The functional dimension of geodiversity: geo-ecosystem services assessment for sustainable land-planning in French Guiana

Managing a space and its resources is strictly related to the destination and human and/or ecological needs  that such resources should satisfy. Therefore, land planning might not only imply conservation perspectives but also the transformation, exploitation or even the destruction of such resources.

This is particularly true for some abiotic (lithified and unlithified resources, paleontological and mineral resources) and interfacial resources (soil resources), which are sometimes neglected by land planning processes that focus mainly on biotic resources or on biotic and abiotic water-related dynamics.

For such reasons, over the years, geodiversity assessment studies have been increasingly performed in different regions and at different spatial extents. Indeed, as operational concept, geodiversity implies a measurement and its application is narrowed to a given spatial area, allowing the identification of clusters for prioritization and planning purposes.

Nevertheless, previous geodiversity assessment studies suggested that the assessment of the variation—in number and types – of geodiversity entities  (i.e. geotaxa) cannot be, alone, always the only useful support for land planning and/or geoconservation perspectives, particularly when aggregating at larger spatial extents. Geodiversity research should imply as well the assessment of “geofunctionality”, defined as the contribution of geodiversity to socio-ecological functioning and, for instance, in terms of geo-ecosystem services, to human well-being. Indeed, an ecosystem service approach could provide more accurate information about the existence of provisioning, regulating, and cultural benefits supplied by underlying geodiversity processes and the corresponding demand for these services within the socio-ecological system.

The objective of this paper is to present a study involving the assessment of geo-ecosystem services supplied by geodiversity in French Guiana, an Overseas French Territory located in South America, between Suriname and Brazil. Provisioning (e.g. raw materials supply), regulating (e.g. natural habitat regulation) and cultural (e.g. geotourism and geoheritage) services were identified, assessed and mapped at the territory level using an indicator-based approach.

Difference maps were obtained in order to compare the relationship between the levels of the three geo-ecosystem services and a geodiversity index previously assessed in the region by past studies. As observed through the example of French Guiana, geodiversity and geofunctionality might not have always a systematic relationship and geodiversity assessment alone might mislead the development of pertinent sustainable strategies for urban, agricultural and mining planning.

However, these results raise some concerns related, first of all, on the lack of available data on the studied area (for example, soil-related data) which does not allow an exhaustive evaluation of geodiversity. Furthermore, it is essential to distinguish geofunctionality, as the capability of the territory to offer multiple services, from the actual contributions supplied by geodiversity processes and functions to human well-being.