Understorey plants as indicators of site productivity in Pinus sylvestris L. stands
1993
Nieppola, J. (Toronto Univ. (Canada). Dept. of Forestry)
The capabilities of understorey plant species to indicate site productivity, as expressed by site index (H100), were examined using data from 222 sample plots from mature stands of Pinus sylvestris L. in southern Finland. The number of herb species was relatively strongly correlated with site index (r=0.81). Also, the presence of 20-30 species indicated site index well. The link between understorey vegetation and site productivity was primarily based on the distribution patterns of these indicators. In contrast, species cover was poorly related to site productivity. In regressions of species cover on site index, only ten species achieved r2 of 40% or more. No good indicators existed where site index was less than 21 m. The inclusion of soil deposit types (soil texture) in the prediction model compensated for the poor prediction power of understorey plants on sites of low productivity and increased the accuracy of site productivity estimation by approximately 15%. The estimation did not improve when temperature sum was included in the model.
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