Towards a comprehensive geodiversity - biodiversity nexus in terrestrial ecosystems

Challenges related to global change require an integrated approach to managing highly complex natural systems on various scales. Biodiversity and geodiversity are key aspects of nature's diversity, which both interact with each other and affect the diversity of climatic conditions on different scales. In turn, they are affected by and influence the cultural diversity of human societies, in particular through land use. The natural provision of services is existential for humanity, but has long been taken for granted, and not economically valued. The consequences of climate change and biodiversity loss are severe for ecosystem functioning and services. The same applies to abiotic elements of nature, ranging from aquifers through landslides to chemical and physical changes in the atmosphere. Disciplinary barriers and specialization exist for good reasons, but the emerging challenges related to global changes, and the immense capability of Earth Observation, open up new scientific avenues. Powerful computing and data-analysis algorithms are important, but good science needs a sound conceptual and theoretical basis, and interdisciplinarity. Concepts linking geodiversity and biodiversity are urgently needed to guide this endeavour. Here, we compile and assess existing approaches, aiming to provide a comprehensive conceptual framework, including quantitative, qualitative, and functional characteristics of natural systems. Defining and classifying types of entities (e.g., organisms, minerals) and characterising differences (e.g., heterogeneity, change) at appropriate scales are central to the framework. We focus on functional diversity (contribution to fluxes of matter, energy, and information (e.g., genes, species performance)). In short, we work towards a full “geodiversity–biodiversity nexus”.