The strength of the biotic compartment in retaining nitrogen additions prevents nitrogen losses from a Mediterranean maquis

[摘要] Nitrogen (N) is one of the nutrients most limiting to ecosystemproductivity. However, N availability is increasing globally, which mayaffect ecosystem functions and stability. To understand the role of eachecosystem compartment in the cycling of increased N, we studied the initialresponse of a nutrient-poor ecosystem, a Mediterranean maquis, to increasedN deposition. N availability (dose and form) was modified by three Nadditions over the year (middle autumn/winter, spring and summer). Soilinorganic N pools (nitrate in particular) strongly reflected the N additionsin autumn, almost matching the total N added over the three additions.Cistus ladanifer, the dominant plant species, responded to the increased N (cover and Nconcentration in leaves and litter). Given that leaf shedding occurs in thesummer, the importance of this N pool returning to the soil through litterdecomposition on the total soil inorganic N in autumn was investigated. Datasuggest that living plants and litter have a crucial role in preventing Nlosses from Mediterranean maquis. This is the first integrated field studyon how European Mediterranean ecosystems retain increased N of differentforms and doses, however longer-term studies are needed to explore thegenerality of this study's observations.

[学科分类] 地球化学与岩石