摘要 以陕北黄土高原为研究区，利用InVEST固碳功能评价模块，定量评价了退耕还林还草工程背景下土地利用/覆被变化对研究区碳固定效益的影响。结果表明：研究区2000—2010年草地、灌丛、林地面积分别增加了3 204.0、 285.3和122.7 km2，耕地面积减少了3 984.5 km2，退耕还林还草工程土地覆被变化显著。研究区10年间碳固定能力整体提升，其中，延安市境内各流域平均固碳增加量为3.3 t/hm2，固碳总增加量为13.3×106 t，榆林市境内各流域平均固碳增加量为4.0 t/hm2，固碳总增加量为14.5×106 t，退耕还林还草工程固碳效益显著。耕地、草地、荒漠向林地的转化固碳效益最大，其单位面积固碳增量达100 t/hm2以上，耕地向林灌草的转变使研究区固碳总量增加达3 405.77×104 t，其中73.37%的总固碳量比重来自耕地向草地的转化。通过生态系统碳固定重要性分级和空间分区为退耕还林还草工程的科学实施、维持区域碳平衡和碳达峰，保障区域民生福祉具有重要的指导意义。

关键词 退耕还林还草;碳固定;土地覆被变化;InVEST模型;黄土高原

中图分类号 S774 文献标识码 A 文章编号 0517-6611（2021）17-0055-06

doi：10.3969/j.issn.0517-6611.2021.17.016

Abstract The effect of land use/cover change on the carbon fixation benefit of the study area was quantitatively evaluated by using the InVEST carbon fixation function evaluation module in the Loess Plateau of Northern Shaanxi Province. The main conclusions are as follows： The area of grass， scrub and woodland increased by 3 204 km2，285.3 km2 and 122.7 km2 respectively during 2000-2010 in this area.However，farmland reduced a large area of 3 984.5 hm2 mainly converted to above types of land use.The action of the Grain for Green Program （GFGP） has begun to show its effects. During this 10 years， carbon storage of the research area displayed a increasing tendency.The average carbon sequestration increased by 3.3 t/hm2 and the total carbon sequestration increased by 13.3 × 106 tons in Yanan region， meanwhile， the same increased by 4.0 t/hm2 and 14.5×106 tons in Yulin region. The carbon sequestration benefit of the Grain for Green Program （GFGP） was significant. The conversion of cultivated land， grassland and desert to forest land has the greatest carbon sequestration benefit， and the increment of carbon sequestration per unit area is more than 100 t/hm2. The conversion of cultivated land to forest， shrub and grass makes the total carbon sequestration increase to 3 405.77×104 hm2. Among them， 73.37% of the total carbon sequestration came from the conversion of cultivated land to grassland. This study has important guiding significance for the management of ecosystems and the scientific implementation of the GFGP in the Loess Plateau of Northern Shaanxi Province，meanwhile， it has the same important guiding significance for maintaining regional carbon balance and reaching carbon peak.

Key words The Grain for Green Program（GFGP）;Carbon storage;Land use/cover change;InVEST model;Loess Plateau

自2005年千年生態系统评估（millennium ecosystem assessment，MA）报告发布以来，有关于人类福祉与健康的生态系统服务及其功能变化的国内外研究文献大幅增加，全球及区域生态系统服务功能的退化直接影响到人类的可持续发展[1]。全球气候变化是国际科学组织和各国政府高度关注的全球性重大环境问题之一[2-3]，陆地生态系统对维持碳循环和碳平衡、调节气候变化具有重要作用[4-5]，加强区域生态系统管理和保护以提高固碳服务能力，对保障区域可持续发展和民生福祉[6-7]，实现国家碳达峰和碳平衡目标意义重大。……