SGER: Unpredictable Events of Catastrophic Proportions in Temparate Forest Ecosystems: Developing a Baseline to Assess Cascading Effects and Coupled Interactions

最近发展起来的生态学理论认为，重大干扰事件是大尺度环境变化和进化的关键因素。间断平衡和混沌理论假定系统在可选的稳定状态之间发生位移。对这些相对突变的复杂动态的调查通常是在发生重大扰动之后进行的，由于它们的突发性和不可预测性，可以用来描述事件发生前条件的数据相对较少。大量蝉的周期性出现是可以预测的，但它们发生的频率太低，不足以构成不可预测的灾难性干扰事件的极好模型。这项用于探索性研究的小额赠款将从2002年夏天开始在印第安纳州中部建立一套基线测量，预计2004年中期将出现大规模的蝉爆发。在印第安纳州中部，蝉每17年爆发一次，其爆发规模是美国发现的最大规模之一。两次爆发之间的时间间隔太长，以至于蝉栖居的森林系统的大多数元素对爆发的形式和特征没有工作记忆。在疫情爆发前，地下的蝉大量消耗树木根系，而在疫情爆发后，它们可以迅速落叶树冠。它们成为许多物种的猎物，经常导致“捕食者饱和”，因为野生动物狼吞虎咽地吃着看似无穷无尽的昆虫，这种进食模式可以在爆发的那一年和接下来的几年里戏剧性地改变这些捕食者的存活率和繁殖率。产卵会导致受影响树木的破坏或死亡，而树冠的损失会改变林下的小气候，影响蒸腾速率，进而影响地下水和地表水水文。为了建立基线信息，以评估2004年印第安纳州中部蝉爆发的影响，这个由地理、生物、地质、公共和环境事务部门的成员组成的研究小组将在2002年中期开始进行一系列测量。要测量的变量包括营养动态、水文、冠层覆盖、树木生理、幼苗建立和社会经济因素。该奖项将有助于建立基线测量，以便在未来几年进行后续研究。除了为对自然系统和人类系统之间的相互作用进行广泛的调查奠定基础之外，该项目还将产生更广泛的积极影响，包括本科生和研究生的参与和培训，以及建立可用于广泛调查的数据库。

Recently developed ecological theories had identified major disturbance events as crucial factors in large-scale environmental change and evolution. Punctuated equilibrium and chaos theories posit shifts in systems between alternative stable states. Inquiries into the complex dynamics of these relatively abrupt shifts generally have taken place after major disturbances have occurred, with relatively little data available to characterize conditions prior to the events because of their suddenness and unpredictability. Periodic emergence of cicadas in massive numbers are predictable, but they occur infrequently enough to constitute an excellent model of unpredictable disturbance events of catastrophic proportions. This Small Grant for Exploratory Research will establish a set of baseline measurements in central Indiana starting in the summer of 2002 in anticipation of a major cicada outbreak in mid-2004. Cicada outbreaks occur every 17 years in central Indiana, where the size of the outbreak is among the largest found anywhere in the U.S. The time period between outbreaks is so long that most elements of the forest system that the cicadas inhabit effectively have no working memory of the form and character of the outbreak. Before the outbreak, cicadas underground are massive consumption of tree root systems, while after the outbreak, they can rapidly defoliate tree canopies. They become prey to a number of species, frequently inducing "predator saturation" as wildlife gorge on the seemingly endless supply of insects, an eating pattern that can dramatically alter the survival and reproduction rates of those predators during the year of the outbreak and in following years. The laying of eggs can lead to damage or death of affected trees, and loss of tree canopy can alter the microclimatology of the understory and affect transpiration rates, which in turn affects groundwater and surface stream hydrology. In order to develop baseline information against which to evaluate the impacts of the 2004 cicada outbreak in central Indiana, this research team, which includes members drawn from geography, biology, geology, and public and environmental affairs departments, will begin taking a series of measurements in mid-2002. Among variables to be measured are nutrient dynamics, hydrology, canopy cover, tree physiology, seedling establishment, and socioeconomic factors.This award will help establish baseline measurements from which follow-up studies can be conducted in the coming years. In addition to laying the groundwork for a broad range of inquiries into interactions between natural and human systems, the project will have positive broader impacts, including the involvement and training of undergraduate and graduate students and the establishment of databases that can be used for a broad range of inquiries.