Human population growth offsets climate-driven increase in woody vegetation in sub-Saharan Africa
Human population growth offsets climate-driven increase in woody vegetation in sub-Saharan Africa
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DOI：
10.1038/s41559-017-0081
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发表时间：
2017-04-01
影响因子：
16.8
通讯作者：
Fensholt, Rasmus
中科院分区：
文献类型：
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作者：
Brandt, Martin;Rasmussen, Kjeld;Fensholt, Rasmus
撒哈拉以南非洲人口的快速增长产生了对农用土地和森林产品的日益增长的需求，这可能会导致砍伐森林。相反，据报道非洲旱地正在变绿，但这很难与木本植被的变化联系在一起。因此，对木本植被如何对社会经济和环境变化作出反应的理解并不完整。在这里，我们使用被动微波地球观测数据集记录了1992-2011年木本覆盖的土地面积的两种不同趋势：36%的土地面积(6870000千米(2))主要在旱地增加，11%(215万千米(2))减少(215万千米(2))，主要在潮湿地区。木本植物盖度的增加与低人口增长相关，并受到湿润地区二氧化碳增加和旱地降水量增加的推动，而木本植物盖度的减少与人口的高增长有关。这些相反趋势在空间上的不同模式反映了，第一，植被对降水和大气二氧化碳的自然反应，第二，湿润地区的森林砍伐，规模较小，但对生态系统服务，如生物多样性和碳储量来说，很重要。这幅关于木本植被变化的微妙图景挑战了人们普遍认为的非洲木本植被普遍和持续减少的观点。
The rapidly growing human population in sub-Saharan Africa generates increasing demand for agricultural land and forest products, which presumably leads to deforestation. Conversely, a greening of African drylands has been reported, but this has been difficult to associate with changes in woody vegetation. There is thus an incomplete understanding of how woody vegetation responds to socio-economic and environmental change. Here we used a passive microwave Earth observation data set to document two different trends in land area with woody cover for 1992-2011: 36% of the land area (6,870,000 km(2)) had an increase in woody cover largely in drylands, and 11% had a decrease (2,150,000 km(2)), mostly in humid zones. Increases in woody cover were associated with low population growth, and were driven by increases in CO (2) in the humid zones and by increases in precipitation in drylands, whereas decreases in woody cover were associated with high population growth. The spatially distinct pattern of these opposing trends reflects, first, the natural response of vegetation to precipitation and atmospheric CO2, and second, deforestation in humid areas, minor in size but important for ecosystem services, such as biodiversity and carbon stocks. This nuanced picture of changes in woody cover challenges widely held views of a general and ongoing reduction of the woody vegetation in Africa.