Benjamin Misteli

Wetland restoration is increasingly recognized as a nature-based climate solution, but effective planning requires balancing nonlinear ecological responses with economic and implementation constraints. We propose a conceptual and computational framework for climate-oriented coastal wetland restoration that embeds process-based ecosystem modeling within restoration optimization. Restoration strategies are represented as portfolios combining discrete intervention choices with continuous decisions on implementation intensity and spatial allocation. A vertically resolved ecohydrological model simulates soil organic carbon dynamics and decomposition-driven CO$_2$ and CH$_4$ emissions, allowing environmental outcomes to arise from the interaction between restoration decisions and ecosystem processes.The framework is illustrated through a benchmark analysis and an application to the Ebro Delta. The benchmark shows that alternative objective specifications select distinct interior and corner solutions from the same ecological trade-off. In the Ebro Delta application, imposing a budget constraint reallocates restored area from the deep-rooted vegetation type toward the less expensive shallow-rooted type, while maintaining high vegetation densities and compliance with the methane target, although the CO$_2$ target is exceeded. Global sensitivity analysis identifies the density and spatial allocation of the deep-rooted vegetation type as the main drivers of restoration performance.The results show that restoration outcomes depend not only on total vegetation cover but also on portfolio composition and implementation intensity. The proposed framework provides a flexible methodology for integrating process-based ecological models into restoration planning under alternative environmental objectives and resource constraints.

Accurate quantification of greenhouse gas (GHG) fluxes from aquatic systems is essential for constraining regional and global carbon budgets. Closed floating chambers are widely used to measure carbon dioxide (CO ₂ ) and methane (CH ₄ ) fluxes at the water–air interface, yet large uncertainties persist due to subjective processing of chamber time series. In particular, the treatment of nonlinear patterns and abrupt events such as ebullition often relies on expert judgment, which may strongly influence flux estimates. We present the first quantitative assessment of bias arising from expert subjectivity in the processing of floating chamber measurements. Seventeen researchers, all of whom participated in field sampling, independently evaluated a common dataset of 794 incubations from 36 European coastal wetlands. Each expert visually selected valid data segments and flagged abnormal time series prior to flux calculation. In total, 2679 manual inspections were compared with fully automated flux estimates based on untrimmed time series. Experts showed substantial variability in flagging abnormal measurements and handling nonlinear or irregular concentration patterns. While flux variability was generally low for most CO ₂ and CH ₄ incubations, disagreements exceeded 100% for curved or temporally complex time series. For CH ₄ , ebullition was a major source of divergence, but marked variability also occurred when ebullition contributed only marginally to total fluxes. This methodological experiment demonstrates that expert judgment introduces significant, previously unquantified uncertainty into aquatic GHG flux estimates. We advocate for transparent, standardized, and reproducible data‐processing workflows, including automated tools for objective identification and treatment of nonlinearities.

Le rôle structurant des macrophytes sur les communautés aquatiques : une approche internationale et multi groupes: Les proliférations végétales sont une source majeure de préoccupations pour les gestionnaires. Les herbiers denses de macrophytes peuvent entraver les activités humaines telles que la navigation de plaisance, la pêche, etc. Afin de limiter ces nuisances, l’arrachage mécanique est la mesure de gestion généralement utilisée. Néanmoins, ces herbiers aquatiques constituent des habitats pour la faune et un potentiel support de biodiversité. Les effets des herbiers denses de macrophytes et de leur arrachage sur la biodiversité ne sont pas clairement connus. Nous supposons que les herbiers denses de macrophytes ont un impact positif sur la richesse et l'abondance du zooplancton, du phytoplancton et des macroinvertébrés. Ainsi, notre hypothèse est que l’arrachage réduise la biodiversité dans les sites gérés. Nos résultats ont démontré que la présence des herbiers de macrophytes est favorable à la biodiversité et ce pour les trois groupes étudiés. Toutefois l’effet est site dépendant. Nous avons mis en évidence par ailleurs qu’une pression d'échantillonnage plus importante est nécessaire au sein des herbiers par comparaison avec l’eau libre. Nous avons également établi que le zooplancton est influencé par la présence de plantes mais que l’effet varie en fonction du type biologique de l’espèce de macrophyte. L' arrachage mécanique des macrophytes affecte négativement la biodiversité globale, en particulier le zooplancton et les assemblages de macroinvertébrés. En revanche, il a un effet positif sur le phytoplancton. L’impact de l’arrachage sur les communautés est plus marqué une semaine après mais diminue avec le temps. Il est également site dépendant. Cette thèse souligne l'importance de considérer les impacts de la gestion sur les services écosystémiques (rôle d’habitat) et sur la biodiversité dans le cadre du développement durable.

Coastal wetland restoration is widely promoted as a tool for climate change mitigation, but its effect on the carbon cycle is not well constrained. We conducted a systematic review and meta-analysis of peer-reviewed field studies that directly contrasted restored with altered sites, covering carbon stocks and greenhouse gas fluxes across mangroves, saltmarshes, seagrass meadows, brackish systems, and coastal freshwater wetlands. Literature searches yielded 66 studies and 257 pairwise restored versus altered site comparisons. Multilevel random-effects models with nested study effects showed significant increases after restoration in soil carbon, aboveground biomass, and belowground biomass. Mean greenhouse gas flux changes after restoration were non-significant for CO₂, CH₄, and N₂O. Meta-regressions detected no significant differences among wetland types, though this result is constrained by unbalanced evidence across systems and studied parameters. The available data are geographically biased toward tropical and subtropical Asia, with minimal coverage in Africa and limited data from temperate and cold coastal regions. Among the covered variables dissolved organic carbon is critically underrepresented, constraining whole-system impact estimates. Overall, the data examined in this study show that restoration consistently rebuilds biomass and soil carbon without a detectable systematic “cost” from methane or nitrous oxide, indicating positive outcomes for greenhouse gas fluxes. To translate these findings into policy-ready estimates, monitoring of greenhouse gases and dissolved organic carbon should be expanded, altered versus restored designs should be prioritized, and underrepresented regions and wetland types should be targeted.

Changing weather patterns and receding glaciers are predicted to increase flow intermittency in alpine streams. If aquatic macroinvertebrate communities largely comprise taxa adapted to perennial flows, an increase in flow intermittency substantially reduces biodiversity and affects functional processes. We conducted a before-after-control-impact field experiment to examine how macroinvertebrate communities in an alpine headwater stream responded to and recovered from a repeated experimental increase in flow intermittency. Flow in one channel was manipulated to simulate increased summer intermittency (June–September) over two consecutive years, whilst an adjacent channel served as a control. We monitored the density of benthic macroinvertebrates, periphyton and organic matter at approximately monthly intervals over three years during the snow-free period. Before manipulation, both channels had similar ecological properties. The flow manipulation reduced the overall macroinvertebrate density, and especially the proportional rheophile density, across both years. Recovery of the macroinvertebrate community following experimental flow intermittency took more than a year, and longer than our study period. This could be due to long aquatic life stages, dispersal limitation and biotic interactions. We conclude that climate-induced changes in alpine stream flow regimes can lead to a fundamental shift in macroinvertebrate assemblages through local extinctions, mostly of rheophilic species.