Stand dynamics 11 years after retention harvest in Rocky Mountain lodgepole pine

Transcription

1 Stand dynamics 11 years after retention harvest in Rocky Mountain lodgepole pine Justin S. Crotteau and Christopher R. Keyes University of Montana Applied Forest Management Program

2 The take-home message Retention harvesting is a viable tool to create structural heterogeneity in lodgepole pine stands. Heterogeneity is good. But heterogeneity is costly.

3 Outline Background Retention harvesting Tenderfoot Creek Experimental Forest Three lenses into stand dynamics Stand structural changes Growth Mortality

4 Gustafsson et al. 2012, Bioscience Retention harvesting Defined a silvicultural cutting used to create structural diversity and maintain biological legacies in stands Maguire et al. 2006, Allg. Forst- u. J.-Ztg Simonsson et al. 2015, Scan J For Res

5 Gustafsson et al. 2012, Bioscience Retention harvesting Where it is commonly used Current state of knowledge Fedrowitz et al. 2014, J Appl Ecol

6 Tenderfoot Creek E.F. Where Forest type Fire history

7 The Tenderfoot Project Goals Experimental design Implementation Measurement

8 Outline Background Retention harvesting Tenderfoot Creek Experimental Forest Three lenses into stand dynamics Stand structural changes Growth Mortality

9 Stand structural changes 1. Overstory 1. Stand density metrics 2. Diameter distributions 3. Species composition 2. Regeneration 1. Composition and Density

10 Stand structural changes 1.1. Overstory stand density metrics Mean and 1 standard error of mean

11 Stand structural changes 1.1. Overstory stand density metrics Mean and 1 standard error of mean

12 Stand structural changes 1.1. Overstory stand density metrics Standard deviation and 1 standard error of standard deviation

13 Stand structural changes 1.2. Overstory diameter distributions

14 Stand structural changes 1.2. Overstory diameter distributions

15 Stand structural changes 1.2. Overstory diameter distributions

16 Stand structural changes 1.2. Overstory diameter distributions

17 Stand structural changes 1.3. Overstory species composition

18 Stand structural changes 2.1. Regeneration composition and density

19 Stand structural changes 2.1. Regeneration composition and density

20 Stand structural changes 2.1. Regeneration composition and density

21 Outline Background Retention harvesting Tenderfoot Creek Experimental Forest Three lenses into stand dynamics Stand structural changes Growth Mortality

22 Growth 1. Overstory tree growth

23 Growth 1. Overstory tree growth Test P-value Control vs Treated Aggregated vs Dispersed Burned vs Unburned Period1 vs Period Interaction: Cut + Burn Interaction: Period + Cut Interaction: Period + Burn D 100% greater U 42% greater P2 41% greater P2 U 92% greater than P2 B, but 15% less in P1

24 Growth 2. Seedling height growth

25 Growth 2. Seedling height growth Test P-value Aggregated vs Dispersed Burned vs Unburned Interaction: Cut + Burn Test P-value Aggregated vs Dispersed Burned vs Unburned Interaction: Cut + Burn Agg 15% faster

26 Outline Background Retention harvesting Tenderfoot Creek Experimental Forest Three lenses into stand dynamics Stand structural changes Growth Mortality

27 Mortality 1. Effects of burning Annual mortality Annual mortality Retention Pattern RxFire Initial TPA Initial QMD rate, P1 rate, P2 Control Unburned % 1.8 % Aggregated Unburned % 4.3 % Dispersed Unburned % 4.0 % Aggregated Burned % 6.1 % Dispersed Burned % 13.5 %

28 Mortality 2. Agents Bark beetles Mountain pine beetle Retention Pattern Unsuccessful attacks Successful attacks TOTAL TREES Control % Aggregated % Dispersed % TOTAL

29 Mortality 2. Agents Bark beetles Mountain pine beetle Retention Pattern Unsuccessful attacks Successful attacks TOTAL TREES Control % Aggregated % Dispersed % TOTAL Ips spp. Retention TOTAL Rx Fire Infested dead Pattern TREES Control Unburned % Aggregated Unburned % Dispersed Unburned % Aggregated Burned % Dispersed Burned % TOTAL

30 Mortality 2. Agents Bark beetles Mountain pine beetle Retention Pattern Unsuccessful attacks Successful attacks TOTAL TREES Control % Aggregated % Dispersed % TOTAL Ips spp. Retention TOTAL Rx Fire Infested dead Pattern TREES Control Unburned % Aggregated Unburned % Dispersed Unburned % Aggregated Burned % Dispersed Burned % TOTAL Retention Pattern Rx Fire Initial QMD QMD of beetleevidence dead Control Unburned Aggregated Unburned Dispersed Unburned Aggregated Burned Dispersed Burned

31 Mortality 2. Agents Wind Sunscald Initial Ht:DBH of dead trees no beetle evidence Initial Ht:DBH of trees still living in 2011 Retention Pattern RxFire Control Unburned Aggregated Unburned Dispersed Unburned Aggregated Burned Dispersed Burned

32 Outline Background Retention harvesting Tenderfoot Creek Experimental Forest Three lenses into stand dynamics Stand structural changes Growth Mortality Recap: More variability and greater overstory densities in Agg Better overstory growth as time passes, best in Disp and without burning Burning really hurt survival; MPB wasn t a big factor Plenty of PICO regen, though more ABLA than hoping for Agg is slightly better enviro for PICO regen growth

33 The take-home message Retention harvesting is a viable tool to create structural heterogeneity in lodgepole pine stands. Heterogeneity is good. But heterogeneity is costly. Why is it worth it? Partial economic returns Aesthetics (maintains overstory) Habitat diversity Plant biodiversity Watershed outflow Improved resilience to fire Improved resistance to beetles

34 Acknowledgements USDA FS RMRS: Ward McCaughey Helen Smith Sharon Hood Elaine Sutherland David Wright Joel Egan UM CFC: Tom Perry Dave Affleck

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36 Stand structural changes 2.1. Regeneration densities over time Should this figure have SE shading like the overstory figure does? Odds are it will look messy

37 Mortality Probability of mortality by treatment and period Period 1 Period 2 Agg trees survives better than control Only Disp:U survival as good as control Both P1 and P2 models have low pseudo-r2 values. No interaction. No DBH effect. Use consistent treatment colors. Should these figs even be in here? Did not account for nesting.