Chironomid communities from subalpine peatlands in subtropical China as indicators of environmental change

Abstract

The composition of Chironomidae communities and the ecological significance of such assemblages in peatlands have received little attention, especially in subtropical alpine regions. We report on the spatial distribution of subfossil chironomids and environmental controls on the insects in three subalpine peatlands from subtropical, central China. We found 44 genera and 62 morphotypes in 41 surficial peat samples. The taxa are different from those found in shallow freshwater lakes in the same region, as terrestrial/semi-terrestrial taxa are common in the peatland chironomid communities. Dissimilarities were observed among the three investigated peatlands, and spatially heterogeneous microhabitats also showed notable differences in particular species abundances, even within the same peatland. Important taxa that are associated with specific peatlands, and/or illustrate within-peatland community differences, include Tanytarsus pallidicornis-type 2, which is related to lower conductivity, and Neozavrelia, which is associated with greater redox potential and pH. Multivariate statistical analysis revealed significant relationships between chironomid community composition and three environmental factors (conductivity, redox potential and pH). Anthropogenic influences and autogenic processes in peatlands likely modify the biotic communities, either through direct or indirect changes in peatland hydrology and chemistry. Low chironomid concentrations and diversity in Erxianyan Peatland may reflect ecological degradation caused by intense human activities, including the harvest of Sphagnum. This study provides information about subtropical peatland biodiversity and illustrates the utility of subfossil chironomids as proxies for past hydro-chemical changes in peatlands.