Comparison of soil labile organic carbon in Chinese fir plantations and natural secondary forests in north subtropical areas of China
中国北亚热带天然次生林与杉木人工林土壤活性有机碳库的比较

Aims Our objective was to assess the effects of land use type conversion on the soil liable organic carbon pool in north subtropical areas of China.Methods We used reference land unit to collect soil samples in natural secondary forests and Chinese fir(Cunninghamia lanceolata) plantations and analyzed liable organic carbon in the depth of 0-60 cm.Important findings 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 soil of natural secondary forests were higher than those in Chinese fir plantations.The variations in amplitude for these four parameters were 19.0%-32.6%,0.8%-30.3%,3.8%-54.1% and 6.3%-38.6%,respectively.There were significant differences in the depth of 0-10 cm and 10-20 cm(p < 0.05)(WSOC was only significantly different in the depth of 0-10 cm).The ratios of WSOC and EOC to TOC content in Chinese fir plantations were higher than those in natural secondary forests.WSOC,EOC and LFOM were significantly related to TOC in the two forest stands,and the correlation coefficients of EOC and LFOM to TOC in natural secondary forests were higher than those in Chinese fir plantations.TOC,WSOC,EOC and LFOM were all significantly related to soil nutrients(total N,hydrolysis N and available K,Ca and Mg).