The TERRA approaches to unravel the interactions between the geo- and the biosphere in a changing world

Interactions between the living and non-living components of the Earth system—the biosphere and the geosphere—are the prerequisites for a habitable planet and provide the resources required by humans. Although the scale of anthropogenic global change is unprecedented, the fundamental laws of nature governing the responses of the geo- and biosphere remain unchanged. The TERRA Cluster of Excellence will investigate how geo-biosphere interactions respond to and influence environmental change. TERRA tests the hypothesis of whether the geosphere’s diversity stabilizes the biosphere and, vice versa, whether biodiversity stabilizes the geosphere – and asks: if this is the case, how? To target this challenge, one primary goal of TERRA will be to generate a discipline-overarching concept on system’s stability, applicable to the geo- and the biosphere, to quantitatively integrate the stability concept into predictive models. Based on that, the quantitative description of diversity-stability interrelationship within and across spheres is the overarching goal of TERRA.TERRA’s four research themes are organized along the continuum of different temporal and spatial scales. Theme 1 “Geo-Biosphere Interactions in the Geological Past” involves investigations at sites where high-fidelity records of past geo-biosphere interactions are well preserved across key time intervals. In one project, we will focus on the paleo-biodiversity hotspot at the Miocene site Hammerschmiede in Southern Germany. Understanding past Geo-Biosphere Interactions provides the baseline of geo-biosphere interactions without anthropogenic influence, and thus a foundation for identifying and quantifying anthropogenic impacts under contemporary and future conditions.Theme 2 “Large-Scale Contemporary Geo-Biosphere Interactions” develops a process-based understanding of present-day geo-biosphere interactions on spatial scales on which experimental manipulation is impossible. In our initial projects we aim to disentangle Geo-Biosphere Feedbacks in the FynBOS biome, a mediterranean biodiversity hotspot, and will assess how anthropogenically-enhanced species invasion can be analyzed as “local experiments” to understand self-organizational patterns in novel ecosystems.Theme 3 focuses on “Small-Scale Contemporary Geo-Biosphere Interactions” to provide mechanistic understanding of feedbacks between the geo and the biosphere on scales small enough to allow well-controlled experiments (µm to 100 m). The central field plots of our Diversitorium infrastructure form a large geodiversity manipulation experiment, modulating mineralogy, texture and climate variability independently. We will, in first projects, also investigate sites with high spatial geological heterogeneity, such as Alpine peatlands, to assess how geodiversity shapes geo-bio-systems and their stability.Across scales, Theme 4 “Geo-Biosphere Interactions in the Future” shall build and investigate future scenarios based on observational, experimental, and modeling results, guided by the principle of ’past extremes informing the future’. Using machine learning, climate and vegetation modelling, we aim to advance our understanding of past and present vegetation changes identifying the underlying complex and cascading series of biosphere-geosphere feedbacks. Model-based comparison of past and present Earth-System states allows deciphering systematic differences between dynamics under natural conditions and anthropogenic