EcoYield-SAFE Model

The Yield-SAFE model was created under the SAFE (Silvoarable Agroforestry For Europe) project. Is was designed to be as simple as possible, following a minimal modelling approach, arising as an equation- and parameter-sparse ecophysiologically based simulation model that is easily implementable. Conceptualized for predicting resource capture, growth and production in forestry, arable and agroforestry systems, its few equations and parameters allow for more robust parameter values to be identified from available (but scarce) data. It considers the system to be spatially homogeneous and works in a daily time step. For each day, the model calculates the light intercepted by trees and crop and, taking into account the water availability, derives predictions for tree and crop yields. This is accomplished by means of equations for tree leaf area, crop leaf area, crop biomass, tree biomass, number of tree branches, soil water and temperature sum.

Within the AGFORWARD project, the model has been further improved. Some updates were made directly to the existing equations, to improve model performance. Other developments include implementations of new ecosystem dynamics that interact with the existing state variables, and complementary modules to estimate new indicators (livestock integration, cork production, fruit production, soil carbon model integration, nitrogen leaching).

The model has been helping researchers predict the effects on production, economy and enviroment on agroforestry systems of factors such as climate change, different tree and crop species, different soil types and various management practices. It has enabled the modelling of crops under agroforestry systems, showing these systems consistent better performance when compared with pure arable ones.


Dupraz C, Burgess PJ, Gavaland A, Graves AR, Herzog F, Incoll LD, Jackson N, Keesman K, Lawson G, Lecomte I, Mantzanas K, Mayus M, Palma J, Papanastasis V, Paris P, Pilbeam DJ, Reisner Y, van Noordwijk M, Vincent G, van der Werf W (2005). SAFE (Silvoarable Agroforestry for Europe) Synthesis Report. SAFE Project (August 2001-January 2005).

van der Werf, W., Keesman, K., Burgess, P., Graves, A., Pilbeam, D., Incoll, L.D., Metselaar, K., Mayus, M., Stappers, R., van Keulen, H., Palma, J., Dupraz, C., 2007. Yield-SAFE: A parameter-sparse, process-based dynamic model for predicting resource capture, growth, and production in agroforestry systems. Ecol. Eng. 29, 419-433. doi:DOI 10.1016/j.ecoleng.2006.09.017

Graves, A.R., Burgess, P.J., Palma, J., Keesman, K.J., van der Werf, W., Dupraz, C., van Keulen, H., Herzog, F., Mayus, M., 2010. Implementation and calibration of the parameter-sparse Yield-SAFE model to predict production and land equivalent ratio in mixed tree and crop systems under two contrasting production situations in Europe. Ecol. Modell. 221, 1744-1756. doi:10.1016/j.ecolmodel.2010.03.008

Palma, J., Graves, A., Crous-Duran, J., Paulo, J., Oliveira, T., Garcia de Jalón, S., Kay, S., Burgess, P., 2016a. Keeping a parameter sparse concept in agroforestry modellling while integrating new processes and dynamics: new developments in Yield-SAFE , in: Gosme, M. (Ed.), 3rd European Agroforestry Conference - Celebrating 20 Years of Agroforestry Research in Europe. EURAF, Montpellier, pp. 356-359.

Palma, J., Graves, A., Crous-Duran, J., Upson, M., Paulo, J., Oliveira, T.S., Garcia de Jalón, S., Burgess, P., 2016b. Yield-SAFE Model Improvements. Report for Milestone 29 (6.4) of the AGFORWARD project. Lisboa.


Model Development

Wopke van der Werf, Karel Keesman, Paul Burgess, Anil Graves, David Pilbeam, L.D. Incoll, Klaas Metselaar, Martina Mayus, Roel Stappers, Herman van Keulen, João Palma, Christian Dupraz, Josep Crous-Duran, Silvestre Garcia de Jalón, Mathew Upson, Tânia Oliveira, Joana A. Paulo, Nuria Ferreiro-Domínguez, Gerardo Moreno

Interface Developers

João Palma, Ana Tomás

Model Calibration

João Palma, Anil Graves, Paul Burgess, Karel Keesman, Joana A. Paulo, Margarida Tomé, Mathew Upson, Josep Crous-Duran, Tânia Oliveira, ...

Data Collection for Calibration

Paul Burgess, Herman van Keulen, Gerardo Moreno, Joana A. Paulo, Margarida Tomé, Mathew Upson, Karel Keesman, Sónia Faias, ...