Abstract: In order to evaluate the effect of afforestation mode on soil physical and chemical properties and the function diversity of microbial community, we studied soil pH, nutrient content and metabolism function diversity of soil microorganisms in three plantation forests, including pure coniferous forest (Larix olgensis), pure broadleaf ash forest (Fraxinus mandshurica), and their mixed forest (F. mandshurica + L. olgensis) in Douling, Xinbin of Liaoning Province. The results showed that, compared to the coniferous forest, the concentrations of total N, available N, total P and available P in the mixed forest increased by 37.1%, 35.6%, 9.5% and 12.9%, respectively. Total carbon source utilization capacity (AWCD) by soil microbial communities was in the order of F. mandshurica forest > mixed forest > L. olgensis forest, indicating that soil microbial metabolic activity in L. olgensis forest was the lowest. There were differences in microbial utilization rate of six major carbon sources among the three forests. The mixed forest had significantly higher microbial utilization rates in L-arginine, Lasparagine, pyruvic acid methyl ester, putrescine, N-acetylD-glucosamine, D-galacturonic acid, D-glucosaminic acid, and 4-hydroxybenzoic acid (eight kinds of carbon source) than the coniferous forest. Principal component analysis showed that carbohydrate and amino acids were important factors affecting soil metabolic activity. There was no significant difference in Simpson’s diversity index of soil microbes among the three forests. The Shannon’s index was in order of F. mandshurica forest > mixed forest > L. olgensis forest. Our results demonstrated that planting F. mandshurica and L. olgensis trees together can improve soil fertility and promote soil microbial activity.

Key words: agricultural landscape, landscape heterogeneity, Fengqiu Country, the lower reaches of the Yellow River., amphibians