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Drought alters carbon fluxes in alpine snowbed ecosystems through contrasting impacts on graminoids and forbs
Author(s) -
Johnson David,
Vachon Jérémie,
Britton Andrea J.,
Helliwell Rachel C.
Publication year - 2011
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2010.03613.x
Subject(s) - graminoid , forb , ecosystem , biomass (ecology) , environmental science , dissolved organic carbon , agronomy , ecology , biology , grassland
Summary• Climate change is predicted to increase the frequency of drought events in alpine ecosystems with the potential to affect carbon turnover. • We removed intact turfs from a Nardus stricta alpine snowbed community and subjected half of them to two drought events of 8 d duration under controlled conditions. Leachate dissolved organic carbon (DOC) was measured throughout the 6 wk study period, and a 13 CO 2 pulse enabled quantification of fluxes of recent assimilate into shoots, roots and leachate and ecosystem CO 2 exchange. • The amount of DOC in leachate from droughted cores was 62% less than in controls. Drought reduced graminoid biomass, increased forb biomass, had no effect on bryophytes, and led to an overall decrease in total above‐ground biomass compared with controls. Net CO 2 exchange, gross photosynthesis and the amount of 13 CO 2 fixed were all significantly less in droughted turfs. These turfs also retained proportionally more 13 C in shoots, allocated less 13 C to roots, and the amount of dissolved organic 13 C recovered in leachate was 57% less than in controls. • Our data show that drought events can have significant impacts on ecosystem carbon fluxes, and that the principal mechanism behind this is probably changes in the relative abundance of forbs and grasses.