Abstract: Six silvicultural patterns of plantation forests, including coniferous forests (Pinus massoniana, Cunninghamia lanceolata), broadleaf forests (Mytilaria laosensis, Castanopsis hystrix) and mixed forests (Pinus massoniana+Castanopsis hystrix, Pinus massoniana +Castanopsis fissa), were selected at the Experimental Centre of Tropical Forestry, Chinese Academy of Forestry in July 2013, and soil nematode communities and soil physicochemical properties were investigated to reveal the effects of silvicultural patterns on the soil nematode communities. A total of 16853 individuals of nematode were extracted, belonging to 53 genera, 32 families, 8 orders and 2 phyla. The mean density of the nematodes was 1873 ind·100 g^-1 dry soil. The dominant genera were Iotonchus, Microlaimus and Chrysonema. Principal component analysis (PCA) showed that the structures of soil nematode communities were similar between the C. lanceolata forest and the M. laosensis forest, and the same pattern was observed between the C. hystrix forest and the mixed P. massoniana + C. hystrix forest. The densities of soil nematodes were smaller in the C. hystrix forest and the mixed P. massoniana + C. hystrix forest than in the other forests. The Shannon index and Pielou index of soil nematode communities in the P. massoniana and M. laosensis forests were greater than those of the other forests. The highest density and lowest Shannon index and Pielou index were found in the mixed P. massoniana + C. fissa forest. The differences in taxonomic richness, freeliving nematode maturity index (MI), plantparasitic maturity index (PPI) and PPI/MI index were not significant among these silvicultural patterns. However, predatorsomnivores, bacterivores, plant parasites and Wasilewska index (WI) differed significantly among these silvicultural patterns. Correlation analysis showed that the densities of plant parasites, bacterivores and fungivores were affected significantly by soil P content, while a significant positive relationship was found between soil K content and the density of predatorsomnivores. These results demonstrated that different silvicultural patterns influenced the functional structure and composition of soil nematode communities. Soil P and K were the main factors affecting the trophic structure of soil nematode communities.

Key words: nitrogen sources, carbon sources, organic acid, 16S rDNA, Pantoea sp