Regional factors rather than forest type drive the community structure of soil living oribatid mites (Acari, Oribatida)

Abstract

Most European forests are managed by humans. However, the manner and intensity of management vary. While the effect of forest management on above-ground communities has been investigated in detail, effects on the below-ground fauna remain poorly understood. Oribatid mites are abundant microarthropods in forest soil and important decomposers in terrestrial ecosystems. Here, we investigated the effect of four forest types (i.e., managed coniferous forests; 30 and 70 years old managed beech forests; natural beech forests) on the density, diversity and community structure of oribatid mites (Acari). The study was replicated at three regions in Germany: the Swabian Alb, the Hainich and the Schorfheide. To relate changes in oribatid mite community structure to environmental factors, litter mass, pH, C and N content of litter, fine roots and C content of soil were measured. Density of oribatid mites was highest in the coniferous forests and decreased in the order 30 years old, 70 years old, and natural beech forests. Mass of the litter layer and density of oribatid mites were strongly correlated indicating that the litter layer is an important factor regulating oribatid mite densities. Diversity of oribatid mites was little affected by forest type indicating that they harbor similar numbers of niches. Species composition differed between the forest types, suggesting different types of niches. The community structure of oribatid mites differed more strongly between the three regions than between the forest types indicating that regional factors are more important than effects associated with forest type.

Do shifts in soil Oribatida (Acari, Oribatida) give information on differences in fruit yield of Chinese star anise?

“…This result contrasted with those of previous studies, which suggested that Oribatida abundance was positively correlated with litter mass and the concentration of C in soil (Erdmann et al, 2012) and negatively correlated with soil pH (Haagvar and Amundsen, 1981;Erdmann et al, 2012) and the concentration of N in litter and fine roots (Erdmann et al, 2012).…”

“…Regarding litter, a strong positive correlation between litter mass and oribatid abundance has been reported in the literature (e.g., Erdmann et al, 2012), but we found no significant correlation in the current study. Because there was also no significant difference in litter depth between the low-and high-yielding plantations (Table A1), we cannot explain this finding Table 4.…”

“…Prior studies stated that Oribatida abundance was negatively correlated with soil pH (Erdmann et al, 2012). Soil pH is generally accepted to regulate Oribatida density indirectly rather than directly, since most Oribatida species tolerate even very acidic conditions (Hågvar, 1990).…”

“…Soil pH can influence Oribatida mites through bottom-up effects by affecting soil microorganisms (Bååth and Anderson, 2003;Dequiedt et al, 2011), the prey of oribatid mites. Soil acidity also indirectly affects oribatid mite densities by controlling the density of macro-decomposers, in particular earthworms, which are likely to affect oribatids via bioturbation, for example, by reducing the thickness of organic layers (Erdmann et al, 2012) and mixing litter and mineral soil (e.g., Maraun et al, 1999). In our study, soil pH did not differ significantly between the two plantations (Table A1).…”

“…Although the linkages between Oribatida community structure and soil pH (e.g., Van Straalen et al, 1988;Lebrun and van Straalen, 1995), forest stand age (Zaitev et al, 2002), tree species (Migge et al, 1998;Sylvain and Buddle, 2010), forest type and regional factors (Erdmann et al, 2012), as well as forest type, log type, and regional factors (Bluhm et al, 2015) have been comprehensively studied, the deterministic factors are still poorly understood. In the current study, no causal link between Oribatida assemblage and fruit yield were found, a result that has not previously been described.…”