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1 Polish Journal of Ecology

1 2005

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Floristic analysis of the two woodland-meadow ecotones differing in orientation of the forest edge

Orczewska A., Glista A.

Polish Journal of Ecology

2005

Vol. 53, nr 3

365-382

Studies on the transition zones between plant communities using the statistical method by Matuszkiewicz, have been predominantly conducted in forest communities or in ecotones between wetland and meadow communities. Although boundaries between forest and meadow (as a result of human pressure on the landscape, namely forest fragmentation) are of ecological interest, no previous attempts have been made to estimate the width of such ecotones using Matuszkiewicz.s approach. We applied the method in the studies on floristic changes across two, woodland.meadow ecotones (Arrhenatheretum elatioris/Tilio cordatae-Carpinetum betuli typicum and Scirpetum sylvatici/Tilio cordatae-Carpinetum betuli corydaletosum communities), located at forest edges differing in their orientation. The aim of the research was to estimate the width and character of those ecotones and to investigate whether the possible differences in vegetation are related to the prevailing aspect (orientation) of the woodland edge. To characterise the floristic composition of the two adjacent communities, the method of Greig-Smith.s square (16 quadrats of 4 m2 each) was chosen. To determine the floristic changes across each ecotone, transects 38 m in length and formed of 2 x 2 m quadrats were set perpendicularly to the woodland-meadow boundary. Diagnostic species for the main communities were determined and their incidence along the transect was observed. Differences in species composition that were observed along the transects allowed us to distinguish three contrasting sectors. The first one represents typical meadow communities, the second sector represents a typical ecotone, and the third one contains typical woodland communities. Our results showed that the width of the ecotones differed depending on the orientation of the woodland edge. In the transect between Arrhenatheretum elatioris and Tilio cordatae-Carpinetum betuli typicum communities, situated on a SE-oriented forest edge, it was estimated at 10 m, whereas in the second transect, the transition zone between the Scirpetum sylvatici and Tilio cordatae-Carpinetum betuli corydaletosum was narrower, reaching 6 m. This was located on a NW-oriented woodland edge. Our observations confirm the results of many other studies, which show that transition zones between woodland and meadow are wider on edges that receive more light, than in north-facing ones. The differences in the size of the transition zone at the two study sites are clear despite the fact that the two types of meadow communities differed in the number of mowing cycles per season. The Arrhenatheretum elatioris community is mown twice a year, and its ecotone with the woodland is wider than in the case of the Scirpetum sylvatici community. The latter is mown only once in the vegetation season but its transition zone remains 4 m narrower than in the first situation. It seemed that the increase in vegetation management (two mowing cycles instead of one) did not contribute to the reduced width of the ecotone. When looking at the distribution of species representing different syntaxonomic groups, in both transects, no meadow plants from the Molinio-Arrhenatheretea class or other species of open habitats were recorded deeper than 6 m into the woodland interior. On the other hand, forest species from the Querco-Fagetea class were found much further into the area of meadow. Thus, no strong pressure of meadow communites on woods was recorded, but the opposite situation, where forest species extended into the meadow area, took place. Such a tendency was observed regardless of the aspect of the woodland edge. Differences in physiological amplitude of species allowed us to distinguish, after Ranney et al. (1981), a group of: meadow-oriented species, which neither occurred in ecotone nor woodland, strongly edge-oriented species, and strongly forest interior-oriented species, avoiding the ecotones and meadows. A group of species present along the whole transect (ubiquitous) was very poorly represented. Contact zones between woodlands and meadows observed in the course of our studies and statistical analysis, give support to the model of a discontinuum. In both ecotones studied, the edge effect was recorded; in transect 1 it can be described as a 'double edge effect' (variable = species richness, has both maximum and minimum in the ecotone close together); negative on the meadow side and positive on the woodland side of the ecotone, and at the second study site as the 'positive edge effect'.