期刊
GLOBAL CHANGE BIOLOGY
卷 15, 期 10, 页码 2493-2502出版社
WILEY
DOI: 10.1111/j.1365-2486.2009.01970.x
关键词
biomass production; Carex curta; Carex decidua; decomposition; Dendrobaena octaedra; earthworms; ecosystem functioning; global change; global warming; ozone depletion; soil heterotrophs
资金
- NSF/DOE/NASA/USDA/EPA/NOAA
- United States National Science Foundation [IBN 9524144, IBN 9814357]
- CONICET
- InterAmerican Institute for Global Change Research
- USDA/CREES [2008-34263-19485]
Combined effects of co-occurring global climate changes on ecosystem responses are generally poorly understood. Here, we present results from a 2-year field experiment in a Carex fen ecosystem on the southernmost tip of South America, where we examined the effects of solar ultraviolet B (UVB, 280-315 nm) and warming on above- and belowground plant production, C : N ratios, decomposition rates and earthworm population sizes. Solar UVB radiation was manipulated using transparent plastic filter films to create a near-ambient (90% of ambient UVB) or a reduced solar UVB treatment (15% of ambient UVB). The warming treatment was imposed passively by wrapping the same filter material around the plots resulting in a mean air and soil temperature increase of about 1.2 degrees C. Aboveground plant production was not affected by warming, and marginally reduced at near-ambient UVB only in the second season. Aboveground plant biomass also tended to have a lower C : N ratio under near-ambient UVB and was differently affected at the two temperatures (marginal UVB x temperature interaction). Leaf decomposition of one dominant sedge species (Carex curta) tended to be faster at near-ambient UVB than at reduced UVB. Leaf decomposition of a codominant species (Carex decidua) was significantly faster at near-ambient UVB; root decomposition of this species tended to be lower at increased temperature and interacted with UVB. We found, for the first time in a field experiment that epigeic earthworm density and biomass was 36% decreased by warming but remained unaffected by UVB radiation. Our results show that present-day solar UVB radiation and modest warming can adversely affect ecosystem functioning and engineers of this fen. However, results on plant biomass production also showed that treatment manipulations of co-occurring global change factors can be overridden by the local climatic situation in a given study year.
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