© 2000 Heron Publishing—Victoria, Canada
Effects of stand composition and thinning in mixed-species forests: a modeling approach applied to Douglas-fir and beech
H. H. Bartelink (1)
Department of Environmental Sciences, Group of Silviculture and Forest Ecology, Wageningen Agricultural University, P.O. Box
342, 6700 AH Wageningen, The Netherlands (hank.bartelink@btbo.bosb.wau.nl) / Received October 13, 1998
Summary
Models estimating growth and yield of forest stands provide important tools for forest management. Pure stands have been modeled
extensively and successfully for decades; however, relatively few models for mixed-species stands have been developed. A spatially
explicit, mechanistic model (COMMIX) is presented that simulates growth of mixed-species forest stands, and takes account
of the effects of management on stand dynamics.
Previously, it was shown that COMMIX satisfactorily reproduced the development of monospecific stands. In the present study,
the model was used to simulate growth and yield in mixed stands differing in the proportions of species present. The concept
of a "replacement series" was used to compare productivities of the mixed stands. The model was also used to analyze effects
of thinning regimes and stand composition on productivity. Model simulations indicate that productivity of a mixed stand will
generally be intermediate between the productivities of monospecific stands of the contributing species. However, stand composition,
and especially thinning regime, will strongly affect stand productivity. The simulations are discussed with reference to the
effects of resource partitioning, canopy stratification, complementarity, spatial pattern, crown dynamics, and phenology on
the growth and yield of mixed stands. The study highlights the value of using mechanistic approaches to predict mixed stand
development in relation to management regime.
Keywords:
distance-dependency, growth, management, mixed stands, productivity, replacement series, simulation, yield.
