RT Journal Article SR 00 ID 10.1016/j.envpol.2013.03.060 A1 Ochoa Hueso, Raúl A1 Maestre, Fernando T. A1 Rios, Asuncion de los A1 Valea, Sergio A1 Theobald, Mark Richard A1 Vivanco, Marta G. A1 Manrique, Esteban A1 Bowker, Mathew A. T1 Nitrogen deposition alters nitrogen cycling and reduces soil carbon content in low-productivity semiarid Mediterranean ecosystems. JF Environmental Pollution YR 2013 FD 2013-08 IS 179 SP 185 OP 193 AB Anthropogenic N deposition poses a threat to European Mediterranean ecosystems. We combined data from an extant N deposition gradient (4.3–7.3 kg N ha−1 yr−1) from semiarid areas of Spain and a field experiment in central Spain to evaluate N deposition effects on soil fertility, function and cyanobacteria community. Soil organic N did not increase along the extant gradient. Nitrogen fixation decreased along existing and experimental N deposition gradients, a result possibly related to compositional shifts in soil cyanobacteria community. Net ammonification and nitrification (which dominated N-mineralization) were reduced and increased, respectively, by N fertilization, suggesting alterations in the N cycle. Soil organic C content, C:N ratios and the activity of β-glucosidase decreased along the extant gradient in most locations. Our results suggest that semiarid soils in low-productivity sites are unable to store additional N inputs, and that are also unable to mitigate increasing C emissions when experiencing increased N deposition. SN 0269-7491 LK https://oa.upm.es/25901/ UL http://www.sciencedirect.com/science/article/pii/S0269749113001930