1. Improving longleaf pine mortality predictions in the Southern Variant of the Forest Vegetation Simulator R. Justin DeRose 1 John D. Shaw 2 Giorgio Vacchiano 3 James N. Long 1 1 Utah State University, 2 Rocky Mountain Research Station, 3 Università di Torino Photo: Antonin Kusbach

2. Outline Size-density relationships FVS-predicted mortality Longleaf pine Mortality in longleaf Simulate natural mortality using FVS Conclusions / Recommendations

3. Size-Density Relationships Density management diagram Trajectory through time

4. Mortality in SN variant 3 types… ρ = f(Dq x ) 1.Background mortality 2.Density-dependent mortality, SDI > 55% & Dq < 10.0, x =1.6 3.Density-dependent mortality, SDI > 55% Dq > 10.0, x = 2 Phase 1 Phase 2 Phase 3

5. Longleaf pine DMD Mature Stand Boundary (MSB) –LL range-wide dataset –Even-aged –Pure ρ = f(Dq x ) then, –Perhaps x > 2 MSB Shaw and Long, 2007, SJAF Stand # 10001

6. MSB Shaw and Long, 2007, SJAF Mechanisms? Increasing chance of density-independent mortality? Less occupied growing space? Zeide (1985), ‘self- intolerance’? Assmann (1970) ‘crown disengagement’? Red pine

7. MSB Dq TPA Ponderosa pine Dq TPA Utah juniper Dq TPA Douglas-fir Dq TPA Aspen

8. Shaw and Long, 2007, SJAF Importance Increasingly managing for large D trees –RCW (Shaw and Long, 2007, SJAF) (F & W Guidelines)

9. Simulate MSB 1.THIN… keyword every cycle? 2.Iteratively adjust BAMax / SDIMax? 3.Use MSB to constrain size- density relationship?

10. Results Event Monitor, FixMort keyword IF Dq approaches MSB THEN 10% mortality / cycle

11. Results

12. Conclusions FVS models background mortality fine at small diameters Self-thinning mortality appears fine BAMax mortality is unrealistic

13. Conclusions We need a better approximation of natural mortality We have a fix, albeit rough –Iterative FixMort simulates well but… –Must know MSB for your species

14. Recommendations Replace BAMax mortality Species-specific fitted relationships (like MSB) Dq TPA Dq TPA

15. Acknowledgements Forestry Branch of the Fort Bragg Natural Resource Division U.S. Army Environmental Center P. Wefel and J. Stancar for their continuing support D. Donnelly for early project support