Ochoa-Hueso, RaúlArróniz-Crespo, MaríaBowker, Matthew A.Maestre, Fernando T.Pérez Corona, EstherTheobald, Mark R.Vivanco, Marta G.Manrique, Esteban2023-06-192023-06-192014-090167-6369, ESSN: 1573-295910.1007/s10661-014-3822-6https://hdl.handle.net/20.500.14352/35649Nitrogen (N) deposition has doubled the natural N inputs received by ecosystems through biological N fixation and is currently a global problem that is affecting the Mediterranean regions. We evaluated the existing relationships between increased atmospheric N deposition and biogeochemical indicators related to soil chemical factors and cryptogam species across semiarid central, southern, and eastern Spain. The cryptogam species studied were the biocrust-forming species Pleurochaete squarrosa (moss) and Cladonia foliacea (lichen). Sampling sites were chosen in Quercus coccifera (kermes oak) shrublands and Pinus halepensis (Aleppo pine) forests to cover a range of inorganic N deposition representative of the levels found in the Iberian Peninsula (between 4.4 and 8.1 kg N ha−1 year−1 ). We extended the ambient N deposition gradient by including experimental plots to which N had been added for 3 years at rates of 10, 20, and 50 kg N ha−1 year−1 . Overall, N deposition (extant plus simulated) increased soil inorganic N availability and caused soil acidification. Nitrogen deposition increased phosphomonoesterase (PME) enzyme activity and PME/nitrate reductase (NR) ratio in both species, whereas the NR activity was reduced only in the moss. Responses of PME and NR activities were attributed to an induced N to phosphorus imbalance and to N saturation, respectively. When only considering the ambient N deposition, soil organic C and N contents were positively related to N deposition, a response driven by pine forests. The PME/NR ratios of the moss were better predictors of N deposition rates than PME or NR activities alone in shrublands, whereas no correlation between N deposition and the lichen physiology was observed. We conclude that integrative physiological measurements, such as PME/NR ratios, measured on sensitive species such as P. squarrosa, can provide useful data for national-scale biomonitoring programs, whereas soil acidification and soil C and N storage could be useful as additional corroborating ecosystem indicators of chronic N pollution.engBiogeochemical indicators of elevated nitrogen deposition in semiarid Mediterranean ecosystemsjournal articlehttps://link.springer.com/article/10.1007/s10661-014-3822-6restricted access574.3(460)AcidificationBiocrustsBioindicatorsC and N storageCryptogamsN depositionNitrate reductasePhosphomonoesteraseSemiarid MediterraneanEcología (Biología)2401.06 Ecología animal