The Collembola fauna of lrish forests – a comparison between forest type and microhabitats within the forests

Forest is the climax vegetation for most of Ireland. Yet, at the beginning of the twentieth century, because of deforestation, only 1.4 % of the land area was afforested. Currently government policy encourages afforestation and at present approximately 10 % of the land is forested. More than 90 % of these forests are plantation forests and most of this new forest consists of exotic trees, such as Sitka spruce (Picea sitchensis) introduced from North America. Little is known of the invertebrate fauna of these plantations and it is of interest to know the composition of the fauna and whether it differs from those of native tree species. In the current study we focus on the Collembola fauna occurring in the canopy and soil microhabitats of Irish forests and show that these differ between tree species and microhabitat within the forest. In particular, native oak forests harbour many more Collembola species than the other forest types investigated and non-native forests appear to harbour fewer species than do forests of native species. However, this is a not a simple relationship as first rotation Sitka spruce forests harboured more species than some native forest types. The main differences in species composition are between those species living in bark or in epiphytic cover on the trees with deciduous species having different species to conifers.