Cross-Site: Collaborative Research: Effects of Different-Sized Herbivores on Grassland Plant Diversity

这项研究解决了不同大小的哺乳动物食草动物对植物多样性的影响，在六个不同的北美草原网站。 这些站点代表两组站点，它们的固有站点生产力不同。 一种假设是，生产力的差异将导致食草动物对植物多样性的影响非常不同。 在低生产力的网站，大多数植物物种是足够高的质量，所有食草动物消费，但捍卫，使较大的食草动物吃劣质植物，而较小的食草动物饲料的种子优势植物。 在高生产力的网站，竞争优势物种可能只消耗较大的草食动物，可以适应其低N含量。 这些权衡表明，较大的食草动物将有更大的影响，植物生物量在高生产力的网站，而较小的食草动物将有更大的影响，生物量在低生产力的网站。 此外，较大的食草动物可能会增加高生产力地点的多样性，减少低生产力地点的多样性，而较小的，更具选择性的食草动物可能会产生相反的效果。 本提案的目标是开始监测长期（未来10 - 20年）计划的前3年，因为植物物种组成和多样性的变化可能需要很长时间才能对处理做出充分反应。LTER和承诺支持这一项目的其他地点的合作网络应大大促进这种监测。 这些结果应该提供一个草食动物在控制草原植物多样性的作用的一般理解，并应援助努力恢复，保护和管理草原生态系统。

This study addresses the effects of different-sized mammalian herbivores on plant diversity at six different North American grassland sites. These sites represent two sets of sites that differ in their inherent site productivity. One hypothesis is that differences in productivity will lead to very different effects of herbivores on plant diversity. At low productivity sites, most plant species are of sufficiently high quality to be consumed by all herbivores, but are defended such that larger herbivores eat inferior plants, while smaller herbivores feed on seeds of dominant plants. At high productivity sites, competitively dominant species may be consumed only by larger herbivores that can accommodate their low N content. These trade-offs suggest that larger herbivores will have greater effects on plant biomass at high productivity sites, while smaller herbivores will have greater effects on biomass at low productivity sites. In addition, larger herbivores may increase diversity at high productivity sites and reduce it at low productivity sites, while smaller, more selective ly foraging herbivores may have the opposite effects. The goal for this proposal is to begin monitoring for the first 3 years of a long-term (next 10 - 20 years) program as it is likely that changes in plant species composition and diversity will require that long to respond fully to treatments. The collaborative network of LTER and other sites committed to support this project should greatly facilitate such monitoring. The results should provide a general understanding of the role of herbivores in controlling grassland plant diversity, and should aid efforts to restore, preserve, and manage grassland ecosystems.