Studies of the African savannas have used national parks to test ecological theories of natural ecosystems, including equilibrium, non-equilibrium, complex adaptive systems, and the role of top-down and bottom-up physical and biotic forces. Most such studies have excluded the impact of pastoralists in shaping grassland ecosystems and, over the last half century, the growing human impact on the world’s rangelands. The mounting human impact calls for selecting indicators and integrated monitoring methods able to track ecosystem changes and the role of natural and human agencies. Our study draws on five decades of monitoring the Amboseli landscape in southern Kenya to document the declining role of natural agencies in shaping plant ecology with rising human impact. We show that plant diversity and productivity have declined, biomass turnover has increased in response to a downsizing of mean plant size, and that ecological resilience has declined with the rising probability of extreme shortfalls in pasture production. The signature of rainfall and physical agencies in driving ecosystem properties has decreased sharply with growing human impact. We compare the Amboseli findings to the long-term studies of Kruger and Serengeti national parks to show that the human influence, whether by design or default, is increasingly shaping the ecology of savanna ecosystems. We look at the findings in the larger perspective of human impact on African grasslands and the world rangelands, in general, and discuss the implications for ecosystem theory and conservation policy and management. The Amboseli study shows the value of using long-term integrated ecological monitoring to track the spatial and temporal changes in the species composition, structure, and function of rangeland ecosystems and the role of natural and human agencies in the process of change. The study echoes the widespread changes underway across African savannas and world’s rangelands, concluding that some level of ecosystem management is needed to prevent land degradation and the erosion of ecological function, services, and resilience. Despite the weak application of ecological theory to conservation management, a plant trait-based approach is shown to be useful in explaining the macroecological changes underway.

中文翻译：

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非洲稀树草原景观的植物生态学的长期变化及其对生态系统理论和保护管理的影响

对非洲大草原的研究已使用国家公园来测试自然生态系统的生态理论，包括平衡，非平衡，复杂的适应系统以及自上而下和自下而上的物理和生物力的作用。大多数此类研究都排除了牧民对塑造草地生态系统的影响，并且在过去半个世纪中，人类对世界牧场的影响越来越大。不断增加的人类影响要求选择能够跟踪生态系统变化以及自然和人类机构作用的指标和综合监测方法。我们的研究基于对肯尼亚南部安博塞利景观的监测，历时五十年，以记录自然因素在人类影响力增强中对塑造植物生态系统的作用下降。我们发现植物多样性和生产力下降了，随着平均植物尺寸的缩小，生物量的周转增加了，生态恢复力也随着草场产量极度短缺的可能性增加而下降。随着人类影响的增加，降雨和物理机构在推动生态系统特性方面的作用已急剧下降。我们将Amboseli的发现与克鲁格和塞伦盖蒂国家公园的长期研究进行了比较，以表明无论是设计还是默认的人类影响都正在日益影响热带稀树草原生态系统。通常，我们从更大的角度看待人类对非洲草原和世界牧场的研究结果，并讨论对生态系统理论以及保护政策和管理的意义。Amboseli的研究表明，使用长期综合生态监测来跟踪牧场生态系统的物种组成，结构和功能的时空变化以及自然和人类机构在变化过程中的作用非常有价值。该研究呼应了非洲大草原和世界牧场正在发生的广泛变化，认为需要某种程度的生态系统管理来防止土地退化以及生态功能，服务和复原力的侵蚀。尽管生态学理论在保护管理方面的应用很薄弱，但基于植物性状的方法仍可用于解释正在进行的宏观生态学变化。牧场生态系统的功能，功能以及自然和人类机构在变化过程中的作用。该研究呼应了非洲大草原和世界牧场正在发生的广泛变化，认为需要某种程度的生态系统管理来防止土地退化以及生态功能，服务和复原力的侵蚀。尽管生态学理论在保护管理方面的应用很薄弱，但基于植物性状的方法仍可用于解释正在进行的宏观生态学变化。牧场生态系统的功能，功能以及自然和人类机构在变化过程中的作用。该研究呼应了非洲大草原和世界牧场正在发生的广泛变化，认为需要某种程度的生态系统管理来防止土地退化以及生态功能，服务和复原力的侵蚀。尽管生态学理论在保护管理方面的应用很薄弱，但基于植物性状的方法仍可用于解释正在进行的宏观生态学变化。