Grasshopper population dynamics and meteorological parameters ‐ lessons from a case study

Population dynamics of grasshoppers differing in phenology were analysed on a xerothermic meadow in central Germany, The study was based on standardized annual sweep net samples in relation to meteorological factors |mean and maximum temperature, rainfall, sunshine) from May through September of current and previous year, respectively. Three grasshopper species, the early hatching Euthystira brachyptera , the phenologically intervening Stenohothrtis lineatus. and the late hatching Gomphocerus rufus ., were investigated over ten years during three periods: 1971 74, 1983 85, 198789. By means of stepwise linear regression and a cross‐validation procedure a subset of meteorological parameters was extracted which best described the field sampling data of the grasshoppers. This subset of variables was then used in multiple linear regression analyses in order to model the long‐term population dynamics of the grasshoppers from 1971 to 1990, The selected variables for each species revealed different influences of meteorological parameter combinations reflecting the different phenologies. The dynamics of the three gomphocerine species modelled for 20 yr (1971 1990) differed both with maxima and minima in different years and in the fluctuation factors from 29 (E. brachyptera) to 155 (S. lineatus). In comparison with fluctuation trends in populations of other sites within the region some species‐specific and habitat‐specific population dynamics must be assumed. There were no significant correlations between annual aridity (precipitation‐temperature)‐indices and densities of the three populations studied.