Grantham Centre for Sustainable Futures, University of Sheffield, Sheffield, S10 2TN, UK.
Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
New Phytol. 2018 Oct;220(1):10-24. doi: 10.1111/nph.15236. Epub 2018 May 28.
Tropical savannas have a ground cover dominated by C grasses, with fire and herbivory constraining woody cover below a rainfall-based potential. The savanna biome covers 50% of the African continent, encompassing diverse ecosystems that include densely wooded Miombo woodlands and Serengeti grasslands with scattered trees. African savannas provide water, grazing and browsing, food and fuel for tens of millions of people, and have a unique biodiversity that supports wildlife tourism. However, human impacts are causing widespread and accelerating degradation of savannas. The primary threats are land cover-change and transformation, landscape fragmentation that disrupts herbivore communities and fire regimes, climate change and rising atmospheric CO . The interactions among these threats are poorly understood, with unknown consequences for ecosystem health and human livelihoods. We argue that the unique combinations of plant functional traits characterizing the major floristic assemblages of African savannas make them differentially susceptible and resilient to anthropogenic drivers of ecosystem change. Research must address how this functional diversity among African savannas differentially influences their vulnerability to global change and elucidate the mechanisms responsible. This knowledge will permit appropriate management strategies to be developed to maintain ecosystem integrity, biodiversity and livelihoods.
热带稀树草原的地表植被以 C 类草为主，火和食草动物的存在限制了潜在降雨量以下的木本植物覆盖。稀树草原生物群系覆盖了非洲大陆的 50%，包含了多种生态系统，其中包括茂密的 Miombo 林地和塞伦盖蒂草原，以及散布的树木。非洲稀树草原为数千万人提供了水、放牧和觅食、食物和燃料，拥有独特的生物多样性，支持野生动物旅游。然而，人类的影响正在导致稀树草原广泛而加速的退化。主要威胁包括土地覆盖的变化和转变、景观破碎化破坏食草动物群落和火灾模式、气候变化以及大气 CO2 浓度上升。这些威胁之间的相互作用还了解甚少，对生态系统健康和人类生计的后果尚不清楚。我们认为，非洲稀树草原主要植物群系的植物功能特征的独特组合使它们对生态系统变化的人为驱动因素具有不同的敏感性和恢复力。研究必须解决非洲稀树草原之间的这种功能多样性如何不同地影响它们对全球变化的脆弱性，并阐明负责的机制。这一知识将允许制定适当的管理策略来维护生态系统的完整性、生物多样性和生计。
