Plant-Microbe Interactions and the Production of Dissolved Organic Carbon and Nitrogen

摘要：植物与微生物的相互作用与溶解有机碳和氮的产生陆地生态系统的氮(N)饱和度是当代最重要的生态学问题之一。密歇根理工大学和密歇根大学的研究人员正在向密歇根州北部的阔叶林中添加硝酸盐（NO3-），以了解这种常见的森林类型对长期N添加的反应。6年后，各种变化表明，长期氮添加改变了生态系统过程。这些包括溶解有机碳、溶解有机氮和硝酸盐的更大的淋失，以及土壤呼吸作用的减少。在接下来的三年里，研究小组将继续添加硝酸盐，以了解这些变化背后的具体机制，并确定它们是否会随着时间的推移而持续存在，或者它们只是暂时的反应，会随着生态系统适应更高水平的N可用性而逐渐消失。如果这些变化持续或扩大，它们可能对这种广泛分布的森林类型产生深远的影响。

Abstract00-75397PregitzerPlant-microbe interactions and the production of dissolved organic carbon and nitrogenNitrogen (N) saturation of terrestrial ecosystems is one of the most important contemporary ecological issues. Researchers at Michigan Technological University and the University of Michigan are adding nitrate (NO3-) to northern hardwood forests in Michigan to learn how this common forest type responds to chronic N additions. After six years, a variety of changes indicate chronic N additions have altered ecosystem processes. These include much greater leaching losses of dissolved organic carbon, dissolved organic nitrogen and nitrate, and reduced soil respiration. Over the next three years the research team will continue the nitrate additions in order to learn the specific mechanisms behind these changes and to determine if they will persist over time or if they are only temporary responses that will fade as the ecosystems adjust to higher levels of N availability. If the changes persist or magnify, they could have profound effects on this widely-distributed forest type.