Nowadays, urban sprawl is generating nuisances: the increase of artificial surfaces to the detriment of natural surfaces has consequences on urban environment quality (urban heat island, pollution'), but also on the energy consumption. With the increase of urban population it is necessary to find compromises. In the project VegDUD, vegetation is observed as one of the possible solutions for the sustainable development of cities. - Practices : What are the traditional and novel practices of the urban vegetation ? How interesting are they from the climatic and urban points of view ? How can we formalize the overall (environmental, social, economical) assessment of these practices ? The urban vegetation TYPOLOGIE task group will construct a pluridisciplinary documentation of vegetation set-ups and of their characteristics to answer these first questions. - Instrumentation : Do we know how to quantify the various impacts of vegetation set-ups on the environment ? How much do the increase of artificial surfaces modify these impacts ? What are the best spatial and temporal scales to assess these vegetal techniques ? MODELISATION task group will implement urban vegetation representations in climatology, hydrology, sound propagation, and building energy models. Several scales will be considered, from the architectural scale up to that of the city. It will be completed by an EXPERIMENTATION task group where suited measurement techniques will be implemented to understand the physical processes generated by the vegetation. Experimental campaigns will allow validating the models developed in MODELISATION tasks. - Urban vegetation modeling : What are the techniques allowing to rapidly acquire a sufficient understanding of urban vegetation presence at a large scale ? How can we build numerical models rendering the building-vegetation interactions in the actual city and in the extrapolations of the future city ? How can we construct realistic scenarios allowing to help taking policy decisions or to propose solutions adapted to a sustainable urban development ? To answer this new domain of questions, the PHYSIOGRAPHIE task group will set a GIS based on the typology constructed in the TYPOLOGIE tasks. This GIS will incorporate the new understandings and the alternative scenarios. It will propose simulations and applications to a urban development model including vegetation. Vice versa, it will also allow to integrate and display the simulation results. - Vegetation impact assessment : With which criteria, at which spatial and temporal scales, can we compare the impacts of the various vegetation implantation techniques (vegetal roofs, micro hanging gardens, porous parking lots, filtering roadways, urban lagoons, urban rivers) ? What is the method for an overall assessment ? Can we identify a typo-genealogy of vegetal ambiences in relation with climatic, perceptive, and societal characteristics ? - Retrospective analysis and anticipation : What will be the long term impacts of the actual policies ? What are the possible alternatives ? What is the best vegetation effort with respect to ambience, energy, hydrology stakes ? Can we imagine the urban vegetation as an appropriable space, adapted to the cultural organization of each society ? We will answer these questions in two task groups, EvalPRIV and EvalCOLL, which separate the private use (gardens, architectural set-ups) and the collective use (public gardens, parks) of urban vegetation. In each of these two tasks we will consider the questions of retrospective and prospective analyses. These tasks rely mainly on comparative simulations with the models developed within MODELISATION. The set-ups will be first individually assessed for their small scale impacts, then large scale projections of the most interesting ones will be analyzed. The assessments will not be limited to the physical roles of vegetation, they will integrate the economical constraints, the sensible aspects and the usages of vegetation. Indeed, the sustainable development planning of a vegetation development in an urban site can be isolated neither from the built environment where the citizens will live, nor from the pluri-sensory experience of the users. The final objective of these assessments is to complete the vegetation typology to propose an operational tool allowing to orientate a climatic policy of the urban vegetation.