Dissertation Research: The Functional Significance of Denitrifier Population Diversity to Nitrous Oxide Productionin Terrestrial Ecosystems

小行星9311380 本研究旨在探讨环境因子与硝化细菌多样性对农业与草地生态系统反硝化作用时空变异性的影响。 需要解决的具体问题包括：1）在何种程度上，以及在何种情况下，具有不同氧化亚氮生产潜力的生态系统之间的硝化菌群落组成存在差异？2)来自不同生态系统的净化器产生一氧化二氮的速率不同吗？和3）空间和时间的变化，一氧化二氮的生产反映了差异，在占主导地位的堆肥人口以及差异，在环境控制？ 这些问题将通过从不同的化学条件，影响一氧化二氮通量率，孵化表征一氧化二氮通量率的生态系统土壤采样，和净化隔离表征社区结构。 %%% 反硝化细菌是在厌氧呼吸过程中将植物可利用的氮转化为植物不可利用的气态一氧化二氮的细菌。 因此，除草剂对土壤肥力和植物产量有直接影响。 反硝化作用也很重要，因为一氧化二氮是一种重要的温室气体，也是平衡层臭氧衰减的催化剂。 影响反硝化过程的环境因素已被研究，但它们的相对重要性和特定的反硝化剂种类组成的意义尚不清楚。 本研究将评估环境控制与净化器多样性对氧化亚氮排放速率的相对贡献。 ***

9311380 Robertson This proposal will examine the effect of environmental factors and diversity of denitrifying bacteria on the spatial and temporal variability of denitrification in agricultural and grassland ecosystems. Specific questions to be addressed include 1) to what extent, and under what circumstances, is denitrifier community composition different among ecosystems with different nitrous oxide production potentials?, 2) do denitrifiers from different ecosystems produce nitrous oxide at different rates?, and 3) does spatial and temporal variability in nitrous oxide production reflect differences in dominant denitrifier populations as well as differences in environmental controls? These questions will be addressed by sampling soil from ecosystems that differ in chemical conditions that affect nitrous oxide flux rates, incubating to characterize nitrous oxide flux rates, and denitrifier isolation to characterize community structure. %%% Denitrifiers are bacteria that, during anaerobic respiration, convert nitrogen from a form available to plants to gaseous nitrous oxide not available to plants. Thus, denitrifiers have a direct impact on soil fertility and plant production. Denitrification also is important because the nitrous oxide is an important greenhouse gas and a catalyst of statospheric ozone decay. Environmental factors affecting denitrification processes have been examined, but their relative importances and the significance of particular denitrifier species composition is not known. This study will all evaluation of the relative contributions of environmental controls and denitrifier diversity to nitrous oxide flux rates. ***