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dc.contributor.authorLacombe, Guillaume
dc.contributor.authorRibolzi, Olivier
dc.contributor.authorde Rouw, Anneke
dc.contributor.authorPierret, Alain
dc.contributor.authorLatsachak, Keoudone
dc.contributor.authorSilvera, Norbert
dc.contributor.authorPham Dinh, Rinh
dc.contributor.authorOrange, Didier
dc.contributor.authorJaneau, Jean-Louis
dc.contributor.authorSoulileuth, Bounsamai
dc.contributor.authorRobain, Henri
dc.contributor.authorTaccoen, Adrien
dc.contributor.authorSengphaathith, Phouthamaly
dc.contributor.authorMouche, Emmanuel
dc.contributor.authorSengtaheuanghoung, Oloth
dc.contributor.authorTran Duc, Toan
dc.contributor.authorValentin, Christian
dc.date.accessioned2016-08-27T00:52:31Z
dc.date.available2016-08-27T00:52:31Z
dc.date.issued2016-07-08
dc.identifier.citationContradictory hydrological impacts of afforestation in the humid tropics evidenced by long-term field monitoring and simulation modelling 2016, 20 (7):2691 Hydrology and Earth System Sciencesen
dc.identifier.issn1607-7938
dc.identifier.doi10.5194/hess-20-2691-2016
dc.identifier.urihttp://hdl.handle.net/10150/618979
dc.description.abstractThe humid tropics are exposed to an unprecedented modernisation of agriculture involving rapid and mixed land-use changes with contrasted environmental impacts. Afforestation is often mentioned as an unambiguous solution for restoring ecosystem services and enhancing biodiversity. One consequence of afforestation is the alteration of streamflow variability which controls habitats, water resources, and flood risks. We demonstrate that afforestation by tree planting or by natural forest regeneration can induce opposite hydrological changes. An observatory including long-term field measurements of fine-scale land-use mosaics and of hydrometeorological variables has been operating in several headwater catchments in tropical southeast Asia since 2000. The GR2M water balance model, repeatedly calibrated over successive 1-year periods and used in simulation mode with the same year of rainfall input, allowed the hydrological effect of land-use change to be isolated from that of rainfall variability in two of these catchments in Laos and Vietnam. Visual inspection of hydrographs, correlation analyses, and trend detection tests allowed causality between land-use changes and changes in seasonal streamflow to be ascertained. In Laos, the combination of shifting cultivation system (alternation of rice and fallow) and the gradual increase of teak tree plantations replacing fallow led to intricate streamflow patterns: pluri-annual streamflow cycles induced by the shifting system, on top of a gradual streamflow increase over years caused by the spread of the plantations. In Vietnam, the abandonment of continuously cropped areas combined with patches of mix-trees plantations led to the natural re-growth of forest communities followed by a gradual drop in streamflow. Soil infiltrability controlled by surface crusting is the predominant process explaining why two modes of afforestation (natural regeneration vs. planting) led to opposite changes in streamflow regime. Given that commercial tree plantations will continue to expand in the humid tropics, careful consideration is needed before attributing to them positive effects on water and soil conservation.
dc.description.sponsorshipFrench watershed network SOERE-RBV (reseau des bassins versants); French Observatory for Sciences of Universe (Observatoire des Sciences de l'Univers); CGIAR research program on Integrated Systems for the Humid Tropics; French ANR TECITEASY [ANR-13-AGRO-0007]en
dc.language.isoenen
dc.publisherCOPERNICUS GESELLSCHAFT MBHen
dc.relation.urlhttp://www.hydrol-earth-syst-sci.net/20/2691/2016/en
dc.rights© Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License.en
dc.titleContradictory hydrological impacts of afforestation in the humid tropics evidenced by long-term field monitoring and simulation modellingen
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Grad Collen
dc.identifier.journalHydrology and Earth System Sciencesen
dc.description.noteOpen Access Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
refterms.dateFOA2018-06-12T23:15:45Z
html.description.abstractThe humid tropics are exposed to an unprecedented modernisation of agriculture involving rapid and mixed land-use changes with contrasted environmental impacts. Afforestation is often mentioned as an unambiguous solution for restoring ecosystem services and enhancing biodiversity. One consequence of afforestation is the alteration of streamflow variability which controls habitats, water resources, and flood risks. We demonstrate that afforestation by tree planting or by natural forest regeneration can induce opposite hydrological changes. An observatory including long-term field measurements of fine-scale land-use mosaics and of hydrometeorological variables has been operating in several headwater catchments in tropical southeast Asia since 2000. The GR2M water balance model, repeatedly calibrated over successive 1-year periods and used in simulation mode with the same year of rainfall input, allowed the hydrological effect of land-use change to be isolated from that of rainfall variability in two of these catchments in Laos and Vietnam. Visual inspection of hydrographs, correlation analyses, and trend detection tests allowed causality between land-use changes and changes in seasonal streamflow to be ascertained. In Laos, the combination of shifting cultivation system (alternation of rice and fallow) and the gradual increase of teak tree plantations replacing fallow led to intricate streamflow patterns: pluri-annual streamflow cycles induced by the shifting system, on top of a gradual streamflow increase over years caused by the spread of the plantations. In Vietnam, the abandonment of continuously cropped areas combined with patches of mix-trees plantations led to the natural re-growth of forest communities followed by a gradual drop in streamflow. Soil infiltrability controlled by surface crusting is the predominant process explaining why two modes of afforestation (natural regeneration vs. planting) led to opposite changes in streamflow regime. Given that commercial tree plantations will continue to expand in the humid tropics, careful consideration is needed before attributing to them positive effects on water and soil conservation.


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