Relationships
between boreal understorey vegetation and chemical composition of the organic
layer, stand productivity and climatic factors were studied on 27 coniferous
monitoring plots along a S–N gradient in Finland using ordination techniques
(fitting environmental vectors and surfaces to the NMDS pattern). Total N,
exchangeable Ca and Mg, BS, pH and organic layer thickness formed the subset of
variables with maximum correlation with plant community composition. Of the
stand parameters, site index ( H ₁₀₀), volume and basal area
correlated best with the vegetation pattern. Our results support the hypothesis
that site productivity can be predicted on the basis of the occurrence of
understorey plants. This was especially true in herbaceous plants, where the
number of species well depicted the site index on both pine and spruce plots. We
present quantitative evidence that the response curves along an extensive
nitrogen gradient varied between species representing dwarf shrubs, herbs,
grasses, mosses and lichens.