内蒙古草地生态系统碳源/汇时空格局及其与气候因子的关系

草地净生态系统生产力(NEP)能够表征草地生态系统的固碳能力,直接定性定量地描述草地生态系统的碳源/汇性质和大小.因此,研究区域尺度草地生态系统NEP具有重要的实践意义.基于卫星遥感资料,地面气象观测资料及实地采样数据,结合光能利用率模型估算了2001-2012年内蒙古草地生态系统净初级生产力(NPP).同时,应用土壤呼吸模型估算了逐月平均土壤呼吸量(Rs),进而估算内蒙古草地净生态系统生产力(NEP).研究揭示了2001-2012年内蒙古草地生态系统NPP,NEP年际变化规律,气候因子的年际变化规律,以及草地NPP,NEP与主要气候因子的关系.结果表明:2001年以来,内蒙古草地生态系统整体发挥碳汇效应,净碳汇总量达到0.55 Pg C,年均固碳率约为0.046 Pg C/a;研究区大部分草地NPP,NEP与降水均呈正相关关系,与温度相关性不显著,内蒙古草地生态系统仍有巨大的固碳潜力.

Spatial-temporal features of carbon source-sink and its relationship with climate factors in Inner Mongolia grassland ecosystem

In this paper, field sampling data, remote sensing data, and ground meteorological observation data were used to estimate the net primary productivity (NPP) in the grassland ecosystem in Inner Mongolia from 2001 to 2012 based on a light use efficiency model. The spatiotemporal distribution of the NEP in the Inner Mongolia grassland ecosystem was then analyzed by estimation of the NPP and soil respiration from 2001 to 2012. This paper also investigated the response of the NPP and NEP to main climatic variables on the spatial and temporal scales from 2001 to 2012. Results showed that most of the grassland area in Inner Mongolia has functioned as a carbon sink since 2001 and that the annual carbon sequestration rate amounts to 0.046 Pg C·yr^-1. The total net carbon sink of the Inner Mongolia grassland ecosystem over the 12-year period reached 0.557 Pg C. The carbon sink area accounted for 60.28% of the total grassland area and sequestered 0.692 Pg C, whereas the C source area accounted for 39.72% of the total grassland area and released 0.135 Pg C. The NPP and NEP of the Inner Mongolia grassland ecosystem have more significant correlations with precipitation than with temperature, and the Inner Mongolia grassland ecosystem has great potential for carbon sequestration.