Eddy-covariance measurements and surface energy balance in almond orchards. Results and challenges.

This work is based on the energy flux measurements in almond orchards conducted in the framework of a research project focused on the water status monitoring of this crop in semi-arid environments. An eddy-covariance system was installed in a central location of a 11 ha young almond orchard in 2017 and data of the components of the energy balance equation were collected for 3 years. In 2020 the tower was moved to a nearby plot, to monitor a 10 ha mature almond orchard in this case. Both sites are located in Albacete (southeast Spain), and datasets are available through the European Fluxes Database Cluster.

The complex structure of the trees and the small size of the fields are a challenge for the characterization of the surface energy balance in almond orchards. This work analyzes the footprint area contributing to the turbulent flux measurements, as well as the energy balance closure as a function of the canopy height and the instruments deployment. Also, registered CO₂ flux data allows a discussion on the behavior of the almond trees as carbon sinks in these environments.

Flux databases in woody crops are quite scarce in global networks. The measurement site introduced in this work will contribute with valuable flux data to the study of these expanding crops in semi-arid areas.