International Research Fellowship Program: Ecological Consequences of Large-Herbivore Declines under Different Rainfall Regimes

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。国际研究奖学金计划使美国科学家和工程师能够在国外进行9至24个月的研究。该项目的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持罗伯特·M·普林格尔博士为期24个月的研究奖学金，与国际昆虫病理学和生态学中心(CIPE)的法比安·哈斯博士、肯尼亚国家博物馆的查尔斯·沃鲁伊博士和肯尼亚姆帕拉研究中心的M·金奈德博士合作。最近的研究表明，大型哺乳动物食草动物可能是？强大的相互作用者？它们的移除将引发生物群落的重大变化。该项目旨在记录和解释肯尼亚大草原植物群落和无脊椎动物群落在排除有蹄类食草动物的情况下的短期(2-3年)反应，并研究这些反应如何取决于降雨量的变化。这是利用四个1公顷处理的独特实验完成的：完全排除(去除所有大于4公斤野兔的食草动物)，排除所有大于6公斤的食草动物，仅排除巨型食草动物(大象和长颈鹿)，以及无围栏控制(所有动物存在)。每个处理都在自然降雨梯度的三个水平上重复三次。项目人员正在测试四个具体的假设。I：排除食草动物改变了单个植物的适口性，增加了补充，降低了物种的均衡性，并增加了栖息地水平的结构复杂性。II：通过对植物的这些影响，排除草食动物导致草食性和肉食性节肢动物总生物量增加。节肢动物个体的间接反应各不相同，但取决于(A)食物广度和寄主植物偏好、(B)觅食策略和(C)捕食脆弱性。IV：直接和间接影响的强度与降雨量呈负相关。人类正在减少世界各地的大型食草动物数量，气候变化可能会导致降水模式发生戏剧性的变化。然而，没有人知道这些变化将如何影响非洲稀树草原和黄石生态系统等标志性景观中的生物多样性和生态功能。产生这种知识将揭示关于大型哺乳动物如何影响生态动态以及这些影响如何受到环境背景调节的基本事实。它还将为预测大型哺乳动物在快速变化的世界中减少和灭绝的后果提供基础。到目前为止，对大型哺乳动物迁移的反应的测量一直是特殊的和机会主义的，提供的解释反应背后的机制往往是推测的。此外，在物种丰富的有蹄类协会中进行的少数排除实验大多是？全有或没有，？这意味着无法确定特定物种或亚组的影响，而我们基于大小的顺序排除方法将隔离这些影响。最后，这项实验首次将大型食草动物排除与在多个环境梯度水平上的复制结合在一起，这与最近呼吁生态学家解决物种相互作用的上下文相关性问题是一致的。在发展人力资本和国际合作方面，该项目支持来自肯尼亚农村当地社区的五名全职研究助理。他们的就业为他们提供了宝贵的、可转让的技能(识别肯尼亚本土生物多样性、数据输入和计算机培训、管理和团队合作经验)。这些人也来自一个被种族冲突撕裂的地区(直到2008年1月)，他们来自不同的种族群体和宗教；合作巩固了克服种族差异的纽带。当地人和他们的孩子将被带着导游参观实验设施，使他们能够在教育环境中与生物多样性互动，这将促进该地区的环境管理。该项目还涉及肯尼亚的三个研究机构(以及美国和加拿大的三所大学)之间的合作，这些研究机构长期以来一直是分开运作的；这种合作将建立内部和国际伙伴关系和能力，以促进未来的联合努力。该项目还为该地区鲜为人知的无脊椎动物的未来工作奠定了基础。最后，这项工作的保护和管理影响将以短文形式向非科学受众传播，并将在肯尼亚当地媒体和全球网络上发表。

0852961PringleThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Robert M. Pringle to work with Dr. Fabian Haas at the International Centre for Insect Pathology and Ecology (CIPE), with Dr. Charles Warui at the National Museums of Kenya, and with Dr. M. Kinnaird at the Mpala Research in Kenya.Recent studies suggest that large mammalian herbivores may be ?strong interactors? whose removal will precipitate major changes in biological communities. This project aims to document and explain the short-term (2-3 year) responses of plant and invertebrate communities to the exclusion of ungulate herbivores in a Kenyan savanna, and also to examine how these responses are contingent upon variability in rainfall. This is being done using a unique experiment with four 1-ha treatments: total exclusion (removal of all herbivores larger than 4-kg hares), exclusion of all herbivores larger than 6-kg dik-diks, exclusion only of megaherbivores (elephants and giraffes), and unfenced control (all animals present). These treatments are each replicated three times at three levels of a natural rainfall gradient. Project personnel are testing four specific hypotheses. I: Herbivore exclusion alters the palatability of individual plants, enhances recruitment, reduces species evenness, and increases structural complexity at the habitat level. II: Via these effects on plants, herbivore exclusion leads to increased total biomass of both herbivorous and carnivorous arthropods. III: Indirect responses of individual arthropod species vary, but depend on (a) diet breadth and host-plant preference, (b) foraging strategy, and (c) predation vulnerability. IV: The strength of both direct and indirect effects is negatively correlated with rainfall. Humans are reducing large-herbivore populations worldwide, and climate change promises dramatic changes in precipitation patterns. Yet nobody knows how these changes will affect biodiversity and ecological function in iconic landscapes such as African savannas and the Yellowstone ecosystem. Generating this knowledge will reveal fundamental truths about how large mammals influence ecological dynamics and how these influences are modulated by environmental context. It will also provide a basis for predicting the consequences of large-mammal declines and extinctions in a rapidly changing world. To date, measurements of responses to large-mammal removal have been idiosyncratic and opportunistic, and the mechanisms offered to explain underlying the responses are often speculative. Moreover, the few exclusion experiments conducted in species-rich ungulate guilds have mostly been ?all or none,? meaning that the effects of particular species or subgroups cannot be identified, whereas our sequential size-based exclusion approach will isolate these effects. Finally, this experiment is the first to combine large-herbivore exclusion with replication across multiple levels of an environmental gradient, which is consistent with recent calls for ecologists to address the context-dependence of species interactions. In terms of developing human capital and international collaboration, this project supports five full-time research assistants from local communities in rural Kenya. Their employment provides them with valuable, transferable skills (identification of native Kenyan biodiversity, data entry and computer training, management and teamwork experience). These men are also from different ethnic groups and religions in a region torn (as recently as January, 2008) by ethnic strife; working together cements bonds that overcome ethnic differences. Local people and their children will be taken on guided tours of the experimental facilities, allowing them to interact with biodiversity in an educational setting, which will promote environmental stewardship in the region. This project also involves collaboration among three research institutions in Kenya (as well as three universities in the US and Canada) that have long operated separately; this collaboration will build intra- and international partnerships and capacity that will facilitate future joint endeavors. The project also lays a foundation for future work on the poorly known invertebrates of this region. Lastly, the conservation and management implications of the work will be disseminated in short essays for non-scientific audiences to be published both in local Kenyan media and on the worldwide web.