Functional Ecology

Home EF

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 :

  • Vallet L, Schwartz M, Ciais P, van Wees D, de Truchis A, Mouillot F. 2023. High-resolution data reveal a surge of biomass loss from temperate and Atlantic pine forests, contextualizing the 2022 fire season distinctiveness in France. Biogeosciences, 20, 3803-3825DOI: 10.5194/bg-20-3803-2023

 

Abstract

The frequency and intensity of summer droughts and heat waves in Western Europe have been increasing, raising concerns about the emergence of fire hazard in less fire-prone areas. This exposure of old-growth forests hosting unadapted tree species may cause disproportionately large biomass losses compared to those observed in frequently burned Mediterranean ecosystems. Therefore, analyzing fire seasons from the perspective of exposed burned areas alone is insufficient; we must also consider impacts on biomass loss. In this study, we focus on the exceptional 2022 summer fire season in France and use very high-resolution (10 m) satellite data to calculate the burned area, tree height at the national level, and subsequent ecological impact based on biomass loss during fires. Our high-resolution semi-automated detection estimated 42 520 ha of burned area, compared to the 66 393 ha estimated by the European automated remote sensing detection system (EFFIS), including 48 330 ha actually occurring in forests. We show that Mediterranean forests had a lower biomass loss than in previous years, whereas there was a drastic increase in burned area and biomass loss over the Atlantic pine forests and temperate forests. High biomass losses in the Atlantic pine forests were driven by the large burned area (28 600 ha in 2022 vs. 494 ha yr−1 in 2006–2021 period) but mitigated by a low exposed tree biomass mostly located on intensive management areas. Conversely, biomass loss in temperate forests was abnormally high due to both a 15-fold increase in burned area compared to previous years (3300 ha in 2022 vs. 216 ha in the 2006–2021 period) and a high tree biomass of the forests which burned. Overall, the biomass loss (i.e., wood biomass dry weight) was 0.25 Mt in Mediterranean forests and shrublands, 1.74 Mt in the Atlantic pine forest, and 0.57 Mt in temperate forests, amounting to a total loss of 2.553 Mt, equivalent to a 17 % increase of the average natural mortality of all French forests, as reported by the national inventory. A comparison of biomass loss between our estimates and global biomass/burned areas data indicates that higher resolution improves the identification of small fire patches, reduces the commission errors with a more accurate delineation of the perimeter of each fire, and increases the biomass affected. This study paves the way for the development of low-latency, high-accuracy assessment of biomass losses and fire patch contours to deliver a more informative impact-based characterization of each fire year.

 

Link to the full article

 

Press release and discussions about the article:

 

Associated subject on soil smoldering: 

  • Vallet L, Abdallah C, Lavaux T, Joly L, Ramonet M, Ciais P, Lopez M, Xueref-Remy I, Mouillot F. 2023. Soil smoldering in temperate forests: a neglected contributor to fire carbon emissions revealed by atmospheric mixing ratios. EGUsphere preprint - LIEN