气候和人为因素对草地变化的响应研究:以川西北若尔盖县为例

Response of Climate and Human Factor on the Variation of Grassland:a Case Study on Ruoergai County

以川西北若尔盖县为研究区,采用MOD17A3数据估算实际NPP,基于Thornthwaite纪念模型模拟气候变化导致的潜在NPP,采用残差分析法分离人类活动导致的NPP变化,并运用一元线性回归方程的斜率来刻画分析每个栅格的变化趋势,定量评价2000-2010年气候变化和人类活动对若尔盖县草地变化的相对作用。研究结果表明:(1)在区域尺度上,若尔盖草地在2000-2010年近11 a间体呈现微弱恢复趋势,草地恢复面积比例为53.7%,草地退化面积比例为46.3%,退化区域主要分布在研究区的东南部和西部地区;(2)在11 a尺度上,人类活动和气候变化对草地生长的贡献率分别为76.22%和23.78%,实际NPP与潜在NPP之间的残差为3 316.37 g/(m^2·a)(以C计),表明生态保护与工程建设取得了极为显著的效果;(3)在时间尺度上,人类活动对草地恢复的正影响呈上升趋势,2000-2010年人为NPP回归斜率为37.30,表明生态项目实施具有长效性。

The study selected Ruoergai County in the northwest Sichuan Province as the study area,MOD17A3 was used to estimate the actual NPP. Based on Thornthwaite Memorial model to simulate potential NPP caused by climate change,using residual analysis to separate the influence of human activities exerted on NPP,and then utilizing the slope of one-variable linear regression equation to analyze the change tendency of each raster,a quantitative analysis was made for the impact of climate change and human activities in the study area from 2000 to 2010. The results indicated that at the regional scale,the grass of Ruoergai County in northwestern Sichuan showed a tendency of restoration as the rate of recovery area reached to 53.7% while the degradation area was within 46.3%. The degradation was mainly distributed in southeast and west of the study area. At the scale of 11 years,the contribution of human activities and climate change were respectively 76.22 % and 23.78%;the residual between potential NPP and actual NPP was 3 316.37 g C/（m-2·a）,which showed the ecological protection and construction project had achieved significant results. At the time scale,there was a rising trend of human-activity positive impact toward grass as human NPP regression slope is 37.30 from 2000 to 2010,indicating ecological project was a long-term design.