Biomass functions for short rotation forestry.

摘要

This paper summarizes the results of regression analyses of the relations between tree dimensions (height, diameter) and dry weight (kiln drying 103.5 degrees C until weight stability), based on extensive data from a wide range of poplar (Populus sp.) and willow (Salix sp.) short rotation stands in East Germany. Statistical tests showed that various types of functions can be used to adequately describe the relations between tree biomass and tree dimensions (R2>0.95). The integration of tree height into the respective models did not significantly improve the coefficient of determination. Thus, the allometric equation, which requires only one parameter (diameter) presents itself as a suitable standard function. Comparative analyses of different diameters (at heights of 0.1, 0.6, and 1.3 m) proved that dbh (d1.3) can be proposed unrestrictedly for the construction of biomass functions. Tree diameters at 0.1 m may be derived from d1.3 by regression models based on the close statistical relation between d0.1m and d1.3. Multiple analysis of variance was used to confirm that the coefficients a0, a1 do not show any statistically significant differences between the analysed clones. However, there are significant effects of stand density and mean stand height on the values of both coefficients. Based on the results, the formulation of generalized biomass functions should be possible which, in addition to individual dbh values, only require a few stand parameters as input variables that can easily be measures in the field..