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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - BIODESERT (Biological feedbacks and ecosystem resilience under global change: a new perspective on dryland desertification)

Teaser

Summary

Changes in climate and land use (e.g., increased grazing pressure), are two main global environmental change and desertification drivers. Understanding how drylands (arid, semi-arid and dry-subhumid areas) will respond to them is crucial because they cover 45% of the worldâ€™s land surface and host over 38% of the human population. Drylands are also of paramount importance for biodiversity, as they host many endemic plant and animal species, and include about 20% of the major centers of global plant diversity and over 30% of the designated endemic bird areas.

Using a combination of field observations of dryland ecosystems gathered around the world, satellite data, experiments conducted under controlled conditions and mathematical modeling, the ERC-funded BIODESERT project aims to: 1) test how changes in climate and grazing pressure determine spatio-temporal patterns in ecosystem functioning in global drylands, 2) assess how attributes of biological communities, such as biodiversity, modulate ecosystem resilience (i.e. their ability to respond to and recover from disturbances) to climate change and grazing pressure at various spatial scales (from local to global), 3) test and develop early warning indicators of desertification, and 4) forecast the onset of desertification and its ecological consequences under different climate and grazing scenarios.

Because of the extent of dryland ecosystems globally, and the dependence of an important part of the worldÂ´s population on them, it is crucial to better understand how the provision of ecosystem services by drylands, which his strongly linked to ecosystem functions such as biomass production and nutrient cycling, is being affected by climate change and desertification. Land degradation in drylands already affects ~250 million people in the developing world, a number that is likely to increase as a consequence to climate change and human population growth. The topics being addressed by BIODESERT are thus of major societal importance, as the knowledge generated by the project can help to improve human livelihoods in drylands worldwide, and by doing so to safeguard the sustainability of our planet.

Work performed

The BIODESERT research team, together with an international network of more than 60 collaborators working in all continents except Anctarctica, is carrying out the first global field survey aiming to evaluate how joint changes in aridity and grazing pressure affect ecosystem structure and functioning in drylands. So far, we have already surveyed according to a standardized field protocol more than 300 field plots in 25 countries from six continents (Argelia, Argentina, Australia, Botswana, Brazil, Canada, China, Chile, Ecuador, Hungary, Iran, Israel, Kazakhstan, Kenya, Mexico, Mongolia, Namibia, Palestine, Peru, Portugal, South Africa, Spain, Tunisia, USA and Venezuela), and additional surveys are underway in Niger, Morocco and Portugal. These surveys have generated more than 16000 soil and plant tissue samples, which are being analyzed in the laboratories of the host institution by the BIODESERT research team. In addition to this global field survey, we have been/are conducting different experiments under controlled conditions, and are developing conceptual, analytical and modelling approaches to achieve the objectives of the project.

The work conducted to date includes testing key ecological questions related to the objectives of the project, such as the â€œinsurance hypothesisâ€, which states that biodiversity can increase ecosystem stability (i.e. the capacity of ecosystems to not experience unexpected large changes in its characteristics across time). Recent experiments suggest that climate change can impact how biodiversity influences ecosystem stability, but most evidence of the biodiversityâ€“stability relationship obtained to date comes from local studies performed under a limited set of climatic conditions and in ecosystems other than drylands. In a recent study conducted under BIODESERT and published in PNAS (GarcÃa-Palacios et al., doi: www.pnas.org/cgi/doi/10.1073/pnas.1800425115), the relationship between biodiversity and ecosystem stability was examined for the first time in natural ecosystems at the global scale, rather than in small-scale, controlled studies. We coupled 14 years of temporal remote sensing measurements of plant biomass with field surveys of diversity in 123 dryland ecosystems from all continents except Antarctica to show a strong climate dependency of the biodiversityâ€“ecosystem stability relationship. Our findings suggest that land management should be adapted to the aridity conditions if we aim to secure stable plant production. For instance, promoting higher species richness may represent a simple yet effective strategy to stabilize plant biomass over time in the face of the increasing aridity forecasted for drylands worldwide.

Final results

The global field survey that we are establishing as part of BIODESERT is going beyond the state of the art in terms of its global coverage, number of field sites surveyed, plant/soil samples being collected and amount of data being generated. This unique survey and the data it is generating will allow us to test multiple questions at the edge of multiple research fronts, including community/ecosystem ecology, global change biology and desertification.

We expect that the data that will be generated within BIODESERT will provide a mechanistic understanding on the processes driving the capacity of ecosystems to maintain multiple functions simultaneously, known as â€˜multifunctionalityâ€™, under different global change scenarios, as well as key insights to forecast future scenarios for the provisioning of ecosystem services in drylands, and to test and develop early warning indicators of desertification. This is of major importance to attain global sustainability and key Millennium Development Goals, such as the eradication of poverty.