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Unravelling evapotranspiration controls and components in tropical Andean tussock grasslands |
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| Authors: | Ana E Ochoa-Sánchez Patricio Crespo Galo Carrillo-Rojas Franklin Marín Rolando Célleri |
| Institution: | 1. Departamento de Recursos Hídricos y Ciencias Ambientales, University of Cuenca, Cuenca, Ecuador;2. Departamento de Recursos Hídricos y Ciencias Ambientales, University of Cuenca, Cuenca, Ecuador
Faculty of Engineering, University of Cuenca, Cuenca, Ecuador Faculty of Agricultural Sciences, University of Cuenca, Cuenca, Ecuador;3. Departamento de Recursos Hídricos y Ciencias Ambientales, University of Cuenca, Cuenca, Ecuador Faculty of Chemical Sciences, University of Cuenca, Cuenca, Ecuador;4. Departamento de Recursos Hídricos y Ciencias Ambientales, University of Cuenca, Cuenca, Ecuador Faculty of Engineering, University of Cuenca, Cuenca, Ecuador |
| Abstract: | The study of the environmental factors that control evapotranspiration and the components of evapotranspiration leads to a better understanding of the actual evapotranspiration (ET) process that links the functioning of the soil, water and atmosphere. It also improves local, regional and global ET modelling. Globally, few studies so far focussed on the controls and components of ET in alpine grasslands, especially in mountainous sites such as the tussock grasslands located in the páramo biome (above 3300 m a.s.l.). The páramo occupies 35 000 km2 and provides water resources for many cities in the Andes. In this article, we unveiled the controls on ET and provided the first insights on the contribution of transpiration to ET. We found that the wet páramo is an energy-limited region and net radiation (Rn) is primarily controlling ET. ET was on average 1.7 mm/day. The monthly average evaporative fraction (ET/Rn) was 0.47 and it remained similar for wet and dry periods. The secondary controls on ET were wind speed, aerodynamic resistance and surface resistance that appeared more important for dry periods, where significantly higher ET rates were found (20% increase). During dry events, transpiration was on average 1.5 mm/day (range 0.7–2.7 mm/day), similar to other tussock grasslands in New Zealand (range 0.6–3.3 mm/day). Evidence showed interception contributes more to ET than transpiration. This study sets a precedent towards a better understanding of the evapotranspiration process and will ultimately lead to a better land-atmosphere fluxes modelling in the tropics. |
| Keywords: | Andes mountain net radiation páramo transpiration tropics |