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

Manuel Delgado-Baquerizo, Fernando T. Maestre, Antonio Gallardo, David J. Eldridge, Santiago Soliveres, Matthew A. Bowker, Ana Prado-Comesaña, Juan Gaitán, José L. Quero, Victoria Ochoa, Beatriz Gozalo, Miguel García-Gómez, Pablo García-Palacios, Miguel Berdugo, Enrique Valencia, Cristina Escolar, Tulio Arredondo, Claudia Barraza-Zepeda, Bertrand R. Boeken, Donaldo BranOmar Cabrera, José A. Carreira, Mohamed Chaieb, Abel A. Conceição, Mchich Derak, Ricardo Ernst, Carlos I. Espinosa, Adriana Florentino, Gabriel Gatica, Wahida Ghiloufi, Susana Gómez-González, Julio R. Gutiérrez, Rosa M. Hernández, Elisabeth Huber-Sannwald, Mohammad Jankju, Rebecca L. Mau, Maria Miriti, Jorge Monerris, Ernesto Morici, Muchai Muchane, Kamal Naseri, Eduardo Pucheta, Elizabeth Ramírez, David A. Ramírez-Collantes, Roberto L. Romão, Matthew Tighe, Duilio Torres, Cristian Torres-Díaz, James Val, José P. Veiga, Deli Wang, Xia Yuan, Eli Zaady

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)36-45
Number of pages10
JournalGlobal Ecology and Biogeography
Volume25
Issue number1
DOIs
StatePublished - Jan 1 2016

Keywords

  • Aridity
  • Depolymerization
  • Global change
  • Human impacts
  • Mineralization
  • N cycle

ASJC Scopus subject areas

  • Global and Planetary Change
  • Ecology, Evolution, Behavior and Systematics
  • Ecology

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    Delgado-Baquerizo, M., Maestre, F. T., Gallardo, A., Eldridge, D. J., Soliveres, S., Bowker, M. A., Prado-Comesaña, A., Gaitán, J., Quero, J. L., Ochoa, V., Gozalo, B., García-Gómez, M., García-Palacios, P., Berdugo, M., Valencia, E., Escolar, C., Arredondo, T., Barraza-Zepeda, C., Boeken, B. R., ... Zaady, E. (2016). Human impacts and aridity differentially alter soil N availability in drylands worldwide. Global Ecology and Biogeography, 25(1), 36-45. https://doi.org/10.1111/geb.12382