LTREB renewal: Climatic change and community organization across three trophic levels: long-term research at a sentinel site in semiarid north-central Chile

半干旱和干旱土地的增加可能影响全球的经济稳定和社会。这个长期项目研究了影响半干旱社区的变化力量，从而成为气候变化导致干旱加剧的社会后果的重要哨兵。自1989年以来，降雨模式的意外变化和物种入侵取代了本地物种的相互作用，成为智利北部半干旱刺灌丛群落的主要驱动力。从该地点获得的长期生态数据直接有助于对这些不断变化的环境进行明智管理的决策。它还将提供信息，通过提高公众对野生动物和自然区域的了解，帮助他们了解决策过程。该项目将与北美半干旱地区正在进行的研究进行重要的比较，在北美，长期变化的重要驱动因素不同。该项目代表了美国和智利研究人员和管理人员之间的长期合作，并将为美国学生参与国际研究提供宝贵的机会。这个长期的野外项目利用20个实验网格，每个月对小型哺乳动物和短暂植物进行采样，每三个月测量一次灌木覆盖情况，每四个月采集一次土壤样本以估计种子密度，并评估狐鸮的饮食。先前的研究结果记录了食肉动物对被El淹没的小型哺乳动物和植物的影响Niño&amp；#8208；降雨有关。基于对全球气候变化导致的更频繁和更强烈的厄尔Niño事件的预测，该项目将强调气候变化和入侵物种（lagomorphs，许多短暂的植物）在该栖息地群落水平动态中的双重和互动作用。未来五年收集的数据将进行分析，以回答三个重要问题：1)未来五年的重大厄尔尼诺Niño事件是否会逆转自2002年以来显而易见的趋势，或者是否发生了一个关键的转变，在可预见的未来将保持稳定？2)自2003年以来，多年生灌木覆盖面积的明显减少和入侵植被的增加可能会导致哪些进一步的变化？3)这些变化对智利中北部半干旱区有什么更广泛的影响？通过与智利、西班牙和美国的多名研究人员的广泛合作，这些目标得以实现。该研究整合了全球气候变化背景下的人口、群落和地理生态学，并预测了植被响应，跨越3个营养水平，并为半干旱系统中生物与非生物因素的相对重要性以及自上而下与自下而上的控制提供了重要见解。

Increases in semi-arid and arid lands may affect economic stability and societies globally. This long-term project examines the shifting forces that influence a semi-arid community and thus serves as an important sentinel for societal ramifications of increased aridity with climate change. Since 1989, unexpected changes in rainfall patterns and species invasions have replaced native species interactions as key drivers of a semi-arid thorn scrub community in northern Chile. Long-term ecological data from this site contribute directly to decisions on wise management of these changing environments. It also will provide information to help the general public understand the decision-making process by improving their knowledge of its wildlife and natural areas. The project will provide important comparisons with ongoing research in semi-arid sites in North America, where important drivers of long-term change differ. The project represents a long-term collaboration between US and Chilean researchers and managers, and will provide valuable opportunities for US students to participate in international research. This long-term field project utilizes 20 experimental grids in which small mammals and ephemeral plants are sampled monthly, cover by shrubs is measured every three months, soil samples are taken every 4 months to estimate seed density, and fox owl diets are assessed. Previous results document the effects of predators on small mammals and plants that were overwhelmed by El Niño‐associated rainfall. Based on predictions of more frequent and intense El Niño events as a consequence of ongoing global climate change, the project will emphasize the dual and interactive roles of climate change and invasive species (lagomorphs, numerous ephemeral plants) on community-level dynamics in this habitat. Data collected over the next five years will be analyzed to answer three important questions: 1) will a major El Niño event in the next 5 years reverse the trends that have been apparent since 2002, or has a critical transition occurred that will be stable for the foreseeable future? 2) what further changes may ensue from the apparent decline in perennial shrub cover and an increase in invasive vegetation since 2003? and 3) what will be the consequences of these changes for the north-central Chilean semiarid zone more generally? These goals are facilitated by extensive collaboration with multiple investigators in Chile, Spain, and the United States. This research integrates population, community, and geographical ecology in the context of global climate change and predicted vegetative responses, spans 3 trophic levels, and provides important insight into the relative importance of biotic vs. abiotic factors, and top-down versus bottom-up control in semi-arid systems.