Studies have demonstrated a relationship between plant species diversity within urban green spaces (UGS) and psychological restoration of visitors. However, the majority of "non ecologist" visitors are not able to perceive all the different plant species present within UGS. More work is thus needed to explore and better understand the underlying processes of this relationship. Recent studies have suggested that "non ecologist" visitors are able to perceive landscape heterogeneity within UGS, which is related to species diversity based on landscape ecology theories. The goal of this study was to test whether landscape heterogeneity can begin to elucidate the relationship between species diversity within UGS and psychological restoration of visitors. Within 13 UGS in Rennes (France) we tested if relationships can be established between i) measured landscape heterogeneity, ii) landscape heterogeneity perceived by visitors, and iii) psychological restoration of visitors. We measured landscape heterogeneity using different landscape-level metrics, and quantified psychological restoration and perception of landscape heterogeneity of 390 visitors using in situ questionnaires. Our results evidenced that within UGS visitors are able to perceive landscape compositional and configurational heterogeneity, and that they gain psychological restoration from landscape configurational heterogeneity. We advise that enhancing landscape configurational heterogeneity within UGS could help designers and managers increase both their environmental and social benefits.

Dans un contexte de rationalisation économique et de modernisation technique des services urbains, la gestion des services d'eau est un enjeu politique non négligeable tant il met en oeuvre des processus d'arbitrages entre acteurs différenciés issus des sphères politiques, des services techniques des collectivités, comme du monde économique et de la société civile. À l'échelle des agglomérations, les processus actuellement à l'oeuvre peuvent être interprétés sous l'angle des régimes urbains dans lesquels des intérêts différents et dispersés trouvent à s'entendre dans une gouvernance hybride et par le biais d'échanges de ressources. L'article s'intéresse ainsi aux services d'eau comme levier de capacité politique en ciblant les Communautés urbaines et d'agglomération en France. Ces Communautés constituent en effet des terrains d'investigation et des scènes d'émergence de la capacité politique locale. Mais cette émergence s'opère dans des configurations plurielles plus ou moins stabilisées, pour lesquelles les outils stratégiques de planification et les effets du leadership institutionnel peuvent constituer des leviers de cohésion.

Water quality standards (QS) and river monitoring are widely accepted as preventive management strategies for the preservation of watercourses and at the same time they are criticized for imposing universal threshold values, leading to regulatory rather than voluntary action. Based on the example of nitrate, the article explains how QS applications are the result of national or regional negotiations, with no direct link to the scientific foundations underlying the development of these tools. These conflicting perceptions and how these tools are actually used are illustrated by the situation in Brittany. Here, the monitoring network and actions to prevent increasing nitrate concentrations in rivers form part of regional programs set up jointly by all the main stakeholders. However, while QS can act as an alarm signal, their effectiveness depends on local political support, which depends on the extent to which river quality is recognized as a key factor in regional development.

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