Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa.
Conservation South Africa, 301 Heritage House, Claremont, 7375, South Africa.
Nat Commun. 2018 Jun 11;9(1):2272. doi: 10.1038/s41467-018-04616-8.
While global deforestation induced by human land use has been quantified, the drivers and extent of simultaneous woody plant encroachment (WPE) into open areas are only regionally known. WPE has important consequences for ecosystem functioning, global carbon balances and human economies. Here we report, using high-resolution satellite imagery, that woody vegetation cover over sub-Saharan Africa increased by 8% over the past three decades and that a diversity of drivers, other than CO, were able to explain 78% of the spatial variation in this trend. A decline in burned area along with warmer, wetter climates drove WPE, although this has been mitigated in areas with high population growth rates, and high and low extremes of herbivory, specifically browsers. These results confirm global greening trends, thereby bringing into question widely held theories about declining terrestrial carbon balances and desert expansion. Importantly, while global drivers such as climate and CO may enhance the risk of WPE, managing fire and herbivory at the local scale provides tools to mitigate continental WPE.
虽然人类土地利用导致的全球森林砍伐已经得到量化，但同时木本植物侵入（WPE）开阔地区的驱动因素和程度仅在区域范围内为人所知。WPE 对生态系统功能、全球碳平衡和人类经济有着重要的影响。在这里，我们使用高分辨率卫星图像报告称，过去三十年，撒哈拉以南非洲的木本植被覆盖面积增加了 8%，而 CO 以外的多种驱动因素能够解释这一趋势的 78%的空间变化。燃烧面积的减少以及更温暖、更湿润的气候推动了 WPE 的发生，但在人口增长率高、食草动物（特别是食草动物）高度和低度极端的地区，这种情况有所缓解。这些结果证实了全球绿化趋势，从而对陆地碳平衡下降和沙漠扩张的普遍理论提出了质疑。重要的是，虽然气候和 CO 等全球驱动因素可能会增加 WPE 的风险，但在当地范围内管理火灾和食草动物为缓解大陆 WPE 提供了工具。
