The direct and indirect effects of plantation forestry expansion on usable water in the southeastern US

美国南部，特别是东南部地区，拥有一些最集中管理的森林。目前，种植的松树约有4000万英亩，占美国南部整个森林面积的20%左右。经济模型预测，工业和私人所有者加速了美国东南部松树种植园的面积扩张，部分原因是联邦政府减少从西部森林采伐木材的政策。在过去的50年里，这种扩张主要是用更年轻、生长更快的火炬松取代了天然的老松林。考虑到这种土地覆盖变化的区域规模，美国东南部未来的水资源规划必须考虑到松树人工林面积的迅速扩大。该项目评估了这种快速土地利用转换对蒸散（土壤和植物直接向大气中流失的水分）和地下水补给的直接影响，以及它对东南地区夏季降雨的间接影响。考虑到森林是降水的“第一用户”，这种直接影响可以显著改变东南部的“可用”水。关于间接影响，根区土壤水分和开始降雨之间的联系现在引起了极大的注意，因为它可能对用其他用途取代天然森林所带来的变化起关键作用。以前的研究要么集中在地上的水运动途径，要么集中在地下的过程。本文提出了一个完整的土壤-植物-大气数学模型，以解决松林扩张的影响。该模型及其各组成部分将根据若干长期实地实验单独和集体地进行评估。鉴于美国东南部人口的快速增长，干旱频率和持续时间的增加对可用水资源的影响可能会像树木一样严重。第一个用户?沉淀的水。因此，该项目更广泛的意义在于开发机械数学模型，可以识别松树人工林扩张导致的未来水资源脆弱性。该项目支持1名研究生和1名博士后，实现了水文、生态和大气科学研究和跨学科培训的整合，为下一代科学家解决大规模土地覆盖变化和水资源脆弱性等复杂的社会问题做好了准备。作为一项公众推广活动，该项目利用了北卡罗来纳自然科学博物馆最近的举措，旨在展示博物馆在科学发现和解决公众社会问题方面的进步之间的交叉点。

The southern United States, particularly its Southeastern region, includes some of the most intensively managed forests. Currently, planted pines are at some 40 million acres and occupy about 20 percent of entire forested area in the southern United States. Economic models predict accelerated areal expansion in pine plantations within the Southeastern US by industry and private owners, in part, due to federal policies to reduce timber harvesting from western forests. Over the last 50 years, this expansion primarily replaced natural and thus older pine forests with younger and faster growing Loblolly pines. Given the regional scale of this land-cover change, future water resources planning for the Southeastern US must account for the rapid areal expansion in pine plantation area. This project evaluates the direct effects of this rapid land-use conversion on evapotranspiration (loss of water to the atmosphere directly from the soil and through plants) and groundwater recharge, as well as its indirect effects on summertime rainfall initiation within the Southeast region. Given that forests are "first-users" of precipitated water, this direct effect can significantly alter "usable" water in the Southeastern. With regards to the indirect effects, the link between root-zone soil water and the initiation of rainfall is now attracting significant attention as potentially having a key role on the alterations brought about by the replacement of natural forests with other uses. Previous studies focused either on aboveground pathways of water movement or on below ground processes. Here, a complete soil-plant-atmosphere mathematical model is proposed to address the impacts of pine plantation expansion. The model and its various components will be evaluated individually and collectively against a number of long-term field experiments.Given the rapid growth of the human population in the southeastern US, the consequences of increased drought frequency and duration can be severe on usable water resources as trees are ?first users? of precipitated water. Hence, the broader significance of this project lies in the development of mechanistic mathematical models that can identify future vulnerabilities of water resources resulting from pine plantation expansion. This project supports a graduate student and a post-doctoral fellow, which enables integration of research and inter-disciplinary training in hydrology, ecology, and atmospheric sciences and prepares the next generation of scientists to tackle complex societal problems such as large scale land cover changes and water resources vulnerability. As a general public outreach, the project leverages recent initiatives at the North Carolina Museum of Natural Sciences that seeks to showcase museums as illuminating the intersection between scientific discovery and advancements in addressing societal problems to the public.