TITLE

Carbon cycling in extratropical terrestrial ecosystems of the Northern Hemisphere during the 20th century: a modeling analysis of the influences of soil thermal dynamics

AUTHOR(S)
ZHUANG, Q.; McGUIRE, A. D.; MELILLO, J. M.; CLEIN, J. S.; DARGAVILLE, R. J.; KICKLIGHTER, D. W.; MYNENI, R. B.; DONG, J.; ROMANOVSKY, V. E.; HARDEN, J.; HOBBIE, J. E.
PUB. DATE
July 2003
SOURCE
Tellus: Series B;Jul2003, Vol. 55 Issue 3, p751
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
ABSTRACT There is substantial evidence that soil thermal dynamics are changing in terrestrial ecosystems of the Northern Hemisphere and that these dynamics have implications for the exchange of carbon between terrestrial ecosystems and the atmosphere. To date, large-scale biogeochemical models have been slow to incorporate the effects of soil thermal dynamics on processes that affect carbon exchange with the atmosphere. In this study we incorporated a soil thermal module (STM), appropriate to both permafrost and non-permafrost soils, into a large-scale ecosystem model, version 5.0 of the Terrestrial Ecosystem Model (TEM). We then compared observed regional and seasonal patterns of atmospheric CO2 to simulations of carbon dynamics for terrestrial ecosystems north of 30�N between TEM 5.0 and an earlier version of TEM (version 4.2) that lacked a STM. The timing of the draw-down of atmospheric CO2 at the start of the growing season and the degree of draw-down during the growing season were substantially improved by the consideration of soil thermal dynamics. Both versions of TEM indicate that climate variability and change promoted the loss of carbon from temperate ecosystems during the first half of the 20th century, and promoted carbon storage during the second half of the century. The results of the simulations by TEM suggest that land-use change in temperate latitudes (30�60�N) plays a stronger role than climate change in driving trends for increased uptake of carbon in extratropical terrestrial ecosystems (30�90�N) during recent decades. In the 1980s the TEM 5.0 simulation estimated that extratropical terrestrial ecosystems stored 0.55 Pg C yr-1 , with 0.24 Pg C yr-1 in North America and 0.31 Pg C yr-1 in northern Eurasia. From 1990 through 1995 the model simulated that these ecosystems stored 0.90 Pg C yr-1 , with 0.27 Pg C yr-1 stored in North America and...
ACCESSION #
10075471

 

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