Study On Forest Soil Organic Carbon In Mountain Of Beijing Western Areas

Through studying 5 kinds of broadleaved forest (Quercus variabilis, Acer truncatum, Juglans mandshurica, Maxim Quercus liaotungensis, Koidz Betula dahurica Pall) and 4 kinds of coniferous forest (Pinus tabulaeformis,Platycladus orientalis,Larix principis-rupprechtii,May -r Picea meyeri) by field surveying and lab analyzing, which selected in Beijing Xishan Forest Farm and Baihua Forest Farm, this essay researched soil physics, chemistry properties, total soil organic carbon, soil easily oxidized carbon, soil particulate organic carbon and soil humus carbon under different vegetation types, and discussed the relationship between forest soil organic carbon and soil nutrients, as well as the relations among the different fractions of soil organic carbon. This research is benefit for the inspection of mountainous region soil quality system and estimation of the soil organic carbon pool in Beijing, simultaneously, the result also provide the basis to the rational use of forest land resources.Six points were concluded in this essay.①Both in the Xishan Forest Farm and in Baihua Forest Farm, the organic matter, total soil nitrogen, soil available nitrogen, soil available Phosphorus, soil available Potassium under broadleaved forests were generally higher than those under coniferous forests, moreover, it presents vertical decreasing tendency.②The content of total soil organic carbon under different vegetation types decreased along with the increasing of soil depth. Furthermore, the content of total soil organic carbon under broadleaved forests was higher than those under coniferous forests.③The change rules of soil easily oxidized carbon and soil particulate organic carbon were similar as the change rules of total soil organic carbon. In the experiment of easily oxidized carbon, using 333mmolL-1KMnO4 as oxidant, the content of easily oxidized carbon was to the highest.④The research of forest soil humus carbon indicated that the value of HA/FA in Baihua Forest Farm was between 1.26 and 1.41, meanwhile, the value of HA/FA in Xishan Forest Farm was between 0.89 and 1.02. Therefore, the environment in Baihua Forest Farm was more suit for the formation of humic acid.⑤In Xishan Forest Farm, the value of EOC/SOC was between 27.55% and 30.93%, the value of POC/SOC was between 21.87% and 39.17%, the value of HC/SOC was between 66.29% and 73.99%. In Baihua Forest Farm, the value of EOC/SOC was between 18.79% and 34.45%, the value of POC/SOC was between 23.52% and 39.51% and the value of HC/SOC was between 65.13% and 75.34%. The different fractions of soil organic carbon showed significant positive correlation, and among the active organic carbons, compared with the total soil organic carbon, the total soil easily oxidized carbon and its fractionⅡ,Ⅲ,as well as the soil particulate organic carbon, present more sensitivity to the environmental change.⑥The total soil organic carbon, the total soil easily oxidized carbon and its fractions, as well as soil particulate organic carbon present extremely significant or significant positive correlation to total soil nitrogen, soil available nitrogen, soil available phosphorus and soil available potassium. But there was no obvious correlation between soil humic carbon and soil nutrients which are mentioned above.This research determined the easily oxidized carbon and particulate organic carbon of forest soil and discussed the relations among the different forest soil organic carbon fractions in Beijing mountainous areas for the first time.