Mites occurring in the canopy of Sitka spruce growing in Ireland

Following centuries of deforestation, the area of forest in Ireland is increasing at a rate of between 20,000 and 25,000 hectares annually. However, the vast majority of the afforestation has been with Sitka spruce which is native to North America. In this study we describe the oribatid fauna of a Sitka spruce canopy in Ireland and compare it with the fauna occurring in the canopies of North America. In Ireland, 24 species of Oribatida, representing 20 genera, were recorded from two arboreal microhabitats: canopy (leaves and branches) and epiphytic moss. Two of these species, Malaconothrus (M.) egregius and Ophidiotrichus tectus, were new records for Ireland and the latter was the first record of the genus Ophidiotrichus. Diversity indices and rarefaction curves demonstrate that oribatid mite diversity is greatest in both canopy and epiphyte samples collected at the upper heights. Over 50% of the oribatids recovered from the canopy were Brachypilina and the assemblage was dominated by Phauloppia lucorum and Camisia segnis, with the remainder of the species being poorly represented (except Chamobates schuetzi and Eupelops acromios). Of the 19 species found in the moss, P. lucorum and Zygoribatula exilis were the most abundant taxa, and C. segnis was uncommon. In this microhabitat, 91% of individuals collected were Brachypilina which is not unexpected. Species richness is considerably lower than in similar habitats with native Sitka spruce and arboreal genera, such as Dendrozetes and Scapheremaeus, were not found in this study.