Growth responses to thinning from below in uneven-aged interior Douglas-fir dominated stands

486-499

Artikel aus einer Zeitschrifte-journal

200211700

Canadian Journal of Forest Research 2024, 54(5) ; Jrg. 54 ; 5 (2024) , 486-499

We assessed the impacts of three approaches to thinning from below with varying spatial patterns on several stand and individual tree variables for interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco), interior spruce (Picea glauca (Moench) Voss × Picea engelmannii Engelm.), and lodgepole pine (Pinus contorta Dougl. Ex Loud. var. latifolia Englem.) in central British Columbia, Canada. The three thinning treatments were two experimental “clumped” treatments (3m Clumped and 5m Clumped) and the Standard (more uniform spacing) thinning treatment that was employed operationally at that time.We used long-term data from 24 plots measured five times over 21 years. Thinning increased stand basal area increment, with the plots that received the 5m Clumped treatment having significantly higher periodic annual relative basal area increment than the unthinned Control plots. The responses for the two clumped treatments were not any lower than the Standard. The 3m Clumped treatment was best if one is concerned about fast recovery of the growing space; however, the 5m Clumped spacing treatment may be preferable if higher individual tree vigour is needed for resistance and resilience to fire, insects, and disease.
Keywords: pre-commercial thinning, long-term silviculture study, stand density, complex stands, uneven-aged