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

0852961 pringle2009年美国复苏和再投资法案（公法111-5）为该奖项提供资金。国际研究奖学金项目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。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Robert M. Pringle博士与国际昆虫病理学与生态学中心（CIPE）的Fabian Haas博士、肯尼亚国家博物馆的Charles Warui博士以及肯尼亚Mpala研究所的M. Kinnaird博士开展为期24个月的研究。最近的研究表明，大型食草哺乳动物可能是？强大的扶少团团员吗?它们的移除将导致生物群落发生重大变化。该项目旨在记录和解释肯尼亚稀树草原上植物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。这是通过一项独特的1公顷处理实验来完成的：完全排除（去除所有大于4公斤的草食动物），排除所有大于6公斤的草食动物，仅排除大型草食动物（大象和长颈鹿），以及无围栏控制（所有存在的动物）。这些处理在自然降雨梯度的三个水平上各重复三次。项目人员正在测试四个具体的假设。1：排除草食动物改变了单个植物的适口性，增强了补充，降低了物种的均匀性，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，排除食草动物导致草食性和食肉性节肢动物的总生物量增加。个体节肢动物的间接反应各不相同，但取决于(a)饮食宽度和寄主-植物偏好，(b)觅食策略，以及(c)捕食脆弱性。直接效应和间接效应的强度都与降雨量呈负相关。人类正在减少世界范围内大型食草动物的数量，气候变化预示着降水模式的巨大变化。然而，没有人知道这些变化将如何影响非洲大草原和黄石生态系统等标志性景观的生物多样性和生态功能。产生这些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环境背景调节的基本真相。它还将为预测在快速变化的世界中大型哺乳动物数量减少和灭绝的后果提供基础。迄今为止，对大型哺乳动物移除的反应的测量一直是特殊的和机会主义的，并且提供的解释潜在反应的机制通常是推测性的。此外，在物种丰富的有蹄类行会中进行的少数排除实验大多是？全部还是没有？这意味着特定物种或亚群的影响无法确定，而我们基于顺序大小的排除方法将隔离这些影响。最后，该实验是第一个将大型食草动物排斥与环境梯度多层次复制相结合的实验，这与生态学家最近呼吁解决物种相互作用的环境依赖性是一致的。在开发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5名全职研究助理。他们的工作为他们提供了宝贵的、可转移的技能（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）。这些人来自不同的民族和宗教，他们生活在一个因种族冲突而四分五裂的地区（就在2008年1月）；共同努力巩固了克服种族差异的纽带。当地居民和他们的孩子将在导游的带领下参观实验设施，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独立运作；这种合作将建立国内和国际伙伴关系和能力，促进未来的共同努力。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意义将以短篇文章的形式传播给非科学读者，并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.