Abstract
The present research aims to establish the depth of abiotic and invertebrate edge-effects occurring in plantations of two conifer species, and the resulting effects of management practices on 'edge' and 'core' invertebrate communities. Near complete invertebrate samples were collected using chemical knockdown allowing analysis of invertebrates at the order, family, genus, species and guild level. Similar invertebrate densities per m[2] ground area occurred in both tree species, although communities differed between them, Pinus sylvestris supporting a more diverse community than Picea sitchensis. Species richness, diversity and densities varied with distance from plantation edge with the Acarina, Araneae, Coleoptera, Collembola, Diptera and Hemiptera showing particularly strong responses to edge proximity. Abiotic edge-effects, although variable between transects, occurred to an average depth of 30 metres with an approximate 1 C drop in temperature and a 5% increase in relative humidity towards the core. Invertebrate edge-effect depths varied with species, ranging from 5 to 80 metres. In P. sitchensis invertebrate richness and densities, particularly for Coleoptera, Araneae and Hemiptera were higher in the edge habitat, whilst increased richness and diversity occurred in the core of P. sylvestris. Edge habitat is key to optimising richness in P. sitchensis, however application of core-area models shows that current plantation management fails to maximise edge habitat. Reduction of patch size and/or increasing edge features will increase species richness. In contrast core habitat is vital to species richness in P. sylvestris. Current small patch size limits invertebrate richness, increased patch size and implementation of edge buffer zones would protect core habitat thus enhancing invertebrate species richness.