liams (47, 48) methods; and readily soluble phosphorus by the Truog and Meyer (40) modified method. In the next series of determinations all of the soil samples were used. The entire set consisted of 93 soil samples. Mechanical an- alysis was carried out by the Bouyoucos (6) hydrometer method. General soil samples, in addition to the usual treatment, were used to determine the amount of material coarser than 2 mm. Moisture equiva- lent values were determined in a Briggs and McLane centrifuge ac- cording to the method of Veihmeyer, et al. (43). Other methods used were as follows : Loss on ignition according to the general procedure given by Wright (49) ; total nitrogen according to the Kjeldahl meth- od as modified by Stubblefield and DeTurk (35) ; hydrogen ion con- centration, pH values, by using a glass electrode pH meter ; exchange- able hydrogen by the Pierre and Scarseth (30) method, with modi- fication; exchangeable bases by the Chandler (7) method, modified by Lunt (23) ; exchangeable bases were obtained by subtracting the two base exchange values thus secured and base saturation percentage was calculated. STATISTICAL ANALYSIS After the field work was completed, transect charts of the roots of the 80 trees investigated formed a ready reference. The roots were recorded in five size classes, and the roots of others not under investiga- tion were recorded by different symbols. Each horizon boundary was shown on these charts. Since three series of transects, 1 foot apart, were made around each tree, every tree had three sets of maps for its root record and each set had four maps corresponding to four sides of the square. A count of the number of roots recorded on the maps gave the total number of roots in each class per tree. It was also possible to determine the vertical areas of horizons because all mapping was done to scale. From the areas of the horizons the num- ber of roots could be expressed per square foot of each horizon. An examination of the tables gives useful information from which conclusions can be drawn. To ascertain the validity of such oonclu- 128 Connecticut Experiment Station Bulletin 454 sions the data were examined statistically by the analysis of variance as described by Fisher (13, 14) and Snedecor (32, 33). The analysis of variance has the objective of determining whether a given differ" ence is enough. larger than that ascribable to chance alone for it to be considered significant. This is ascertained bv referring the variance Figure 9. Close view of the 2x2 foot block of soil left around a Norway spruce tree after final excavation. These transects expose the atypical soil profile in Merrimac loamy sand. Soil horizon boundaries arc marked. Note wide and dark Bi-,i horizon which is the third from the surface. Peoples Forest, Pleasanl Valley, Connecticut. ratio or ClF" value in question to statistical tables which show hew Large a value could be expected by chance alone, once in 20 trials and once iii LOO trials. If the observed V is Larger than that expected at odds of one in 20. the factor is called significant; if Larger than that at odd- of (»ne in 100, it is called highly significant. For the analysis of variance of root data three separate values, one for each transect around an individual tree, were combined be- cause the separate values did not represent any uniform distance from the stem of the tree. Once this was done it was felt that tin' Large size root- could not he included, because such roots might have been recorded more than once in \arious transects. Furthermore, the -mall roots should indicate only feeding roots of trees and as such are of special interest. The O horizon was eliminated from consideration because only a few roots were found in t liis horizon in Merrimac loamy -and and none at all in Charlton fine sandv loam. The Bi and B« Interpretation of Results 120 horizons were combined into one B horizon because of the extreme scarcity of roots in the B2 horizon in Charlton loam. If the B2 hori- zon was eliminated instead of combining it with the Bi horizon the comparison between the two soils would be thrown out of balance. Root numbers in the A and B horizons in the two soils were compared as in an experiment with split plots. The series of tests that were conducted on the soil samples in the laboratory produced a considerable amount of data. Some of these data, such as chemical tests on the two soils, served as unreplicated descriptive material. Other tests based upon individual random sam- ples, were evaluated by the analysis of variance. The statistical analysis of soil properties differed from the usual procedure in that there were no true replicates from which an error term could be computed. Two samples of soil were taken from each horizon about each tree in the study, one from a zone with many roots and the other from a zone with few or no roots. All samples from the same zone, horizon, species of tree and type of soil were combined for soil analysis, giving 60 measurements in all of each soil factor. The analysis of variance was divided into two parts. The first was based upon the sums of the paired values from the two zones of high and low root . concentration. These sums were used to differentiate the Merrimac loamy sand from the Charlton sandy loam by comparing the principal differences between them and the first order interactions between the main effects with the second order interactions which ser- ved as the error. The second part was based upon the differences in each soil property about the same trees between the zone with many and that with few roots. This part of the analysis determined which soil factors favored root growth, again in comparison with the higher order interactions. In all of these calculations, however, each soil property was treated in a separate analysis of variance, although the different fac- tors were not independent of one another. The objective was to relate soil characteristics as commonly measured to root development. Some of these relations no doubt could be explained largely if not entirely by the interrelations between factors. The independent effect of each factor upon root development could be determined by covariance and related techniques, but this lies outside the scope of the present inves- tigation and should be based upon more extensive data with true rep- licates. DISCUSSION AND INTERPRETATION OF RESULTS Physical Soil Properties Physical properties of the two soils received special attention in this investigation. It has been pointed out in the review of literature that there is more or less general agreement among investigators that physical properties of forest soils are very important from the point of view of forest growth and development of tree roots. 130 Connecticut Experiment Station Bulletin 4r»4 Aggregate Analysis Methods of aggregate analyses are not as vet established on a firm basis. In analyzing aggregates, they were subdivided originally into live size classes. Although the latter proved rather erratic, the sum of all aggregates, expressed as a percentage of the dry weight of soil sample, clearly differentiated the two soils. The results of four ran- dom samples from both the A and Bi horizons in the two soil t}'pes are shown in Table 2. Table 2. Aggregate Analysis of Merrimac Loamy Sand and Charlton Fixe Sandy Loam Soils. (Values are based on four random samples analyzed in duplicate) Soil type Soil horizon Total of the five in percentage of dry aggregate size weight of soil classes sample Average Merrimac loamy sand A 6.72 1.68 10.75 3.57 5.91 4.08 4.72 3.73 7.02 3.26 Charlton fine sandy loam A B, 23.39 6.97 31.11 19.41 24.87 13.48 34.60 11.58 30.49 12.86 The data in Table 2 have been analyzed statistically in Table 3. Charlton fine sandy loam contained more aggregate than the Merri- mac loamy sand and in both soil types a higher proportion of ag- gregates was present in horizon A than in horizon Bi. Both differ- ences were highly significant in comparison with their respective er- rors. The ratio of the aggregates in horizon A to those in Bi, how- ever, did not differ between soil types. By transforming the per- centages in Table 2 to their logarithms before computing the analysis of variance in Table 3, the variance Avas stabilized and the variability in the ratios of the aggregates could be tested critically by the inter- action between soils and horizons. Table 3. Analysis of Variance for Total Aggregates in Percentages of Oven Dry Weight of Soil Samples in A and Bi Horizons of Merrimac Loamy Sand and Charlton Fine Sandy Loam (Based upon the data in Table 2 transformed to logarithms) Degrees Mean Observed Variation due to of freedom square F Types of soil 1 1.53357 50.08' Plot error 6 0.03062 Soil horizons 1 0.S3213 28.25' Interaction between soils and horizons 1 0.00725 0.39 Subplol error 6 0.01884 Total 15 1 Significant at the l percent le\ el. Physical Properties of Soil-in-place Samples Data for physical properties »>l' soil-in-place samples were ob- tained from analyses <>f samples taken with 250 cc. cylinders from the middle of the A and l> horizons and from samples taken with L000 Interpretation of Results 131 cc. cylinders at three fixed depths below the surface. The results of these two samplings are not strictly comparable. The difference in the size of cylinders was responsible for some discrepancies. It might be expected that the smaller cylinders would allow a relatively greater amount of side play and, as a consequence, air capacity and pore volume percentages would be greater. Deductions from Table 4 prove this to be the case. Difference in the method of spacing the samples, one above another, was responsible for another portion of the discrepancies. One set was taken from the middle of the A and Bi horizons, while the other set was taken at 2, 8 and 14 inches below the surface. In the first set soil horizons were mixed, particularly at the 8-inch depth, because these samples were taken with cylinders 10 cm. in height and came from the zone where the boundary between the A and Bi horizons was encountered. Table 4. Physical Properties of Merrimac Loamy Sand and Charlton Fine Sandy Loam Soils. c o N O JC o 0) Q. £ <-> 5! ^ a O-C &&1 01 E 0 +- > c 01 01 u O 01 a. CL to & c U 01 .h 01 < CL Water holding capacity percent u vjl 01 u £ Q) => > c — . 01 >.*- 2/>.5? ' aj qj < no :» 01 >■ o E -Q £ ro hj q> lO oc o od - I ■■ 01 ■ S ■ - > ac t-^ V* and Charlton Fine Sandy Loam Soils. (Values represent percentages of dry weight; based on composite samples.) Soil horizon Gravel 2 mm percent Composition of material less than 2mm. type and profile Sand percent Silt percent Clay percent Bouyoucos colloid equivalent percent Moisture equivalent percent Merrimac loamy sand (Typical profile) A Bx B2 G 0.35 0.50 1.46 3.67 74.6 79.5 85.7 88.7 20.2 16.6 12.0 9.8 5.2 3.9 2.3 1.5 10.0 7.3 4.4 3.2 13.11 8.82 4.59 3.88 Merrimac loamy sand (Atypical profile) A Bx Bx-d B2 g 0.33 0.42 0.23 1.10 2.37 75.1 74.4 79.0 85.7 88.4 19.8 20.6 17.1 12.0 9.8 5.1 5.0 3.9 2.3 1.8 10.2 10.0 8.0 5.4 3.2 13.56 11.56 9.50 5.40 3.76 Charlton fine sandy loam (Typical profile) A Bi B2 G 4.01 5.42 6.00 5.77 56.6 58.8 63.0 60.6 33.5 29.4 24.7 21.0 9.9 11.8 12.3 18.4 22.4 21.2 17.9 25.1 21.48 13.68 10.33 13.08 All physical properties of soil-in-place samples, with the excep- tion of water-holding capacity on a weight basis, tended to differ in the A horizons of both soils more than in the Bi horizons. In seeking an explanation of this condition it must be noted that Charlton soil showed signs of greater biological activity than the Merrimac soil. Higher total nitrogen percentages in the Charlton soil, which will be discussed later, also point to the greater biological activity in this soil. 134 Connecticut Experiment Station Bulletin 4.~>4 7, w - z £ o t/j H w -' 7 OS < o N U H 2 ^ c3 - u < T) 3 n-4 o < o o i> (V o o — 1.1 NT S OF Few O u tn <: «j a > 2 p &* W g 3 < •. (5 < • N 1-3 ~ < -. Li H £ «■ H /" — 3 - ". i - w fl = pq PQ h 5 "5 o |u3DJad •Amb9 ajn4. -sio^. oo^-t-ccu-, oxc^ — x — — ~-. -r t "". ? "f ir, f^ - X N C >r: it. — ' u"> cq rsi c ci ci ;< -f to cd ■* csi x' On uS o c ■ o 0) iU3D.IBd ■Ainbs PJ3] -|0D SOD -noAnog rnNinTfir.mco;? O 00 Is. to cq OC o\ vdm o io t^i c\ c Vi x ^ cvi x c ci ^^ r^ r^; o\ vol fi CNJ On NO ";a- ON GO NO "^: .c c 4USDJ8d CMNONCNqts.X'^ocMCMXCMcooqNq ■*' ' cm' ^4 -^r co ^ -^ co i-4 co •*t C: CO m' is! On" rf- oc ooofo 00 rf' ON VOONCN On ^4 ts! -4 b a ;uaDJ3d pues fOKvjoqfoiooq^oovoqKuioNO i< cm' cd ts! co oc uS -4 t< j< o r-i 1< co o\ rsxxtsxxrs.xxtsxoNisxx «-h CM CM tsl r\j on" IS CO X — rs. ts. cm no' "S On NO rsNNX c o 4U3DJSd 'Amba ejni -sro/\| GOtO\0\0'HO\tOOCOU)fOK)vCi-io\ co^o\oqvqi-;cM^i-iNOM-i^-o cm ts! ^ cm' is -^-' co' t< t}-" cm oc i co co x' -*t csi oc -t-' X X lO c o n ;u9DJ3d ■Ajnbs pioj -|0D SOD -noAnog rHN'<5N^qvOO;-;i-(fmXOiM ON tsl Tf" o ts ^f 00 no" -^ 00 ts C5 CO "-) n' ^^ On On On NO CO is. cq — < oq ON ON tsi i^-' o o c 0 }U3DJ3d 00qitNit'to\'/)N^;rtKr-<\qo ^ r^ eg iO ro oj fO CM »-i f*5 <"*>' i-< Tf r\i rt CO i-i X Tf CO i-4 i-O On no CO •<*■' co CM CM' E 0 2 is 4U3DJ3d 4I!S ^^i-;fqM3O^rf^C7s0qis.\qi-HO\C\I Cn -t ^ C\ vri d « VC O 00 lO O OS rt-° o\ cq rt no CNlWd NO NO i-> ■* On O no' Cm' b 5 4U3DJSd pues q q u> in q is n m Tt oq (Nj n oq if / oq uS ^4 trj .-4 lo KKK00 Soil hori- zon < oa.pq « X, > ^ u to u CI O -'3 s On- « •/) 4> U 1) > U u •— a U *^ CO 01 a. .i | erg sit* U 'r' O 4, • - n -' P u q ■ a. o — ^~ Interpretation of Results 135 vOOO'^OVOMOOiHON'tONMN rt \0 6 T-i ^t 6 t-5 Tf rH M' Tf i-J tH Tf t— i NHr- I C\1 t— It— I CM t— It— I CM T— It— I N tH H vqOT-;tHvooqNifi' no in o no' cm 1-! K ^'l^.toN'Oioio^.oqqqqq inttfONr-1 CJ O in Hr-iirinNKMrtuirt OjHHNHHNrHHNrtHMr-lrH enm cm NO") t-i \dt-H OOT-Hoqininrqt^oojvq q-q t->. cm t-h H!<)KNHO\0\oiHH'0\t-idcCC> q^ooNiOr-iifirHq^tfqojrrqio T-i t-H o odddts os t— i o\ d t-i cd d m' On en co oddt-i THrMtNNOO\wts.inNioif)OOn50 en cm' in ^t-" r-J no in -h oo' dtots-tt-Jd cococMenencMcococMeococMeococM oc on o Tf' T-4l< en en cm q'tioq,tqqNiott(M^oooo\N in no l on o rt-' vd o \d oo' o minNOinmNoinmNOminNOinmNO en 00 N vok-h in in no » P u § gH 136 Connecticut Experiment Station Hull, tin 4~»4 All differences, of physical properties between horizons ascertained from the analyses of soil-in-place samples point to the much more fa viua I ile conditions for root growth in the A horizon. Highly sig- nificant interactions between horizons and soils indicate more rapid changes in the physical conditions of Charlton soil from the A to Bi horizon in comparison to Merrimac soil. Mechanical Analysis Textural differences between the two soils were quite pronounced. This can be seen from the field description and from examination of Tables 6 and 7. Gravel coarser than 2 mm. was present in the G hor- izons in both soils but the amount in Charlton soil was almost twice as great as in Merrimac soil. In the A horizons the two soils differed eyen more in their grayel content. In Charlton soil it was still high but in Merrimac soil the quantity present was negligible. The three soil fractions of sand, silt, and clay are given as percentages in Table 7. The two controlling components, the sand and claj', reflected the existing differences and have been analyzed statistically in Table S. The percentage of silt and the Bouyoucos colloid equivalent, which in- cluded the clay and the finer part of the silt, are given for descriptive purposes. For the differentiation of soil types, the data from zones with many roots have been added to those from zones with few or no roots for the computations in the upper part of Table 8. The outstanding difference between the two soil types was the higher percentage of sand and smaller percentage of clay in the Mer- rimac loamy sand. The percentage of sand rose with increasing depth in both soils but more sharply in the Merrimac loamy sand, both trends being highly significant. The percentage of clay, on the other hand, decreased with depth in Merrimac loamy sand but increased with depth to nearly the same extent in Charlton sandy loam, as shown by a mean square for soil horizons hardly larger than the error coupled with a very significant variance ratio or F for the interaction between soils and horizons. The percentages in the two soils of sand and clay and also of the correlated silt and Bouyoucos colloid equiva- lent agreed most nearly in the A horizons ami diverged progressively ;it I he lower horizons or depths. Field records also had noted a smaller difference in the two soil types in the A than in the C> hori- zon. The above observations are consistent with the modem theories 'it' pedology. Glinka (15) has shown that, regardless of the parent material, undisturbed soils under the Mime climatic conditions will in time become essentially the same. The two soils in this investiga- tion have different parent material, hut they were located only 20 miles apart. Since there was n variation of some l.'.ii feet iii elevation be- tween the two areas, some local climatic differences undoubtedly ex- isted, but the genera] climantic conditions were very much alike: hence the two soils tended In lieeome similar. The A horizons, being most exposed to the element-, showed the greatest response to the climate; Bi horizons, being more protected, displayed effects of climate to a lesser degree, and the c, horizons leasl oi' nil. Interpretation of Results 137 U rt < 6 !> ° y. 2 S M w o ►J « < > K >-I rt 13 < o a « w S £ W < [i. rt [/J o iJ s X « B LI fa K- ►J « u < h WW u w txj S w h < u wN pq < w 3 u < & o < J M < ix > fa O < •Si >\±* < n < H ►J PS «1 oo K w U J w p < ^ H < 2? oooo t^ CO t— I lO NNO no no t— i CO 00 CM 1^ no ■«*■ co cm' ■*' o CM HO On-* ■<*■ NO CM -vi- ^t- co NO\fO co co CO ON nOOHin OONmrH lOOO O i-i 1-H 1-H O O O ^«K O "St" r-i r>> i-h t^. ■HfTt oofoi-i ^r O cm' i-H O CM O On o CM co m r^ o CM O VOCN^ONM i— i co o o in. ti- co vq t-h \o o o <-< «-i o u; NOOO NO NO Tj" i— i ■* CM CM ^f "* O co io o CO ON CM co i— i O co co m oo "Hf CM NO NO; CM O t-h O oc ^t- ■ NO l-O ■**■ co CM O t-h o -h 8!*; "8 00 ° CU THNt ^1 Tf CO OOt-h CM ^t" CM O' * G O .^ m .a u a » « i rj o w « CLI .2 o -• horizon. which may he attributed to the high percentage of inorganic colloids in the glacial till of the C> layer. Moisture equivalent values averaged significantly higher in zones with many coots than in neighboring soil zones with few or no roots. emphasizing the importance of soil moisture in the economy of trees. The contrast in moisture equivalent between the two zones was several times more marked in the heavier Charlton fine sandy loam with its two-fold high percentage of moisture equivalent values than in the lighter Merrimac loamy sand. Root growth proved more sensitive i" moisture relations in the heavier soil. The significant interaction mi Table 8 between root zones and soil horizon- showed that the re- sponse varied with depth. Two zones of root concentration had nearly the 3ame moisture equivalent in the A horizon, but differed markedly in the B horizon-, the difference being most pronounced at the Bj level in the heavier Charlton soil and at the B« level in the Interpretation of Results 139 lighter Merrimac loamy sand. This finding is consistent with that of Lutz et al. (25), who found that moisture equivalent values were un- mistakably higher for zones with many roots, especially in the lower soil horizons. Several investigators, Morgan (27) and others, have noted that a degree of correlation exists between moisture equivalent values and other properties of soils. The large number of soil samples analyzed in this investigation offered an opportunity to test the direct corre- lation existing between moisture equivalent values and other soil properties. The highest correlation coefficient (r = 0.907) was found for the loss on ignition. Since, loss on ignition largely reflects the presence of organic matter in the soil, it can be well understood why it was closety related to the moisture equivalent. The content of or- ganic matter in turn may account for the related values of total nitro- gen and of total base capacity found in the soil sample analyses. The correlation coefficient between moisture equivalent and total nitrogen was 0.834, and between moisture equivalent and total base capacity it was 0.871. Moisutre equivalent with Bouyoucos colloid equivalent values gave a smaller correlation coefficient of 0.778 which would be expected, since not only organic colloids but also inorganic colloids are involved in the latter. All of the correlations thus found to exist be- tween moisture equivalent and other soil properties are in general agreement with those given by Morgan (27). Chemical Properties Analyses of Certain Chemical Elements in the Two Soils Earlier authors placed more stress on the chemical relationships of forest soils than is done now. Exception is made in the case of nitrogen which is still considered to be important. It was decided to compare the two soils under investigation for some of the more im- portant chemical elements. The results of these analyses are shown in Table 9. The A horizons of the two soils agreed closely with respect to total calcium, potassium, magnesium and phosphorus. The first three of these elements did not vary to any appreciable extent between hor- izons in Merrimac loamy sand. In Charlton fine sandy loam there was some increase in these elements from the A to Bs horizon, but a very sharp rise occurred in the G horizon. The percentage of total phosphorus decreased in both soils from the A to lower horizons, but in Charlton soil increased again in the Ci horizon. The total amounts of calcium, potassium, magnesium and phosphorus in the two soils and several horizons differed much less than the physical properties. Differences in the distribution of tree roots between the two soils and the soil horizons, which will be discussed later, were not related to the amounts of these chemical elements in the soil. The absence of differences in these elements in the A horizons of the two soils is not in harmony with the fact that the parent material of the two soils differs in mineral composition, as attested by the chemical differences in the Ci horizons. Total calcium, potassium, 14<> Connecticut Experiment Station Bulletin 454 o 5 h-1 « to = U £ z « Z .b c/5 •-< < » o *- * ^ h 2 :_ a >£ c u a -J- Cin i . -t- ^_ Base satura tion percer co »— i co co CO to l^ CO 3\ ~' C CO O Cs ^1 O C: CM cc ""; «0 -. to _' .— « to o 00 CM On On 1-4 •<* «-4 CM ON to Id CO CM CM co o 0) >. 00— -. Tot a n O C c 2— ai o ^X 00 — i CM 00 Soluble phos- phorus p. p. m. «-i to CO 00 CM CM CM »-i O —i CM »-i t^ CM CM CM (V) r-H o co to c\ b . a> up c & 3 ^E i—i to O CM CO co CM to C^J i— i M^rtrH in N X M o -* --I oo CM i-H CM t^ O to ■<*■ o CO ^fr t— I pH CM CO CO CM r- 1 CO O to CM i— i i-i o o p p o o o o o CM CM CM to -i- 1 —■ o NOOO O O O O : fD (11 o 1 H LI a to CM O VC co no -i- « c Q O *^ > < iC ^ g u h a o a >. S3 •.. - X 5 N -./ 3d en J u □ <=> < cMcvvOTf cm Tf Tf 0>C\N^O -ejn;es O Tf co C»i Tf C\ C'*'-'Mir,fCNK cococvj-ocOCMcOTfTj-cocOTfCMOqco co co Tf Tf 9seg '3 Ul 'A^oedeD aSueipxa 1^ ^1 CO fO I CO rM 00 r»3 »-i 00 Tf Ol rsl CO »-< t>I CO t-J t-* co i— i XioON |e;oi san|eA Hd CO to u-; co to to CM O 'O *>J io \C •>) to VO. CM to VO "VI Tf ro VO » CO *— < "~- X K t»5 ir, (\] co "t X ifl r'1 2 " ^J 3! rt " ^ " " 2 ™ R1 !• " O c: to NtlH CM £>. vo cm OOOOOOOOOOOOOOO O C O ~ © oo ;u33J3d uoi4.;u3; Tf tN.i-H Tf O O VO CM ON co lO CO CV CO UO SSO-] Tf CM i-i Tf rv) i— i Tf C\j t-H Tf Cm' O Tf rH t-i TftMrt Tf "O CM y- 1 ;uejjad uoj; -Bjn4?s aseg o>cctovqcococ^cococMTfoqcococq odr\icooiOTt;io'^:cocot->!^Hcdco-H CMCOCMCOcoCMCOCOiOcocotoCvjCOto LU AipedeD aSueipxa san|eA Hd 4uaDjad ua3oj|iu |8401 4U3DJ3d uo!4|uSi uo ssoi t->I co" i-h 00 co r-i CO CO i CM i t-x <0 T-i t>L co <— ( N^OCA\OOMvOl'5000\X,t CMTfvOCMTfinco^OCM^O^OCMtovO i/~j io to 10 to to to to to to to to to to to CM CM to l^» CM <^1 Tf ^OOvONNcoto^t r-lOOT-jOOt-HOOt-HOOr-jOO O O O O O C © ©©©©'©©©'© Tf 1-H CM I/J CO CO Tf Tf cm to vq lO ITJ lO Tf o r^ CM TT ,-H ~ o o tM'-itMrttC)rH^r,)rtTffMo CO LO ^f iciMN Tf oi ~ r,vr,inm CM i^ VO CM •-; o o p o o o o Tf CO OS Tf VO Tf VO co Tf co CM" ^ ^'S ^mpq^pgcq^pqpcj^cqeQ^cqpq Oh rt CO . •— o b ri' P.-3 .5 £ >.'-n 4> — w O, ^ -_- „ bo It «= 4J < ° tn ^ — - - E E &«« Interpretation of Results 143 u-Ju-ju-ju-ju-ju-ju-J'-'"Jiol/"JljOu">u">lJ"5u"5 in«ioKO\'*ooo\tonooto,tMD . .OOCOmOOcoCMVOCOooO^^OOCM rj-iOto-tir)MOOO\Nr- i O 00 Tf u"S On rH ■*' CO t-h CO CO i-H CO co" CM "^ co CM CO !N NO CM CM 00 r-i CO rt Tt" CO CM •<* 10 u-j u-j u-j OfOrnNNMNOOOCrHTl-COcoMDvO CM O O CM O O CM O O CM. O © CM O O 0000000000000 o'o O CM On co 10 O CM O O © O O t.'co >-5 oo\"5,tHcofoqo\iootoa)ooN r-i io CM On NO O0 CM •* cm' u-j Tf-' tJ- >-h vo W cOCMCOCMCMCMCOCOcoco^J-"^-coCM^l- i-5 rf CO o -^-' CO cm ■* cm' cm' no -^f' CM ^ CO in On co co r- ir^cOi— i t-h On 00 CM O -3- O t-h CO ^ i— I -* ; tT r-j -*t LO CM •* iO CM Tf u-> u-j u"j u-j m u-j u-j*u-j u-j u-j u-j u-j u-j u-j u-j u-j N0000Of0N>O'-i000\0N\0OK0\ CMppCMOOCMOOCMOO'CMOO OOOOOOOOOOOOOOO OOTrcvit^cocMOOcoCMONcoCMCOcOT-i .-< CM\q cm' cm'K CO CO CO cou-jlo r^r^co .-! ■* CO' 00 CO ON u-j u-j u-j (M Tf Tj- ■* VO .— i CM O O CM COO CM NO «-J 00 CO cm' s HBg O « N gj o ^ " — - ^ < , 1 u - as W 7 > - < s « . — - /. < as C oq ' >E f- £ V. < x - — - — Q ~ = c 0 in -4- ^ c T3 > QJ LL. O -0 r^ <>« ^ 0 1^ =5 0 ^ MXC com' 0 On O "> Q), CO -2 to 14.00 256.19 201.38 cm co O co 0 on vd no ** c^ co 00 CO CM* -+ OO O 21.48 5.07 53.01 21.36 12.03 2e r- 1 LO CM O co co <"M ON -* rt 2& SJ, c«- o a,. On t^ co co to -3- r-5 cm' d CM lo -^- CC o — 1 m o o CM ■* r-J O f . N X fO O OOlNOVO o •— — cm a vbco >o co ^> \o on "^ co' NO co C\ O co O - C~ O .-i CM CM O ^t- ON CO 'O CO lo O Hino OOO t^ Cn ^f •HQOO r-f vo *-< o o o 000 OOO O) ih K >0 IT, MONOm O O — i-H o 00000 o dodo r^ CM ' Os ""J on no CaO-h'O On CO 'O O --t CM' O" CM ■tvOON ON o\ o CO IO CO CO O ^h O ^) o rvj i_o o O -h O o o o tlO'SI OS o ^o LO O O i-it^l O ui K O tO ^f cm •— 1 ro r> 1 1-10000 o 0 o o d Q i — * ~i -1- m o f« ' u r c u u a T S.a 1 — > 0 ft -r 0 0 ' < — -r -r : :/ a B LI a rs n - B 0 y ft t u V u ' /. 0 1 : J3 -• M •- tH '. — w _ c ■■- "Z u go O ^ ' o ft rt • S -^ • — I OJ 5 - «-> o - : « u N hH -c -0 -a -o q c b a ."^ ^ ."d ••■-' - ^ _■ . ; - > > : : i w w E a c 1 1 - '1 : S — 3 *-* ■*■■' ■/) a id — c - c - •" - a c £ -Z m Interpretation of Results 145 of hydrated inorganic colloids in the d horizon influenced the loss on ignition values for this soil. The difference in loss on ignition between zones of root concen- tration and soil zones lacking roots was highly significant. It in- dicated that the roots were concentrated in the zones with greater con- tent of organic matter. The significant interaction between the two soils and root zones was due to a relath^ely greater difference in Charlton fine sandy loam than in Merrimac loamy sand. Total Nitrogen Total nitrogen in the soil is of considerable importance and has a bearing on its fertility. Nitrogen is an element important for plant growth. Total nitrogen percentages for Merrimac loamy sand and Charlton fine sandy loam are given in Tables 9 and 10. Analysis of variance of total nitrogen for 60 soil samples is given in Table 11. The difference between the two soils was highly significant, the total nitrogen being much higher in Charlton fine sandy loam. The fall in total nitrogen from horizon A to Bi and B2 was ex- ceptionally large and approximately in geometric proportion. High significance of the interaction between the two soils and horizons was due to a much sharper drop in nitrogen from A to B2 in Charlton fine sandy loam than in the Merrimac soil. Nitrogen values for the two soils in the B2 horizon were nearly alike, but in the A layer they were about twice as high for Charlton soil. In Ci total nitrogen for Charl- ton soil was even less than in Merrimac soil. The atypical profile of Merrimac soil showed considerably more nitrogen in the Bi and Bi-d horizons, as compared to the typical Bi horizon. Several investigators have pointed out the favorable influence of nitrogen on tree root development. When roots die they contribute organic matter to the soil. Organic matter and decomposition prod- ucts increase the nitrogen content. Total nitrogen in the soil zones of high root concentration can be either the cause or the effect of the roots present. In the young forest stand used for this study higher total nitrogen percentages occurred in the zones of root concentra- tion than in the soil zones where roots were few or lacking. The dif- ference in total nitrogen values between soil samples from the two zones was statistically highly significant. In Merrimac loamy sand the difference in total nitrogen between areas of high root concentration and those of low root concentration was rather small, but in Charlton fine sandy loam the difference was significantly larger. Mycorrhizae were present in the Merrimac soil in conspicuously large numbers. At times, in the open transects in the field, it appeared that almost all small roots in this soil were mycorrhizal. According to Hatch (17) mycorrhizal roots, by means of the increased absorbing surface, are able to extract the needed nu- trients from the soil more effectively than other types of roots. Thus large differences in nitrogen between the two zones would be less ex- pected in Merrimac soil. In the Charlton soil, where mycorrhizae were few, the association of high nitrogen values with the zones of 146 Connect '/rut Experiment /Station, Bulletin 451 root concentration was more in evidence, a reasonable result from the above assumption. Differences in total nitrogen percentages between the tree species and interaction between tree species and the types of soil were sig- nificant. For white pine and white ash, the soil samples from the zones of high root concentration, showed more total nitrogen, partic- ularly in the Charlton soil, in comparison to corresponding samples for the other tree species. The larger size of the white pine and the greater tendency of white ash trees to build up nitrogen may explain the situation. Soil samples taken around red pine roots on Merrimac soil showed high A'alues; those taken in Charlton soil showed low values as compared to other species. Hydrogen Ion Concentration (pH Values) Slight variations in acidity within the limits usually found in nature are not considered decisive, as has been indicated in the review of literature. Acidity is readily measured with modern pH meters and is considered necessary for a complete description of any soil. Hydrogen ion concentration (pH values) for the two soils is given in Tables 9 and 10. Analysis of variance of pH readings for the 60 soil samples in Table 10 is given in Table 11. The higher pH of Merrimac loamy sand was highly significant in comparison to Charl- ton fine sandy loam, indicating that the latter was the more acid. The differences in pH between horizons were highly significant but the interaction between soils and horizons was less than the "error." The two soils paralleled one another in showing a relatively high acidity in the top layers, which decreased with increasing depth. The two soils investigated belong to the Brown Podzolic group, and similar soils were classified by Lunt (22) as having a mull type of humus layer. In this type of soil a somewhat higher acidity would be expected in the top layers than in the parent material of the 0 horizon. The atypical profile in Merrimac soil showed practically no difference in the acidity of its Bi and Bi-a horizons as compared to the II horizon of the typical profile. The average difference in pH between /.ones of high and low root concentration was too small to be considered significant, but a com- parison of the five species showed in both soils a higher acidity in Zones with many roots than in /ones with few roots for all species excepl ii'*\ oak. In red oak this relation was reversed, the /ones with many roots being significantly less acid. Base Exchange Values I la '■ exchange relation- arc rccci\ ing increasing all cut ion in more recent investigations, as has been pointed oul in the review of liter- ature. Total exchange capacity, exchangeable hydrogen, exchange- able bases and percentages of base saturation were given attention in this investigation. Data concerning the base exchange values for the two soils are given in Tables 9 and L0, and the analysis of variance of 60 soil samples in Table 1 1 . Interpretation of Results 147 The total exchange capacity was significantly higher for Charl- ton fine sandy loam than for Merrirnac loamy sand but in the per- centage of base saturation the two soils were alike. Total exchange capacity decreased sharply from the A to Ci horizon, while base sat- uration percentage increased with increasing depth. There was an ex- ception in the Bi horizon for Charlton soil, which was due presum- ably to the low content of exchangeable calcium and potassium noted before. In the atypical profile of Merrirnac soil the Bi and particular- ly the Bid horizons showed exceptionally high base saturation values. This again coincides with the exceptional values for exchangeable cal- cium and potassium in this horizon. The total exchange capacity in Charlton fine loamy sand dropped notably between the A and Bi hori- zons, and comparatively little from Bi to B2, while in Merrirnac loamy sand it decreased at a geometric rate from the A to Ci horizon. The total exchange capacity differed significantly between the zones of high and low root concentration and was relatively high in the zones with many roots. These results support the conclusion reached by Lutz, et al. (25), who found in older stands of white pine a significantly higher total exchange capacity in the zones of high root concentration than in the soil zones with few or no roots. They concluded that high values of this property favored the development of roots. Although closely similar in the A horizons, in the B2 and particularly in the Bi horizons total base capacity in the zones with many roots was considerably higher than in comparable soil zones with few or no roots. Apparently base exchange values were of greater importance for the development of the roots of trees in the lower soil layers. Significance of interaction between soil types and tree species brings out the facts that total exchange capacity values in the Merrirnac soil were high for Norway spruce and low for white pine as compared to other species. In the Charlton soil these values were high for white ash and low for red pine. Differences in the percentage of base saturation between zones with few and many roots varied significantly with the species of tree. The zones of high root concentration for white ash and red oak had a higher percentage of base saturation than zones with few or no roots, while the reverse was true for red pine. White pine and Norway spruce showed no apparent "preference." From the data on the various soil properties it can be concluded that, aside from a few chemical similarities, the Merrirnac loamy sand and the Charlton fine sandy loam differed in practically all soil qual- ities investigated. Differences in some of the soil properties definitely favored the concentration of tree roots. Root Distribution in the Two Soils Maps or root charts prepared in the field offered an opportunity to study variations in the distribution of tree roots. After defining the differences between the two soils and several soil horizons and measuring their significance, it was concluded that not one soil prop- erty, but the entire complex of properties, was responsible for the dif- ferences in root distribution. 148 Connecticut Experiment Station Bulletin 454 MERRIMAC LOAMY SAND CHARLTON FINE SANDY LOAM Dlstonce from the middle of tronsect fo the tree, feet. Soil I 2 3 Tree I 2 3 species Room mi mm oo» inchti Rocli lor$«r then 001 inclii Figure 10. Number <>f roots in two size classes in vertical sections of soil pro- file horizons in Merrimac loamj sand and I harlton fine sand) loam, I Based on tlic counl "i roots in vertical cross-sections surrounding n'.^lit trees of each species.) Interpretation of Results 149 MERRIMAC LOAMY SAND CHARLTON FINE SANDY LOAM Distance from the middle of transect to the tree, feet. Soil I 2 3 Tree I 2 horizon ^^^^^^^^m ^^ mm sPeci*s ^ ^^^^J^^^^^^>| ^^^ A __ _ ' ": ■ __ ■ I ! : i Roots Ust than 0.05 inches in diameter Roots larger than 0.05 inches in diameter Figure 11. Number of roots in two size classes per square foot of areas of soil profile horizons in Merrimac loamy sand and Charlton fine sandy loam. (Based on vertical cross-sections surrounding eight trees of each species.) 150 Connecticut Experiment Station Bull, tin 454 Three sample root charts are given in Figures 4. 5 and 6. Root maps prepared in the field were used to count tree roots and to deter- mine soil horizon areas. The number of tree roots and the roots per square foot of exposed soil horizon were tabulated. The resulting data are presented graphically in Figures 10 and 11. Photographs of the central root mass. (Figures 12 to 21, inclusive), illustrate the root distribution. In these photographs the small flexible roots do not retain their horizontal position but droop down under their own weight, thus giving the suggestion of somewhat deeper root penetra- tion than was actually the case. Distribution of All Roots The maps and diagrams show that roots in Merrimac loamy sand reached much deeper than they did in Charlton hue sandy loam. Roots of trees in this sandy soil not only penetrated the A and Bi horizons in larger numbers but even reached the Ci horizon. Comparison of photographs of the central root mass confirms this observation. In the review of literature Laitakari (19) was cited as expressing the view that the deepest root systems occurred in saiuW soils and that they decreased in depth in clayey soils. This fact stands out clearly in the present investigation. This also was an important factor con- tributing to the development of shallow root systems in that soil. There was a proportionately greater number of large roots in Merrimac loamy sand than in the Charlton soil. This fact leads to another conclusion, previously expressed by Laitakari (19), i. e., roots of trees growing on light sandy soils do not branch as much as they do in rich soils. More large roots were encountered in the tran- sects in Merrimac loamy sand than in other soils. As the photo- graphs show, branching in this soil was not as extensive as in the other soil, but the roots that were present were larger in size and more widespread. A very rapid decrease in the total number of small and large roots from the A to Bi and B-> horizons stands out clearly. This supports tlif conclusion reached by Lutz, et al., (25) that most of the tree roots are found in the A and B horizons in forest soils. However, the pro- portion of large roots in the lower horizons was greater than in the top soil layers. The decrease in the number of roots in the lower hor- izon was even more noticeable in their distribution per square foot of vertical horizon areas. The rate of decrease between horizons was much more rapid in the Charlton than in the Merrimac soil. ( lomparisons of root distribution in three transects, at 1. 2 and 8- footi distances from the trees, showed that the trees in Merrimac loamy sand have a proportionately greater number of roots at a srreater dis- tance from the stems than is the case in Charlton soil. This is par- ticularly true for the large size roots. It supports the view of Aalto- nen (2) thai roots of trees spread widely in light sandy ^oils which are poor in nutrients; in heavy -oil-, rich in nutrients, the root spread i- less. The Fact thai roots reached deeper in Merrimac loamy sand indicated thai the total volume of soil occupied by the root- of an in- Interpretation of Results 151 dividual tree was much greater in the Merrimac loamy sand than in Charlton fine sandy loam. A comparison of the three transects, 1, 2 and 3 feet from the tree, showed that the number of roots differed less between horizons at the greater distances from the tree. The roots penetrate more deeply and a relatively smaller number of them remained in the A and Bi hori- zons, as compared to the B2. This held true both for the total num- ber of roots and for the number of roots per square foot of the ver- tical areas. At the same time the proportion of large roots increased at the greater distances. In addition to these observations there was a tendency for the root crowns in Charlton soil to produce heavy branching in two horizontal planes. Not all trees showed this but there were- enough of them to make it noticeable. On examining corresponding field maps of the transects these two planes appeared to be at a more or less consistent depth. Heavy branching was in evidence in the A horizon just under the sod and at the boundary of the A and Bi horizons. This resulted in a very distinct two-layered root system for some trees. Evidently the heavier branching occurred at those levels where the greatest quantity of nutrients was available. In Merrimac soil special attention was given to the atypical sec- tions of the soil profile. In counting roots of trees on the root charts, sections of transects having the atypical pattern were separated so that they could be compared with, the typical profiles. Three tree species — red pine, white ash and red oak — had a heavier concentra- tion of roots in the Bi and Bid horizons of the atypical section of pro- files, in comparison to the corresponding Bi horizon of the typical sec- tions of profiles. As shown later, these species had a higher proportion of their roots in the Bi horizon. Red pine showed a most pronounced tendency in this respect. Moreover, red pine roots not only concen- trated in the Bi and Bid horizons of the atypical sections of profiles, but they were fewer in the A horizon of the atypical profiles than in the A horizon of the typical profiles. It must be recalled that in the analyses of several soil properties the Bi and, especially, the Bid horizons proved to foe richer in nutrients than the Bi horizon of the typical profile pattern. On this evidence it can be stated that, if the areas of soil horizons having particularly favorable properties are within the reach of the roots of trees, the roots will have a tendency to concentrate in such areas. The presence of such areas in the lower horizons offers special opportunity for the species of trees with deep root systems. Distribution of Small Roots Data pertaining to the small roots were selected for statistical analysis, omitting those pertaining to large roots for reasons previ- ously mentioned under the heading of statistical analysis. Further- more, there are important differences in the physiological functions of the two types of roots. There is a generally accepted view that large roots have as their function the anchorage of the trees and conduc- tion of nutrients. Small roots are mainly feeding roots. At what 152 Connecticut Experiment station Hull* tin 454 V£3 Q ~ 9 >. - h-) 0) u - o ■- - ! -f' t■ D ~ O a ^ toMnomomOv X incocoo\(3sr>.coco ON •i-CNtoin o-Hin CO c o DO -"IMOfllT; -O U~y LO 1^ a\ m t^ co co ^o on ir, t}- co ■* rnO^K "* — o >— 1 1— ' ■""-irtN CM •~ c 2 o [U c -O J E cj OMN^fOHOOOO r-1 romcor^coococo NO HONOm^^TfN NO Z < tt CM ,— , cm r^ cm ro co ■Tl- Tfri^-rtinttin c en co t^ x ro o — i -h X fo m o "fn ^- fo r^i ^f ^h tJ- <-\) CN] CM co CM CM CM <— < CM Tt CNJ r\) CO CM ■* CM o a) +;4K qoNoo ■-; — < cm ^o 3| cq cm_ on -* ^q ^f ■* cq in qo'tcoq^-,*oo CM .B? o t>! r^ t->! "i o O lON'OvONVDOO NO o -vd o 'o no r< vd ^f NO Ii jj m t^ IN ■* On rt ; On 00 O Tj- O i-« r-i co" o ^r CO cq ^o cq ^h o\ co r* t^ CO CM- r-i CM' O CM CM' O CM inowocnoNN-tq cJO'-icdcdo'-'O o -4- 0) ° f5 01 O" JD m E & z ^ < (^] o m in rrt •<* o eg -H CO co in Tf CO On Tf cq -r c o N -t-' -r -r o\ 3< — .' ro i-H r^ -rf-' -rf co ! «— i o co in >— < r^. (N) t '^- m in N in -i rf' 13 C r- 1 — to 0 >■ E o o ^ r-.0~)lNCMeo'Oeo r i m Oi oo O o 't ■- ico -r cnNO'ON^t-N^rj- — tomc-NM co i^. - o o o j^. o in i^. \o c (omoOi- 1 in co t^, co ITS ro o CD CO ^^ro tT >• 1 ^rtrHrt CM H E m o 2 a E Z - Xr|^ff)OMH CM in m on os cm co co m ON NO CO CM *+ CO in CM r\] X mcom t -h ri rt k m 00 t(- CNl t)- ON « 3\ T NO NO m CM O CO CO NO c < rt-lr-(COm'*rHfO CM rt ^ r— rt CN] CS] ~ "o J o^i-t-rcoo^io co in O 00 fO N In q o in in no On cm cq ^i rq t^. CM DO . ■5g inaJO'dNoo vd d vO cou-j-dco-^iN'din' 6 -rf CO CO -+' in -t NO 'cf in > > > ,9; < < < 1 •^ |s ? u h r- c. •O's, u "- ^ rv X Interpretation of Results 153 rt-_ on oq ^j-_ >o u-> oq in. rv.Tfi-niN.cvju-jfvioq co t-J od \c i i-o iiri i ^ t-! CM O O r-H,0 -i-H CO O r»5 VO 't ^ C\ rn Q\ \D cm co »— < °o co co i— i 0\NO On.tJ- "O t-h CO V*) -Tt- C3 rvvrr-, i — I fMK Chcot^CMOO'— iO\h OM'^ONO't^O CM-^CM^O-Nf-OOO CO i-H rH M- rt rH CO N inOVOONCOCotNOv "NhohhOO '-JIN.CvllOlOOCVIlO O O O T-i O rt o o OcONmCtN^O v£) u-j ^ i/-j "sj- >-o' "^f CM OrHO«ino«K co o\ io oo ^- ^t oo oo 00 ON CM t-h 00 <— i O in\0O0\(NI000\0\ COHrtriMrHrt vqiflOrHioo^t •^ vo ^ irj -rt1 tJ-' CO CM- CM CO ^ 00 CO t— i CM 00 O rnrtONcooi cm' C0CM00-HtN.\0O\~* VO t- i co ■* O r- I -"■ ■tOOmtNON cm' ^f' CM' rr' co ^ CM CM < tf 154: Connecticut Experiment Station Bulletin 47.4 root diameter class this distinction must be made is hard to decide. It is fairly safe to assume that all of the smallest were feeding roots. Data for small root- are given in Table 12, separately for the two soils, five tree species and for the eight individual trees of each spe- cies. Boots are reported both in total numbers and in the number of roots per square foot of the vertical horizon areas. Results of the analysis of variance are niven in Table 13. The number of root- was significantly greater in Charlton line sandy loam than in Merrimac loamy sand. This supports the pre- vious conclusion that, in the richer Charlton soil, copious branching of roots occurred, resulting- in a large number of small roots. At this point it will be observed that Merrimac soil, poor in nutrients, sup- ported trees of the same age and about the same size with a lesser number of feeding roots than was the case for Charlton soil. The difference in the total number of small roots in the two soils was sig- nificant but the results cannot be considered decisive in view of the fact that there was a difference in the type of small roots in the two Table 13. Analysis of Variance for Total Number of Small Roots (Less Thax 0.05 ix. ix Size) axd Number of Small Roots of Trees Per Square Foot in Vertical Sectioxs of Soil Profiles ix Merrimac Loamy Saxd axd Charltox Fixe Saxdy Loam. (Based Upon the Data in Table 12) Variance based on The number ot roots in both A and B hori- zons The difference c>\ number of roots in the A and B hori- zons Variation due to Types of soil Tree species Interaction between and tree species. . . Error Total soils Difference in A and B horizons Interaction between A and B differences and soil types and tree species and soils and species.. Error in A and B difference. Total Grand total 159 : £ 1 4 4 70 79 1 4 4 70 si I Number of small roots Mean Square 87.1J(i 362,946 25.130 IS.572 293,951 96,53] 80,618 53,198 4.502 Observed F 4.691 19.54s 1.35 65.29s 21.-14 17.9L 11.82 Number of roots per square foot of horizon areas Mean Observed Square 125.53 203.4c 21.71 7.39 7Q9.81 (4.2-. (-4.27 24.08 2.31 17.38- 27 52 2.94* 307.01= 27.80-' 27.80 10.42- alflcanl --it the 5 i"-. ■■• al level, nlflcanl ;it the i pen enl level. soils. In Merrimac Loamy sand small roots were predominantly my- <•(irrliiz.il with Large absorbing surface, and in consequence ;i Lesser n ninl >n fine sand^ Loam. It i- believed thai the influence of ^>il fertility i- evident primarily in the type <>!' roots developed, and thus only in- directly in the number of roots. Interpretation of Results 155 There was a highly significant difference between the two types of soil in the numbers of small roots per square foot of the vertical horizon areas. It was much greater in Charlton fine sandy loam than in Merrimac loamy sand. This leads us to a conclusion reached by other investigators, as cited in the review of literature, that rich soils induce more copious branching and produce a higher concentration of small xoots in a given volume of soil. The presence of a heavy con- centration of small roots in Charlton fine sandy loam is confirmed by the photographs of root crowns. Highly significant differences existed between the A and B hori- zons in the total number and the numbers of roots per square foot of horizon areas. The number of small roots in the A horizon was greater than in the B horizon. Interactions between the A and B differences and soils were also highly significant. A relatively greater number of small roots occurred in the A horizon of Charlton soil than in the A horizon of the Merrimac soil. Thus it is true that small roots of trees on heavy Charlton soil not only had greater concentration in a given volume of soil, but this concentration was most pronounced in the A horizon of this soil. Root Distribution of the Five Tree Species Some differences in root distribution between the five tree species can be noted from the examination of the root distribution diagrams and tables. In analyzing statistically the total number of small roots and the numbers of small roots per square foot of the horizon areas, with reference to the tree species, the significance of the differences in the two cases paralleled one another. The differences were highly sig- nificant between tree species, in the first order interaction between tree species and horizons, and in the second order interaction between species, soils and horizons. Results of the statistical analysis indi- cated that the differences between the five tree species in the distribu- tion of small roots were real and substantial. Root Distribution White pine trees had the greatest number of roots of all sizes. This was true in both soils. White pine roots concentrated mostly in the A horizon and were reduced in numbers in the Bi and B2 horizons, falling off to insignificant numbers in the G horizon in Merrimac loamy sand. In Charlton fine sandy loam the concentration of roots fell off rapidly in the Bi horizon, and were negligible in the B? hor- izon. White pine roots reduced gradually in number with a greater and greater proportion of them extending into the deeper horizons of transects farther away from trees in Merrimac soil. This was true for the total numbers of roots and for roots per square foot of tran- sects. This reduction in numbers at a greater distance from the trees with increasing proportions of roots in lower horizons was attained more rapidly in Charlton soil. Red pine trees ranked next to white pine in number of roots but they had considerably fewer roots. Red pine roots were almost even- 156 Connecticut Experiment Station Bulletin 454 ly distributed between the A and Bi horizons, but fell off considerably in the B2 horizon in Merrimac soil. In Charlton soil the concentra- tion of red pine roots was greater in the A horizon, but a larger pro- portion of them extended into the Bi horizon than was the case for white pine roots. Only a few reached into the B= horizon. The num- ber of red pine roots in Merrimac soil remained almost unchanged but gradually diminished per square foot in the transects farther away from the trees. In Charlton fine sandy loam the number of roots gradually decreased with increase in distance from the trees. Xorway spruce was next to the lowest in the total number of roots of all sizes. The proportion of small roots was slightly greater in this species than in the two pines. Xorway spruce roots showed the greatest concentration in the A horizon ; they fell oif very rapidly in the Bi horizon, and were extremely few in the Bs horizon in both soils. Norway spruce roots did not fall off in numbers with the in- crease in distance from the trees, but showed a slight increase in Mer- rimac soil; on a square foot basis, there was a gradual reduction in numbers. Fewer roots at greater distances from the trees were re- corded in the Charlton soil. White ash occupied the middle position among the five tree spe- cies investigated for the total number of roots. The proportion of small roots was considerably greater for this species as compared to others. In Merrimac loamy sand, roots of white ash were more nu- merous in the A horizon, fell off slightly in the Bi horizon, and Avere reduced sharply in the B2 layer. In Charlton fine sandy loam the largest number of roots was found in the Bi horizon, slightly less in the A horizon, and only a few were found in the B-- horizon. In both soils the number of roots was greatest in the transects at one foot dis- tance from the trees. In the other two transects, the number remained almost the same. The number of roots per square foot in the two areas gradually, declined, the greater the distance from the trees. Red oak had the smallest number of roots in both soils, in com- parison to the other four species. The proportion of small roots in red oak was almost as high as it was in white ash. The number of toots in Merrimac loamy sand was the largest in the A horizon. It fell off slightly in tlic I)i horizon, and \v;is negligible in the Ba horizon. In Charlton fine sandy loam the largest number was in the A horizon and it fell sharply in the Bi layer. In both soils the number of roots gradually diminished, the greater the distances from the trees. In Charlton soil red oak roots were not found in the Bj horizon LB outer t ransects. This can be att ributed to the very small size of these t ices. Root Arrangement in the Central Root Mass Representative photographs of the central root mass for each species of \vi-i^. one on each soil, are given in Figures \- and 13. Opinions have been expressed that root crowns of individual trees of the -;ime species may differ to a greater extent among themselves than they do from other species. An examination Of the entire set. of so photographs revealed that although individual trees varied within the pecies, tne species differed one from another appreciably. Interpretation of Results 157 Figure 12. Upper left', central root mass of white pine tree grow- ing in Merrimac loamy sand and, upper right, in Charlton fine sandy loam. Center left, central root mass of red pine tree growing in Merrimac loamy sand and, center right, in Charlton fine sandy loam. Bottom left, central root mass of Norway spruce tree growing in Merrimac loamy sand and, bottom right, in Charlton fine sandy loam. 158 Connecticut Experiment station Bulletin 454 White pine showed a short stubby tap root which in some cases was difficult to distinguish. Heavy branching occurred immediately under the root collar, with large root- extending into the soil in all directions. Small roots formed a heavy mass around the root crown. On Merrimac soil roots reached much deeper under the center of the i in a 05^ 2 ■ **\ i ^05. ; 10 s "S -^^^ X 0 IS |20 15 20 25 25 30 30 L-tn i i .JBl&gi Figure 13. Upper left, central rool mass of white ash tree grow inKr iii Merrimac loamy sand and, upper right, in Charlton fine sandj loam. Lower left, central rool mass ol red oak tree growing in Merrimac loamy sand and, lower right, in Charlton fine sandy loam. tree than in Charlton soil, and main branch roots turned more sharply downward. Rool crowns were more shallow in Charlton soil, and Lateral roots did noi into deeper layers of the soil in the immedi- ate vicinity of the rool crowns. In white pine small branches were very numerous, with n lew exceptions. One of the rool crowns shown Interpretation of Results 159 for Charlton soil had the two-layered effect which was mentioned before. Red pine indicated a strong tendency to form a tap root, but this was not always present, or at least it was not always a prominent fea- ture of the root system. Heavy branching occurred immediately un- der the root collar, but large roots assumed a downward trend more sharply than in white pine. Small roots did not form as heavy and compact a mass as they did in white pine. In Charlton soil lateral roots displayed a tendency to spread out in a more level plane than they did in Merrimac soil. The root crowns in Charlton soil were shallow but less so than in the case of white pine. Norway spruce did not show any tap root in the true sense of the word. Lateral branching occurred almost wholly from one common point at the base of the tree. Lateral roots remained near the surface and did not assume a prominent downward trend as they did on the two pines. Small branches formed a considerable mass of roots but this mass was quite shallow. It would be .well to recall that the roots of Norway spruce remained in the A horizon. This conclusion is sup- ported by the photographs. White ash, as a rule, had a tap root which branched into a few heavy roots maintaining their conspicuous downward trend. In Charlton soil, in a few cases, the tap root was practically absent, but some prominent branches always maintained their downward trend with the same type of vertical rooting habit. From these character- istic vertical roots single lateral branches were developed at intervals. Lateral branches did not come out in a mass as they did in conifers. They maintained their size unusually well. Lateral branches pro- ceeded outward horizontally or assumed a gradual downward trend, and in turn produced some vertical, long branches, small in diameter. As a result of this angular branching small roots never formed a compact mass but were hanging in long strings. Red oak definitely showed the presence of a tap root, which in some cases turned horizontally and continued its development on the same plane. This horizontal trend of the tap root was an exception in Merrimac soil, but vertical branching of the tap root was common. In Charlton soil, it Avas the long vertical tap root that was an excep- tion. High water table and compactness of Charlton soil did not allow the development of deep roots by any species. The tap root of red oak, because of these conditions, could not continue its downward trend. The turning of the tap root of this tree in Charlton soil fre- quently gave a stunted appearance of its root system. The poor growth of red oak on this soil was perhaps a result of retarded root development. The two-layered root sj^stem could be seen in oak as well as in other species. Lateral branching of red oak roots was quite extensive. These roots developed in large numbers and in groups in contrast to the single branching of white ash. Lateral roots as a rule maintained a more or less horizontal position. Small roots were scat- tered and never formed a closely woven mass, but were more numer- ous and not as lono- as in white ash. 160 Connecticut Experiment Station Bulletin 4.">4 SILVICULTURAL DISCUSSION Within the 36 square feet of ground area around each tree investi- gated in the field, a number of roots of adjoining trees of the same or different species were found. These roots are represented by differ- ent symbols listed in the tables in the author's dissertation. The vigor and height growth of trees on adjacent ground were invariably less than the trees under study. Consequently, the neighboring trees did not have nearly as extensive or well developed root systems as those under investigation. Stevens (34) indicated that crown de- velopment is related to the extension of the root system. This view was supported by the fact that in the outermost transect, which was on a theoretical boundary between two trees, the larger number of roots were those of the tree under investigation. Other facts can be observed from the field maps and the tables. The number of roots coming into the transects from the outside was considerably greater in Merrimac than in Charlton soil. This is one additional fact in support of the conclusion already reached that trees have more spreading root systems in the lighter Merrimac soil than in heavier Charlton soil. A proportionately larger number of roots coming into the transects from the outside was found in lower hori- zons. This again sustains the previous conclusion that more roots of trees reach into deeper horizons at a greater distance from the trees. The number of roots coming into the transects from outside trees in- creased when the trees under study were smaller. Such smaller trees had fewer roots of their own and it was to be expected that the roots of other trees would (invade the soil around them more promptly. The number of roots coming into the transects from the outside de- creased from the first transect, 3 feet away from the tree, to the third one which was only 1 foot from the tree. This was due to the obvious fact that the soil was already well occupied b}' roots of trees under investigation and the distance from other trees Avas increasingly great. The roots of other trees frequently extended well within the area occupied by those under investigation. Since the crowns of the trees concentrate their roots in sections of the Bi horizon which were rich in nutrients. Photographs of the central root masses of trees were used to show the differences existing between the five tree species investigated. The tree species differed in tap root formation, density of central root mass, type <>f root branching, and manner of spreading of roots from the tree. Vigorous trees had better root development than poor indi- viduals of the same age. Root distribution in relation to roots of bordering trees which occurred in the transects served as a basis for the discussion of root competition in a forest stand. The root development id' a forest stand (Vas suggested to be divided into four stages: free root growth, pe- riod id' invasion, period of root competition, and period of release from competition. In the seven-year-old plantations investigated the roots of tree- spread more widely than the boundaries of their crown pro- jections, invading areas adjacent to the neighboring trees. The stands under investigation were placed in the second stage because it was shown in the root charts that root density of small roots in the A hori- zon did not approach a constant : therefore the "soil capacity" for roots \\a- not reached, and the period of root competition had not begun. The period of root competition in a forest stand may precede or lollou the closing of tree crowns above the ground depending on the -ite quality. Root competition frequently must he the most important Literature Cited 165 factor of suppression and dominance of trees in a forest stand on good and poor sites alike. Information made available with regard to root systems, root distribution, and root distribution as influenced by soil properties and two soil types of the five tree species investigated, can serve as a background on which to formulate some silvicultural practices. LITERATURE CITED 1. Aaltonbn, V. T. t)ber die Ausbreitung und den Reichtum der Baumwurzeln in den Heidewaldern Lapplands. Acta Forestalia Fennica 14:1-55. 1920. 2. . On the space arrangement of trees and root competition, Jour, of For. 24:627-644. 1926. 3. Adams, W. R. Effect of spacing in a jack pine plantation. Vermont Agr. Exp. Sta. Bui. 282. 51 pp. 1928. 4. Aldrich-Blake, R. N. Recent research on the root systems of trees. Fores- try 3 :66-70. 1929. 5. Association of Official Agricultural Chemists. Official and tentative methods of analysis 2nd ed. Washington, D. C. 535 pp. 1925. 6. Bouyoucos, George John. Directions for making mechanical analysis of soils by the hydrometer method. Soil Science 42:225-229. 1936. 7. Chandler, R. F. Jr. Cation exchange properties of certain forest soils in the Adirondack section. Jour. Agr. Res. 59:491-506. 1939. 8. Coile, T. S. Soil samplers. Soil Science 42:139-142. 1936. 9. . Distribution of forest tree roots in North Carolina Piedmont soils. Jour, of For. 35:247-257. 1937. 10. Craib, I. J. Some aspects of soil moisture in the forest. Yale Univ. School For. Bui. 35. 61 pp. 1929. 11. Dittrich, Heinrich von. Untersuchungen uber die Bodengare. Bodenkunde und Pflanzenernaherung. Verlag Chemie. 16 (61) :16-50. 1939. 12. Ely, Joseph B. Root distribution of white pine in relation to certain physical characteristics of soil profile horizons. Yale Univ. School For. Master's Thesis. 35 pp. 1935. 13. Fisher, R. A. Statistical methods for research workers. 6th ed. xiii + 339 pp., Oliver and Boyd, London. 1936. 14. . The design of experiments. 2nd ed. xi + 260 pp., Oliver and Boyd, London. 1937. 15. Glinka, K. D. The great soil groups of the world and their development. Translated from the German by C. F. Marbut. Mimeographed copy. 235 pp., Edwards Brothers, Ann Arbor, Mich. 1927. 16. Grasovsky, A. Some aspects of light in the forest. Yale Univ. School For. Bui. 23. 23 pp. 1929. 17. Hatch, A. B. The physical basis of mycotrophy in Pinns. Black Rock Forest Bui. 6. 168 pp. 1937. 18. Hilf, H. H. Wurzelstudien an Waldbaumen. Die Wurzelausbreitung und ihre waldbauliche Bedeutung. 121 pp., M. and H. Schaper, Hannover. 1927. 19. Laitakari, Erkki Mannyn juuristo. Morfologinen tutkimus. (The root sys- tem of pine, Pinus silvestris.) (English summary, pp. 307-380.) Acta For- estalia Fennica 33:1-380. 1929. 20. Little, Silas, Jr. Root distribution of white pine in relation to certain physi- cal characteristics of soil profile horizons. Yale Univ. School For. Master's Thesis. 51 pp. "1936. 21. Luncs, G. Reshershes recentes sur les racines des arbres forestier. Bullitin de la Societe Centrale Forestier de Belgique 38:531-538, 1931. 22. Lunt, Herbert A. Profile characteristics of New England forest soils. Con- necticut Agr. Exp. Sta. Bui. 342, pp. 743-836. 1932. 166 Connecticut Experiment Station Bulletin 454 23. — — . Soil analyses significant in forest soils investigations and methods of determination : I. Exchangeable bases, exchangeable hydrogen, and total base capacity. Soil Science Society of America. Proceedings, 1940, 5 : 344-347. 1940. 24. Lutz, Harold- J. Disturbance of forest soil resulting from the uprooting of trees. Yale Univ. School For. Bui. 45. 37 pp. 1940. 25. , Ely, Joseph B., Jr., and Little, Silas, Jr. The influence of soil profile horizons on root distribution of white pine. Yale Univ. School For. Bui. 44. 75 pp. 1937. 26. Melder, Chr. Vlianie kornevoy systemy na raspredelenie podrosta okolo sos- novych semennikov v suchom boru. (Influence of root system of seed trees on distribution of reproduction in a forest growing on dry sandy soil.) Izvestia Imperatorskago Lesnogo Institut. Issue 21. St. Petersburg, pp. 215-246. 1911. 27. Morgan, M. F. Base exchange capacity and related characteristics of Con- necticut soils. Soil Science Society of America. Proceedings, 1939, 4:145- 149. 1939. 28. Oskamp, Joseph, and Batter, L. P. Soils in relation to fruit growing in New York. Part III. Some physical and chemical properties of the soils of the Hilton and Monroe areas, Monroe County, and their relation to orchard per- formance. New York Agr. Exp. Sta., Ithaca. Bui. 575. 34 pp. 1933. 29. Pearson, G. A. The other side of the light auestion. Jour, of For. 27 : 807-812. 1929. 30. Pierre, W. H. and Scarseth, G. D. Determination of the percentage base saturation of soils and its value in different soils at definite pH values. Soil Science 31:99-114. 1931. 31. Russell, E. W. and Tamhane, R. V. The determination of the size distribu- tion of soil clods and crumbs. Jour, of Agr. Science 30 :210-234. 1940. 32. Snedecor, G. W. Calculation and interpretation of analysis of variance and covariance. 96 pp. Collegiate Press Inc., Ames, Iowa. 1934. 33. . Statistical methods applied to experiments in agriculture and biology, xiii -f- 341 pp. Collegiate Press Inc., Ames, Iowa. 1937. 34. Stevens, Clark Leavitt. Root growth of white pine (Pinus strobus L.). Yale Univ. School For. Bui. 32. 62 pp. 1931. 35. Stubblefield, F. M. and Deturk, E. E. Effect of ferric sulphate in shorten- ing Kjeldahl digestion. Indust. and Eng. Chem., Anal. Ed. 12:396-399. 1940. 36. Sudworth, G. B. Check list of the forest trees of the United States, their names and ranges. U. S. Dept. of Agr. Misc. Circ. 92. 295 pp. 1927. 37. Swetloff, N. F. Issledovanie vliyania usloviy mestoproizrostania na korne- vouyu sistemu sosny v institutskom (b. pargolovskom) uchebnom lesprom- choze. (Investigation of the influence of the site conditions on the root sys- tem of pine in the experimental forest of Leningrad Forest Academy. ) Troudy lesotechnicheskoy academh, lesovodstvennyi tzikl. Issue 1 (38). Len- ingrad, pp. 103-126. 1931. 38. Tolski, A. P. Materialy po izucheniyou formy e razvitiya korney sosny e drugich drevesnych porod. (Materials on the investigation of form and de- velopment of root system of pine and other trees.) Troudy Opytnich Lesnich estv. Issue 3. St. Petersburg. 1905. 3'). — . Materialy po izoucheniyou stroeniya e jisnedeyatelnosty kor- ney sosny. (Materials on the study of form and functions of pine roots.) rroudj po Lesnomu Opitnomu Delu v Rossii. Issue 3. St. Petersburg. 118 pp. 1907. 40. I ki in,, EMIL and MEYER, A. H. Improvements in the Deniges eolorimetrie method Eoi phosphorus and arsenic. Indust. and Eng. ("hem., Anal. Ed. 1 : ... I 19. 1929. 41. Ti iii, Lewis M. A comparison of roots of southern shortleaf pine in three .,,1 Ecology 17:649-658. 1936. 42. \ '■■iii--, II. Die Bewurzelung der ECiefer, Fichte und Buche. Tharandter For- stliches Jahrbuch 78:65-85. 1927. Literature Cited 167 43. Veihmeyer, F. J., Oserkowsky, J., and Teeter, R. B. Some factors affecting the moisture equivalent of soils. Proceedings and Papers of the First Inter- national Congress of Soil Science, 1927. Part 2, Comm. 1. pp. 512-534. 1928. 44. Volk, Garth W. and Jones, Randall. The use of perchloric acid in the deter- mination of total phosphorus in soils. Proc. of Soil Science Society 2 : 197- 200. 1937. 45. Weaver, John E. The ecological relations of roots. Carnegie Institution of Washington (D. C.) Pub. 286. vii + 128 pp. 1919. 46. West, Eric S. The root distribution of some agricultural plants. Jour, of the Council for Scientific and Industrial Research (Commonwealth of Aus- tralia). 7:87-93. 1934. 47. Williams, Rice. The determination of exchangeable calcium in carbonate- free soils. Jour, of Agr. Science 18:439-445. 1928. 48, . The determination of exchangeable bases in soils. Magnesium, potassium and total bases. Jour, of Agr. Science 19:589-599. 1929. 49. Wright. C. H. Soil analysis and chemical methods. A handbook of physical and chemical methods. 2nd ed. 276 pp. Thomas Murby and Co., London. 1939. University of Connecticut Libraries 39153029045152 0 1 5 • . U.O.fl. J - . ■ ■ • . 1 2 M 1 - ' . 3 jl ■ •• I ■ g . ■ .. ■ -' • 4 3 ■ . 1 ■ — ^^Hfl - nii|iiii iiii|iiii nil mi OREGON RULE CO. J U.S.A. 1 :