%0 Research articles
%T Analysis of drier rich Betula pubescens fens, rich Sphagnum warnstorfii fens and rich Picea abies mires in the aapa mire area of Finland: compositional gradients, type variants and macro-topography
%A Laitinen, Jarmo
%A Muurinen, Lauralotta
%A Ruuhijärvi, Rauno
%D 2022
%J Suo - Mires and peat
%V 73
%N 1
%U http://suo.fi/article/10739
%X <p>Rich fens belong to one of the most threatened habitats in Finland. Their three classifications across Finland or Europe include (1) floristic Finnish vegetation types (mire site types) used as basic vegeta­tion units nationally, (2) Finnish habitat types used for evaluating the vulnerability of various rich fens nationally, and (3) the Braun-Blanquet units used for understanding continental scale classification and distribution of varying rich fen vegetation. All those classifications play a specific role for evaluating the vulnerability of the rich-fen variation locally, nationally and continentally.</p>
<p>We tested the classification of three Finnish mire site types, (1) drier rich <em>Betula pubescens </em>fens (in current B-Bl system <em>Saxifrago-Tomentypnion </em>alliance), (2) Rich <em>Sphagnum warnstorfii </em>fens (<em>Sphagno warnstorfii-Tomentypnion nitentis</em>) and (3) rich <em>Picea abies </em>mires (<em>Braunmoorbrücher </em>Ruuhijärvi 1960, not classified in B-Bl up to date). Studied mire site types represent <em>Sphagnum warnstorfii </em>rich vegetation in the form presented by the classic Finnish sample plot material (Ruuhijärvi 1960). In recent field surveys, a question has appeared, if types 1 and 2 are in fact ´too similar´. The possible problem derives from the fact that, in the Finnish mire site type classification, which is based on main mire vegetation units (site groups) and well-established compositional directions of variation (<em>Varia­tionsrichtungen</em>), floristic differences between close-by mire site types may be very small. We made a material-based test classification and prefer studying problematic parts of classification with a carefully chosen sample-plot material including vegetation variation around the problem. Large-scale vegetation surveys then provide the overall view for the larger scale hierarchy within the classification. We ask, (1) what are the compositional gradients within the material, (2) what are the most characteristic and other characteristic species of objective test units (clusters, subclusters), and how the test-classification units deviate from the mire site types. (3) Additionally, we ask, if the test-classification provides ideas for commenting the Finnish habitat type classification and the Braun-Blanquet classification.</p>