Simulated climate change in subarctic soils: responses in nematode speciescomposition and dominance structure

The nematode fauna at two contrasting subarctic sites was studied at Abisko , Swedish Lapland. One site was a dwarf shrub dominated, tree-line heath (4 50 m a.s.l.) and the other a high altitude fellfield (1150 m a.s.l.). Respo nses in the composition of the nematode fauna to eight growing seasons with simulated climate change were monitored. The environmental manipulations c onsisted of temperature increase by using passive greenhouses, NPK fertiliz ation, and a combination of both. A total of 98 species was found at the si tes, with twice as many species at the heath compared to the climatically h arsh fellfield. Species similarity was low, most likely due to differences in soil type and vegetation cover. The environmental perturbations caused d istinct changes in dominance and trophic structure. Taxa common at both sit es responded similarly with increases in Aphelenchoides, Filenchus and Plec tus, and decreases in Eudorylaimus, Monhystrella and Teratocephalus. Genera lly, the manipulations changed the trophic composition in favour of fungal and plant feeding species, indicating a shift in the decomposition pathway.