Research For The Dynamics Of Substantial And Energetic Status During The Decay Of Plant Residues In Soils Under Different Vegetations

In area of Ziwuling forest after recovering of secondary forest, the degrees of soil development were different in different parts of landform because of the variations in soil water contents, the sequence of vegetation recovery and vegetation types. The difference of soil nutrient, soil microorganisms(区系)and microbial biomass were compared under different vegetations in this research. Selecting corn straw, Spodiopogon sibiricus, purple medic straw, Quercus liaotungensis and Hippophae rhamnoides as decaying materials, the characteristics of the remainders during the process of decay and humic acids in soils under different vegetations was also studied by normal analysis combined with thermal analysis (DTA) and infrared spectrum analysis. It can accumulate data for the research of the accumulation and decomposition of soil organic matter, the situation of soil fertility and soil microorganism, and also can provide foundations for soil and water conservation and the reconstruction of environment. The main conclusions were as follows:1. The vegetation types made a significant effect on the content of soil organic matter, total N, available N, available P and available K, and the nutrient content almost increased followed by the sequences of vegetation succession. There is no significant effect on total P and total K, the soil nutrients in abandoned field were lower than those of farmland, which proved that the condition of agroecotype had a certain protective effect on soil fertility. In the hill area of the Loess Plateau, rebuilding of forest from cropland in slopes and vegetation recovery could improve the status of soil nutrients.2. There were increasing trends in amount of three types of soil microorganism (bacteria, fungi and actinomyces) basically during the succession from pioneer forest community to top community. Beside microbial biomass C and P were higher in cropland, there were downtrends in microbial biomass C, N and P followed by vegetation succession, and the soil microbial biomasses under different vegetation were different significant (P<0.05). Correlation analysis indicated that there were tight correlativities between soil microflora, soil micro biomass and soil nutrient.