Abstract: We analyzed functional characteristics of soil microbial community in three typical artificial shelter forests, including Pinus sylvestrisvar. mongolica, Pinus tabuliformis and Populus×canadensisin the windysandy region of northwest Liaoning Province, China, by Biolog-Eco method. Soil chemical properties were measured to explore their correlations with the metabolic activity and functional characteristics of soil microbial community. The results showed that compared with Pinus sylvestris var. ongolica and Pinus tabuliformis, Populus×canadensis had higher soil pH, dissolved organic C and available P concentrations, and lower C/N. There were significant differences in soil microbial community metabolic activities among different forests. The capacity of C source utilization by soil microbial communities (AWCD) was in the order of Populus×canadensisforest >Pinus sylvestrisvar. mongolica forest >Pinus tabuliformis forest. The Shannon diversity index, Simpson diversity index, and McIntosh diversity index of soil microbial community in the Populus×canadensis forest were 3.27, 0.96, and 8.13, respectively, and significantly higher than those ofPinus sylvestris var. mongolica and Pinus tabuliformisforests (P<0.05). There were significant differences in the utilization of the six types of carbon sources by soil microorganisms among different forests. The utilization rates of six carbon sources of Populus×canadensis forest were significantly higher than those of the other two forests (P<0.05). Results of principal component analysis and cluster analysis showed that soil microbial communities could be divided into two different functional groups, coniferous forests (Pinus) and broadleaf forest (Populus), characterized by different principal carbon sources including pyruvic acid methyl ester, i erythritol, and 2hydroxybenzoic acid. Soil pH, DOC, C/N and available P were the main factors affecting AWCD value, Shannon index, Simpson index and McIntosh index. In conclusion, the metabolic activities and functional diversity of soil microbial community in Populus×canadensis plantation were better than those in P. tabuliformis and P. sylvestris var.mongolica plantations. The plantation of Populus×canadensis is suitable for this region.

Key words: wheat, nitrogen, nutrient cycling, nutrient balance.