Transcript of "Andy Gray - Alternatives for creating early seral forest openings"
Alternatives for creating early seral forest openings Andrew Gray
What is an early seral forest? <ul><li>Early seral=Successional stage after disturbance and before tree canopy closure </li></ul><ul><li>Concept of succession developed from studies of abandoned fields and glacier retreat </li></ul><ul><li>But stand development rarely starts from “bare ground” </li></ul>
<ul><li>How much disturbance? </li></ul><ul><li>What needs to be disturbed? </li></ul><ul><li>How long will it remain open? </li></ul>
Gap light and moisture patterns Light Soil moisture N
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
Teakettle study: burn and/or thin? No thin CASPO thin Shelterwood No burn Burn
Understory response to thinning and burning No burn Burn
No burn Burn No burn Burn white fir incense-cedar Jeffrey pine sugar pine
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.”
Conclusions <ul><li>Relatively small gaps or light thinnings in the overstory create local hot-spots of early seral plants, may be beneficial to many organisms. </li></ul><ul><li>Understory density and disturbance affects composition and the speed of crown closure. </li></ul><ul><li>Light prescriptions can be counterproductive; severe or repeated disturbances may be important for maintaining high-quality early seral conditions. </li></ul>
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