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Impacts of chronic N input on the carbon and nitrogen storage of a postfire Mediterranean‐type shrubland
Author(s) -
Vourlitis George L.,
Hentz Cloe S.
Publication year - 2016
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2015jg003220
Subject(s) - chaparral , leaching (pedology) , shrubland , environmental science , nutrient , deposition (geology) , nitrogen , mediterranean climate , soil carbon , agronomy , chemistry , soil water , ecology , ecosystem , soil science , biology , paleontology , organic chemistry , sediment
Mediterranean‐type shrublands are subject to periodic fire and high levels of nitrogen (N) deposition, but little is known how chronic N deposition affects carbon (C) and N storage during succession. We conducted a long‐term experiment in Californian chaparral to test the hypothesis that chronic N enrichment would increase postfire C and N accumulation. The experimental layout consisted of a randomized design where four 10 × 10 m plots received 5 g N m −2 annually since 2003 and four 10 × 10 m plots served as controls. Aboveground and belowground C and N pools and fluxes were measured seasonally (every 3 months) for a period of 10 years. Added N rapidly increased soil extractable N pools and decreased soil pH; however, total soil C and N storage were not affected. Added N plots initially had significantly lower C and N storage than control plots, presumably because of nutrient losses from leaching and/or higher belowground C allocation. However, rates of aboveground N and C storage became significantly higher in added N plots after 4–5 years of exposure, thus increasing fuel buildup, which has implications for future fire intensity. This recovering chaparral stand is not yet “N saturated” after 10 years of chronic N input. However, N leaching continues to be higher in added N plots, indicating that postfire chaparral stands in high‐N deposition areas can be important sources of N to groundwater/aquatic systems even if productivity is stimulated by N input.