Collaborative Research: Convergence and Contingencies in Savanna Grasslands

草原和稀树草原占地球陆地面积的八分之一，作为牧场具有重要的经济意义，并受到人类活动的高度影响。它们还具有巨大的保护价值，并支持世界上大多数剩余的大型本地放牧动物，特别是在非洲。对维持稀树草原最重要的因素，包括其自然火和放牧制度，有一个基本的了解，是管理和保护稀树草原所必需的。科学家们质疑不同地区的草原功能是否相似。功能的趋同意味着生态理解和保护战略可以推广到全世界的稀树草原。但是，特定于一个地区的偶然因素，如进化历史的差异或存在的食草动物的类型，可能会导致一些稀树草原的独特反应。本研究的目的是比较北美和南非稀树草原的关键生态过程对火灾和放牧的反应。科学家们将利用三个正在进行的长期实验来控制火灾返回间隔和大型食草动物的存在。将比较植物生产力、植物多样性和养分循环的反应，并评估反应的机制，如植物性状或进化历史的差异。需要进行比较研究，阐明全世界人类改变火灾和放牧制度的后果，以便制定管理战略，确保具有生态和经济重要性的稀树草原的可持续性。这项研究将提供这样做所需的基本知识，并为青年科学家、研究生和本科生提供培训和重要的全球和文化经验。最后，虽然已经建立了合作关系，但将向南非的科学家和管理人员提供成果。

Grasslands and savannas occupy one eighth of the land surface on Earth, are economically important as grazing lands, and are highly impacted by human activities. They also have tremendous conservation value and support most remaining large native grazing animals in the world, particularly in Africa. A fundamental understanding of the factors most important for sustaining savanna grasslands, including their natural fire and grazing regimes, is required for their management and conservation. Scientists have questioned whether grasslands in different regions function similarly. Convergence in functioning would mean that ecological understanding and conservation strategies could be generalized for savanna grasslands worldwide. But contingent factors specific to a region, such as differences in evolutionary history or the types of grazers present, may lead to unique responses in some savanna grasslands. The goal of this research is to compare responses of key ecological processes to fire and grazing in North American and South African savanna grasslands. Scientists will take advantage of three ongoing, long-term experiments that manipulate fire return interval and the presence of large grazers. Responses of plant productivity, plant diversity and nutrient cycling will be compared, and the mechanisms underlying responses, such as differences in plant traits or evolutionary histories, will be assessed. Comparative research elucidating the consequences of human alterations of fire and grazing regimes worldwide is needed to enable development of management strategies that can insure the sustainability of ecologically and economically important savanna grasslands. This research will provide the basic knowledge necessary to do so, as well as afford training and important global and cultural experiences for young scientists, graduate students and undergraduates. Finally, though collaborations that are already established, results will be made available to scientists and managers in South Africa.