Changes in water fluxes partition related to the replacement of native dry forests by crops in the Dry Chaco. (December 2020)

• Record Type: Journal Article
• Authors: Rodriguez, Paula; Giménez, Raúl; Nosetto, Marcelo D.; Jobbágy, Esteban G.; Magliano, Patricio N.
• Is Part Of: Journal of arid environments. Volume 183(2020)
• Publication Date: 2020-12
• Subjects: Corn -- Deforestation -- Ecohydrology -- Land use/ cover change -- Woodlands -- Zea mays; Arid regions ecology -- Periodicals; Arid regions -- Periodicals; Écologie des régions arides -- Périodiques; Régions arides -- Périodiques; 577.54
• DOI: 10.1016/j.jaridenv.2020.104281
• Languages: English
• ISSNs: 0140-1963

Abstract

Abstract: Land-use change has been the strongest driver of vegetation cover change in the world. In the South American Dry Chaco (~1 M km 2 ; PPT/ET0 < 0.65), native dry forests are experiencing high deforestation rates that tend to continue in the coming years. Here, we used a hydrological model (Hydrus 1-D) to analyze changes in the water balance triggered by the replacement of dry forests by annual rainfed summer crops. We found that transpiration represented the main water vapour flux in both vegetation covers (59 and 48% of annual rainfall in dry forest and cropland, respectively), followed by evaporation (31 and 30%, respectively) and interception (11 and 9%, respectively). Runoff was five times higher in the cropland compared to the dry forest (10 vs. 2%; p < 0.01). Deep drainage was a negligible water flux in dry forests but it represented 4% of annual rainfall in croplands (p < 0.01), reaching values of zero and 130 mm year −1 for dry and wet years, respectively. Our results highlight the key role of vegetation cover controlling ecosystem water fluxes in the Dry Chaco. More generally, we suggest that the expansion of dryland cultivation can modify the regional water balance and threaten the primary production of ecosystems in the long run. Highlights: Evapotranspiration accounted for >87% of annual rainfall in cropland and dry forest. Transpiration representing the main dominant component in both covers. Dry forest showed a higher and less seasonal T/E ratio than cropland. Runoff was four times higher in the cropland than in the dry forest. Deep drainage represented 3.7% of annual rainfall in the cropland.