Stand and neighbourhood parameters as determinants of plant species richness in a managed forest

Abstract. Patterns of species richness in a managed forest were related to ecological factors at two spatial scales. Local variables within a plot (5 m × 5 m) included 13 soil classes and nine stand classes. Neighbourhood variables were defined within a 25 m radius from the focal plot and were measured using a Neighbourhood Diversity Index (NDI - total diversity of different stand classes) and nine Neighbourhood Scores (NS - relative dominance of a given stand class). 224 species were registered in the survey of which 138 were true forest species. Local parameters (stand and soil class) were weak predictors of total and forest species richness. High total and forest species richness were significantly related to high values of NDI (i.e. heterogeneous neighbourhoods). Regression trees showed that total species richness was best predicted by the amount of roadside habitat in the neighbourhood and NDI. Forest species richness was positively related to NDI and negatively related to the amount of coniferous stands in the neighbourhood.