Data from: Opportunities for biodiversity gains under the world’s largest reforestation programme

Reforestation is a critical means of addressing the environmental and social problems of deforestation. China’s Grain-for-Green Program (GFGP) is the world’s largest reforestation scheme. Here we provide the first nationwide assessment of the tree composition of GFGP forests and the first combined ecological and economic study aimed at understanding GFGP’s biodiversity implications. Across China, GFGP forests are overwhelmingly monocultures or compositionally simple mixed forests. Focusing on birds and bees in Sichuan Province, we find that GFGP reforestation results in modest gains (via mixed forest) and losses (via monocultures) of bird diversity, along with major losses of bee diversity. Moreover, all current modes of GFGP reforestation fall short of restoring biodiversity to levels approximating native forests. However, even within existing modes of reforestation, GFGP can achieve greater biodiversity gains by promoting mixed forests over monocultures; doing so is unlikely to entail major opportunity costs or pose unforeseen economic risks to households.

植树造林是解决森林砍伐所引发的环境与社会问题的关键途径。中国退耕还林工程（Grain-for-Green Program, GFGP）是全球规模最大的植树造林项目。本研究首次对全国范围内退耕还林工程林地的树木组成开展系统性评估，并首次完成结合生态学与经济学的综合研究，旨在解析该工程对生物多样性的影响。全国范围内，退耕还林工程林地绝大多数为单一人工林或组成结构极简的混交林。本研究以四川省的鸟类与蜂类为研究对象，结果显示：退耕还林植树造林活动通过混交林可小幅提升鸟类多样性，而单一人工林则会导致鸟类多样性下降，同时还会造成蜂类多样性的大幅损失。此外，当前所有退耕还林工程的植树造林模式，均无法将生物多样性恢复至接近原生林的水平。不过，即便在现有植树造林模式框架内，通过推广混交林而非单一人工林，退耕还林工程仍可实现更显著的生物多样性提升，且该举措大概率不会产生高额机会成本，也不会对农户造成未预期的经济风险。