Probing the causes of ecosystem change
Satellite data has great potential for detecting changes in ecosystems. An EU-funded project is combining space and ground data to develop an innovative method of monitoring ecosystems, to give early warnings of ecosystem change and biodiversity loss.
© Stéphane Masclaux #62786737, 2019 source: stock.adobe.com
Our planet is undergoing fundamental changes in climate and land-use, but exactly what this means for biodiversity and the functioning of ecosystems is not fully understood. Today, we have multiple data streams that could help provide answers. However, there is a need to develop new methods of integrating this data to better understand how terrestrial ecosystems function.
The EU-funded BACI project is investigating the potential of combining data from European Space Agency (ESA) Sentinel satellites with ground-based observations to monitor ecosystems. It is developing a novel Biosphere-Atmosphere Change Index (BACI) to identify changes in ecosystem functions at an early stage.
The projects early warning system will be capable of automatically detecting critical transitions in ecosystems, and attributing them to either environmental or societal change. This will enable prompt and appropriate actions to address the degradation of ecosystem services and biodiversity loss.
BACI has shown how satellites provide added value in monitoring biodiversity and to measure the impact of extreme events, such as drought or heatwaves, on ecosystems. But we have also taken many conceptual steps into the future, says project manager Miguel Mahecha of the Max Planck Institute in Germany.
One example is that we have now reconstructed the global gross primary production, in terms of the uptake of CO2, for every half hour over more than a decade. We have also conducted special case studies on changes in vegetation states in protected areas.
The project brings together experts from many different disciplines, for example, from the fields of remote sensing and ecology, to translate space data into indicators of change for ecosystems.
A key advance has been the formulation of new Essential Ecosystem Variables (EEVs) to detect changes in ecosystem functioning. EEVs help monitor the planets fundamental feedback systems, such as the flux of heat from the Earth's surface to the atmosphere that is associated with evaporation or transpiration.
It's the fusion of different satellite data, climate data, and ground observations that enable us to make an accurate assessment of the processes of interest, says Mahecha.
Our results can be used to map ecosystem functions to continental scales, he explains. While data from satellites have great spatiotemporal coverage, they are typically hard to interpret. We offer ways to translate these data streams into units that can be directly interpreted.
The project team are validating their methods by focussing on several key regions in Europe and Africa. The goal is to identify hotspots of change, namely, the Boreal, Black Sea and Mediterranean regions, Western Africa, Horn of Africa, and South Africa. All of these regions are also undergoing major societal-ecological transformations. The project is disentangling climate-induced ecosystem changes and socio-economic/ecological transformation processes.
The automatic near real-time implementation of the projects algorithms and indicators, involving the integration of data from ESA Sentinels using state-of-the-art machine learning methods, requires a different way of thinking about the data.
One key issue is to change the paradigm of assessing one data set after the other for a specific problem, says Mahecha. We are in a difficult transition where the data processing paradigm is changing, from the idea of downloading and processing data at home, to data curated remotely and assessed via web interfaces. This leads to friction, as it remains unclear where the future really is in terms of data hosting. Every researcher today has to rethink their way of working in the coming years.