Andy Gray - Alternatives for creating early seral forest openings
- 1. Alternatives for creating early seral forest openings Andrew Gray
- 2. What is an early seral forest? Early seral=Successional stage after disturbance and before tree canopy closure Concept of succession developed from studies of abandoned fields and glacier retreat But stand development rarely starts from “bare ground”
- 3. How much disturbance? What needs to be disturbed? How long will it remain open?
- 5. Important disturbance characteristics Disturbance size Disturbance severity (residual structure and composition: over- and under-story) Available resources: light, soil moisture, nutrients Disturbance frequency
- 7. HJA old-growth Trout Ck. old-growth Panther Ck. mature Martha Ck. mature
- 8. Gap light and moisture patterns Light Soil moisture N
- 12. Fig. 4. Average differences in soil moisture between the clearcut and the forested areas during spring (April-June), summer (July-September), and fall (October-November), 1960-1980. Positive values indicate higher soil moisture in the clearcut area. Solid data points represent significant differences (t~ = 0.05, t-test of inequality) between the clearcut and forested areas. P.W. Adams et al. 1991. For. Ecol. Manage. 41: 249-263 Soil moisture is temporarily more abundant after clear-cutting
- 13. Change in species richness by gap size
- 14. Changes in cover of residual and invader species Mean of summed cover by species group
- 15. Residual plants can take the heat
- 16. Density of natural regeneration after 3 growing seasons Hemlock in old-growth only. Density in mature stands=0.
- 17. Tree canopy closure was faster in old-growth stands
- 18. Where’d my early seral go?
- 19. Blue River Landscape Study: based on natural-disturbance regimes
- 20. Landscape area 1 (N. Fk. Quartz)
- 21. Forb species in BRLS study
- 22. Teakettle study: burn and/or thin? No thin CASPO thin Shelterwood No burn Burn
- 23. Understory response to thinning and burning No burn Burn
- 24. No burn Burn No burn Burn white fir incense-cedar Jeffrey pine sugar pine
- 26. Is NFMA a barrier to enhancing early-seral forest? "... all forested lands in the National Forest System shall be maintained in appropriate forest cover with species of trees, degree of stocking , rate of growth, and conditions of stand designed to secure the maximum benefits of multiple use sustained yield management in accordance with land management plans.”
- 27. Seral conditions on private lands
- 28. Conclusions Relatively small gaps or light thinnings in the overstory create local hot-spots of early seral plants, may be beneficial to many organisms. Understory density and disturbance affects composition and the speed of crown closure. Light prescriptions can be counterproductive; severe or repeated disturbances may be important for maintaining high-quality early seral conditions.