Satellite-based Estimates of Land Degradation Across the Southern Cone of South America in Support of the 2030 Agenda for Sustainable Development

Abstract:

Land degradation occurs on over a quarter of the Earth’s ice-free land area and adversely affects the livelihoods of approximately 1.3 to 3.2 billion people. However, degradation, which is recognized by the United Nations Sustainable Development Goals (SDGs) as an important global environmental issue, is complex and key uncertainties exist regarding its extent, severity, and rate of change in many parts of the world. The goal of this study is to use satellite-based observations of productivity and land cover to assess land degradation across 11 different ecoregions in the South American Southern Cone from 1999 to 2019. Specifically, we use Landsat-based datasets at 30 m spatial resolution of enhanced vegetation index (EVI2), land cover change and fractional cover of bare ground, woody, and herbaceous vegetation within the Land Degradation Neutrality framework as part of SDG 15.3. Our results demonstrate widespread degradation across the subcontinent as well as extensive areas with signs of early decline. Decline in the Dry Chaco and Atlantic Forest is due to conversation of forests for commodity crop agriculture and pasturelands. In the savannas of Uruguay and Mesopotamia in northeastern Argentina, on the other hand, decline is the result of industrial scale pine and eucalyptus plantations. Lastly, arid and semi-arid ecoregions (i.e., Patagonia and Low Monte), which are the least resistant and resilient to climate and land use disturbances, show significant areas of both desertification and woody encroachment. We compare our results against those generated using Trends.Earth, a Conservation International platform for monitoring land degradation, which uses satellite observations at 250 m spatial resolution. Our results, with improved spatial and thematic detail, provide a more nuanced characterization of degradation for the subcontinent, including early signs of decline in addition to areas that have already been degraded. Monitoring the decline and productivity of land, as part of the 2030 Agenda for Sustainable Development, is necessary for assessing the provisioning of ecosystem services, ensuring food security, and increasing the resilience of land systems to the joint stresses imposed by climate change and a growing world population.