Cross-Site: Collaborative Research: Mycorrhizal Responses to Nitrogen Eutrophication at Five Mesic to Semiarid Sites

跨站点：合作研究：五个中等到半干旱地区菌根对氮富营养化的反应

• 批准号: 9526564
• 负责人: Edith Allen
• 金额: $ 11.48万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-02-01 至 2000-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9526564&HistoricalAwards=false
• 关键词: Cross; Site; Collaborative; Research; Mycorrhizal

9526564 Allen Although nitrogen is frequently the most limiting nutrient in ecosystems, continuous, elevated inputs of nitrogen may cause significant ecosystem stress. Deposition of anthropogenic nitrogen has been associated with recent losses of plant as well as fungal diversity throughout Europe. Little is known about the effects of atmospheric nitrogen deposition on the structure and function of North American grasslands and shrublands, although as much as 30 kg nitrogen per hectare per year is deposited in southern California, with lesser amounts elsewhere in the US. The three principal objectives of this research will be to (1) assess species composition changes of fungi during nitrogen eutrophication in mesic to semiarid grasslands using microscopy and immunoflourescence, (2) assess the kinds of mycorrhizal fungi under nitrogen eutrophication to indicate the mutualistic or parasitic effects of fungi, and (3) conduct bioassays to determine whether inferior mutualists predominate after nitrogen eutrophication. This study will examine the effects of nitrogen eutrophication on mycorrhizae at four experimental grasslands within the Long-term Ecological Research network and at a shrub-grasslands in southern California. These grasslands in Michigan, Minnesota, Kansas, New Mexico, and California form a precipitation and fertility gradient. The effects of nitrogen euthrophication will be studied on plants, mycorrhizal fungi and soils in experiments that have previously been established and in new plots at these sites. This research is designed to assess the ranges and variances of mycorrhizal responses to nitrogen at three scales: at individual plant-root interfaces, within grasslands communities, and across a climatic and soil gradient. This is a first step toward assessing the potential effects of nitrogen eutrophication on the structure and functioning of mycorrhizae-plant interactions in grasslands in the US. This research is important because grasslands are the basis for range re sources and beef production in North America.

9526564 Allen 虽然氮通常是生态系统中最受限制的养分，但持续、增加的氮输入可能会导致严重的生态系统压力。 人为氮的沉积与最近整个欧洲植物和真菌多样性的丧失有关。 尽管南加州每年每公顷氮沉积量高达 30 公斤，而美国其他地方的氮沉积量较少，但人们对大气氮沉积对北美草原和灌木丛的结构和功能的影响知之甚少。 本研究的三个主要目标是（1）利用显微镜和免疫荧光评估中湿至半干旱草原氮富营养化期间真菌的物种组成变化，（2）评估氮富营养化下菌根真菌的种类以指示互利或寄生真菌的影响，以及（3）进行生物测定以确定氮富营养化后劣质共生体是否占主导地位。 这项研究将研究长期生态研究网络内的四个实验草地和南加州灌木草地的氮富营养化对菌根的影响。 密歇根州、明尼苏达州、堪萨斯州、新墨西哥州和加利福尼亚州的这些草原形成了降水和肥力梯度。 将在先前建立的实验和这些地点的新地块中研究氮富营养化对植物、菌根真菌和土壤的影响。 这项研究旨在评估三个尺度上菌根对氮的反应的范围和差异：单个植物根界面、草原群落内以及跨气候和土壤梯度。 这是评估氮富营养化对美国草原菌根-植物相互作用的结构和功能的潜在影响的第一步。 这项研究很重要，因为草原是北美牧场资源和牛肉生产的基础。