PARENT SESSION
Poster Session 23: Soil Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Influence of climate warming on soil mesofauna of coniferous forests of temperate latitudes.

Melecis, Viesturs¹, Jucevica, Edite ¹, Salmane, Ineta¹, Ventins, Janis¹, ¹ Institute of Biology, Salaspils, Latvia

ABSTRACT- Long-term (1992-2002) studies of soil mesofauna (Enchytraeidae, Collembola and Gamasina) were performed at the National LTER Network sites of Latvia, represented by young (30-40 years), middle-aged (50-70 years), and old (150-200 years) Scotch pine forests. Statistically significant increase of positive (>+4^o C) temperature sums (PTS) took place during the study period. No trends were found in mean air temperatures (MAT) and soil moisture (SM). Sampling of soil fauna was performed once a year, on the end of August. Soil microarthropods were collected from series (n=100) of soil samples (5 cm² x 10 cm) by using modified high gradient extractor, and Enchytraeids from series (n=30) of soil samples (23 cm² x 10 cm) by using wet funnel techniques. In total, 67 species of Collembola (total density 1820-28100 ind/m²), 46 species of Gamasina mites (1040-6120 ind/m²) and 7 species of Enchytraeidae (8300-10 700 ind./m²) dominated by Cognettia sphagnetorum and Achaeta spp. were recorded. Nonmetric Multidimensional Scaling (NMS) of Collembola data yielded two intercorrelated (r=0.455, p<0.05) axes. Axis 1, explaining 48.6% of data variation had strong correlation with PTS (r=0.66, p<0.01), and Axis 2 (38.6%) with SM (r=-0.62, p<0.01). Temporal trajectories of communitiesy along Axis 1 describing climate warming was strongly controlled by the fluctuations in SM. Interactive effects of these factors became apparent as loops in the trajectories. The species richness showed statistically significant decrease during the study period from 29-36 to 13-26 species. NMS of Gamasina data yielded three axes. Axis 3 (35.2%) was correlated with SM (r=-0.536, p<0.01), Axis 2 (23.7%) with MAT (r =-0.496, p<0.05), and Axis 1 (15,7%) with PTS (r=-0.531, p<0.05). Therefore, fluctuations in SM played the most important role in formation of community structure. Species richness of mites was declining during the period of study from 13-19 species in 1992 to 9-11 species in 2002 and was correlated with Axis 1 and Axis 2. Positive correlations with SM were recorded for the total numbers of Enchytraeids (r=0.593, p<0.05) and C. sphagnetorum (r=0.597, p<0.01). Density of Achaeta spp. had positive correlation with MAT (r=0.543, p<0.01).

Key words: climate warming, soil mesofauna, pine forests