Kitaibelia vol. 7 – no. 2. (2002) p.187-205.
Florisztikai és cönológiai vizsgálatok a somogyi Dráva-völgy rétjein
Floristical data about the occurence of 409 vascular plant species on meadows of the river alluvium are presented. The occurence of species with underscored names, and all other species occurences in localities (village fields) with initials marked by an asterisk, were not mentioned in earlier publications referring concretely to the studied area (except some sporadic data of the author). 30 community types (mainly associations) investigated in 1996-2000 are characterised. A new association (Arrhenathero-Molinietum arundinaceae ass. nov.) and 2 new subassociations are described. 4 treatments (1: moderately grazed by cattle, 2: mowed for 5 years, also grazed previously, 3: mowed, 4: not used) were compared on the basis of plant strategy (’social behaviour’) types and species abundance patterns. The results suggest that the pastures are the most disturbed habitats among the studied treatment groups (the disturbance order: grazed > mowed for 5 years (grazed befor) > mowed > not used). The most stressed group seems to be the mowed one. The greater heterogenity of ’not used’ group (manifests itself also in the distribution of ecological indicator values for nutrient supply) is suspected to be the result of some positive feedback processes. Fig. 1 and Fig. 2. show the diversity ordering and the rank-abundance curves of treatment groups, respectively. The importance (and diversity) of medium frequency species is greater on the mowed meadows than on the pastures. The author argues that this is a reason for the greater aesthetic value of hayfields.