Abstract
Abstract. Dehesa ecosystem consists of widely-spaced oak trees combined with crops, pasture and Mediterranean shrubs. It is located in the southwest of the Iberian Peninsula, where water scarcity is recurrent, severely affecting the multiple productions and services of the ecosystem. Upscaling in situ Gross Primary Production (GPP) estimates in these areas is challenging for regional and global studies, given the significant spatial variability of plant functional types and the vegetation stresses usually present. The estimation of GPP is often addressed using light use efficiency models (LUE-models). Under soil water deficit conditions, biomass production is reduced below its potential rate. This work investigates the effect of different parameterizations to account for water stress on GPP estimates and their agreement with observations. Ground measurements of GPP are obtained using an Eddy Covariance (EC) system installed over an experimental site located in Córdoba, Spain. GPP is estimated with a LUE-model in the footprint of the EC tower using several approaches: a fixed value taken from previous literature; a fixed value modified by daily weather conditions; and both formulations modified by an additional coefficient to explicitly consider the vegetation water stress. The preliminary results obtained during two hydrological years (2015/2016 and 2016/2017) are compared, focusing on specific wet and dry periods.
Highlights
IntroductionDehesa (known as montado in Portugal) ecosystem combines forest, agricultural and extensive livestock productions, presenting important ecosystem services and cultural values
Dehesa ecosystem combines forest, agricultural and extensive livestock productions, presenting important ecosystem services and cultural values. It is composed of sparse trees and an undergrowth of shrub, pasture or herbaceous crop, constituting a characteristic landscape of the southwest of the Iberian Peninsula (Parsons, 1962)
The values obtained for fPAR and W for the area vary between 0.2 and 0.7, and 0.03 and 1.10, respectively with average values for the study period of 0.44 and 0.38
Summary
Dehesa (known as montado in Portugal) ecosystem combines forest, agricultural and extensive livestock productions, presenting important ecosystem services and cultural values. It is composed of sparse trees (mainly holm oak) and an undergrowth of shrub, pasture or herbaceous crop, constituting a characteristic landscape of the southwest of the Iberian Peninsula (Parsons, 1962). The assimilation of CO2 due to the vegetation is represented by the gross primary production (GPP) This production is often estimated from remote sensing based on the works of Monteith (1972) that use biophysical variables and subsequently validated with eddy covariance (EC) systems Under soil water deficit conditions, biomass production is reduced below its potential rate, but this effect is sometimes addressed only indirectly by these models
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
