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会影响全球经济稳定和社会。这一长期项目考察了影响半干旱社区的不断变化的力量，从而成为气候变化导致的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当地物种的相互作用，成为智利北部半干旱荆棘灌木丛群落的关键驱动因素。来自该站点的长期生态数据直接有助于明智地管理这些不断变化的环境。它还将提供信息，通过提高公众对其野生动物和自然区域的了解，帮助他们了解决策过程。该项目将提供与北美半干旱地区正在进行的研究的重要比较，在这些地区，长期变化的重要驱动因素不同。该项目代表着美国和智利研究人员和管理人员之间的长期合作，将为美国学生提供参与国际研究的宝贵机会。这个长期的实地项目利用了20个实验网格，其中每月对小型哺乳动物和短命植物进行采样，每三个月测量灌木覆盖情况，每四个月采集土壤样本以估计种子密度，并评估狐狸猫头鹰的饮食。之前的研究结果证明了捕食者对小型哺乳动物和植物的影响，这些动物和植物被厄尔尼诺现象和伴随的降雨淹没了。基于对持续全球气候变化导致厄尔尼诺现象更加频繁和强烈的预测，该项目将强调气候变化和入侵物种(沼泽植物、大量短命植物)在该栖息地的社区一级动态中的双重和交互作用。未来五年收集的数据将被分析以回答三个重要问题：1)未来5年的重大厄尔尼诺事件是否会扭转自2002年以来的明显趋势，或者是否发生了在可预见的未来将保持稳定的关键转变？2)自2003年以来，多年生灌木覆盖率的明显下降和入侵植被的增加可能会带来哪些进一步的变化？3)这些变化将对智利中北部的半干旱地区产生什么样的影响？通过与智利、西班牙和美国的多名调查人员进行广泛合作，这些目标得到了促进。这项研究在全球气候变化和预测的植被反应的背景下，整合了种群、群落和地理生态学，跨越了3个营养级别，并对半干旱系统中生物和非生物因素以及自上而下和自下而上控制的相对重要性提供了重要的见解。

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.