50 Year Development of Ponderosa Pine Saplings and Poles Using Six Different Thinning Regimes in the Black Hills Growing Stock Levels

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2 50 Year Development of Ponderosa Pine Saplings and Poles Using Six Different Thinning Regimes in the Black Hills Growing Stock Levels Russ Graham and Terrie Jain Forest Service, Rocky Mountain Research Station Moscow, ID

3 Stand Metrics Basal area Trees per acre Quadratic mean diameter Crown competition factor Growth basal area Leaf area index Stand density index Growing stock level (GSLs) ie., levels of growing stock study (LOGS)

4 Growing Stock Levels Even-aged Stands Clifford Myers (1960, paper published 1967) Basal area per acre when the DBH is 10 inches Suggested trees and basal area per acre for stands with mean DBHs less than 10 inches Used data from the Black Hills to develop his best basal area and trees per acre for a given DBH

5 Basal area per acre (sq ft) GSL 80 Best Provided target BAs for stands with different DBHs that could be tended to reach a 10 inch mean DBH when the BA was 80 square feet Bates Harmon Myers BH Best Black Hills NF DBH ( inches)

6 Basal area per acre (sq ft) GSLs Developed in the Black Hills Basal Area Best bracketed proportionally below and above Best "80" % 50% 75% 125% 150% DBH inches

7 GSLs Developed in the Black Hills Trees per Acre Best bracketed proportionally below and above 25% 50% 75% 125% 150%

8 Growing Stock Levels for Black Hills Ponderosa Pine On the Black Hills Experimental Forest in 1963-Site Index year-old pole stands DBH 0.5 ac plots 65-year-old sapling stands DBH 0.25 ac plots Target BA describes Growing Stock Level (GSL) when mean diameter is <10 inches. GSL and BA are equal when average diameter is 10 inches Myers west-wide ponderosa pine GSL study 1967

9 Growing Stock Levels for Black Hills Ponderosa Pine Targeted Basal Areas (GSLs) 20, 40, 60, 80, 100, 120 and a control Three plots of each GSL for both saplings and poles Measured 1963, 68, 73, 78, 84, 91, 93, 98, 2003, 06, 10, 14 Pole

10 Trees Per Acre Thinnings 8: 1963 through 2006 Major: 1968, 1973, 1998 Minimal mortality in GSLs Thinning Thinning

11 Stand Density Index Black Hills ponderosa pine Maximum 459 X = lower limit of self thinning (264, 57.5%) Y= lower full occupancy (161, 35%) Z= onset of competition (115, 25%) Thinning Thinning

12 Basal Area Thinning regimes rather than GSL test e.g., pole 20 GSL in prescription 5 years e.g., sapling 20 GSL in prescription 10 years Difficult to maintain precise prescription in small plots let alone within stands and landscapes Thinning Thinning

13 Quadratic Mean Diameter (QMD) saplings, pole GSLs statistically similar QMDs Thinning Thinning Sapling

14 1998 Thinning Response (BA-PAI) Age 100 years Trees in every GSL significantly increased growth rate after thinning Largest magnitude low densities greatest percentage high densities

15 1998 Thinning Response (QMD-PAI) GSL 20 sapling 86 % increase BA 48 sq ft/acre SDI 83 (onset of competition 115) GSL 20 pole 146 % increase BA 45 sq ft/acre SDI 70

16 Removals Saplings 9 thinnings Poles 10 thinnings Not all plots Unmerchantable 1968 poles some merch. Trees/ac. removed Cubic ft./ac. removed

17 Cubic Volume Unthinned stands produced the most cubic volume Poles started with more and had more volume 60, 80, 100, similar Thinning Thinning

18 Board Feet 80, 100, 120 poles 10 to 11.3 MBF/ac. 40,60, 100, 120 saps 6 to 7.7 MBF/ac. Pole GSL 80 plot 62 in MBF/ac. Thinning Thinning

19 Yield Standing Plus Harvest Captured some mortality GSL 80, 100, to 14 MBF/ac. Pole GSL 80 plot 35 in MBF/ac. Cubic feet Board feet

20 Balance of QMD and Volume Yield Thinning regimes represented by pole GSLs 80, 100, 120 appear to produce considerable volumes with QMDs 10 to 13 inches

21 Pre-commercial thinning FVS Estimates Black Hills Variant By age 30 To target density for desired volume and QMD The intermediate thinnings were generally noncommercial GSL plots were 65 yrs old in 1960 Saplings: 3.9 QMD Poles: 6.8 QMD

22 Mountain Pine Beetles

23 Mountain Pine Beetles Trees and board foot loss 2010 to to 40% losses in GSLs 20 and and 74 % of volume lost in unthinned Even though Graham et al said 40 to 70 sq. ft. resistant

24 Western White Pine and Associates Graham Trees per Acre Square Spacing Age 24 FVS projections To age 10 high seedling densities (18/sq ft) not affect tree development Cleaning at 8 years More height growth WL, WWP compared to no thin 40% more BA Ingrowth compete with crop trees Age 10 to 30 years most important Future stand compositions and stand dynamics determined Later treatments more costly and less effective Grand fir responds readily but heart rotts can increase Western red cedar Responds poorly if suppressed Best on WRC habitat types Greatest benefit : improved stand and tree quality

25 Tom Graham, Pat, and Dick