The Influence of Sward Management on Foliage Arthropod Communities in a Ley Grassland

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Abstract
The influence of different systems of grazing and silage production on the foliage fauna of a grass lea was investigated. Most arthropods were caught in D Vac suction nets (up to 10,351 individuals m-2) in long conserved silage swards and least (as few as 394 individuals m-2) in short swards subject to periodic heavy grazing. Immediate, non-persistent population fluctuations accompanied management-induced changes in sward height: the abundance of most groups, particularly larger insects, increased during conservation for silage, and acarine and collembolan numbers fell most under heavy grazing and following cutting. The cropping systems had no overall influence on the range of dominant taxa collected. The concept of a faunal spectrum is introduced to represent faunas containing large numbers of species and was used in a comparative analysis of treatment differences. Faunal abundance was subject to other modifying influences, notably successional increases associated with lea establishment. Atypical weather can largely override effects of cropping procedures, and principal coordinate analysis showed that seasonality predominantly influences community structure. In short-term lea systems, cropping management, acting within a framework of other factors, limits foliage arthropod abundance by maintaining a predominantly short sward length and by modifying microclimatic conditions.