The oribatid mite community (Acarina) of pure and mixed stands of beech ( Fagus sylvatica) and spruce ( Picea abies) of different age

Abstract

In November 1994, the density of oribatid mite species was determined in litter and soil of pure and mixed stands of beech ( Fagus sylvatica) and spruce ( Picea abies) of an age of ca. 30 and 120 years. The study sites were located in the Solling, a plateau of red sandstone in northern Germany. The stands grow on acidic brown-earth with a moder humus form. The average oribatid mite density was 160 000 ind m −2 and a total of 68 species was present. The diversity and density of the two age classes did not differ significantly indicating little effect of stand age on the structure of oribatid mite communities. The diversity and density did not differ significantly between beech, spruce and mixed stands. However, more `endemic' species (species which only occurred in one of the three stands within one age class) occurred in the mixed stands presumably due to a more heterogeneous and patchy habitat structure. Some species of oribatid mites had higher densities in beech than in spruce ( Hypochthonius rufulus C.L. Koch, Nanhermannia coronata Berlese) while others ( Tectocepheus velatus (Michael), Adoristes ovatus/poppei C.L. Koch) were more common in spruce. Parallel to the distinct stratification of organic layers a strong decline of oribatid mite densities occurred from the L/F to the H/Ah and Bv horizon. Small-sized oribatid species like the Brachychthonioidea dominated in the deeper horizons (H/Ah and Bv).