The Hilly Region Of Southern Plantations Soil Organic Carbon Distribution Characteristics

The soil labile carbon is one of the important components of the global carbon cycle. The variation of soil total organic carbon (TOC), water soluble organic carbon (WSOC), readily oxidation carbon (ROC) and their correlations with soil physicochemical properties at four plantations (oak, Chinese fir, bamboo and Pine) were examined in South area of Jiangsu. Our results showed that:(1) The soil TOC concentration ranged in order as follow:oak> Chinese fir>bamboo> Pine; The soil WSOC concentration ranged in order as follow:bamboo> Chinese fir>Pine> oak; The soil ROC concentration ranged as follow:oak> bamboo> Chinese fir>Pine. The WSOC/TOC, ROC/TOC ratios were varied. There were significantly correlations between LOC(WSOC & ROC) and TOC, TN, respectively. Meanwhile, there were no significantly correlations between LOC and other soil basic physicochemical properties.(2) The soil LOC concentration of four plantations were different in three slopes. The concentration were lowest in the middle slope, others were not far-off. However, all of the differences were not significantly. There were no significant differences in WSOC/TOC, ROC/TOC ratios of three slopes. The correlations between LOC (WSOC & ROC) and soil physical and chemical properties about the same in four plantations.(3) the soil TOC concentration decreased with the age increasing, and then increased from the middle-age stand to over mature stage, and its content was highest in the over-mature stage, lower in the medium stage. The WSOC and ROC were more consistent with the trend of TOC, and the changes of WSOC/TOC; ROC/TOC did not stabilize. There were significantly correlations between LOC (WSOC and ROC) and TOC, TN, C/N, respectively. Meanwhile, there were no significantly correlations between LOC and TS, Soil moisture, pH, bulk density, respectively. However the correlations were not identical in the different ages.