DISSERTATION RESEARCH: Modeling the effects of invasive earthworms on watershed nitrogen dynamics

在美国常见的大多数蚯蚓都是非本土的，起源于欧洲，通过人类活动传播到美国及其周围。尽管这些入侵的蚯蚓在农田和花园中被认为是有益的，但它们正在破坏落叶森林。蚯蚓以落叶为食，可以在不到一年的时间里清除整个秋天的落叶。如果没有保护层，裸露的森林土壤容易受到侵蚀、幼苗死亡和养分流失。在被蚯蚓入侵的土壤中，雨水可以迅速将矿物质营养从植物根部输送到附近的溪流或湖泊中。密西西比州卡拉马祖河流域的空间数学模型将用于研究森林和农田中的蚯蚓如何增加河流生态系统中的氮素含量。陆地和水生生态系统的氮素污染是当前非常关注的问题。从陆地向河流和湖泊输送的氮污染了这些水体，并被认为是造成墨西哥湾“死亡区”的罪魁祸首。人们正在使用许多策略，如植被缓冲带，在氮素污染水道之前将其去除，但蚯蚓可能会阻碍植物去除氮素的能力。入侵的蚯蚓不断被作为鱼饵、盆栽植物和卡车轮胎运送到新的地区。一旦蚯蚓入侵，它们几乎不可能被清除。一个蚯蚓入侵的数学模型将被用来突出应该设法减缓氮素损失的景观区域。这项研究将提供土地管理者控制蚯蚓所需的战略，从而保护森林和水生栖息地。

Most of the earthworms commonly found in the U.S. are non-native, originating in Europe and transported to and around the U.S. by human activities. Although viewed as beneficial in farm fields and gardens, these invasive earthworms are damaging deciduous forests. Earthworms feed on fallen leaves, and can remove an entire autumn's leaf fall in less than one year. Without a protective leaf layer, exposed forest soils are subject to erosion, seedling death, and nutrient loss. In soils invaded by earthworms, rainwater can rapidly transport mineral nutrients away from plant roots and into nearby streams or lakes. A spatial, mathematical model of the Kalamazoo River, MI, watershed will be used to study how earthworms in forests and farm fields increase the amount of nitrogen in river ecosystems.Nitrogen pollution of terrestrial and aquatic ecosystems is of great current concern. Nitrogen transported from land to streams and lakes pollutes those water bodies and has been implicated in causing the "dead zone" in the Gulf of Mexico. Many strategies, such as vegetation buffer strips, are being used to remove nitrogen before it can pollute waterways, yet earthworms may be hindering the ability of plants to remove nitrogen. Invasive earthworms are continually being transported to new areas as fishing bait, in potted plants, and on truck tires. Once earthworms invade, they are nearly impossible to remove. A mathematical model of earthworm invasion will be used to highlight areas of the landscape that should be managed to slow the loss of nitrogen. This study will provide strategies needed by land managers to control earthworms and thereby protect forests and aquatic habitats.