EFFECTS OF CLIMATE-CHANGE ON SOIL FAUNA - RESPONSES OF ENCHYTRAEIDS, DIPTERA LARVAE AND TARDIGRADES IN A TRANSPLANT EXPERIMENT

A transplant experiment was carried out on the Moor House National Nat ure Reserve, Cumbria, UK, and two sites with different climatic charac teristics were selected for determining how Enchytraeids, Diptera larv ae and Tardigrades respond to changes in climate. The soil was a cambi c stagnohumic gley, characterized by a high organic matter content and low pH. Vegetated soil cores were taken from near the summit of Great Dun Fell (GDF) and used for the transplant experiment. Cores were the n placed back at GDF (845 m) and also transplanted to Sink Beck (SNK, 480 m), providing a mean annual temperature increase of 2.5 degrees C. In order to discriminate between the effects of temperature and rainf all on the size and vertical distribution patterns of the fauna, a fur ther series of lysimeters were established at SNK, and rainfall inputs were manipulated, intending to provide a total input equivalent to th e ambient rainfall at the top site. At regular intervals, a number of cores were destructively sampled from each treatment (top site-GDF; lo wer site-SNK; enhanced rainfall inputs-SNK) and the vertical distribut ion of the soil fauna determined. Enchytraeidae, Tardigrada and Dipter a were commonly found in soil samples at the Reserve and appeared sens itive to the imposed changes in temperature and moisture. Different sp ecies of enchytraeids responded differently: numbers of Cognettia spha gnetorum were correlated positively with temperature, whereas their ve rtical distribution was determined by moisture. Cernosvitoviella atrat a was unable to avoid dry conditions which apparently caused severe mo rtality when exposed to the elevated temperatures; Achaeta eiseni was a more tolerant species, increasing in numbers with increasing tempera ture. Diptera larvae appeared to be dependent on the moisture status o f the upper soil layers and their populations were reduced at higher t emperatures and lower moisture contents. By contrast, tardigrades were able to survive adverse conditions by entering an anhydrobiotic stage , recovering when seasonal climate improved. General trends in soil fa unal responses to climatological changes in the UK are predicted. (C) 1997 Elsevier Science B.V.