LTER Cross-site: Regional Variation in Direct and Indirect Influences of Animals on a Chihuahuan Desert Grasslands

Peters，Debra PNew Mexico State UniversityDEB 0087289“Regional variation in direct and indirect influences of animals o a Chihuahuan Desert graduates“在奇瓦瓦沙漠草原中，从灌木到草地的草地损失和从灌木地开垦草地是社区动态中的重要问题，这些问题来自于几个直接和间接的过程。 PI将调查对奇瓦瓦沙漠草的持久性和恢复的直接和间接生物影响。 他们提出了一个评估的影响，不同的动物类群的优势草种，黑禾Bouteloua eriopoda。 遗嘱：1）确定不同动物活动对几种植物过程的相对重要性; 2）检验草种建立的局部和区域模式的变化与动物活动和丰度的变化有关的假设。 他们将在两个奇瓦瓦沙漠LTER站点（Sevilleta和Jornada以及大弯国家公园）内对栖息在草和灌木为主的栖息地的种子、幼苗和成年植物进行一系列排除实验。 通过比较动物类群的影响，草是成功的，而不是在那里，动物影响植被的具体假设的测试将被执行。 具体来说，他们将研究四种假设的机制：a）由于蚂蚁和啮齿动物的捕食而导致的种子损失，B）啮齿动物挖掘的贮藏坑中的种子保护和发芽增加，c）由于小型哺乳动物和蚱蜢对幼苗和成年植物的食草性而导致的死亡和种子产量减少，和d）由于食腐蚂蚁在成年植物下筑巢而导致的营养富集和/或水的可用性增加的积极影响。这些实验将帮助我们了解动物的丰富性和草在广泛的范围内补充。 这项工作将阐明动物在沙漠草原产生和维持模式和动态方面的作用。 它还将有助于对直接和间接的植物-动物相互作用的重要性的多尺度视角。对许多系统具有生态学意义的研究领域。

Peters, Debra PNew Mexico State UniversityDEB 0087289"Regional variation in direct and indirect influences of animals o a Chihuahuan Desert grasslands"In Chihuahuan desert grasslands, the loss of grass to shrubs and the reclamation of grasslands from shrublands are important problems in community dynamics that emerge from several direct and indirect processes. The PIs will investigate direct and indirect biotic influences on the persistence and recovery of Chihuahuan desert grass. They propose an assessment of the effects of different animal taxa on the dominant grass species, black grama Bouteloua eriopoda. The will: 1) determine the relative importance of different animal activities for several plant processes and 2) test the hypothesis that variation in local and regional patterns of grass establishment are related to variation in animal activities and abundances. They will perform a series of exclusion experiments on seeds, seedlings, and adult plants inhabiting grass- and shrub-dominated habitats within two Chihuahuan desert LTER sites (the Sevilleta and Jornada and Big Bend National Park). By comparing the effects of animal taxa where grasses are successful versus where they are not, tests of specific hypotheses by which animals influence vegetation will be performed. Specifically, they will examine four hypothesized mechanisms: a) seed loss due to predation by ants and rodents, b) seed protection and increased germination in cache pits dug by rodents, c) mortality and diminished seed production due to herbivory by small mammals and grasshoppers on seedlings and adult plants, and d) the positive effects of nutrient enrichment and/or increased availability of water due to the nesting of scavenging ants under adult plants. These experiments will help us understand animal abundance and grass recruitment at broad scales. The work will clarify the role of animals in generating and maintaining patterns and dynamics in desert grasslands. It will also contribute to a multi-scale perspective on the importance of direct and indirect plant-animal interactions... a research area of ecological significance to many systems.