BLM LIBRARY 88053008 U OF LAND MANAGEMENT TECHNICAL BULLETIN NO, 99-01 February 1999 PHOTOGRAPHIC GUIDE TO MEDIAN STUBBLE HEIGHTS BUREAU OF LAND MANAGEMENT Challis Resource Area Salmon, Idaho QK 938 .M3 P55 1999 ->HARY DG50,ST-150A EDERAI NTER DENVER, COLORADO 80225 Acknowledgments This photographic field guide was prepared by the staff of the Bureau of Land Management's, Challis Resource Area to provide a practical monitoring tool for determining stubble height on riparian areas. In particular, the staff recognizes David Blackstun for analyzing the field data and developing the procedure for using the median instead of the average stubble height and Dianne Simodynes for compiling the photographs for the publication. Thanks to Melinda Ritacco and Ervin Cowley for formatting and preparation for publication. BLMUr^ ARY 3LDG 5 ~0A ER FE CENTER P.O. B^ ,047 ER, COLO* iADO 80225 Soot Contents Page)^ Riparian Monitoring and Median Stubble Height 1 Figure 1 : Form for data collection and determining median stubble height 2 Median Stubble Height - 1 inch 3 Median Stubble Height - 2 inches 5 Median Stubble Height - 3 inches 7 Median Stubble Height - 4 inches, Sedge 9 Median Stubble Height - 4 inches, Grass/Forb 11 Median Stubble Height - 5 inches, Sedge 13 Median Stubble Height - 5 inches, Grass/Forb 15 Median Stubble Height - 6 inches 17 Median Stubble Height - 7 inches 19 Median Stubble Height - 8 inches 21 Location Index of Key Area Sites 23 Riparian Monitoring and Median Stubble Height Key areas have been established to monitor effects of grazing on riparian and aquatic habitats. The locations for potential key sites were inspected by interdisciplinary teams comprised of BLM staff representing various expertise to determine if the a site was representative of the entire habitat. Key areas are advantageous because they provide a good indication of grazing use without having to monitor the entire area being grazed. Stubble height measurements are a simple and effective tool to monitor rangeland use in these key areas. Individual plant measurements are collected from herbaceous vegetation such as grasses, sedges, and rushes, while excluding forbs. Generally stubble heights of 4 to 6 inches are an acceptable standard. Plants with this much height remaining usually provide effective streambank protection, prevent sedimentation, and maintain or improve plant communities. Within the key area, measurements are taken on both sides of the stream, along the greenline, usually within 3 feet of the waterline. Fifty measurements (using a pace point method) on each side of the stream for a total of 100 samples. At each pace, the plant or cluster of plants located at the tip of the observers toe is measured to the nearest one-half inch. example, in a even numbered data set, 100 samples, the 50* and 51st values would be averaged giving the median value (see Figure 1 ). A median value provides a better representation of the overall community than the average. Usually there is not a normal distribution of data points. That is the number of short stubble heights or tall stubble height are not evenly distributed. In some cases, extra tall plants may over influence the average number. For instance, fifteen stubble height measurements provided the following data: .5", 1", 1", 4", 4", 4", 5", 6", 6", 6", 7", 7", 7", 7", 7". The average for the sample would be 4.8 inches. However, the median is 6.0 inches. The average is more sensitive to extremes making the median more accurate without complicated statistical analysis. References: a. Challis Resource Area Monitoring Procedures, April 1996 b. Statistical Evaluation of Stubble Height Data, David E. Blackstun Once all samples have been collected, the median stubble height value is determined. The samples are ranked in descending order from the smallest to the highest value. The median value is the single mid-point for and odd number of samples and the average of the two mid-point values. For Figure 1: Form used for data collection and determining median stubble heights. Stubble Height Form June 27, 1994 Allotment: I Pasture: I Key Area: I Observers: I I Stubble Stubble Stubble Stubble Stubble Measurement ! Measurement ', Measurement Measurement Measurement Date Date Date Date Example r I I I I I Inches R8 LB RB | LB | HB | LB R8 LB | RB 'I LB 0.5 1.0 1.5 II 2.0 III 2.5 III 3.0 II I 3.5 mil a 4.0 | WITH! in 4.5 L_ "HU.ll •mil 5.0 I i m\ m 5.5 llll mi 6.0 III TKllll 6.5 i I I -HI] I 7.0 i III 7.5 III 8.0 I! 8.5 i I II 9.0 I I II 9.5 I 10.0 10.5 ! 11.0 11.5 12.0 I >12 I Total | I I 50 | 50 Bank Median! I I I 4.0~1 6.0 Total Median I i I 5.0 i Notesl I i I I t i I I I Median Stubble: Mark aopropnate inch group for each measure. The median is the middle number of the readinas. If there are 100 measurements and the 5Ctn and 51st are *5 and 5.0. the median is « ':'■:■ ^li^KirT'i-iE CBC-KAl, Upper Marker, Near View, 6/27/96 Median Stubble Height - 1 inch CBC-KAl, Upper Marker, Wide View, 8/26/94 Median Stubble Height - 2 inches if,! LHC-KA3, Lower Marker, Near View, 9/26/95 Median Stubble Height - 2 inches LHC-KA3, Lower Marker, Wide View, 9/26/95 Median Stubble Height - 3 inches TC-KA2, Photo Point 1, Near View, 10/3/96 Median Stubble Height - 3 inches TC-KA2, Photo Point 1, Wide View, 10/3/96 Median Stubble Height - 4 inches, Sedge CBC-KAl, Lower Marker, Near View, 6/12/95 Median Stubble Height - 4 inches, Sedge CBC-KAl, Upper Marker, Widw View,6/ 12/95 10 Median Stubble Height - 4 inches, Grass/Forb LGC-KAl, Upper Marker, Near View, 6/27/96 II Median Stubble Height - 4 inches, Grass/Forb LGC-KAl, Upper Marker, Wide View, 6/27/96 12 Median Stubble Height - 5 inches, Sedge HBC-KA2, Upper Marker, Near View, 10/4/96 13 Median Stubble Height - 5 inches, Sedge HBC-KA2, Photo Point 3, Wide View, 10/4/96 14 Median Stubble Height - 5 inches, Grass/Forb LHC-KA3, Upper Marker, Near View, 7/24/95 15 Median Stubble Height - 5 inches - Grass/Forb LHC-KA3, Upper Marker, Wide View, 7/24/95 16 Median Stubble Height - 6 inehes rapi BRC-KAl, Lower Marker, Near View, 7/16/96 17 Median Stubble Height - 6 inches BRC-KAl, Upper Marker, Wide View, 6/13/96 Median Stubble Height - 7 inches HBC-KA2, Upper Marker, Near View, 6/13/96 19 Median Stubble Height - 7 inches HBC-KA2, Upper Marker, Wide View, 6/13/96 20 Median Stubble Height - 8 inches RC-KA2, Upper Marker, Near View, 9/25/95 21 Median Stubble Height - 8 inches RC-KA2 (Wide View) 9/25/95 22 Location Index of Key Area Sites 1.0" CBC-KAl 2.0" LHC-KA3 3.0" TC-KA2 4.0" Grass/Forb LGC-KA1 4.0" Sedge CBC-KAl 5.0" Grass/Forb LHC-KA3 5.0" Sedge HBC-KA2 6.0" BRC-KA1 7.0" HBC-KA2 8.0" RC-KA2 Corral Basin Creek Key Area #1 Little Hat Creek Key Area #3 Thompson Creek Key Area #2 Long Creek Key Area $1 Corral Basin Creek Key Area #1 Little Hat Creek Key Area #3 Horse Basin Creek Key Area #2 Bear Creek Key Area #1 Horse Basin Creek Key Area #2 Road Creek Key Area #2 E1 ■' :?'"ARY BLOv ..: v> i.-150A DENVER F u D£i RAL CENTER P.O. BOX 25047 DENVER, COLORADO 80225 23 BLDC TT-150A ®l «AL CENTERS K^.oOX 25047 DENVER, COLORADO 80225 C*i c 2 r 31 o a > > £ <^> ZH °°^ m pi j^ vO a 0- hJ o CO U « ft o c n- V£> 03 tr o LO o 70 50 00 CD o o CD & • 73 ^ ►c 3; 72 M trt? ua O 50 CD H- P- Q Ln m 7] 6LM LlBF . KS150ABLD( OENVER FEDE P.O. BOX DENVER, CO 802 QK 938 .M3 P55 1999 Photographic guide to media stubble heights US DEPARTMENT OF THE INTERIOR .BUREAU OF LAND MANAGEMENT Idaho State Office 1387 S. VinnellWay DS4]S*DS®S Boise, Idaho 83709 BLM/ID/GI-99/013+1150