In wetland ecosystems, ammonia oxidation highly depends on the activity of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), which are, therefore, important for studying nitrogen cycling. However, the ammonia-oxidizer communities in the typical high-elevation wetlands are poorly understood. Here, we examined ammonia-oxidizer communities in soils from three wetland types and 31 wetland sites across the Qinghai–Tibetan Plateau. The amoA gene of AOA and AOB was widespread across all wetland types. Nitrososphaera clade (Group I.1b) overwhelmingly dominated in AOA community (90.36%), while Nitrosospira was the principal AOB type (64.96%). The average abundances of AOA and AOB were 2.63 × 104 copies g−1 and 9.73 × 103 copies g−1. The abundance of AOA amoA gene was higher in riverine and lacustrine wetlands, while AOB amoA gene dominated in palustrine wetlands. The environmental conditions, but not spatial distance, have a dominant role in shaping the pattern of ammonia-oxidizer communities. The AOA community composition was influenced by mean annual temperature (MAT) and mean annual precipitation (MAP), while MAT, conductivity and plant richness, pH, and TN influenced the AOB community composition. The net nitrification rate had a significant correlation to AOB, but not AOA abundance. Our results suggest a dominant role for climate factors (MAT and MAP) in shaping community composition across a wide variety of wetland sites and conditions.

Unravelling the patterns, potential processes and mechanisms underlying biodiversity has always been a crucial issue in community ecology. It is also a necessary first step for any conservation and restoration to better adapt fragile ecosystems to a changing climate. However, little is known regarding the structure and maintenance of plant communities in typical high-altitude wetlands. Here, we made a comprehensive analysis of the diversity and composition of wetland plant communities based on the distribution of plants near the shorelines of 19 lakes across the Qinghai-Tibetan Plateau. The latitude, mean annual temperature (MAT) and mean annual precipitation (MAP), along with the edaphic properties, were the dominant predictors affecting the taxonomic and phylogenetic α-diversity. Besides diversification, ecological drift, mixing with weak dispersal and weak selection shaped the community composition of wetland plants in our study. The latitude and MAP predictors, although modest, showed an impact on the community structure.