Remote-sensing based tools to monitor grassland ecosystem services

Abstract

The provision of ecosystem services (ES) by agricultural systems is a shared objective of agricultural policies in most developed countries in response to an increasing demand from society. Sustainable management of grassland ecosystems leads to enhanced soil fertility, ensures food security, acts as natural filters and purifiers of water, and functions as carbon sinks, sequestering carbon dioxide and mitigating climate change. All of these goals are deeply interconnected with several SDGs. The Common Agricultural Policy (CAP) of the European Union is environmentally oriented. However, a broad consensus indicates that the current policy instruments are not effectively promoting the provision of ES. Thus, it is essential to develop efficient and innovative policy instruments to enhance ES's agricultural provision. One of the challenges for applying new policy instruments, such as results-based payments (OECD, 2015), is the quantification of ES supply, usually involving intensive and specialized field data. Therefore, there is a need to create quantitative indicators for ES based on reliable and affordable data. Remote sensing data can be an effective tool, especially if the data are easily accessible, available at an appropriate scale, and provided free of cost. Olive groves and Mediterranean oak savanna were used in this work as case studies to examine the herbaceous layer's contribution to the provision of ecosystem services. In both ecosystems, grasslands play a relevant role in supplying provisioning (such as forage, freshwater or genetic library), regulating (carbon sequestration, soil conservation, climate, and air quality regulation) and cultural services (aesthetic appreciation, cultural identity). The biomass or above-ground net primary production (ANPP) and biodiversity are essential integrators of ecosystem functioning. Biomass is responsible for the input level of various ecosystem services, and it is directly connected to carbon sequestration and soil conservation. Biodiversity, on the other hand, contributes to the processes that underpin other ecosystem services and constitutes an ecosystem good that humans directly value. This work describes the general scheme to measure several grassland ES (GES) in olive groves and oak savannas, including ANPP, biodiversity, carbon sequestration, and aesthetic appreciation, and preliminary results about the ANPP and biodiversity are presented.