Comparison On Soil Labile Organic Carbon Under Chinese Fir Plantations And Natural Secondary Forests In East Of North Subtropical Areas

To access the effects of land use type conversion on soil liable organic carbon andseasonal dynamics law of soil labile organic carbon in natural secondary forests and Chinese firplantations in east of north subtropical areas, soil samples of0-60cm in the four seasons werecollected in two sorts of mature forests, natural secondary forest and Chinese fir plantations,located at Miaoshanwu Forest Ecosystem Research Station in Fuyang, Zhejiang Province. Themain results were as follows:1、Difference of soil labile organic carbon between natural secondary forests and Chinesefir plantations.(1) The contents of soil total organic carbon (TOC), easily-oxidized carbon (EOC),water-soluble organic carbon (WSOC) and light fraction organic matter (LFOM) in the soildepth of0-60cm in natural secondary forests were higher than those in Chinese fir plantationsduring the four seasons and the range of variation were0.5%-44.9%,0.8%-30.3%,1.2%-85.4%and6.3%-57.6%, respectively. The difference of WSOC content was notsignificant between the two forest types.(2) The mean fraction of WSOC of Chinese fir plantations was higher than that of naturalsecondary forsets, and the differences in0-10cm and10-20cm soil layers were significant.Carbon activity of Chinese fir plantations was higher than that in natural secondary forsets,with significant or extremely significant differences..(3) Content of TOC, WSOC, EOC and LFOM were extremely significantly related to eachother, and soil nutrients were significantly or extremely significantly related to soil labileorganic carbon.2、Seasonal dynaics law of soil labile organic carbon in Chinese fir plantations and naturalsecondary forests. (1)There were no clearly seasonal dynamics of TOC content in soil depth of0-10cm and10-20cm in Chinese fir plantations and natural secondary forests among the four seasons.(2)Seasonal dynamics of WSOC content were basically the same in soil depth of0-10cmand10-20cm in Chinese fir plantations and natural secondary forests. Content of WSOC inwinter was significantly higher than spring, summer and autumn. Content of WSOC was thelowest in summer, and the differences with other seasons were significant. The result wasembodied in winter> spring> autumn> summer.(3) EOC content of0-10cm soil layer in Chinese fir plantations followed the order winter> autumn> summer> spring, and the difference of content of EOC between winter and springwas significant. Content of EOC in summer was significantly lower than the other seasons innatural secondary forests. The seasonal dynamics law of EOC content in10-20cm soil layerswas basically the same with0-10cm soil layer in Chinese fir plantations, while content of EOCin natural secondary forests followed the order autumn> winter> summer> spring.(4) Seasonal dynamics of LFOM in Chinese fir plantations and natural secondary forestswere basically the same in soil layers of0-10cm and10-20cm, following the order autumn>summer>winter> spring, and significant differences of LFOM content were found amongthe four seasons.