%0 Research Notes
%T Vegetation succession and diversity on Teuravuoma experimental drainage area in northern Finland
%A Hotanen, Juha-Pekka
%A Nousiainen, Hannu
%A Paalamo, Päivi
%D 1999
%J Suo - Mires and peat
%V 50
%N 2
%U http://suo.fi/article/9783
%X This case study deals with the effects of forest drainage on six mire site types represented by 33 permanent sample plots within a Finnish aapa mire complex located in north boreal vegetation zone. We analysed the main compositional gradients, the abundances of plant species and the diversity of vegetation. The vegetation descriptions were made about at the time of drainage in 1933 and after that in 1943, 1950 and 1994. The forest drainage emphasized the importance of spruce mire and hummock-level bog influences (mire margin and mire expanse effects respectively) in controlling the structure of plant communities. The change of plant community was greatest on fertile mire site types, also spruce mire influence promoted the secondary succession. As expected, the shallow-rooted and/or demanding flark-level vascular plants and (eutrophic) fen mosses had not been able to adapt to the ground water level drawdown. At first, after drainage, species number, Shannon's H' and Simpson's D increased: many mire species of hummock and intermediate level microsites had increased while also pioneer and forest species had colonized the plots. By 1994, however, as the mire species were decreasing these measures had turned to decline except on the (most) infertile site types. Pielou's J' and the evenness based on D reacted vaguely, decreasing a little, though, from 1933 to 1994. Thus, in such cases the dominance in the vegetation had increased. The beta-diversity describing here the differences between plant communities (or site types) decreased along with the hydrological conditions becoming more uniform after drainage.