黑河流域NPP对气候变化及人类活动的响应?

基于改进的CASA光能利用率模型,利用Spot VEGETATION逐旬NDVI数据,对黑河流域1998—2007年植被NPP进行了估算,在掌握10年黑河流域植被NPP变化趋势基础上,探讨不同类型植被NPP对气候变化的响应机制,定量评估2000年后黑河调水与生态保护建设工程的实施效果.结果表明:从1998—2001年间植被覆盖区域年NPP处于显著下降趋势;而2001—2007年间植被类型NPP处于显著上升趋势,2001年成为这10年间NPP趋势变化的转折点.在大规模黑河调水与生态保护建设之后(2002—2007年)的5年期间,黑河上、中、下游所有土地覆盖类型的NPP残差均大于0,表明调水与生态建设工程已经取得成效.人类活动对中游NPP平均贡献率11.5%,对上游NPP平均贡献率5.29%,对下游NPP平均贡献率3.23%.

Response of NPP to climate change and human activities in the Heihe River basin

Annual net primary Productivity (NPP)in the Heihe River basin from 1998 to 2007 was estimated on temporal scale of ten-days from Spot VEGETATION NDVI dataset with modified CASA light use efficiency model.Changing tendency of NPP in the Heihe River basin from 1998 to 2007 was analyzed. Response of NPP to climate change for various land cover types in upper,middle and lower reaches was also investigated.Effects of water transfer project in the Heihe River and ecological construction on vegetation NPP change were quantitatively assessed after separating contributions of climate change and human activities.It was found that NPP of vegetated area experienced a significant decrease from 1998 to 2001,but it increased significantly from 2001 to 2007.Year 2001 is the key transition point of NPP change in the last ten years, coinciding with deployment time of water transfer project and ecological construction.During the 5 years (2002-2007)after implementation of water transfer project and ecological construction,the residuals of mean NPP for various land cover types in upper,middle and lower reaches are greater than 0,indicating that water transfer proj ect and ecological construction have had a positive impact on ecosystem.The contribution rate of human activities on NPP in middle,upper and lower reaches was 11.5%,5.29% and 3.23%,respectively.