Throughfall reduction in a cacao agroforest: tree water use and soil water budgeting

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dc.contributor.author Köhler, M en
dc.contributor.author Schwendenmann, Luitgard en
dc.contributor.author Hölscher, D en
dc.date.accessioned 2014-10-13T23:04:22Z en
dc.date.issued 2010-07-15 en
dc.identifier.citation Agricultural and Forest Meteorology, 2010, 150 (7-8), pp. 1079 - 1089 en
dc.identifier.issn 0168-1923 en
dc.identifier.uri http://hdl.handle.net/2292/23214 en
dc.description.abstract In a cacao agroforest with Gliricidia shade trees we studied the effects of experimentally reduced throughfall on tree sap flux densities and soil water budget. The objectives of our study were: (1) to identify the response of cacao and Gliricidia sap flux densities to reduced soil water availability, and (2) to analyze the changes in stand level soil water partitioning, measured as changes in transpiration, drainage and soil moisture storage under reduced throughfall. The study was conducted in Sulawesi, Indonesia at a site where ambient precipitation was 2841 mm yr(-1). The research site was subdivided into three control plots and three plastic roof plots in which net precipitation was reduced by 71% through the use of a sub-canopy roof for 13 months, to create rainfall conditions similar to an extended El Nino event. The two species differed in their sap flux response to declining soil water content. Daily Gliricidia sap flux declined at higher soil water contents than cacao, while Gliricidia sap flux declined in response to all levels of vapor pressure deficit (VPD) and cacao only responded to high levels of VPD. Average monthly sap flux densities of cacao and Gliricidia in the roof plots decreased linearly with decreasing soil water content reaching a maximum reduction of 21% (cacao) and 29% (Gliricidia) as compared to control plots. Cacao withdrew water mainly from the topsoil where small amounts of throughfall entering gaps in the roof frequently rewetted the soil. Therefore the competition between the two species for water resources during long periods with only little precipitation was low or in favor of cacao. Average daily stand transpiration was 1.3 mm in roof plots and 1.5 mm in control plots. Measured soil water contents were simulated satisfactorily by the application of a one-dimensional soil water model based on Richards unsaturated flow equation. The model suggested that drainage amounted to 1554 mm yr(-1) in control plots. Drainage in roof plots was greatly reduced, totaling 299 mm yr(-1). Soil moisture storage in the control underwent minor variations while it was heavily reduced in roof plots. Drainage in roof plots was a large driver of changes in soil moisture storage especially in deeper soil layers while precipitation and root water uptake were the main influencing factors for the topsoil. Deep root water uptake seemed to play a minor role in this experiment. Despite the strong reduction in net precipitation, declines in stand transpiration were moderate, suggesting that the stand did not react sensitively to the reduced throughfall scenario. (C) 2010 Elsevier B.V. All rights reserved. en
dc.language EN en
dc.publisher Elsevier Science en
dc.relation.ispartofseries Agricultural and Forest Meteorology en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from http://www.elsevier.com/journal-authors/author-rights-and-responsibilities http://www.sherpa.ac.uk/romeo/issn/0168-1923/ en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.subject Drainage en
dc.subject Transpiration en
dc.subject Gliricidia sepium en
dc.subject Indonesia en
dc.subject Sap flux density en
dc.subject Theobroma cacao en
dc.subject COCOA THEOBROMA-CACAO en
dc.subject HYDRAULIC CONDUCTIVITY en
dc.subject SAP FLOW en
dc.subject CENTRAL SULAWESI en
dc.subject RAIN-FOREST en
dc.subject DROUGHT en
dc.subject TRANSPIRATION en
dc.subject DYNAMICS en
dc.subject MODEL en
dc.subject EVAPOTRANSPIRATION en
dc.title Throughfall reduction in a cacao agroforest: tree water use and soil water budgeting en
dc.type Journal Article en
dc.identifier.doi 10.1016/j.agrformet.2010.04.005 en
pubs.issue 7-8 en
pubs.begin-page 1079 en
pubs.volume 150 en
dc.rights.holder Copyright: Elsevier Science en
pubs.end-page 1089 en
dc.rights.accessrights http://purl.org/eprint/accessRights/RestrictedAccess en
pubs.subtype Article en
pubs.elements-id 119923 en
pubs.org-id Science en
pubs.org-id School of Environment en
dc.identifier.eissn 1873-2240 en
pubs.record-created-at-source-date 2010-11-12 en


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