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Measuring and modelling energy partitioning in canopies of varying complexity using MAESPA model
- Vezy, Rémi, Christina, Mathias, Roupsard, Olivier, Nouvellon, Yann, Duursma, Remko, Medlyn, Belinda, Soma, Maxime, Charbonnier, Fabien, Blitz-Frayret, Céline, Stape, José-Luiz, Laclau, Jean-Paul, de Melo Virginio Filho, Elias, Bonnefond, Jean-Marc, Rapidel, Bruno, Do, Frédéric C., Rocheteau, Alain, Picart, Delphine, Borgonovo, Carlos, Loustau, Denis, le Maire, Guerric
- Agricultural and forest meteorology 2018 v.253-254 pp. 203-217
- Coffea, Eucalyptus, agroecosystems, agroforestry, air temperature, canopy, evaporation, evapotranspiration, forest ecosystems, leaves, photosynthesis, plantations, radiative transfer, simulation models, soil, surface water, vapor pressure, Brazil, Costa Rica
- Evapotranspiration and energy partitioning are complex to estimate because they result from the interaction of many different processes, especially in multi-species and multi-strata ecosystems. We used MAESPA model, a mechanistic, 3D model of coupled radiative transfer, photosynthesis, and balances of energy and water, to simulate the partitioning of energy and evapotranspiration in homogeneous tree plantations, as well as in heterogeneous multi-species, multi-strata agroforests with diverse spatial scales and management schemes. The MAESPA model was modified to add (1) calculation of foliage surface water evaporation at the voxel scale; (2) computation of an average within-canopy air temperature and vapour pressure; and (3) use of (1) and (2) in iterative calculations of soil and leaf temperatures to close ecosystem-level energy balances. We tested MAESPA model simulations on a simple monospecific Eucalyptus stand in Brazil, and also in two complex, heterogeneous Coffea agroforests in Costa Rica. MAESPA satisfactorily simulated the daily and seasonal dynamics of net radiation (RMSE = 29.6 and 28.4 W m⁻²; R² = 0.99 and 0.99 for Eucalyptus and Coffea sites respectively) and its partitioning between latent-(RMSE = 68.1 and 37.2 W m⁻²; R² = 0.87 and 0.85) and sensible-energy (RMSE = 54.6 and 45.8 W m⁻²; R² = 0.57 and 0.88) over a one-year simulation at half-hourly time-step. After validation, we use the modified MAESPA to calculate partitioning of evapotranspiration and energy between plants and soil in the above-mentioned agro-ecosystems. In the Eucalyptus plantation, 95% of the outgoing energy was emitted as latent-heat, while the Coffea agroforestry system’s partitioning between sensible and latent-heat fluxes was roughly equal. We conclude that MAESPA process-based model has an appropriate balance of detail, accuracy, and computational speed to be applicable to simple or complex forest ecosystems and at different scales for energy and evapotranspiration partitioning.