Community structure and vertical distribution of Collembola and Cryptostigmata in a dry-turf cushion plant

Abstract

In a dry-turf grassland ecosystem in the east of Austria, cushions of Dianthus lumnitzeri Wiesbaur (Caryophyllaceae) were inspected. The abundance, community structure, and vertical distribution of hemi- and euedaphic Collembola and Cryptostigmata were studied. Notable differences in the strategies of resource use by these two groups were detected. Collembola with annual mean densities of 7000 – 22000 individuals m-2 and large annual fluctuations in population size prefer the F layer but migrate vertically during severe microclimatic conditions to spread over the whole profile. Cryptostigmata (average adult densities up to 37000 individuals m-2, weak annual fluctuations) are confined to the F layer even in midsummer. A strict nutritional affinity to plant material in certain stages of decomposition is proposed as the explanation. Reflecting the distinction in spatial distribution, the community structure of Collembola appeared very even, with 6 species out of 13 sharing dominance while 1 oribatid genus out of 26 accounted for 64% of all individual Cryptostigmata. These obvious differences emphasize the finding that different mesofaunal taxa may develop different strategies in the formation of communities. Therefore, analysis of the whole community should be prefered to analysis of taxocoenoses.