Mesostigmatid mites in four classes of wood decay.

We studied the mesostigmatid mite community in four classes of wood decay in mixed (pine-oak) forest stands in the Wielkopolska region, Cental-West Poland. A total of 80 samples, including bark, phloem and rotten wood of coniferous and deciduous species logs, were taken in August 2006 and 2007. Decay classes were a qualitative, categorical index based on visual assessment of decomposition in coarse woody debris. A total of 3621 mesostigmatid mites were counted and identified to 91 species. In general the total number of species was diverse in the decay classes and ranged from 35 (classes I and II) to 58 (class IV). The average number of species did not differ significantly among wood decay classes. Also the abundance of mesostigmatids did not differ significantly among wood decay classes, but the highest abundance was observed in the last class (IV). Cluster analysis of the species identity index showed that the microhabitats were divided into two main clusters: relatively undecayed wood and decayed wood. Species accumulation curves showed that relatively decayed wood (class IV) had a greater rate of species accumulation than undecayed wood from the class I decomposition.