CARVALHO, C. J. R.

FORTINI, L. B.

MULKEY, S. S.

OLIVEIRA, F. A.

VASCONCELOS, S. S.

ZARIN, D. J.

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Moisture stress constrains carbon flux rates in an Eastern Amazonian regrowth forestD.J. Zarin', S.S. Mulkey', S.S. Vasconcelos", L.B. Fortini", C.J.R. Carvalhos, F.A.Olivcira6;School of Forest Resources and Conservation, University of Florida, P.O. Box 110760,Gainesville, FL 32611-0760 USA, /drJ!1 ti. ólficc1l1; 2University ofFlorida,LlliJI ".<' !iht"_'llijl,iL'-'cli;; 3Faculdade de Ciências Agrárias do Pará,~t~;!.:i.!.;lilLih'Ll', li:; hr; "Universiry of Florida.Juc.i-t..n lilll! -l:~.J.!L'l; 5EMBRAPA-CPA TU, ~'.!~,:dl".).~'=l'::.'-'~;L.'c:L;l.bL~~L~;.!l~i:;6Faculdade de Ciências Agrárias do Pará,Rates of carbon uptake and accumulation in forests are strongly influenced by climate. InAmazonian regrowth forests, more attention has been focused on land-use impacts oncarbon accumulatíon than on climatic constraínts, although a recent synthesís indicatesthat most ofthe intersíte dífferences in aboveground carbon accumulatíon ín those forestsare related to differences in the length of the dry season and soil texture. To test theeffects of altered dry-season moísture availability on carbon flux rates in an EasternAmazonían regrowth forest, weínitiated an irrigatíon experiment in a ló-year-old standnear Castanhal, Pará. During the first year oftreatment, we added 5 mm day' to four 400m2 plots from August through December; all measurements were made in 100 m2 samplcareas nested in the center of the treatment plots. Compared to control plots in the samestand, preliminary results ofthe irrigation experiment included significantly higher soi!CO2 eftlux during especially droughty periods and significantly higher maximumphotosynthetic capacity (Arna,,)throughout the dry season in Miconia cílíata (Rich.) DC, acommon understory species. Leafwater potentials were significantly higher for both M.ciliata and Vismia guianensis (Aubl.) Choisy, a common overstory species. V.guianensis Amaxvalues did not díffer significantly between treatment and control plots,but instantaneous water-use cfficiency (AnlaJGs) was lower under irrigation. Thesepreliminary results suggest that above- and below-ground carbon fluxes in thís EasternAmazonian regrowth forest are constrained by moisture stress during the dry season.

Moisture stress constrains carbon flux rates in an Eastern Amazonian regrowth forest.

RCAAP - Repositório Científico de Acesso Aberto de Portugal

http://www.alice.cnptia.embrapa.br/alice/bitstream/doc/406232/1/5434.pdf

Moisture stress constrains carbon flux rates in an Eastern Amazonian regrowth forest.

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