Título:
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Biogeochemical indicators of elevated nitrogen depositionin semiarid Mediterranean ecosystems
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Autores:
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Ochoa-Hueso, Raúl ;
Arróniz-Crespo, María ;
Bowker, Matthew A. ;
Maestre, Fernando T. ;
Pérez Corona, Esther ;
Theobald, Mark R. ;
Vivanco, Marta G. ;
Manrique, Esteban
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Tipo de documento:
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texto impreso
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Editorial:
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Springer Verlag, 2014-09
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Dimensiones:
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application/pdf
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Nota general:
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info:eu-repo/semantics/restrictedAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias Biomédicas: Biología: Ecología
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Tipo = Artículo
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Resumen:
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Nitrogen (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.
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En línea:
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https://eprints.ucm.es/id/eprint/47971/1/Ochoa-Hueso%2C%20R.%20et%20al.%202014.%20Biogeochemical%20indicators%20of%20elevated....pdf
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