Research activities

The understanding of the functional basis of how organisms interact with each other and with their environment is a key research objective of our department. Trait approaches are used to characterize functional community structure, to quantify the effects of organisms on ecosystem functioning, and for the parameterization of models on species distribution and ecosystem carbon and water balance. A particularly strong research focus lies on the impact of global change factors such as increasing drought and land use change on biodiversity and ecosystem processes. Using field and laboratory experiments and modeling approaches, we study mainly terrestrial ecosystems with a focus on Mediterranean systems, but also including tropical ecosystems mainly in South America, and temperate and alpine ecosystems.

Head of the department: Stephan HÄTTENSCHWILER

Key words

Biogeochemical cycles | Climate change | Community structure | Functional diversity | Functional traits | Global change | Mechanistic modelling | Mediterranean ecosystems | Plant-soil interactions | Soil ecology | Terrestrial ecosystems | Water relations

New publication :

• Lucie Mahaut, Philippe Choler, Pierre Denelle, Eric Garnier, Wilfried Thuiller, Jens Kattge, Servane Lemauviel-Lavenant, Sandra Lavorel, François Munoz, Delphine Renard, Josep M. Seera-Diaz, Nicolas Viovy & Cyrille Violle 2023. Trade-offs and synergies between ecosystem productivity and stability in temperate grasslands. Global Ecology and Biogeography, DOI: 10.1111/geb.13645
  
  

Abstract

It is crucial to monitor how the productivity of grasslands varies with its temporal stability for management of these ecosystems. However, identifying the direction of the productivity–stability relationship remains challenging because ecological stability has multiple components that can display neutral, positive or negative covariations. Furthermore, evidence suggests that the direction of the productivity–stability relationship depends on the biotic interactions and abiotic conditions that underlie ecosystem productivity and stability. We decipher the relationships between grassland productivity and two components of its stability in four habitat types with contrasting environments and flora.

We used c. 20,000 vegetation plots spread across French permanent grasslands and remotely sensed vegetation indices to quantify grassland productivity and temporal stability. We decomposed stability into constancy (i.e., temporal invariability) and resistance (i.e., maximum deviation from average) and deciphered the direct and indirect effects of abiotic (namely growing season length and nitrogen input) and biotic (namely plant taxonomic diversity, trait diversity and community-weighted mean traits) factors on productivity–stability relationships using structural equation models.

We found a positive relationship between productivity and constancy and a negative relationship between productivity and resistance in all habitats. Abiotic factors had stronger effects on productivity and stability compared with biotic factors. A longer growing season enhanced grassland productivity and constancy. Nitrogen input had positive and negative effects on grassland productivity and resistance, respectively. Trait values affected the constancy and resistance of grassland more than taxonomic and trait diversity, with effects varying from one habitat to another. Productivity was not related to any biotic factor.

Our findings reveal how vital it is to consider both the multiple components of stability and the interaction between environment and biodiversity to gain an understanding of the relationships between productivity and stability in real-world ecosystems, which is a crucial step for sustainable grassland management.

Link to the full article