基于水供给服务空间流动模型的渭河流域水资源安全格局

基于VIC模型量化了渭河流域水资源供需平衡关系;构建了水供给服务流动模型,模拟了渭河流域2005年、2010年和2015年的水资源安全格局,利用地理探测器探寻了区域水资源安全的主要驱动力.结果 表明:①流域内水资源供需矛盾突出,平均每年有10.89％的地区经上游水资源补给后达到用水安全,补给不充分和未受补给的区域增加,...     

中国亚热带地区造林对土壤碳周转的影响

Afforestation in China’s subtropics plays an important role in sequestering CO2 from the atmosphere and in storage of soil carbon (C). Compared with natural forests,plantation forests have lower soil organic carbon (SOC) content and great potential to store more C. To better evaluate the effects of afforestation on soil C turnover,we investigated SOC and its stable C isotope (δ13C) composition in three planted forests at Qianyanzhou Ecological Experimental Station in southern China. Litter and soil samples were collected and analyzed for total organic C,δ13C and total nitrogen. Similarly to the vertical distribution of SOC in natural forests,SOC concentrations decrease exponentially with depth. The land cover type (grassland) before plantation had a significant influence on the vertical distribution of SOC. The SOC ?13C composition of the upper soil layer of two plantation forests has been mainly affected by the grass biomass 13C composition. Soil profiles with a change in photosynthetic pathway had a more complex 13C isotope composition distribution. During the 20 years after plantation establishment,the soil organic matter sources influenced both the δ13C distribution with depth,and C replacement. The upper soil layer SOC turnover in masson pine (a mean 34% of replacement in the 10 cm after 20 years) was more than twice as fast as that of slash pine (16% of replacement) under subtropical conditions. The results demonstrate that masson pine and slash pine plantations cannot rapidly sequester SOC into long-term storage pools in subtropical China.