Air warming alters tundra CO{sub 2} flux directly and through changes in plant community composition

Journal Article · Thu Jun 01 04:00:00 EDT 1995 · Bulletin of the Ecological Society of America

OSTI ID:95805

Hobbie, S E; Chapin, III, F S ^[1]

---

1. Univ. of California, Berkeley, CA (United States)

We manipulated air temperature in Alaskan tussock for 3 years to determine the consequences for carbon (C) and nitrogen (N) plots during the growing season increased air temperature by 4{degrees}C, but did not affect soil temperature, moisture, or nutrient availability. Warming stimulated ecosystem CO{sub 2} flux in 2 ways: (1) short term (i.e., daily) variation in air temperature was positively correlated with gross photosynthesis and ecosystem respiration, and (2) at any given temperature, greenhouse-treated plots had higher rates of gross photosynthesis and respiration. Higher gross photosynthesis was associated with increased leaf biomass and N of the dwarf shrub Betula nana. Higher ecosystem respiration was associated with increased root N and a trend toward increased aboveground stem biomass. We estimated that because greenhouses stimulated gross photosynthesis more than they did ecosystem respiration over the growing season, warming should have caused a net sequestration of {approximately}100 g C m{sup -2}, equivalent in magnitude to aboveground net primary production (ANPP) in this ecosystem. Our failure to measure this net sequestration as increased ANPP could have resulted from greenhouse stimulation of early- or late-season respiration when photosynthetic rates were neglible or of root production (not measured). Our results suggest that direct effects of increased air temperature on plant growth and consequent changes in plant community composition may contribute to how arctic ecosystems will feed back to rising concentrations of atmospheric CO{sub 2}.

• OSTI ID: 95805
• Report Number(s): CONF-9507129--
• Journal Information: Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 2 Vol. 76; ISSN BECLAG; ISSN 0012-9623
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AMBIENT TEMPERATURE
CARBON DIOXIDE
CARBON SINKS
CLIMATIC CHANGE
ECOSYSTEMS
NITROGEN
PHOTOSYNTHESIS
PLANT GROWTH
RESPIRATION
SHRUBS
TUNDRA