Journal
ECOLOGY
Volume 90, Issue 10, Pages 2700-2710Publisher
WILEY
DOI: 10.1890/08-2026.1
Keywords
carbohydrate; carbon; China; climate warming; ecosystem; photosynthesis; respiration; temperate steppe; temperature
Categories
Funding
- National Natural Science Foundation of China [90511006, 30590382, 30821062]
- Ministry of Science and Technology of China [2007CB106803]
- Chinese Academy of Sciences (Hundred Talents Program)
- State Key Laboratory of Vegetation and Environmental Change
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A mechanistic understanding of the carbon (C) cycle-climate change feedback is essential for projecting future states of climate and ecosystems. Here we report a novel field mechanism and evidence supporting the hypothesis that nocturnal warming in a temperate steppe ecosystem in northern China can result in a minor C sink instead of a C source as models have predicted. Nocturnal warming increased leaf respiration of two dominant grass species by 36.3%, enhanced consumption of carbohydrates in the leaves (72.2% and 60.5% for sugar and starch, respectively), and consequently stimulated plant photosynthesis by 19.8% in the subsequent days. Our experimental findings confirm previous observations of nocturnal warming stimulating plant photosynthesis through increased draw-down of leaf carbohydrates at night. The enhancement of plant photosynthesis overcompensated the increased C loss via plant respiration under nocturnal warming and shifted the steppe ecosystem from a minor C source (1.87 g C.m(-2).yr(-1)) to a C sink (21.72 g C.m(-2).yr(-1)) across the three growing seasons from 2006 to 2008. Given greater increases in daily minimum than maximum temperature in many regions, plant photosynthetic overcompensation may partially serve as a negative feedback mechanism for terrestrial biosphere to climate warming.
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