부산대학교 도서관

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1365-2486.2008.01694.x Byline: ERIC A. DAVIDSON (*), DANIEL C. NEPSTAD (*), FRANCOISE YOKO ISHIDA ([dagger]), PAULO M. BRANDO ([double dagger],s.) Keywords: Amazon Basin; Brazil; climate change; CH; CO; NO; nitrogen; NO; soil carbon Abstract: Abstract Changes in precipitation in the Amazon Basin resulting from regional deforestation, global warming, and El Nino events may affect emissions of carbon dioxide (CO.sub.2), methane (CH.sub.4), nitrous oxide ([N.sub.2]O), and nitric oxide (NO) from soils. Changes in soil emissions of radiatively important gases could have feedback implications for regional and global climate. Here, we report the final results of a 5-year, large-scale (1 ha) throughfall exclusion experiment, followed by 1 year of recovery with natural throughfall, conducted in a mature evergreen forest near Santarem, Brazil. The exclusion manipulation lowered annual [N.sub.2]O emissions in four out of five treatment years (a natural drought year being the exception), and then recovered during the first year after the drought treatment stopped. Similarly, consumption of atmospheric CH.sub.4 increased under drought treatment, except during a natural drought year, and it also recovered to pretreatment values during the first year that natural throughfall was permitted back on the plot. No treatment effect was detected for NO emissions during the first 3 treatment years, but NO emissions increased in the fourth year under the extremely dry conditions of the exclusion plot during a natural drought. Surprisingly, there was no treatment effect on soil CO.sub.2 efflux in any year. The drought treatment provoked significant tree mortality and reduced the allocation of C to stems, but allocation of C to foliage and roots were less affected. Taken together, these results suggest that the dominant effect of throughfall exclusion on soil processes during this 6-year period was on soil aeration conditions that transiently affected CH.sub.4, [N.sub.2]O, and NO production and consumption. Author Affiliation: (*)The Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02540-1644, USA ([dagger])CENA, University of Sao Paulo, Av. Centenario, 303 Piracicaba, SP, Brazil ([double dagger])Instituto de Pesquisa Ambiental da Amazonia, Av. Rui Barbosa, 136 Santarem, PA, Brazil (s.)Department of Botany and School of Natural Resources and Environment, University of Florida, 220 Bartram Hall, Gainesville, FL 118526, USA Article History: Received 28 December 2007 and accepted 5 May 2008 Article note: Correspondence: Eric A. Davidson, tel. +1 508 540 9900, fax +1 508 540 9700, e-mail: edavidson@whrc.org