COLLABORATIVE RESEARCH: Will climate change alter rates of old field succession across the U.S. Eastern Deciduous Forest? A cross-latitude experimental network

美国东部被遗弃的农业用地以一种成熟的模式恢复为森林，在这种模式中，草本植物的“老田”逐渐让位给树木。这种从农田到森林的转变是生态系统发展中的一个关键事件，因为它推动了野生动物的丰富，影响了生态系统储存碳和循环养分的方式，并经常改变以外来或本地植物物种为主的景观之间的平衡。这一过程的一个令人困惑的方面是，东北地区的老田野可以持续几十年，但东南地区往往在不到10年的时间里就会过渡到森林，尽管有许多“入侵”的树种是共同的。这是因为东南部气候温暖，树木在与草本植物竞争中生长得更快吗？如果是这样的话，随着气候变暖，“老田野”会更快地变成森林吗？或者，这些地区可能在其他方面（例如土壤质量）有所不同。在这个项目中，pi设计了一个实验来明确地回答这个问题，使用从纽约到佛罗里达的六个实地实验网络。在每个地点，研究人员将控制古老的田间植物和入侵树木的组成（使用北部和东南部常见的物种），并改变土壤条件以接近北部和南部的土壤。研究人员将监测树木入侵每个实验群落的速度，并利用这些结果制定一个模型，该模型可以预测气候、土壤肥力和特定物种的特征如何影响美国东部森林发展的速度。这些结果将是理解美国东部农业景观如何在下个世纪继续变化的关键，并将为利益相关者提供有关碳封存、生物多样性和其他生态系统服务的土地管理问题的信息。两名研究生和几名本科生将在两名初级教员的支持下接受培训。该项目还包括使用美国东部的几个核心生态研究设施。

Abandoned agricultural land in the Eastern United States returns to forest in a well-established pattern in which "old fields" of herbs and grasses gradually give way to trees. This field-to-forest transition is a key event in ecosystem development because it drives wildlife abundance, influences how ecosystems store carbon and cycle nutrients, and often changes the balance between landscapes dominated by alien or native plant species. One puzzling aspect of this process is that old fields can persist for decades in the Northeast, but tend to transition to forests in less than 10 years in the Southeast, despite having many of the "field invading" tree species in common. Is this due to the warmer climate of the Southeast, where trees can grow more quickly in competition with herbs and grasses? If so, will "old fields" become forests more quickly as the climate warms? Alternatively, the regions may be different in other ways (e.g. soil quality). In this project the PIs have designed an experiment to definitively answer this question, using a network of six field experiments from New York to Florida. At each site, researchers will control the composition of the old field plants and invading trees (using species common to both the North- and Southeast), as well as varying the soil conditions to approximate northern and southern soils. Researchers will monitor the rate at which trees invade each experimental community, and use the results to formulate a model that can make predictions about how climate, soil fertility, and characteristics of particular species influence the rate of forest development in the Eastern United States.These results will be key for understanding how agricultural landscapes of the Eastern United States will continue to change over the next century, and will inform stakeholders on land management issues with respect to carbon sequestration, biological diversity, and other ecosystem services. Two graduate students and several undergraduates will be trained, through the support of two junior faculty. The project also includes use of several core ecological research facilities in the Eastern United States.