Columnar Cacti; A Critical Resource For Avian Consumers? Quantifying Avian Community Responses and Nutrient Fluxes in Natural and Experimental Settings

柱状仙人掌；

• 批准号: 0213659
• 负责人: Blair Wolf
• 金额: $ 30万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0213659&HistoricalAwards=false
• 关键词: Columnar; Cacti; Critical; Resource; Avian

Large columnar cacti, such as the saguaro (Carnegiea gigantea), are prominent features ofmany ecosystems. Because of their extensive distribution and abundant production of largesucculent fruit they play an important role in structuring food webs and ecosystems. Up untilnow, however, researchers studying the ecological and evolutionary aspects of plant-frugivoremutualisms have largely ignored this important group of plants. These succulent fruit may beparticularly important in hot deserts where high air temperatures and water scarcity mayconstrain animal behavior as well as the timing and investment in reproduction. The saguaro'sfruit are available during the driest and hottest period (June-July) of the summer in the SonoranDesert, before the onset of monsoon rains.In this research, I use a two-faceted approach to assessing the importance of a uniqueresource, the saguaro, to a community of avian consumers. The proposed research has severalfeatures that set it apart from earlier studies examining plant -animal interactions: 1) it combinesobservational data of resource use by individual consumers with direct measurements nutrienttransfer between the plant resource and a community of consumers using stable isotopes astracers; 2) it quantifies both temporal changes in fruit availability and changes in avianabundance, diversity, and productivity and 3) it directly manipulates resource availability,through fruit removal, while quantifying changes in consumer abundance, diversity, andproductivity. Taken in concert, these studies provide a unique approach to assessing theimportance of presumed irkeystonely or irfoundationlr resources by: 1) directly quantifying theflux of nutrients between a primary producer and individual consumers and 2) through a fruitremoval experiment, examining the effects of the fruit resource on consumer abundance,biodiversity, and productivity.I expect this research to produce an extensive array of new insights into: 1) the water andenergy balance of desert birds; 2) the role of cacti as consumer resources in arid and semi-aridecosystems; 3) frugivory and nutrient transfer rates between plant-consumer interactions and 4)community dynamics as it relates to changes in resource levels. This work will also quantify howdifferent consumer groups (seed predators versus seed dispersers) interact with the plant to affectthe plant's reproductive potential. It will provide the first comparative analysis of traditionalmethods of studying resource use to the newer techniques using stable isotopes.At the same time, it will be among the first studies to quantify the effects of removal of apresumed irKeystone Plant Resourcele on the abundance, diversity and reproductive output of anentire animal community. This research will also be the first to quantify the importance of asingle resource to the nutrient and water balance of multiple species of different body sizes,foraging modes and dietary guilds in any ecosystem. This work should also provide importantnew empirical evidence on how home range size and foraging mode affect individualexploitation of a resource system.Finally, this research will bring all facets of the scientific process to a large number ofgraduate and undergraduate students. Twenty undergraduate students and 1 graduate student willobtain extensive research experience working on this project and it is likely that many more willbe trained through the REU program. This research is bound to have a major inpact with thepublic as well, because of my association with the Arizona-Sonora Desert Museum. Researchresults from this project will be the basis of a centerpiece display at the museum that explores thescientific process and the interactions of saguaros with the other inhabitants of the SonoranDesert.

大型柱状仙人掌，如巨型仙人掌，是许多生态系统的显著特征。由于它们广泛的分布和大量生产巨大的肉质水果，它们在构建食物网和生态系统中发挥着重要作用。然而，到目前为止，研究植物-果树互惠关系的生态和进化方面的研究人员在很大程度上忽视了这一重要的植物群体。这些多汁的水果在炎热的沙漠中可能特别重要，那里高温和缺水可能会限制动物的行为以及繁殖的时机和投资。在Sonoran沙漠夏季最干燥和最热的时期(6-7月)，在季风雨开始之前，可以买到saguaro的果实。在这项研究中，我使用两个方面的方法来评估一种独特的资源-saguaro对于鸟类消费者社区的重要性。这项拟议的研究有几个特点，使其有别于早先对动植物相互作用的研究：1)它结合了个人消费者使用资源的观测数据，以及使用稳定的同位素登陆器在植物资源和消费者群体之间的营养转移的直接测量；2)它量化了水果可获得性的时间变化和鸟类丰度、多样性和生产力的变化；3)它通过水果去除直接操纵资源的可用性，同时量化消费者丰度、多样性和生产力的变化。综上所述，这些研究提供了一种独特的方法来评估假定的不重要或基础资源的重要性：1)直接量化初级生产者和个人消费者之间的营养流动；2)通过水果去除实验，检查水果资源对消费者丰度、生物多样性和生产力的影响。我预计这项研究将对以下方面产生广泛的新见解：1)沙漠鸟类的水和能量平衡；2)仙人掌作为消费者资源在干旱和半干旱生态系统中的作用；3)植物-消费者互动之间的果树和养分转移率；4)群落动态，因为它与资源水平的变化有关。这项工作还将量化不同的消费者群体(种子捕食者和种子传播者)如何与植物相互作用，以影响植物的繁殖潜力。它将首次对研究资源利用的传统方法与使用稳定同位素的新技术进行比较分析。同时，它将是第一批量化移除未恢复的基石植物资源对整个动物群的丰度、多样性和繁殖产量影响的研究之一。这项研究还将首次量化单一资源对任何生态系统中不同身体大小、觅食方式和饮食协会的多种物种的营养和水平衡的重要性。这项工作还将为研究栖息地大小和觅食模式如何影响个体对资源系统的开发提供重要的新的经验证据。最后，本研究将把科学过程的方方面面带给大量的研究生和本科生。20名本科生和1名研究生将在这个项目上拥有广泛的研究经验，很可能会有更多的人通过REU计划接受培训。由于我与亚利桑那州-索诺拉沙漠博物馆的联系，这项研究肯定也会对公众产生重大影响。这个项目的研究结果将成为博物馆中心陈列的基础，探索科学过程以及萨瓜罗人与索诺兰沙漠其他居民的互动。