Sensitivity of boreal forest carbon balance to soil thaw

Science

Volumn 279, Issue 5348, 1998, Pages 214-217

  Goulden, M L ^a,c   Wofsy, S C ^a   Harden, J W ^b   Trumbore, S E ^c   Crill, P M ^d   Gower, S T ^e   Fries, T ^b   Daube, B C ^a   Fan, S M ^a   Sutton, D J ^a   Bazzaz, A ^a   Munger, J W ^a  

^a HARVARD UNIVERSITY   (United States)

^b U S GEOLOGICAL SURVEY   (United States)

^c UNIVERSITY OF CALIFORNIA   (United States)

^d UNIVERSITY OF NEW HAMPSHIRE   (United States)

^e UNIVERSITY OF WISCONSIN MADISON   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

BOREAL FOREST; CARBON; SOIL THAW; SPRUCE FOREST;

ARTICLE; BIODEGRADATION; CANADA; CARBON DIOXIDE FIXATION; CLIMATE; FOREST; PRIORITY JOURNAL; SOIL; THAWING;

CANADA, MANITOBA;

BRYOPHYTA; PICEA; PICEA MARIANA;

EID: 6844251585     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.279.5348.214     Document Type: Article

References (45)

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13. 2 at six altitudes. The half-hour eddy flux was added to the change in storage to calculate the net ecosystem exchange (NEE), with the sign convention that positive fluxes are from the forest. See also (14).
14. 2 at the moss surface of three sphagnum and two feather moss sites was measured every 3 hours from May to October 1996 with an automated closed-chamber gas-exchange system.
15. 12C compared with a decay-corrected oxalic acid standard [S. E. Trumbore, in Mass Spectrometry of Soils, T. Boutton and S. Yamasaki, Eds. (Dekker, New York, 1996), pp. 311-340].
16. 12C compared with a decay-corrected oxalic acid standard [S. E. Trumbore, in Mass Spectrometry of Soils, T. Boutton and S. Yamasaki, Eds. (Dekker, New York, 1996), pp. 311-340].
17. 12C compared with a decay-corrected oxalic acid standard [S. E. Trumbore, in Mass Spectrometry of Soils, T. Boutton and S. Yamasaki, Eds. (Dekker, New York, 1996), pp. 311-340].
18. J. W. Harden, K. P. O'Neill, S. E. Trumbore, H. Veldhuis, B. F. Stocks, J. Geophys. Res., in press. The carbon in the moss layer at 10 points along a transect was determined at seven sites within 100 km of Thompson, Manitoba, that ranged in age since the last burn. The accumulation of moss at the primary site was calculated from these data with a model that assumed constant inputs of carbon, first-order decomposition, and rates of lateral spread of recolonizing mosses.
19. S. T. Gower et al., J. Geophys. Res., in press. The 1985 to 1994 wood increment in four 15 x 15m plots on feather moss was calculated from ring width by using site-specific allometric equations. Sequential inventories in 1993 and 1994 found no spruce mortality. The sphagnum areas were not sampled and we assume that the wood increment there was negligible.
20. The northern study area Old Black Spruce site (NOBS) of the Boreal Ecosystem-Atmosphere Study (BOREAS) [P. J. Sellers et al., Bull. Am. Met. Soc. 76, 1549 (1995)] is 40 km west of Thompson, 25 km east of Nelson House, and 4 km south of Route 391 (55.879°N, 98.484°W).
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26. -1 to account for remaining errors.
27. 2.
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31. 2 efflux on windy nights and air temperature (5, 14).
32. deep is root respiration and deep decomposition.
33. -1 at the feather moss sites and no net exchange at the sphagnum sites. This pattern apparently reflects a large difference in root respiration and litter input.
34. J. W. Raich and W. H. Schlesinger, Tellus Ser. B Chem. Phys. Meteorol. 44, 81 (1992), but see J. Lloyd and J. A. Taylor [Funct. Ecol. 8, 315 (1994)] and M. Kirschbaum [Soil Biol. Biochem. 27, 753 (1995)].
35. J. W. Raich and W. H. Schlesinger, Tellus Ser. B Chem. Phys. Meteorol. 44, 81 (1992), but see J. Lloyd and J. A. Taylor [Funct. Ecol. 8, 315 (1994)] and M. Kirschbaum [Soil Biol. Biochem. 27, 753 (1995)].
36. J. W. Raich and W. H. Schlesinger, Tellus Ser. B Chem. Phys. Meteorol. 44, 81 (1992), but see J. Lloyd and J. A. Taylor [Funct. Ecol. 8, 315 (1994)] and M. Kirschbaum [Soil Biol. Biochem. 27, 753 (1995)].
37. As measured by time-domain reflectometry within 100 m of the tower [R. H. Cuenca, S. F. Kelly, D. Gochis, Eos, Nov. 12 Suppl. (1996)].
38. 2 versus time was used to calculate respiration. We do not know whether all of the deep carbon is labile and note that some of it is charcoal and probably recalcitrant. See also J. S. Clein and J. P. Schimel [Soil Biol. Biochem. 27, 1231 (1995)].
39. J. Bubier, unpublished material.
40. -1, whereas the laboratory incubations (23) suggest a somewhat higher rate.
41. The mean temperature at the Thompson Airport (40 km east) from 1 June to 15 July was 13.6°C in 1994, 15.0°C in 1995, and 15.2°C in 1996. The comparable mean from 1969 to 1996 was 13.1°C, and the intervals in 1995 and 1996 were among the five warmest on record. The mean temperature at the site was 1°C cooler in 1997 than in previous years, indicating near-normal temperatures in 1997. The diurnal range from 1 June to 15 July was 15.2°C in 1994, 15.5°C in 1995, 14.3°C in 1996, and 14.1°C from 1969 to 1996. The range in 1995 was the second largest on record and implies that solar radiation was 8% above average (12). The annual mean temperatures during the study were close to the 1969-1996 average. See also J. Overpeck et al., Science 278, 1251 (1997) and W. L. Chapman and J. E. Walsh, Bull. Am. Meteorol. Soc. 74, 33 (1993).
42. The mean temperature at the Thompson Airport (40 km east) from 1 June to 15 July was 13.6°C in 1994, 15.0°C in 1995, and 15.2°C in 1996. The comparable mean from 1969 to 1996 was 13.1°C, and the intervals in 1995 and 1996 were among the five warmest on record. The mean temperature at the site was 1°C cooler in 1997 than in previous years, indicating near-normal temperatures in 1997. The diurnal range from 1 June to 15 July was 15.2°C in 1994, 15.5°C in 1995, 14.3°C in 1996, and 14.1°C from 1969 to 1996. The range in 1995 was the second largest on record and implies that solar radiation was 8% above average (12). The annual mean temperatures during the study were close to the 1969-1996 average. See also J. Overpeck et al., Science 278, 1251 (1997) and W. L. Chapman and J. E. Walsh, Bull. Am. Meteorol. Soc. 74, 33 (1993).
43. The interannual trends in carbon balance were not obviously related to variation in deep soil temperature (Fig. 1). The reliability of these measurements as an indicator of interannual variability in thaw depth is uncertain because placement of the probes may have disturbed the local conditions, one of the sites was disturbed by the installation of ancillary equipment in 1995, and the horizontal distribution of soil frost may have varied from year to year.
44. A uniform 2.5°C increase in temperature would increase the annual number of sunlit hours on days with mean temperatures above freezing by ∼8%. The length of the growing season at Harvard Forest, where warming in spring is more gradual and the growing season is shorter because the forest is deciduous, is more sensitive to warming (5, 14).
45. This work was supported by the U.S. National Aeronautics and Space Administration. We thank the BOREAS science team; the BOREAS support staff; and especially P. Sellers, F. Hall, K. Spence, D. Hodkinson, B. Lesley, R. Mendelson, A. Dunn, and M. Pender.