Ecological importance of meadow patches in protected forest area : floristic diversity and the dynamics of insect communities

The present studies deal with the practical and theoretical problems of meadows in structure and functioning of the forest complex. Floristic, phytosociological and entomological studies involved fragments of two meadows located in large forest complex Kampinos National Park (Central Poland): a 'mid-forest' meadow surrounded by forest and 'near-forest' meadow situated in the boundary between forest and open area. The plant community developed on mid-forest meadow can be classified as Lysimachio-Filipenduletum ulmarie Hadc et al. 1997, on near-forest meadow as Deschampsietum caespitose Horvatic 1930. Both studied meadow communities are very widespread in Kampinos National Park and in whole Poland. Insect community containing various trophic guilds from Chloropidae family (Diptera) was chosen as representative of the entomocoenosis. From the standpoint of landscape ecology the processes of plant and insects species dispersion from meadow to forest and vice versa, across the forest meadow ecotone were analysed. The obtain results revealed that the meadows and their ecotones are refuge habitats for many plant and Chloropidae species increasing plant and entomofauna biodiversity of forest landscape. Proximity of meadows did not cause significant changes in the floristic composition of forest vegetation. Fears concerning the negative impact of meadows on natural forest vegetation through penetration of alien plant species and phytophagous Chloropidae seem to be unfounded. Ecotone was an important barrier for most plant and Chloropidae species in their dispersion from meadow to forest and vice versa. In the case of mid-forest meadow 93% of plant species did not cross ecotone, for near-forest meadow it was 83%. A high index of dispersion of Chloropidae species in mid-forest transect and poor differentiation of their numbers between zones indicate substantial colonisation of the whole system by Chloropidae, however, ecological properties of this fauna (saprophage species, a lack of distinct dominant, low density) minimised the risk it might pose to meadow complex or to adjacent forest. Near-forest meadow with much richer and diverse Chloropidae fauna contributed minimally to the fauna of ecotone and adjacent forest. Only 25% of species number of Chloropidae colonised all zones of the transect there and their majority (55%) exclusively inhabited the meadow ecosystem. It was found, that, from the point of view of natural forest protection, the role of adjacent meadows is very significant. They make 'traps' for certain groups of phytophagous insects.