Évaluer, restaurer, comprendre : comprendre pour évaluer et restaurer, restaurer et évaluer pour mieux comptrendre

Écologie-éthologi

Influence de la nature et de la fréquence des perturbations sur les banques de diaspores dans les communautés végétales aquatiques

L'objectif de ce travail a été d'évaluer l'effet de la nature et de la fréquence des perturbations sur les stratégies de régénération des végétaux aquatiques, et sur leur degré d'implication probable dans le maintien des communautés végétales dans les zones humides fluviales. La quantification de la banque de diaspores et de la végétion établie a été réalisée 1) dans des bras morts soumis à des perturbations de nature différente (crue décapantes ou exondations, 2) dans une zone humide soumise à une perturbation nouvelle (restauration) et 3) dans des zones humides réparties sur un gradient de connectivité avec le cours actif. Ces expériences ont permis d'aboutir aux conclusions suivantes : - Les stratégies de régénération mises en oeuvre par des végétaux aquatiques sont dépendantes de la nature de la perturbation (crue vs. exondation). -La superposition de deux régimes de perturbation sélectionne d des traits différents de ceux favorisés par l'une ou l'autre des perturbations. - Une perturbation nouvelle pour l'écosystème (restauration de conditions aquatiques permanentes par dragage ses sédiments) entraîne une augmentation de la densité de diaspores dans la banque, mais la génération de la communauté repose principalement sur des rhizomes et des fragments végétatifs. Les zones humides les moins fréquemment connectées au cours actif sont caractérisées par la présence d'une banque persistante d'origine endogène. La plus forte densité de la banque et la plus forte liaison entre la banque et la végétation établie sont rencontrées dans les zones humides à niveau de connectivité intermédiaire. Les zones humides les plus connectées sont caractérisées par une banque de diaspores participant peu à la végétation établie, et donc vraisemblablement d'origine exogène (dérive). Une forte connectivité en milieu péri-fluvial est souvent associée à un régime de perturbations. Connectivité et perturbations contrôlent conjointement la composition de la banque de diaspores et ses relations avec la végétation établie.LYON1-BU.Sciences (692662101) / SudocPARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Are Mechanical and Biological Techniques Efficient in Restoring Soil and Associated Biodiversity in a Brownfield Site?

Brownfield technosol restoration represents a real opportunity to minimize land consumption, but it often requires intensive intervention and reconstruction, leading to soil donor site destruction and potential pollution. Using a former oil refinery brownfield site, this research compares the short-term (one year) impact of localized restoration methods, including soil surface scarification, organic matter addition, earthworm inoculation (locally and commercially sourced), on the soil fauna and vegetation properties. Vegetation rapidly covered the bare soil, but few significant impacts were observed in terms of the soil or vegetation structure. The initial positive impact of soil scarification on surface compaction quickly faded and earthworm inoculations did not seem to impact soil characteristics. Natural soil colonization by vegetation or fauna was the major driver in soil modification. The analysis of an intermediate reference showed a delay of multiple decades between vegetation, fauna density, and soil structure improvement, as well as the achievement of a soil of “good biological quality”. We conclude that the use of engineer species on brownfield soil in its actual form is not an early restoration step but should be tested in later steps (e.g., when organic matter content is sufficient). However, additional research is needed in engineer species selection and multi-compartment approaches. A better understanding of the impacts of natural colonization in the early stages of technosol restoration is also essential for restoration techniques’ improvement

Are Mechanical and Biological Techniques Efficient in Restoring Soil and Associated Biodiversity in a Brownfield Site?

Brownfield technosol restoration represents a real opportunity to minimize land consumption, but it often requires intensive intervention and reconstruction, leading to soil donor site destruction and potential pollution. Using a former oil refinery brownfield site, this research compares the short-term (one year) impact of localized restoration methods, including soil surface scarification, organic matter addition, earthworm inoculation (locally and commercially sourced), on the soil fauna and vegetation properties. Vegetation rapidly covered the bare soil, but few significant impacts were observed in terms of the soil or vegetation structure. The initial positive impact of soil scarification on surface compaction quickly faded and earthworm inoculations did not seem to impact soil characteristics. Natural soil colonization by vegetation or fauna was the major driver in soil modification. The analysis of an intermediate reference showed a delay of multiple decades between vegetation, fauna density, and soil structure improvement, as well as the achievement of a soil of “good biological quality”. We conclude that the use of engineer species on brownfield soil in its actual form is not an early restoration step but should be tested in later steps (e.g., when organic matter content is sufficient). However, additional research is needed in engineer species selection and multi-compartment approaches. A better understanding of the impacts of natural colonization in the early stages of technosol restoration is also essential for restoration techniques’ improvement

Brownfields over the years: from definition to sustainable reuse

International audienceUrban development is often confronted with a lack of available space. Brownfield sites offer great potential for sustainable urban planning because of their often-central location and the benefits associated with their redevelopment. Although the interest in brownfield regeneration has led to a lot of research on this topic, there is not yet a comprehensive review of brownfield research. In this review, we analyze the research on brownfields and provide a picture of the published case studies. We focus primarily on brownfields research in the United States, Europe, and People’s Republic of China. This exploratory research is based on an analysis of the published scientific literature available in the Web of Science database. Initially used in North America, the term “brownfield” quickly became popular in the rest of the world, particularly in Europe. However, with the exception of the United States, there is no specific legislation for these sites; their protection is often based indirectly on directives or laws related to soil pollution, biodiversity, or the environment. The perception of the potential use of brownfield sites varies considerably from one part of the world to another, and international collaborations among researchers from different parts of the world remain limited. Most of the described reuses of brownfield sites are forms of soft reuse (53%), and the type of reuse of a site depends more on the surrounding urbanization levels and the specific region than on the past use of a brownfield site. Despite the continued interest in the rehabilitation of these sites, especially due to the increasing demand for nature in the city following the COVID-19 crisis, many questions regarding the future of brownfield sites remain unanswered. The factors influencing their successful redevelopment are unclear, and further research is urgently needed to ensure a truly sustainable re-use of these sites

Impact des activités anthropiques sur la dynamique et l état de conservation d un habitat naturel (exemple de la chenalisation des Rivières à renoncules (UE 3260))

La France doit évaluer l état de conservation de ses habitats naturels en réponse à la Directive Habitats. Nous avons donc regardé l impact de pressions type chenalisation, sur la physico-chimie et 3 communautés (oiseaux, plantes, invertébrés) de l habitat UE 3260, ou Rivières à Renoncules . 17 stations (6 contrôles/11 chenalisées) sur 4 rivières, ont été suivies saisonnièrement en 2006-07. La chenalisation conduit à des changements physiques de l habitat à plusieurs échelles spatiales : station, faciès (ex : radier, mouille) et microhabitat. Pour les 3 communautés, la richesse est plus faible en situation chenalisée. Les taxons dominants sont ubiquistes et résistants. La végétation est très informative car elle réagit aux 3 échelles. Les stratégies adaptatives des plantes sont plus variées dans les stations chenalisées à cause des modifications de dynamique de l habitat. Notre étude dégage les outils et mesures de gestion pour préserver l état de conservation de l habitat UE 3260.France must assess the state of conservation of its natural habitats in reply to Directive Habitats. We therefore looked at the impact of pressures such as channelization, on physico-chemistry and on 3 communities (birds, plants, invertebrates) of the habitat EU 3260, or Streams with Water Crowfoot . 17 reaches (6 control/11 channelized) in 4 rivers, were monitored seasonally in 2006-07. Channelization led to physical changes of the habitat in several spatial scales: reach, riffle-pool sequence, and microhabitat. For the 3 communities, richness was lower in channelized reaches than in control reaches. Dominant taxa were ubiquitous and resistant. Plants was an informative community because they reacted to the 3 spatial scales. Adaptive strategies of plant taxa were more diverse in channelized reaches due to the modifications of the dynamic of the EU 3260 habitat. Our study clears tools and measurements of management to preserve the state of conservation of the habitat EU 3260PARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF