Details

Autor(en) / Beteiligte

• Oberbauer, Steven F
• Tweedie, Craig E
• Welker, Jeff M
• Fahnestock, Jace T

Titel

TUNDRA CO^sub 2^ FLUXES IN RESPONSE TO EXPERIMENTAL WARMING ACROSS LATITUDINAL AND MOISTURE GRADIENTS

Ist Teil von

• Ecological monographs, 2007-05, Vol.77 (2), p.221

Ort / Verlag

Durham: Ecological Society of America

Erscheinungsjahr

2007

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• Climate warming is expected to differentially affect ... exchange of the diverse ecosystems in the Arctic. Quantifying responses of ... exchange to warming in these ecosystems will require coordinated experimentation using standard temperature manipulations and measurements. Here, we used the International Tundra Experiment (ITEX) standard warming treatment to determine ... flux responses to growing-season warming for ecosystems spanning natural temperature and moisture ranges across the Arctic biome. We used the four North American Arctic ITEX sites (Toolik Lake, Atqasuk, and Barrow [USA] and Alexandra Fiord [Canada]) that span 10... of latitude. At each site, we investigated the ... responses to warming in both dry and wet or moist ecosystems. Net ecosystem ... exchange (NEE), ecosystem respiration (ER), and gross ecosystem photosynthesis (GEP) were assessed using chamber techniques conducted over 24-h periods sampled regularly throughout the summers of two years at all sites. At Toolik Lake, warming increased net ... losses in both moist and dry ecosystems. In contrast, at Atqasuk and Barrow, warming increased net ... uptake in wet ecosystems but increased losses from dry ecosystems. At Alexandra Fiord, warming improved net carbon uptake in the moist ecosystem in both years, but in the wet and dry ecosystems uptake increased in one year and decreased the other. Warming generally increased ER, with the largest increases in dry ecosystems. In wet ecosystems, high soil moisture limited increases in respiration relative to increases in photosynthesis. Warming generally increased GEP, with the notable exception of the Toolik Lake moist ecosystem, where warming unexpectedly decreased GEP >25%. Overall, the respiration response determined the effect of warming on ecosystem ... balance. Our results provide the first multiple-site comparison of arctic tundra ... flux responses to standard warming treatments across a large climate gradient. These results indicate that (1) dry tundra may be initially the most responsive ecosystems to climate warming by virtue of strong increases in ER, (2) moist and wet tundra responses are dampened by higher water tables and soil water contents, and (3) both GEP and ER are responsive to climate warming, but the magnitudes and directions are ecosystem-dependent. (ProQuest-CSA LLC: ... denotes formulae/symbols omitted.)