Spatial Variability of Soil Organic Carbon and Related Factors in Jiangsu Province,China

Soil organic carbon (SOC) plays a key role in the global carbon cycle.In this study,we used statistical and geostatistical methods to characterize and compare the spatial heterogeneity of SOC in soils of Jiangsu Province,China,and investigate the factors that influence it,such as topography,soil type,and land use.Our study was based on 24 186 soil samples obtained from the surface soil layer (0-0.2 m) and covering the entire area of the province.Interpolated values of SOC density in the surface layer,obtained by kriging based on a spherical model,ranged between 3.25 and 32.43 kg m 3.The highest SOC densities tended to occur in the Taihu Plain,Lixia River Plain,along the Yangtze River,and in high-elevation hilly areas such as those in northern and southwest Jiangsu,while the lowest values were found in the coastal plain.Elevation,slope,soil type,and land use type significantly affected SOC densities.Steeper slope tended to result in SOC decline.Correlation between elevation and SOC densities was positive in the hill areas but negative in the low plain areas,probably due to the effect of different land cover types,temperature,and soil fertility.High SOC densities were usually found in limestone and paddy soils and low densities in coastal saline soils and alluvial soils,indicating that high clay and silt contents in the soils could lead to an increase,and high sand content to a decrease in the accumulation of SOC.SOC densities were sensitive to land use and usually increased in towns,woodland,paddy land,and shallow water areas,which were strongly affected by industrial and human activities,covered with highly productive vegetation,or subject to long-term use of organic fertilizers or flooding conditions.

Temporospatial changes of carbon footprint based on energy consumption in China

Study on regional carbon emission is one of the hot topics under the background of global climate change and low-carbon economic development, and also help to establish different low-carbon strategies for different regions. On the basis of energy consumption and land use data of different regions in China from 1999 to 2008, this paper established carbon emission and carbon footprint models based on total energy consumption, and calculated the amount of carbon emissions and carbon footprint in different regions of China from 1999 to 2008. The author also analyzed carbon emission density and per unit area carbon footprint for each region. Finally, advices for decreasing carbon footprint were put forward. The main conclusions are as follows： （1） Carbon emissions from total energy consumption increased 129% from 1999 to 2008 in China, but its spatial distribution pattern among different regions just slightly changed, the sorting of carbon emission amount was： Eastern China Northern China Central and Southern China Southwest China Northwest China. （2） The sorting of carbon emission density was： Eastern China Northeast China Central and Southern China Northern China Southwest China Northwest China from 1999 to 2003, but from 2004 Central and Southern China began to have higher carbon emission density than Northeast China, the order of other regions did not change. （3） Carbon footprint increased significantly since the rapid increasing of carbon emissions and less increasing area of pro-ductive land in different regions of China from 1999 to 2008. Northern China had the largest carbon footprint, and Northwest China, Eastern China, Northern China, Central and Southern China followed in turn, while Southwest China presented the lowest area of carbon footprint and the highest percentage of carbon absorption. （4） Mainly influenced by regional land area, Northern China presented the highest per unit area carbon footprint and followed by Eastern China, and Northeast China; Central and Southern China, and Northwest China had a similar medium per unit area carbon footprint; Southwest China always had the lowest per unit area carbon footprint. （5） China faced great ecological pressure brought by carbon emission. Some measures should be taken both from reducing carbon emission and increasing carbon absorption.

Spatial econometric analysis of carbon emissions from energy consumption in China

Based on energy consumption data of each region in China from 1997 to 2009 and using ArcGIS9.3 and GeoDA9.5 as technical support, this paper made a preliminary study on the changing trend of spatial pattern at regional level of carbon emissions from energy consumption, spatial autocorrelation analysis of carbon emissions, spatial regression analysis between carbon emissions and their influencing factors. The analyzed results are shown as follows. （1） Carbon emissions from energy consumption increased more than 148% from 1997 to 2009 but the spatial pattern of high and low emission regions did not change greatly. （2） The global spatial autocorrelation of carbon emissions from energy consumption in- creased from 1997 to 2009, the spatial autocorrelation analysis showed that there exists a ＂polarization＂ phenomenon, the centre of ＂High-High＂ agglomeration did not change greatly but expanded currently, the centre of ＂Low-Low＂ agglomeration also did not change greatly but narrowed currently. （3） The spatial regression analysis showed that carbon emissions from energy consumption has a close relationship with GDP and population, R-squared rate of the spatial regression between carbon emissions and GDP is higher than that between carbon emissions and population. The contribution of population to carbon emissions increased but the contribution of GDP decreased from 1997 to 2009. The carbon emissions spillover effect was aggravated from 1997 to 2009 due to both the increase of GDP and population, so GDP and population were the two main factors which had strengthened the spatial autocorrelation of carbon emissions.