Struktur einiger Laubwälder im niederösterreichischen Weinviertel

Summary Above-ground structure of the tree and shrub layers of four deciduous forests in Lower Austria were studied. The four stands occurring on sites of different degrees of favourableness for forest growth have developed largely undisturbed by man since many years. Structure as measured in transects varied with site conditions. The structural differences were apparent in the average values for the stand, in those for the mightiest trees per site, and in populations of the same species at different sites. These latter differences appeared to contribute more strongly to the average differences in stand structure than the structural differences resulting from a change in species composition from site to site. Total height of the stands, stem height and crown length clearly change parallel to site conditions, whereas stem diameter, crown diameter and slenderness ratio do not show such regularity. The ratio of maximal to average tree height per stand appears to give a suitable indication of heterogeneity in stand height. Generally, there seems to be an increasingly stronger development of crowns as site conditions deteriorate. Several of our results can be explained ecologically and have been reported from other studies. However, as our results are based on a restricted data base, further research is necessary to establish the possible general validity of our findings.