何亮 吕渡 郭晋伟 雷斯越 贺洁 张晓萍 杨希华

摘 要：为揭示国家实施退耕还林还草政策以来北洛河流域植被盖度的时空变化特征，采用MODIS反演的2001—2017年植被覆盖数据，分析了北洛河流域2001—2017年光合植被覆盖度的时空变化特征。结果表明：①2001—2006年、2007—2012年、2013—2017年3个时段植被盖度均值分别为60.2%、63.2%和68.5%，植被覆盖状况空间差异明显，3个时段均表现出上游黄土丘陵沟壑区植被盖度最低、中游土石山林区植被盖度最高的特征;②2001—2017年北洛河流域植被盖度整体上表现为上升趋势，植被盖度上升面积占比为90.9%，其中显著上升、上升但不显著面积占比分别为44.3%、46.6%，黄土丘陵沟壑区、黄土高塬沟壑区、土石山林区植被盖度年均变率分别为1.18%、0.64%、0.42%;③对全流域植被盖度显著提高的主要贡献地区为黄土丘陵沟壑区，贡献率为46.3%，主要贡献县域志丹县、吴起县、富县、甘泉县的贡献率分别为23.1%、20.4%、10.6%、10.2%。

关键词：光合植被盖度;时空变化特征;贡献率;北洛河流域

中图分类号：S771;X171.4 文献标志码：A

doi：10.3969/j.issn.1000-1379.2020.02.014

Abstract：In order to reveal the temporal and spatial variation characteristics of vegetation coverage in the Beiluo River Basin since the implementation of The Grain for Green Project， the spatial and temporal variation characteristics of photosynthetic vegetation coverage in the beiluo river basin from 2001 to 2017 were analyzed with the vegetation cover data retrieved by MODIS.The results show that a） during the three periods of 2001-2006， 2007-2012 and 2013-2017， the average vegetation coverage is 60.2%， 63.2% and 68.5% respectively. The spatial difference of vegetation coverage status is obvious and the three periods all show the characteristics of the lowest vegetation coverage in the gullied rolling loess area of the upper reaches and the highest vegetation coverage in the middle rocky-mountain region; b） in the past 17 years， the vegetation coverage in the whole basin， the gullied rolling loess area， gullied loess plateaus and mountainous region shows a significant increase trend， with the annual variation rate of 0.65%/a， 1.18%/a， 0.64%/a and 0.42%/a respectively. Among the 12 major counties in the basin， the vegetation coverage of Zhidan， Wuqi and Jingbian in the gullied rolling loess area has been increased the most rapidly， with a change range of 1.05 to 1.36%/a， and the change range of Huanglong， Huangling and Heshui in the middle mountainous region is the slowest， with a change range of 0.31 to 0.33%/a; c） the main contribution to the significant increase of vegetation coverage in the whole basin comes from the gullied rolling loess area， with a contribution rate of 46.3%. On the county aspect， the main sources come from Zhidan （23.1%）， Wuqi （20.4%）， Fuxian （10.6%） and Ganquan （10.2%） respectively.

Key words： photosynthetic vegetation coverage; spatiotemporal and variation characteristics; Beiluo River basin; rate of contribution

植被是陸地生态系统的主要组分，深刻影响着区域生物化学循环和物质能量循环[1]，是生物圈发挥系统性生态功能的核心部分[2]。地表植被可降低雨滴动能、削弱洪峰、延缓径流、增强土壤抗蚀能力、减少水土流失[3-5]。植被盖度（Fraction of Vegetation Coverage，FVC）不仅用来描述地表植被覆盖状况， 也可反映地表植被长势[6-7]。黄土高原地区生态环境脆弱、土壤侵蚀剧烈[8]，在国家实施大规模的退耕还林（草）政策以来，植被恢复明显，侵蚀产沙和入黄泥沙量明显减少[9]。北洛河流域……