Oberbauer, Steven F; Tweedie, Craig E; Welker, Jeff M; Fahnestock, Jace T; Henry, Gregory HR; Webber, Patrick J; Hollister, Robert D; Walker, Marilyn D; Kuchy, Andrea; Elmore, Elizabeth; Starr, Gregory (2007): (Table 1) Climate characteristics of the four North American Tundra Experiment (ITEX) sites [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.817624, Supplement to: Oberbauer, SF et al. (2007): Tundra CO2 fluxes in response to experimental warming across latitudinal and moisture gradients. Ecological Monographs, 77(2), 221-238, https://doi.org/10.1890/06-0649
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Abstract:
Climate warming is expected to differentially affect CO2 exchange of the diverse ecosystems in the Arctic. Quantifying responses of CO2 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 CO2 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 CO2 responses to warming in both dry and wet or moist ecosystems. Net ecosystem CO2 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 CO2 losses in both moist and dry ecosystems. In contrast, at Atqasuk and Barrow, warming increased net CO2 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 CO2 balance. Our results provide the first multiple-site comparison of arctic tundra CO2 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.
Project(s):
Coverage:
Median Latitude: 72.315832 * Median Longitude: -134.885835 * South-bound Latitude: 68.633330 * West-bound Longitude: -157.400000 * North-bound Latitude: 78.880000 * East-bound Longitude: -75.910000
Minimum ELEVATION: 3 m a.s.l. * Maximum ELEVATION: 740 m a.s.l.
Event(s):
ITEX_AF (Alexandra Fiord) * Latitude: 78.880000 * Longitude: -75.910000 * Elevation: 10.0 m * Location: Ellesmere Island, Canadian Arctic Archipelago * Method/Device: Monitoring station (MONS)
Comment:
Data extracted in the frame of a joint ICSTI/PANGAEA IPY effort, see http://doi.pangaea.de/10.1594/PANGAEA.150150
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Event label | Event | ||||
| 2 | Latitude of event | Latitude | ||||
| 3 | Longitude of event | Longitude | ||||
| 4 | Area/locality | Area | Oberbauer, Steven F | |||
| 5 | ELEVATION | Elevation | m a.s.l. | Geocode | ||
| 6 | Temperature, air, annual mean | MAAT | °C | Oberbauer, Steven F | ||
| 7 | Temperature, air, monthly mean | TTT monthly m | °C | Oberbauer, Steven F | for July | |
| 8 | Precipitation, sum | Precip sum | mm | Oberbauer, Steven F | summer (June-August) | |
| 9 | Comment | Comment | Oberbauer, Steven F | |||
| 10 | Degree days, thawing | TDD | Oberbauer, Steven F |
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
20 data points
Data
| 1 Event | 2 Latitude | 3 Longitude | 4 Area | 5 Elevation [m a.s.l.] | 6 MAAT [°C] | 7 TTT monthly m [°C] | 8 Precip sum [mm] | 9 Comment | 10 TDD |
|---|---|---|---|---|---|---|---|---|---|
| ITEX_AF | 78.880 | -75.910 | Alexandra Fiord, Canada | 10 | -14.6 | 5.0 | summer precipitation very infrequent | 439 | |
| ITEX_BA | 71.300 | -156.667 | Barrow, Alaska, USA | 3 | -12.6 | 3.7 | 57 | 369 | |
| ITEX_AT | 70.450 | -157.400 | Atqasuk, Alaska, USA | 30 | -11.9 | 9.0 | 55 | 618 | |
| ITEX_TL | 68.633 | -149.567 | Toolik Lake, Alaska, USA | 740 | -8.6 | 11.6 | 180 | 905 |