LTER: The Arctic LTER Project: The Future Characteristics of Arctic Communities, Ecosystems, and Landscapes

9810222 Hobbie北极LTER站点位于阿拉斯加州布鲁克斯山脉的北方山麓，苔原植被为莎草和草，混有矮桦树和矮柳树。该遗址的苔原、溪流和湖泊5,000多年来一直未受干扰。这允许分析该生态系统中植物和动物之间的关系，该生态系统不受人类使用的生态遗产的影响。与这种生态稳定性形成对比的是，在过去的30年里，阿拉斯加北方的气候发生了剧烈的变化。该地区的气温每十年上升0.5摄氏度以上。没有人知道这种变暖是否是GCM模型预测的3-5度变化的一部分，但已知北极的其他地区要么没有变化，要么变得更冷。根据几种类型的观察，似乎有一个生物反应，这种区域变暖。该LTER项目的目标是预测该地点未来的生态特征。这种预测是基于对生态系统结构和功能的控制的认识，这些控制是由物理环境和地质因素、气候因素、生物因素以及水和物质从陆地到水的通量变化所施加的。 长期研究的基本思路是：（1）长期监测和调查生态系统特征在时空上的自然变化。这将包括对气候、苔原植物群落和生产力、解冻深度、溪流流量、溪流化学、湖泊温度、湖泊化学、湖泊生产力以及浮游动物和鱼类丰度等变量进行例行监测。(2)与博南扎河LTER计划合作进行的南北区域样带。(3)对生态系统进行实验性操作，并对其进行数十年的维护和测量。这些实验包括苔原变暖、遮蔽和覆盖、排除大型食草动物、湖泊和溪流施肥以及捕食者的增加和减少。(4)综合和建模工作。 总的来说，这项研究将增加我们对生态系统对人类引起的全球环境变化的反应的基本理解。此外，这些分析将有助于生态学中的理论问题，包括与干扰，资源可用性，自上而下与自下而上控制社区以及生态系统结构和功能有关的问题。

9810222HobbieThe Arctic LTER site is located in the northern foothills of the Brooks Range, Alaska, in tundra vegetation of sedges and grasses mixed with dwarf birch and low willows. The tundra, streams and lakes at the site have been undisturbed and unchanged for more than 5,000 years. This allows the analysis of relationships among plants and animals in this ecosystem which is unaffected by an ecological legacy of human use. In contrast to this ecological stability, the climate of northern Alaska has changed remarkablyover the past 30 years. The temperature of the region has increased by more than 0.5oC per decade. No one knows if this warming is a part of the 3-5 degree change predicted by GCM models but it is known that other areas of the Arctic have either not changed or have become colder. Based on several types of observations, there appears to be a biotic response to this regional warming. The goal of this LTER project is to predict the future ecological characteristics of the site. This prediction is based on knowledge of the controls of ecosystem structure and function as exerted by physical setting and geologic factors, climatic factors, biotic factors, and the changes in fluxes of water and materials from land to water. The long-term research is based on the following approaches: (1) Long-term monitoring and surveys of natural variation of ecosystem characteristics in space and time. This will include routine monitoring of variables, such as climate, tundra plant communities and productivity, thaw depth, stream flow, stream chemistry, lake temperatures, lake chemistry, lake productivity and the abundance of zooplankton and fish. (2) A north-south regional transect in cooperation with the Bonanza Creek LTER program. (3) Experimental manipulations of ecosystems which are maintained and measured for decades. These experiments include tundra warming, shading and fertilizing, the exclusion of large herbivores, fertilization of lakes and streams, and the addition and removal of predators. (4) Synthesis and modeling efforts. Overall, this research will add to our basic understanding of the response of ecosystems to human induced global environmental change. In addition, these analyses will contribute to theoretical questions in ecology, including issues related to disturbances, resource availability, top-down vs. bottom-up controls on communities, and ecosystem structure and function.