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

• Published in: Global Ecology and Biogeography
• Main Authors: MANUEL DELGADO-BAQUERIZO, Fernando T Maestre, Antonio Gallardo, David Eldridge, Santiago Soliveres Codina, Matthew Bowker, Ana Prado Comesana, juan gaitan, Jose Luis Quero Pérez, Victoria Ochoa, Beatriz Gozalo, Miguel García Gómez, Pablo Garcia-Palacios, Miguel Berdugo, Enrique Valencia, Cristina Escolar, JOSE TULIO ARREDONDO MORENO, Claudia Elizabeth Barraza Zepeda, Bertrand R. Boeken, Donaldo Bran, Omar Cabrera, JOSÉ ANTONIO CARREIRA DE LA FUENTE, Mohamed Chaieb, Abel Conceição, Mchich Derak, Ricardo Ernst, Carlos Ivan Espinosa, Adriana Florentino de Andreu, Gabriel M. Gatica, Ghiloufi Wahida, Susana Gómez-González, Julio Roberto Gutiérrez Camus, Rosa Mary Hernández, Elisabeth Huber Sannwald, Mohammad Jankju, Rebecca L. Mau, Maria N. Miriti, Jorge Monerris, Ernesto F.A. Morici, Muchane Muchai, Kamal Naseri, Eduardo Pucheta, Elizabeth del Carmen Ramírez-Iglesias, David Ramirez, Roberto Lisboa Romao, Matthew Tighe, Duilio Gilberto Torres, Cristian Torres Díaz, James Val, José Pablo Veiga, Deli Wang, Xia Yuan, Eli Zaady
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley 2016
• Subjects: info:eu-repo/classification/Autor/Aridity; info:eu-repo/classification/Autor/Depolymerization; info:eu-repo/classification/Autor/Global change; info:eu-repo/classification/Autor/Human impacts; info:eu-repo/classification/Autor/Mineralization; info:eu-repo/classification/Autor/N cycle; info:eu-repo/classification/cti/1; info:eu-repo/classification/cti/25; info:eu-repo/classification/cti/2505; info:eu-repo/classification/cti/250507; Antarc*; Antarctica
• Online Access: http://ipicyt.repositorioinstitucional.mx/jspui/handle/1010/2083

"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, which may 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 inorganic N in dryland soils, having a negative impact on key functions and services provided by these ecosystems."