Effects of different soil and water conservation forests on topsoil metabolic functional diversity of soil microbial community in black soil region, northeastern China.

Metabolism diversity of soil microbial carbon sources in surface soil (0 -10 cm) from four soil and water conservation forests, dominantly composed of poplar(Populus nigra var. italica 伊P. cathayan), Manchurian ash (Fraxinus mandshurica), larch (Larix gmelinii) and Scots pine (Pinus sylvestris var. mongolica ) respectively, in typical black soil region of northeastern China was studied by using the method of Biolog ECO-microplate culture. Results showed that the average well color development (AWCD) varied from 0.11 to 0.62 for four stands and the peak value was found in poplar, followed by Manchurian ash, larch and Scots pine, orderly. The microbial functional diversity showed the same changing tendency as AWCD, or poplar Manchurian ash larch Scots pine in consequence, with a variation range of 4 -22, 1.37 -3.00, 0.62 -0.94, and 1.46 -5.21 for richness index, Shannon- Weiner index, Simpson index and McIntosh index, respectively. Polymers are main carbon sources for four forests, in addition to this, the soil microbes of broadleaved forests could also utilize amino acids and carboxylic acids as carbon sources with a higher efficiency and intensity. Based on the significant links between the metabolic diversity of microbial communities and soil physical and chemical properties, we conclude that broadleaved forest may have more metabolic functional diversity of soil microbial community than coniferous forest. The results presented in this paper could provide theoretical basis and reference for soil and water conservation forest construction in typical black soil region