Spatial Distribution Of Forest Soil Organic Carbon Density And The Effects Of Environmental Factors In Zhejiang Province

Carbon sequestration in forest ecosystem is an important research field of global climate change.Soil organic carbon plays an important role in forest carbon-sink, which draws a hotspot attention inacademia. Based on the application of Moran’s I, geostatistics, and GIS techniques, we analyzed thespatial autocorrelation and spatial distribution characteristics of the forest soil organic carbon density(SOCD) in Zhejiang province with the assistance of linear-regression analysis. The main results arefollowing:(1) The average SOCD within0~100cm depth in Zhejiang province was108.96t·hm-2, which waslower than that in the whole country. There were significant differences in SOCD (6.67~1025.59t·hm-2)among the sample points. There is a moderate variation level in SOCD in soil layers of0~10cm,0~30cm and0~100cm in Zhejiang province. Organic carbon in0~30cm of soil layer accounted for65.34%of total SOCD in0~100cm of soil layer.(2) The Global Moran’s I of SOCD in Zhejiang province was0.176, which suggesting a positivespatial autocorrelation. High-high spatial-cluster areas of SOCD were mainly distributed in Chun’an,Jiande, suichang and Longquan areas. A relatively small high-high spatial-cluster area was found closeto the Anji of Huzhou and Deqing. Low-low spatial-cluster areas of SOCD were mainly distributedalong the Lishui-Shaoxing in the middle of Zhejiang province. Most of the high-low outliers were closeto the low-low spatial-cluster areas. On the other hand, the low-high outliers were mainly locatedclosely to the high-high spatial-cluster areas.(3) Exponential model was the most optimized theory model for SOCD in Zhejiang forest, withNugget effect (Nugget/Sill) of67.57%and a range of24.781km, which can well reveal spatialdistribution of SOCD in Zhejiang Province’ forests.(4) The SOCD in Zhejiang province’ forests decreased from southwest to northeast, showing threeparalleled bands distribution: west of Hangzhou Lin’an-Huzhou-Jiaxin, Jinhuaregion-Quzhou-Shaoxing region, and southeast coastal area. In most forest areas of Zhejiang province,SOCD was the patches with more than49.00t·hm-2. The spatial distribution of SOCD in Zhejiangprovince’ forests were agreed with the distribution of forest resource volume. In Hangzhou area, thedifference of SOCD showed a gradual decline from southwest to northeast.(5) There was a significant positive correlation between SOCD and factors, i.e. advantages of treespecies, slope position, age groups, altitude, shrub coverage, shrubs average height and average age.The significant negative correlation was found between herb coverage and SOCD. SOCD in the0~30cm of soil depth was not affected by herb average height. SOCD levels of different dominant treespecies were in the following order: broad-leaved mixed forests> coniferous and broadleaf mixed forest> Chinese fir> hard broad> coniferous mixed forest> pine> bamboo> economic tree species. Theinfluencing factors explained14.90%variation of the SOCD.