Bousfield, Wayne E.

Stipe, Lawrence E.

Wulf, N. William

Undetermined

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•• •••Report 86-5 3450February 1986•PROGRESS REPORT ON THE SPRUCE BUDWORM SILVICULTURAL DEMONSTRATION PROJECTON THE GALLATIN AND LOLO NATIONAL FORESTS• byW. E. Bousfield, N. William Wulf, and L. E. StipeA demonstration of silvicultural prescriptions to reduce damage caused bywestern spruce budworm was established in 1981 (Bousfield et al. 1983). Thepurpose of this effort was to show:1. How different cultural systems affect budworm populations.2. How various cultural systems alter stand response in the presence ofspruce budworm.3. How unmanaged stands respond to budworm defoliation.4. How well the CANUSA-developed decision system predicts variousoutcomes for each cultural system.5. How cost effective various cultural systems are using economicmodels coupled with growth models that incorporate effects of sprucebudworm.Since establishment of the demonstration areas in 1981, only the Gallatin NFstands received the cultural cuts and have been regenerated. The Lolo NFstands were cut in 1985 and monitoring plots will be established followingslash disposal in 1986. Budworm populations have been low on the Lolo andlight to moderate on the Gallatin demonstration stands. This report isconfined to the Gallatin demonstration area (fig. 1).• METHODSStand examinations were conducted on all blocks prior to logging. A seriesof systematic sample points using variable plot sampling for trees greaterthan 5 inches d.b.h. and 1/300-acre plot for trees 5 inches and less weren 	 established in each stand to determine stand structure. Pretreatmentstocking levels are displayed in Tables 1 and 2.•United States	 Forest	 Northern	 P.O. Box 7669•Department of	 Service	 Region	 Missoula, MontanaAgriculture	 59807Table 1.--Pretreatment basal area stocking levels.Standident.Gallatin National ForestBasal argg by speciesDP S	 SAF	 LPP TotalCheck 02 182.8 0 0 33.3 216.1Group selection 03 48.5 13.6 13.4 140.3 215.9Clearcut 06 176.8 6.7 0 53.3 236.8Shelterwood 13 171.1 0 0 0 171.1Shelterwood 18 94.8 0.1 0.2 46.7 141.8Table 2.--Pretreatment trees per acre stocking levels.StandGallatin National ForestWOOlt nay Siert:. by stmacidan1117 5 sAv tpp Tntn1Check 02 1491.2 9.0 300.0 101.2 1892.5Group selection 03 528.6 807.1 1169.9 384.4 2889.8Clearcut 06 1694.3 7.9 50.0 83.2 1835.4Shelterwood 13 1319.5 0 0 0 1319.5Shelterwood 18 1242.7 250.0 300.0 64.4 1857.2Overstory removal 17 1242.7 inn n inn_n 1R6-1 R44_7•n• ••Posttreatment evaluations used similar sampling techniques to measurestocking levels (Tables 3 and 4). At each sample point, a wooden stake wasplaced to mark plot center. Each sample tree was numbered with paint and analuminum nail was placed at breast height facing plot center. Location ofthese points within each block are shown in figure 2.Table 3.--Posttreatment basal area stocking levels.StandGallatin National ForestBasal Area by speciesCheck 02 150.7 6.0 6.8 48.8 211.91Group selection 03 63.5 0 0.5 10.0 74.0Clearcut 06 0 0 0 0 0Shelterwood 13 78.4 0 0 0 78.4Shelterwood 18 38.0 0 0 0 38.1Overstory removal 17 29.4 0 9.4 10.0 48.71 Additional plots and different systematic grids were used when post-treatment plots were established.•••••Table 4.--Posttreatment trees per acre stocking level. 	 •Standidpnt,Gallatin National ForestTrees per acre by speciesDF S	 SAF	 LPP TotalCheck 02 599.7 58.2 244.0 128.0 1029.91Group selection 03 293.7 0 150.0 13.8 456.8Clearcut 06 150.0 0 0 0 150.0Shelterwood 13 472.0 0 0 0 472.0Shelterwood 18 286.7 30.0 60.0 120.0 496.7Overstory removal 17 369.9 0 148.8 113.0 631.81 Additional plots and different systematic grids were used when post-treatment plots were established.••••••Table 5.--Larval densities per 100 shoots by tree class by year.Tree size class in ft.Stand 0-2 2-6 6-30 30-60 Average02 0 1.28 8.21 2.62 3.031981 03 0 0 1.31 .60 .48Pretreatment 06 0 0 1.48 1.07 .6413 0 0 3.08 2.85 1.4817 0 .61 .74 4.85 1.5518 0 10.55 3.76 3.79 4.53Average 0 2.07 3.10 2.63 1.9502 0 5.87 3.09 9.53 4.621982 03 0 4.58 7.98 15.84 7.10Year cut 06 Clearcut no trees13 2.17 15.54 10.47 2.94 7.7817 2.27 2.03 6.90 5.07 4.0718 0 .48 2.70 3.06 1.56Average 0.89 5.70 6.23 7.29 5.03-6-•••00••••INSECT CONDITIONS Each year from 1981 to 1985, western spruce budworm larvae have been sampledduring the late instar period in each block on four height classes of hosttrees. Host classes were 0-2 feet; 2-6 feet; 6-30 feet; 30-60 feet. At eachof 10 sample points from the four tree classes, two 18-inch branches wereremoved and spruce budworm larvae were counted. Not all tree classes werepresent at each point. This was especially more pronounced after the harvestcuts. On smaller trees, the branches were not cut but the entire tree wasused as the sample stratum. Population levels were displayed as sprucebudworm per 100 new shoots.RESULTS TO DATE There seems to be a slight increase in populations in the cut blocks whencompared to the check block. This may be the result of crown development;that is, new shoots are longer and can support more budworm per shootcompared to more dense stands. Defoliation intensities have not been at thelevel where growth depression or top killing is expected, therefore, noassessment on these measurements has been made. Population levels reflectlate instar densities. All larval sampling was done at approximately thesame week each year (Table 5).•• •••••4•••••Table 5.--Larval densities per 100 shoots by tree class by year, cont.Tree size class in ft.rand__Q-2ELLQ___Ar_aga.02	 0.45	 4.77	 4.80	 2.76	 3.201983	 03	 .11	 2.86	 4.25	 4.85	 3.02Posttreatment	 06	 Clearcut no trees13	 0	 6.25	 6.44	 5.40	 4.5217	 0	 5.37	 7.13	 4.93	 4.3618	 1.10	 5.16	 11.73	 9.60	 6.90AysizateO -33	 4.88	 .6,87	 5.51	 4.4002	 .45	 .52	 1.89 1.64 1.131984 03	 0.00	 1.99	 1.92 3.01 1.73Posttreatment 06	 Clearcut no trees13	 0.00	 0.00	 5.13 6.99 3.0317	 0.00	 4.12	 2.94 5.32 3.1018	 .11	 1.04	 2.86 4.95 2.2402 .00	 .95	 1.71 2.76	 1.361985	 03 .00	 1.55	 2.46 5.21	 2.31Posttreatment	 06 Clearcut no trees13 .00	 1.68 4.81	 2.1617 .00	 3.92	 4.51 5.03	 3.3718 .00	 1.21	 3.39 6.25	 2.71 Average	 .00	 1.91	 2.75	 4.81	 2.38Populations of late instar larvae were noticeably lower on the smaller trees(fig. 3). Feeding was often present but larval populations were nearlyabsent. This confirms other reports and supports research findings thatpredation of spruce budworm occurs more frequently on small trees and at thelower crown levels.Future plans are to continue monitoring the population and to evaluate thedecision support system developed by CANUSA which includes a spruce budwormpopulation and damage model. Permanent sample plots in the Lolo NF standswill be established and monitored in 1986.•• •

Progress report on the spruce budworm silvicultural demonstration project on the Gallatin and Lolo National Forests

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Progress report on the spruce budworm silvicultural demonstration project on the Gallatin and Lolo National Forests

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