Zur Entwicklung und Anwendung von österreichischen Biomassefunktionen

Tharandt

2006

S. 202-207

2 Abb., 7 Lit. Ang.

Artikel aus einem BuchUnselbständiges Werk

200133490

During the last two years functions predicting dry matter biomass of branches and branches and needles respectively, were developed for eleven Austrian forest tree species or groups of tree species. The simplest functions require only the diameter at breast height as explanatory variable. More complex models additionally consider tree height and crown parameters. The functions were developed from aleady existing data originally collected in thinning experiments, forest decline and biomass studies, and in a study focussing on the development of tree volume functions. Thus, the available data were inherently quite different. In this study we examined the biomass functions for Norway spruce and beech. In particular, we were interested in the prediction behaviour at individual-tree level, and the impact on estimates at stand level for pure and mixed species stands. Moreover, we were also interested if the differences between biomass predictions of functions, which were developed from different data sources, can be reduced by using models that include crown parameters. According to the results of our investigation, crown parameters are of particular importance concerning the quality of biomass predictions. Functions including crown parameters as explanatory variables yield predictions that reveal a better response to data specific peculiarities. Both, at the individual-tree level and at the stand level functions including crown ratio show smaller differences between predictions compared to the functions that use only diameter at breast height as independent variable. Thus, crown parameters and especially the crown ratio can be regarded as essential variables for reliable biomass estimates.