Assessment of changing agricultural land use: response of vegetation, ground-dwelling spiders and beetles to the conversion of arable land into grassland

摘要

An ecological indicator approach was used to examine the effects of changing agricultural land use on vegetation and ground-dwelling spider and beetle assemblages. An arable land site (control) and six differently managed grassland sites (with different time since conversion from arable land or time of current management) were comparatively investigated in a 3-year study. Whereas species richness increased with decreasing management impact for plants and spiders, the Camargo's evenness (E') index increased for all three examined assemblages. This Suggests a very trustworthy community parameter for ecological indication studies. Differences did occur between the vegetation and the invertebrate groups in the assessment of the grassland sites. Ordination analysis indicated a much better separation of the different sites based on the invertebrate data than is possible on the basis of the vegetation data. These considerable differences were attributable to the short reaction time of these groups to changes in land use: ground-dwelling spiders and beetles mainly respond to changes in the microclimate and the soil-moisture. Efficient indication of restoration management is therefore possible after 3-5 years. Vegetation assemblages appeared as less powerful indicators of short-term restoration processes. We suggest that vegetation monitoring be used as a more powerful long-term approach but that it should be coupled with (short-term and sensitive) invertebrate monitoring (e.g. ground-dwelling spiders and beetles) especially at the beginning of the agricultural restoration processes.