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

FERNANDO T. MAESTRE; SANTIAGO SOLIVERES; JUAN GAITÁN; BEATRIZ GOZALO; MIGUEL BERDUGO; TULIO ARREDONDO; DONALDO BRAN; MOHAMED CHAIEB; CARLOS I. ESPINOSA; WAHIDA GHILOUFI; ROSA M. HERNÁNDEZ; REBECCA L. MAU; ERNESTO MORICI; EDUARDO PUCHETA; ROBERTO ROMÃO; CRISTIAN TORRES-DÍAZ; DELI WANG; ANTONIO GALLARDO; MATTHEW A. BOWKER; JOSÉ L. QUERO; MIGUEL GARCÍA-GÓMEZ; ENRIQUE VALENCIA; CLAUDIA BARRAZA-CEPEDA; OMAR CABRERA; ABEL A. CONCEIÇÃO; ADRIANA FLORENTINO; SUSANA GÓMEZ-GONZÁLEZ; ELISABETH HUBER-SANNWALD; MARIA MIRITI; MUCHAI MUCHANE; ELIZABETH RAMÍREZ; MATTHEW TIGHE; JAMES VAL; XIA JUAN; MANUEL DELGADO-BAQUERIZO; DAVID J. ELDRIDGE; ANA PRADO-COMESAÑA; VICTORIA OCHOA; PABLO GARCÍA-PALACIOS; CRISTINA ESCOLAR; BERTRAND R. BOEKEN; JOSÉ A. CARREIRA; MCHICH DERAK; GABRIEL GATICA; JULIO R. GUTIÉRREZ; MOHAMMAD JANKJU; JORGE MONERRIS; KAMAL NASERI; DAVID A. RAMÍREZ-COLLANTES; DUILIO TORRES; JOSÉ P. VEIGA; ELI ZAADY

Global Ecology and Biogeography

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 24 p. 1 - 8

1466-822X

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