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The diversity of Diptera associated with a British hedge

Dipterists Digest

Abstract

Diptcra (true tlie.s) were recorded at a single hedge, 85 metres in length, on a livestock farm in Devon, southwest England, over a two year period. Of these 8.30 species were identified. Members of some well-represented families were not. or scarcely, included in this total because they were not identified to species level: it is estimated that altogether over 1.000 species were present. The hedge is considered representative of lane-side hedges in south-west England and some other European regions. Excluding families from which few or no individuals were identified to species level. 17% of British species were found. The most species-rich families were Mycetophilidae, Syrphidac. Museidac, Dolichoptxlidae, Limoniidac Hybotidac and Empididae. Observations from the hedge and published literature suggest that the majority of species present benefited from the hedge if not as larval habitat, then for adult food, mating, shelter or movement through the landscape. A minimum of 22% of species recorded at the hedge were considered likely to occur there as larvae: 162 species were recorded from emergence traps: these covered only 0.5% of the ground surface area; 163 species found are known to develop in assiKiation with decaying wood, including 97 of the 132 species recorded that are fungus feeders; 126 are associated with dung and 85 known to develop in living plant tissue. Assemblage analysis and other evidence suggest the hedge’s high species-richness reflected its well structured form with, in addition to the shrub layer, emergent trees, a central bank, a ditch and herb-rich margins at both sides. Other important factors likely to explain the high biodiversity observed were the heterogeneity of other semi-natural habitats nearby, the small scale and high degree of landscape connectivity, the richness of plant species and the low intensity of local agricultural practices. Twenty-seven species considered nationally threatened or scarce were recorded. It is concluded that hedges, when placed in small-scale heterogeneous agricultural landscapes, can provide important resources for Diplcra. facilitating the survival of species-rich and diverse assemblages.

Author(s): ROBERT J. WOLTON; HOWARD BENTLEY; PETER J. CHANDLER; C. MARTIN DRAKE; JOHN KRAMER; ADRIAN R. PLANT

Journal: Dipterists Digest

Year: 2004

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