Minor changes in orthopteran assemblages of Central European protected dry grasslands during the last 40 years

During the past 50 years development of farming practices caused tremendous changes in European agricultural landscapes and many insect species became increasingly restricted to protected areas. Yet little is known about long-term trends of insect diversity and community composition in these often small reserves. We performed a comparative study on changes in orthopteran communities of protected dry grasslands in East Germany, which had been surveyed in the 1960s. Applying the same sampling techniques, we revisited 26 of the original sites in 2008 and 2009. Nearly all sites are controlled by conservation policies and changes in vegetation composition were relatively small, although some sites showed shrub encroachment. Changes in orthopteran diversity were not significant. Community composition showed minor changes which were correlated with evidence of woody plant encroachment as derived from historical and recent aerial imagery. The frequency of some Caelifera species decreased from the 1960s to 2008/2009 with one species inhabiting bare soils (Myrmeleotettix maculatus) showing the strongest decline. Some Ensifera, especially two species inhabiting open woodland and scrub (Tettigonia viridissima, Phaneroptera falcata) showed positive trends. Nevertheless, three different regions (each belonging to a different German federal state) had shown distinct orthopteran assemblages in the 1960s, and these were equally different 40 years later. We conclude that the orthopteran fauna of Central European protected dry grasslands showed small changes in species composition, and overall diversity remained rather constant during the past 40 years, which is in accordance with the minor changes in the surrounding landscape. Consequently, the applied conservation management practises-mainly sheep grazing and trimming-are largely effective.