Could spaceborne multispectral data be used as SMART proxies’ indicators for agroforestry ecosystem services? – A systematic review

Abstract

Agroforestry (AF) is a relevant socio-ecological system in Mediterranean countries that plays a remarkable role in providing ecosystem services (ES). However, AF ecosystems have been declining (e.g. due to land abandonment), compromising the provision of some ES, such as fire regulating services. As a result, Portugal has introduced new legislation to promote fire-smart landscapes through reconversion towards traditional AF, including a payment for ecosystem services (PES) scheme that demands the development of long-term ES monitoring frameworks to guide managers and practitioners. Hence, it is crucial to identify SMART (Specific, Measurable, Achievable, Realistic and Time-sensitive) proxy indicators for AF ES that are cost-effective for long-term use. Thus, this review aims to understand the progress, emerging gaps and opportunities in remote sensing (RS) technologies, particularly by using freely accessible spaceborne multispectral satellite images to assess and monitor agroforestry ES. With only fifteen studies meeting the review criteria, it was possible to confirm that RS was a valuable tool for estimating and monitoring at least eleven ES (three provisioning and eight regulation and maintenance ES). Sentinel-2, a medium spatial resolution satellite from the Copernicus Programme, offers a cost-effective solution for providing ES proxies due to its spatial resolution, continuity, affordability, and accessibility. However, smallholder landscapes may require higher-resolution satellite imagery, especially for carbon stock monitoring in the PES schemes.

Keywords

• Agroforest ecosystem services
• Remote sensing
• Sentinel-2
• Agrosilvopastoral mosaic
• Long-term monitoring