ABR: Experimental Comparison of Ecosystem Process Limitations Between Grasslands Dominated by Large Mammalian Ungulates

9312435 McNaughton本项目将包括在支持丰富的本地有蹄类动物种群的放牧生态系统中通过营养物控制生态系统过程（强调初级生产力、食草动物和次级生产力的消耗、与植物和食草动物营养相关的植物矿物质吸收以及土壤矿化率）的实验研究，强调但不限于氮。 研究地点将在坦桑尼亚的塞伦盖蒂国家公园和黄石国家公园，USA. 试验将测量（1）使生态系统过程饱和所需的氮水平，（2）少量多次施氮的相对效果（可能由慢性空气污染引起）与相当于尿液剂量的单次较大剂量应用相比（一种自然循环途径），（3）氮肥可能导致其他养分缺乏，如初级生产力、微生物活性，或饲料作为有蹄类动物营养源的特性，以及（4）随着大气CO2浓度的增加，必然会出现碳富集的影响。 这些研究将有助于在两大洲和根本不同的气候在本地放牧生态系统的承载能力的定量了解，增加我们的理解，适当的保护战略，支持丰富的有蹄类动物种群的生态系统，并提供有关两个组成部分的信息，如果全球变化（慢性营养富集空气污染，碳富集）在生态系统中支持大型放牧哺乳动物。

9312435 McNaughton This project will consist of experimental studies of the control of ecosystem processes (emphasizing primary productivity, consumption by grazers and secondary productivity, plant mineral uptake as related to plant and herbivore nutrition, and soil mineralization rates) by nutrients, emphasizing, but not restricted to, nitrogen, in grazing ecosystems supporting abundant native ungulate populations. Study sites will be in Serengeti National Park, Tanzania, and Yellowstone N.P., USA. experiments will measure (1) the level of N required to saturate ecosystem processes, (2) the relative effect of small, multiple N applications (as might result from chronic air pollution) compared to a single, larger application equivalent to a urine dose (a natural recycling pathway), (3) the potential for N fertilization to induce deficiencies of other nutrients, as expressed in primary productivity, microbial activity, or properties of forages as an ungulate nutrient source, and (4) the effect of carbon enrichment, which will surely occur as atmospheric CO2 enrichment proceeds. These studies will contribute to a quantitative understanding of carrying capacity in native grazing ecosystems on two continents and in radically different climates, add to our understanding of the appropriate conservation strategies in ecosystems supporting abundant ungulate populations, and provide information about two components if global change (chronic nutrient enrichment from air pollution, and carbon enrichment) in ecosystems supporting large grazing mammals.