Niche Differentiation of Ammonia-Oxidizing Microbial Communities in Arid Land Soils

摘要: Human activity has increased loading of reactive nitrogen (N) in the environment, with important and often deleterious impacts on biodiversity, climate, human health. Since fate N ecosystem is mainly controlled by microorganisms, understanding factors that shape microbial communities becomes relevant urgent. In arid land soils, these microbial communities are not well understood. I aimed to study role cycling microbes, such as the ammonia-oxidizing bacteria (AOB), recently discovered ammonia-oxidizing archaea (AOA), various fungal groups, in soils lands. also tested if niche differentiation among microbial populations a driver differential biogeochemical outcomes. found microbial arid lands structured by environmental to stronger degree than what generally observed mesic systems. For example, in biological soil crusts, temperature selected for AOA warmer deserts AOB colder deserts. Land-use change affects niche differentiation, fungi being major agents N2O production natural lands, whereas emissions could be attributed urban lawns. By contrast, NO3- production native desert managed soils was mainly controlled autotrophic microbes (i.e., AOA) rather than by heterotrophic fungi. determine AOA surprisingly responded positively inorganic availability in both short (one month) long-term (seven years) experimental manipulations an soil, while N enrichment other types known favor over AOA. This work improves our predictions response to anthropogenic increase shows paradigms derived from mesic systems always applicable My dissertation highlights unique ecology ammonia oxidizers draws attention importance in desert soils.