Human impacts and aridity differentially alter soil N availability in drylands worldwide

摘要: Aims Climate and human impacts are changing the nitrogen (N) inputs losses in terrestrial ecosystems. However, it is largely unknown how these two major drivers of global change will simultaneously influence N cycle drylands, largest biome on planet. We conducted a observational study to evaluate aridity impacts, together with biotic abiotic factors, affect key soil variables cycle. Location Two hundred twenty-four dryland sites from all continents except Antarctica widely differing their environmental conditions influence. Methods Using standardized field survey, we measured aridity, (i.e. proxies land uses air pollution), biophysical pH texture total plant cover) six important related cycling soils: N, organic ammonium, nitrate, dissolved organic:inorganic mineralization rates. used structural equation modelling assess direct indirect effects cycle. Results Human increased concentration while reduced it. The were spatially disconnected, which may favour scarcity most arid areas promote its accumulation least areas. Main conclusions We found that increasing anthropogenic pressure disconnected drylands. This implies places low high impact accumulate lowest lose N. Our analyses also provide evidence both enhance relative dominance inorganic soils, having negative functions services provided by