Tropical Forests: Costa Rican Ecosystem Extent Demonstrator

Forests, which span approximately 30% of the Earth’s land surface, play a crucial role in sustaining life and regulating the climate by acting as natural carbon sinks. However, they are often undervalued, increasing their susceptibility to deforestation and degradation, which causes approximately ten percent of global warming. Forest cover continues to decline globally, with 28.3 million hectares lost in 2023. The tropics in particular lost 11.1 million hectares of tree cover according to the Global Forest Watch. Tropical forests are of particular significance as they represent 96% of the world’s deforestation, which has massive impacts on biodiversity and carbon storage.

The 15th meeting of the Conference of the Parties (COP15) under the Convention on Biological Diversity (CDBD) in 2022 saw the international adoption of the Kunming-Montreal Global Biodiversity Framework (GBF), which contains four goals for 2050 and 23 targets for 2030. Target 3 calls for conserving 30% of Land, Waters and Seas, and a vital measure to pursue this is to accurately determine the locations and conditions of ecosystems around the globe.

While Costa Rica makes up only 0.3% of the globe’s surface area, the country contains nearly six percent of the world’s biodiversity. Much of this biodiversity is contained within the country’s rich tropical forests, which are being mapped and assessed through a demonstrator project of the CEOS Ecosystem Extent Task Team (EETT). Supported by CNES and France’s National Research Institute for Agriculture, Food and Environment (INRAE), the objective is to map Costa Rica’s forested ecosystems and their conditions and to assess the conservation potential of secondary forests in human-modified tropical landscapes. The project commenced in mid-2023 and will continue for at least two more years, aiming to investigate the suitability of multi-modal satellite data for forest ecosystem extent mapping.

These outputs will be used for essential biodiversity variable (EBV) assessment, and to understand whether the conservation potential of forests can be assessed directly and indirectly from remote sensing information. Providing the complexity of species in tropical forests, a hierarchical clustering followed by an interaction network analysis was performed to understand interactions between species, making it possible to visualize and analyze complex spatio-ecological systems as a whole from individual interactions to local and global biogeographical properties. Five clusters were identified and validated based on field data (see map). 

The Costa Rican demonstrator builds on existing Essential Biodiversity Variables (EBVs) efforts by working with in situ and remote sensing measurements. Key questions of the project include:

• How can forest ecosystem extent mapping be operationalised to assess a set of biodiversity indicators (RS-EBV’s)?
• Can the conservation potential of forests be assessed using information from multi-sensor satellite imagery?
• Can we assess the conservation potential of forest ecosystems based on the mapping of β diversity predicted directly and indirectly from spectral information?

The project benefits national institutional synergies, including the SINAC (Programa REDD / CCAD-GIZ – SINAC, 2015) and the institutions within the OEFo network (https://onfcr.org/bosques-ticos-seran-monitoreados-por-el-observator). These organizations provide field data from a forest inventory containing 364 plots with 58,773 trees and 1,333 species.

Copernicus multitemporal Sentinel-2 imagery is analysed using biodivMapR package, which enables the creation of diversity maps of Beta diversity based on spectral information.

The project successfully developed and implemented an Open Data Cube (ODC) platform, establishing infrastructure for other users through the National Portal (THEIA, France). This infrastructure, based on the STAC (Spatio Temporal Asset Catalog) specification, has been deployed throughout Costa Rica, enabling full exploration of environmental data. The collections are now available via the STAC API hosted by the Theia Data Centre in Montpellier, France. Different spectral vegetative pixel-wise indices can be calculated for the dry and wet seasons pulling in data via the STAC catalog. Beta diversity helps to understand the differences in species composition between different locations, reflecting the spatial variation in biodiversity.

The follow-up work will expand the data cube technology to enable fusion of different sensors (Sentinel-1,-2, and potentially Radarsat-2), GEDI, and work on different biodiversity classification outputs including ecosystem conditions and functional traits.

The broader conservation aims of the demonstrator project relate to previous and existing efforts such as the Global Forest Observations Initiative (GFOI) and Global Forest Watch (GFW), which aim to monitor global forests and support the reduction of greenhouse gas emissions from the forestry and land use sectors. The project is oriented to support monitoring following the CBD 2030 needs.  GFOI also supports forest monitoring systems, which are essential for effective reporting to climate change agreements, by ensuring the sustained availability of satellite data and guidance for using it.

The CEOS EETT Costa Rica demonstrator project is supported by the CNES-INRAE team: Sandra Luque, Mairi Souza-Oiveira, Mona Bonnier, Remi Cresson, Florian de Boissieu, Samuel Alleaume, Maxime Lenormand, Jean Baptiste Feret.