LTREB: A Long-Term Study of the Role of Biotic and Abiotic Factors in a Chilean Semiarid Community

9615499目前该项目已进入第八个年头，这是一项长期、大规模的实验性操作，旨在研究智利半干旱社区中生物相互作用的重要性，包括捕食、种间竞争和草食。与此同时，正在量化动植物对与气候事件有关的非生物因素的反应。到目前为止的研究结果表明，脊椎动物捕食者对两个核心小型哺乳动物物种的数量和生存有很大影响，而对机会主义物种的影响相对较小。竞争对手的交互作用对某些物种的数量和存活率的显著影响表明了干扰效应。多年生植物和短命植物被排除捕食者/草食动物的异质性效应被检测到。在排除小型哺乳动物的地块上，几个短暂物种的种子减少，这表明草食对植物物种多样性有积极影响。这些生物反应叠加在小型哺乳动物和植物对厄尔尼诺事件的强烈人口反应上。在干旱盛行的时期，由于极端的资源和水资源限制，生物相互作用显得不那么重要。因此，至关重要的是继续监测生物动态，以应对在长时间尺度上变化的周期性非生物力量。这项研究是目前最长的关于生物和非生物因素在温带新热带地区作用的大规模实验研究。

9615499 Meserve This project now in its eighth year is a long-term, large-scale experimental manipulation examining the importance of biotic interactions including predation, interspecific competition and herbivory in a Chilean semiarid community. At the same time, responses of plants and animals to abiotic factors related to climatic events are being quantified. Results thus far have documented that vertebrate predators had major effects on numbers and survival of two core small mammal species, and relatively minor effects on opportunistic ones. Significant time by competitor interactions on numbers and survival of some species suggests interference effects. Heterogeneous effects of predator/herbivore exclusions were detected on plant cover of perennials and ephemerals. Seeds of several ephemeral species decreased on plots where small mammals were excluded suggesting positive effects of herbivory on plant species diversity. These biotic responses have been superimposed on strong demographic responses of small mammals and plants to El Nino events. During prevailing drought periods, biotic interactions appear less important due to extreme resource and water limitation. Consequently, it is vital to continue to monitor the biotic dynamics in response to periodic abiotic forces that vary over long time scales. This study is currently the longest large-scale experimental study of the role of biotic and abiotic factors in the temperate Neotropics.