title: Nitrogen deposition effects on Mediterranean-type ecosystems: an ecological assessment.
abstract: We review the ecological consequences of N deposition on the five Mediterranean regions of the world. Seasonality of precipitation and fires regulate the N cycle in these water-limited ecosystems, where dry N deposition dominates. Nitrogen accumulation in soils and on plant surfaces results in peaks of availability with the first winter rains. Decoupling between N flushes and plant demand promotes losses via leaching and gas emissions. Differences in P availability may control the response to N inputs and susceptibility to exotic plant invasion. Invasive grasses accumulate as fuel during the dry season, altering fire regimes. California and the Mediterranean Basin are the most threatened by N deposition; however, there is limited evidence for N deposition impacts outside of California. Consequently, more research is needed to determine critical loads for each region and vegetation type based on the most sensitive elements, such as changes in lichen species composition and N cycling.
authors.affiliation: Department of Plant Physiology and Ecology, Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain. raul.ochoa@ccma.csic.es
authors.forename: Raúl
authors.initials: R
authors.lastname: Ochoa-Hueso
authors.forename: Edith B
authors.initials: EB
authors.lastname: Allen
authors.forename: Cristina
authors.initials: C
authors.lastname: Branquinho
authors.forename: Cristina
authors.initials: C
authors.lastname: Cruz
authors.forename: Teresa
authors.initials: T
authors.lastname: Dias
authors.forename: Mark E
authors.initials: ME
authors.lastname: Fenn
authors.forename: Esteban
authors.initials: E
authors.lastname: Manrique
authors.forename: M Esther
authors.initials: ME
authors.lastname: Pérez-Corona
authors.forename: Lucy J
authors.initials: LJ
authors.lastname: Sheppard
authors.forename: William D
authors.initials: WD
authors.lastname: Stock
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D044822:Biodiversity; D002980:Climate; D017753:Ecosystem; D004784:Environmental Monitoring; D004787:Environmental Pollution / Q000706:statistics & numerical data; D019083:Mediterranean Region; D009584:Nitrogen / Q000032:analysis / Q000633:toxicity*; D058458:Nitrogen Cycle; D012621:Seasons
chemical_list: D000393:Air Pollutants; D009584:Nitrogen