LTREB: A Long-Term Investigation of the Interplay of Biotic vs. Abiotic Factors in a Chilean Semiarid Community

这项研究的目标是继续并重新聚焦一项长期的、大规模的实验，该实验旨在调查智利半干旱社区中捕食、竞争和食草的重要性。现有的结果表明，对植被最显著的影响是该地区对最近厄尔尼诺-南方涛动（ENSO）事件引起的降雨增加的反应，而不是对食草动物或捕食动物的反应。这一发现表明，在干旱年份，自下而上的效应构成了这个群落，而随着动物数量的增加，与降雨相关的生产力增加，生物相互作用（自上而下的调节）变得更加重要。这项研究的具体目的是继续我们的长期实验，以确认这种可疑的事件模式，并将我们的观察扩展到蜥蜴，鸟类和昆虫。从长远来看，这个实验有望提供一个有指导意义的例子，说明直接和间接影响如何在一个社区中分化，以及它们的重要性如何随着物理环境的变化而变化。除了解决基本的生态问题外，本研究还为了解智利中北部严重荒漠化的半干旱区的生态系统变化提供了重要的基线数据。它仍然是智利和美国学生的宝贵训练基地，并直接为两国的科学发展作出贡献。

The goal of this study is to continue, and to refocus, a long-term, large-scale experiment that investigates the importance of predation, competition and herbivory in a Chilean semi-arid community. Existing results show that the most dramatic effect on vegetation is this area has been in response to increased rainfall associated with a recent El Nino-Southern Oscillation (ENSO) event, rather than to herbivory or predation. This finding suggests the hypothesis that bottom-up effects structure this community during dry years, while biotic interactions (top-down regulation) become more important as animal numbers increase in response to increased productivity associated with rainfall. The specific purpose of this study is to continue our long-term experiment to confirm this suspected pattern of events, and to extend our observations to lizards, birds, and insects. This experiment promises, over the long-term, to provide an instructive example of how direct and indirect effects diverge through a community, and how their importance shifts as the physical environment changes. In addition to addressing basic ecological questions, this study provides important baseline data for understanding ecosystem change in the heavily desertified north-central Chilean semi-arid zone. It continues to be a valuable training ground for Chilean and American students and contributes directly to the development of science in both countries.