Remote sensing estimation of net primary production as monitoring indicator of holm oak savanna management

Abstract The management of large areas such as the dehesa (a multifunctional agrosilvopastoral system) , with approximately 3 million ha in the Iberian Peninsula, requires effective tools to help decision-making on different scales. This work focuses on the monitoring of pasture production using remote sensors. An adaptation of a Light Use Efficiency (LUE) model has been applied using meteorological data and satellite images on two scales: Regional scale – the dehesa area of Andalusia (Southern Spain) with data of the MODerate resolution Imaging Spectroradiometer (MODIS, MOD09Q1 product) during the hydrological years 2013/2104 and 2014/2015; on a field scale – after pasture improvements, using the earth observation satellites SENTINEL-2 during the hydrological years 2015–2016 and 2016–2017. The adaptation of the model proposed in this work pays special attention to: the spatial and temporal interpolation of meteorological variables; the presence of a tree layer as part of the ecosystem that influences spectral data and needs to be taken into account and subtracted accordingly; the estimation of the fraction of photosynthetically active radiation absorbed by the pasture ( fPAR ); and the empirical estimation of the light use efficiency for natural grasslands, using biomass field measurements. The results obtained presented an error of around 13%, considered adequate for the applications addressed in this study, suggesting that this approach can be useful as an indicator for monitoring the net primary production in this ecosystem.