Microbial dynamics in the nitrogen cycle of arid, urban soils: shifts in community composition and rates of ammonia oxidation
Microorganisms play a key role in cycling nutrients in soil, yet their significance is greatly underappreciated in desert environments. Nitrifier microbes perform nitrification, the conversion of ammonium (NH4+) to the more mobile nitrate (NO3-), resulting in a disservice to society by increasing NO3- load into groundwater. In contrast, some microbes are beneficial by removing NO3- or transforming nitrogen (N) compounds into usable forms for plants. Overall, microbes are vital in controlling the availability of N for plants, directly and indirectly affecting ecosystem services. The scientific community is only beginning to value the contribution of different types of microbes in nutrient cycling. However, there is a lack of knowledge about which microbes control N cycling in deserts, despite the vast distribution of arid and semi-arid ecosystems in the world. Arid and semi-arid lands are expected to continue experiencing high rates of land-use change associated with urban development, including intensive and regular use of water and fertilizers in agriculture, grassy lawns, and residential areas. Additionally, it is unclear how the structure and function of microbial communities shift in response to altered N loads. The aim of my research is to identify these microbes and describe the dynamics between microbial community composition and N cycling in response to changes in desert soils.