DAVIDSON, E. A.

FIGUEIREDO, R. de O.

MARKEWITZ, D.

NEPSTAD, D. C.

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  Search  Print PageBrowse by DayBrowse by AuthorBrowse by ProgramMeeting Home96th ESA Annual MeetingESA HomeCOS 55-6 - Simulated drought in the Amazon: Impacts on soil solution andnutrient fluxesWednesday, August 10, 2011: 9:50 AM6A, Austin Convention CenterDaniel Markewitz , Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, GARicardo O. Figueiredo , Embrapa Meio Ambiente, Jaguariúna, BrazilEric A. Davidson , The Woods Hole Research Center, MassachusettsDaniel C. Nepstad , Instituto de Pesquisa Ambiental da Amazônia (Amazon Institute of Environmental Research),Belém, BrazilBackground/Question/MethodsTo assess the effects of changing climate on lowland tropical rainforests in the Amazon, a throughfall reductionexperiment was conducted in the Tapajos National Forest, Para, Brazil from 1999 to 2006.  Rainfall, throughfall, litterleachate, and 25 and 200 cm soil solutions were collected in two 1-ha plots for 1 year prior to throughfall exclusion,during four years of exclusion, and two years after release from exclusion.  A system of plastic panels and gutterssuspended above the soil was used to exclude ~60% of throughfall.    We hypothesized that solution concentrationswould increase during exclusion due to effects of evapoconcentration and potentially due to death of vegetation orslowing of plant growth and nutrient demand.  We hypothesized a rapid flush of nutrients that had built up duringexclusion would be observed after the exclusion treatment ended.  Results/ConclusionsThe seven years of solution chemical analysis, paired with modeled solution fluxes, indicated increased concentrationsin litter leachate and soil solutions in response to decreased water inputs.  During exclusion, tree mortality wasobserved but increasing solution concentrations due to decomposition of necromass or reduced plant uptake were notclearly evident.  Post-exclusion, a large flush of Ca and NO3 were observed at 25 cm depth in the soil.  Increased fluxesat 200 cm depth were also observed for Ca but not for NO3.  The experiment confirmed that water fluxes dominate asa driver of solution chemical fluxes and that the importance of change in chemical concentrations will be outweighed bychanges in water flux with respect to nutrient flux.  Changes in soil water volume may, however, alter other processessuch as microbial decomposition or equilibrium exchange reactions.  Finally, increased dry periods followed byincreased nutrient flushing may limit surficial plant root uptake, but plants in this environment are deeply rooted andlikely well adapted to capturing nutrient flushes.See more of: Biogeochemistry: Biogeo Patterns along Environmental Gradients ISee more of: Contributed Oral Papers1990 M STREET, NW | SUITE 700 | WASHINGTON, DC 20036 | PHONE 202-833-8773 | FAX 202-833-8775 | EMAIL ESAHQ AT ESA.ORGCopyright © . All rights reserved.Banner photo by Flickr user greg westfall.<< Previous Abstract | Next Abstract >>96th ESA Annual Meeting (August 7 -- 12, 2011) http://eco.confex.com/eco/2011/webprogram/Paper30739.html1 de 1 1/3/2012 16:44ERROR: syntaxerrorOFFENDING COMMAND: --nostringval--STACK:/Title ()/Subject (D:20120301164433-03’00’)/ModDate ()/Keywords (PDFCreator Version 0.9.5)/Creator (D:20120301164433-03’00’)/CreationDate (Gutzlaff)/Author -mark- 

Simulated drought in the Amazon: impacts on soil solution and nutrient fluxes.

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