【摘要】 [目的]探究土地利用/覆被变化对鄂尔多斯市草地生态系统净初级生产力(NPP)的影响,为该区退牧还草措施的高效实施和草地资源的合理管理提供理论依据。[方法]基于多源遥感影像数据、多期土地利用/覆被数据和气象数据等,运用光能利用率模型(CASA),模拟鄂尔多斯市草地生态系统净初级生产力(NPP),并进行分析和探讨。[结果](1)鄂尔多斯地区草地NPP总量在2001年(5 700.16Tg)到2015年(7 634.61Tg)间增加了1 934.46Tg;空间分布上存在明显的地域差异性。(2)该市2001—2015年耕地面积持续减少;15a间,林地面积增加了4 593km~2;草地净减少量为786.38km~2,其中草地与未利用地之间的相互转化最大,有大量耕地、林地转变为草地,面积达到376.5km~2。(3)该市2001—2015年草地类型未发生变化地区NPP增长量为1 999.42Tg;草地转为其他土地类型共引起草地NPP减少量为303.98Tg,其中转为耕地、林地和未利用地导致其NPP减少量分别为35.08,69.81和118.28Tg;其他土地类型转化为草地导致NPP的总增加量达128.96Tg,其中由耕地、林地、水域、未利用地转化带来的草地NPP增量分别为36.30,31.39,17.58,151.38Tg。[结论]土地利用/覆被对草地NPP影响较大,耕地和林地向草地的转化、未利用地的重新利用使得草地碳汇总量增加。草地向未利用地、水域、城乡工矿居民用地的转化使得草地生态系统碳汇能力减弱。更多还原

【Abstract】 [Objective]To Explore the effect of land use/cover change on the net primary productivity(NPP)in grassland ecosystem of Ordos City in order to provide theoretical basis for the efficient implementation of grassland grazing mitigation measures and the reasonable management of grassland resources.[Methods]Based on multi-source remote sensing image data,multi-period land use/cover data and meteorological data,using Carnegie Ames Stanford Approach(CASA),the NPP of grassland ecosystem was simulated and the land use change was demonstrated.Upon which,the impact of land use/cover change(LUCC)on grassland NPP in Ordos City was analyzed.[Results](1) The grassland NPP in Ordos City increased gradually from5 700.16 Tg in 2001 to 7 634.61 Tg in 2015.There existed significant regional difference in NPP spatialdistribution.(2) From 2001 to 2015,the area of arable land continued to decrease.While,the area of forest increased,with a total increase of 4 593 km~2.The net reduction of grassland area was 786.38 km~2.For the mutual land use conversion,the one between grassland and unutilized land was the largest.And also there were a large amount of arable land and the woodland,with total area of 376.5 km~2,were converted into grassland.In contrast,the largest decreasing in grassland that was converted to unutilized land was 1 211.50 km~2.(3) From 2001 to 2015,the NPP increased by 1 999.42 Tg in grassland covered area.The changes of grassland to other types of land led to a NPP reduction of 303.98 Tg.Among of them,the conversions to cultivated land,forest and unused land accounted for 35.08 Tg,69.81 Tg and 118.28 Tg,respectively.Additionally,the conversion of other types of land to grassland resulted to an increase of NPP,totaled to128.96 Tg.The increments of grassland NPP from farmland,forestland and water were 36.30,31.39 and17.58 Tg,respectively.[Conclusion]Land use/cover has a greater impact on grassland NPP.Conversions of cultivated land and forest to grassland and reuse of unused land all increased grassland carbon sink.The conversions of grassland to unutilized land,water areas,and urban-rural residents’ land for industrial and mining uses could all weaken carbon sinks of grassland ecosystem.更多还原