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

Abstract

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.