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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Satellite evidence for significant biophysical consequences of the 'Grain for Green' Program on the Loess Plateau in China
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Satellite evidence for significant biophysical consequences of the 'Grain for Green' Program on the Loess Plateau in China

机译：卫星证据表明中国黄土高原“粮食换绿色”计划的重大生物物理后果

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摘要

Afforestation has been implemented worldwide as regional and national policies to address environmental problems and to improve ecosystem services. China's central government launched the "Grain for Green" Program (GGP) in 1999 to increase forest cover and to control soil erosion by converting agricultural lands on steep slopes to forests and grasslands. Here a variety of satellite data products from the Moderate Resolution Imaging Spectroradiometer were used to assess the biophysical consequences of the GGP for the Loess Plateau, the pilot region of the program. The average tree cover of the plateau substantially increased because of the GGP, with a relative increase of 41.0%. The GGP led to significant increases in enhanced vegetation index (EVI), leaf area index, and the fraction of photosynthetically active radiation absorbed by canopies. The increase in forest productivity as approximated by EVI was not driven by elevated air temperature, changing precipitation, or rising atmospheric carbon dioxide concentrations. Moreover, the afforestation significantly reduced surface albedo, leading to a positive radiative forcing and a warming effect on the climate. The GGP also led to a significant decline in daytime land surface temperature and exerted a cooling effect on the climate. The GGP therefore has significant biophysical consequences by altering carbon cycling, hydrologic processes, and surface energy exchange and has significant feedbacks to the regional climate. The net radiative forcing on the climate depends on the offsetting of the negative forcing from carbon sequestration and higher evapotranspiration and the positive forcing from lower albedo.
机译：植树造林已在世界范围内作为解决环境问题和改善生态系统服务的区域和国家政策而实施。中国中央政府于1999年启动了“绿色换粮”计划（GGP），目的是通过将陡坡上的农用土地转变为森林和草地来增加森林覆盖率并控制水土流失。在这里，来自中分辨率成像光谱仪的各种卫星数据产品被用于评估GGP对黄土高原的生物物理影响，黄土高原是该计划的试点地区。由于GGP，高原地区的平均树木覆盖率大幅增加，相对增加了41.0％。 GGP导致增强的植被指数（EVI），叶面积指数以及冠层吸收的光合有效辐射的比例显着增加。通过EVI估算，森林生产力的提高并非受到气温升高，降水变化或大气中二氧化碳浓度升高的驱动。此外，绿化显着减少了地表反照率，导致了积极的辐射强迫和气候变暖。 GGP还导致白天陆地表面温度显着下降，并对气候产生了降温作用。因此，GGP会通过改变碳循环，水文过程和地表能量交换而产生重大的生物物理后果，并对地区气候具有重要的反馈作用。气候的净辐射强迫取决于碳固存和较高蒸散量的负强迫与低反照率的正强迫的抵消。

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