期刊
NEW PHYTOLOGIST
卷 197, 期 4, 页码 1142-1151出版社
WILEY
DOI: 10.1111/nph.12102
关键词
biosphereatmosphere feedbacks; carbon starvation; drought impacts; global change; hydraulic failure; mortality mechanism; nonstructural carbohydrates (NSCs); tree mortality
资金
- Philecology Foundation
- US Department of Agriculture Cooperative State Research Education and Extension Service [2005-38420-15809]
- US Department of Energy National Institute for Climate Change Research Grant [DE-FC02-06ER64159]
- US National Science Foundation [DEB-043526, EAR-0724985, EPScoR 0814387]
- STAR Fellowship [FP-91717801-0]
- US Environmental Protection Agency (EPA)
- Division Of Earth Sciences
- Directorate For Geosciences [0724958] Funding Source: National Science Foundation
Vegetation change is expected with global climate change, potentially altering ecosystem function and climate feedbacks. However, causes of plant mortality, which are central to vegetation change, are understudied, and physiological mechanisms remain unclear, particularly the roles of carbon metabolism and xylem function. We report analysis of foliar nonstructural carbohydrates (NSCs) and associated physiology from a previous experiment where earlier drought-induced mortality of Pinus edulis at elevated temperatures was associated with greater cumulative respiration. Here, we predicted faster NSC decline for warmed trees than for ambient-temperature trees. Foliar NSC in droughted trees declined by 30% through mortality and was lower than in watered controls. NSC decline resulted primarily from decreased sugar concentrations. Starch initially declined, and then increased above pre-drought concentrations before mortality. Although temperature did not affect NSC and sugar, starch concentrations ceased declining and increased earlier with higher temperatures. Reduced foliar NSC during lethal drought indicates a carbon metabolism role in mortality mechanism. Although carbohydrates were not completely exhausted at mortality, temperature differences in starch accumulation timing suggest that carbon metabolism changes are associated with time to death. Drought mortality appears to be related to temperature-dependent carbon dynamics concurrent with increasing hydraulic stress in P.edulis and potentially other similar species.
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