CNRS Cities, Territories, Environment and Societies

Tours, France

CNRS Cities, Territories, Environment and Societies

Tours, France
SEARCH FILTERS
Time filter
Source Type

Bonthoux S.,French National Institute for Agricultural Research | Bonthoux S.,CNRS Cities, Territories, Environment and Societies | Baselga A.,University of Santiago de Compostela | Balent G.,French National Institute for Agricultural Research
PLoS ONE | Year: 2013

To predict the impact of environmental change on species distributions, it has been hypothesized that community-level models could give some benefits compared to species-level models. In this study we have assessed the performance of these two approaches. We surveyed 256 bird communities in an agricultural landscape in southwest France at the same locations in 1982 and 2007. We compared the ability of CQO (canonical quadratic ordination; a method of community-level GLM) and GLMs (generalized linear models) to i) explain species distributions in 1982 and ii) predict species distributions, community composition and species richness in 2007, after land cover change. Our results show that models accounting for shared patterns between species (CQO) slightly better explain the distribution of rare species than models that ignore them (GLMs). Conversely, the predictive performances were better for GLMs than for CQO. At the assemblage level, both CQO and GLMs overestimated species richness, compared with that actually observed in 2007, and projected community composition was only moderately similar to that observed in 2007. Species richness projections tended to be more accurate in sites where land cover change was more marked. In contrast, the composition projections tended to be less accurate in those sites. Both modelling approaches showed a similar but limited ability to predict species distribution and assemblage composition under conditions of land cover change. Our study supports the idea that our community-level model can improve understanding of rare species patterns but that species-level models can provide slightly more accurate predictions of species distributions. At the community level, the similar performance of both approaches for predicting patterns of assemblage variation suggests that species tend to respond individualistically or, alternatively, that our community model was unable to effectively account for the emergent community patterns. © 2013 Bonthoux et al.


Bonthoux S.,CNRS Cities, Territories, Environment and Societies | Balent G.,French National Institute for Agricultural Research
Ecological Complexity | Year: 2015

Metacommunity theory provides a framework to understand how ecological communities vary in space and time. However, few studies have investigated metacommunity processes in a context of long term changes. Environmental changes can impact species distribution and therefore the structure of metacommunities. Using two complementary methods, this study evaluated the temporal variability of bird metacommunity processes in an agricultural landscape after 25 years of changes in land-cover. Bird and landscape data were recorded in the same locations using a series of 256 point counts in 1982 and 2007. First, variance partitioning was applied to quantify the roles of environmental filtering (i.e. landscape composition variables) and spatial variables to organize bird metacommunities each year. Second, changes in the structure of the bird metacommunity were examined by quantifying three of its components: coherence, species turnover and species range boundary clumping. Our results demonstrate that landscape variables explained slightly more bird metacommunity patterns than spatial variation of unknown origin each year. The bird metacommunity had a Clementsian structure (i.e. grouped distribution of species along environmental gradients) which was correlated with a landscape gradient ranging from open farmland to wooded sites. This structure was similar each year. To conclude, the study shows that environmental filtering with specializations to different habitats is a major process in determining bird metacommunities in landscapes. Moreover, our results suggest that metacommunity structure can remain constant over time despite demographic and environmental changes. © 2015 Elsevier B.V.


Sheeren D.,National Polytechnic Institute of Toulouse | Sheeren D.,French National Institute for Agricultural Research | Bonthoux S.,French National Institute for Agricultural Research | Bonthoux S.,CNRS Cities, Territories, Environment and Societies | Balent G.,French National Institute for Agricultural Research
Ecological Indicators | Year: 2014

In this paper we assess the capacity of satellite images to explain and predict bird community patterns in farm-wood landscapes in southwestern France. Our goal is to examine the effect of the images' acquisition date and spatial resolution on the models' performance. We also seek to assess whether unclassified images provide results comparable with classified data (i.e. land-cover map). To do that we constructed species richness models (generalized additive models) based on a sample of 573 counting points and on non-classified images made up of NDVI data and digital height model (DHM), making it possible to quantify the spatial and vertical heterogeneity of habitats. To assess the acquisition date effect, we compared the performance of NDVI data acquired on four different dates (February 4th, June 24th, August 19th and October 18th, 2009) by the same sensor (SPOT-5). To assess the spatial resolution effect, we compared five NDVI images acquired over an identical period (September 2010) but by different sensors (WorldView-2, SPOT-5, SPOT-4, Landsat, MODIS) as well as two DHMs obtained from LiDAR (1 m) and radar (5 m) data. Our results show that for a constant spatial resolution (10 m) it is the NDVI data acquired at the beginning of the autumn that provide the best performance. These data better reveal the landscape requirements of birds during the breeding period. For a given period (September 2010), the higher resolution spatial data (2 m) are the highest performing. However, in view of the cost of WorldView images, we suggest that 10 m data (SPOT-5) provide a good trade-off for studying the distribution of bird communities. For the height data (DHM), the effect of the spatial resolution is not significant. The differences of performance between the spatial resolutions of NDVI data are not as great as those between the data acquisition periods. The performance of unclassified data (NDVI or DHM) is also comparable with that of land-cover maps. This suggests on the one hand that the choice of the NDVI image date is more important than that of the spatial resolution and on the other hand that the NDVI or DHM data are good alternatives to classified data when constructing a bird-habitat predictive model. © 2014 Elsevier Ltd.


Sellami H.,Catholic University of Leuven | La Jeunesse I.,CNRS Cities, Territories, Environment and Societies | La Jeunesse I.,French National Center for Scientific Research | Baghdadi N.,IRSTEA | Vanclooster M.,Catholic University of Leuven
Hydrology and Earth System Sciences | Year: 2014

In this study a method for propagating the hydrological model uncertainty in discharge predictions of ungauged Mediterranean catchments using a model parameter regionalization approach is presented. The method is developed and tested for the Thau catchment located in Southern France using the SWAT hydrological model. Regionalization of model parameters, based on physical similarity measured between gauged and ungauged catchment attributes, is a popular methodology for discharge prediction in ungauged basins, but it is often confronted with an arbitrary criterion for selecting the "behavioral" model parameter sets (Mps) at the gauged catchment. A more objective method is provided in this paper where the transferrable Mps are selected based on the similarity between the donor and the receptor catchments. In addition, the method allows propagating the modeling uncertainty while transferring the Mps to the ungauged catchments. Results indicate that physically similar catchments located within the same geographic and climatic region may exhibit similar hydrological behavior and can also be affected by similar model prediction uncertainty. Furthermore, the results suggest that model prediction uncertainty at the ungauged catchment increases as the dissimilarity between the donor and the receptor catchments increases. The methodology presented in this paper can be replicated and used in regionalization of any hydrological model parameters for estimating streamflow at ungauged catchment. © Author(s) 2014. CC Attribution 3.0 License.


Janeau J.L.,IRD Montpellier | Grellier S.,CNRS Cities, Territories, Environment and Societies | Podwojewski P.,IRD Montpellier
Hydrology Research | Year: 2015

Owing to their high water retention, the volcanic ash-soils of the Northern Andean highlands (páramos) can be considered as natural 'water storage tanks' for drinking water and for irrigation. Vegetation plays an important role in transferring rain to the soil and in controlling the soil water content. To assess this role, we quantified the stemflow process under rainfall simulations for seven of the main plants along an altitude gradient on the Pichincha volcano in Ecuador. The volume of water transferred into the soil was higher at the lower rainfall intensity than at the higher intensity. The results were compared to the stemflow measured with potato and maize crops growing in the lower altitude range. The results showed that the relative volume of stemflow increased with altitude from 8% in the crop area to 58% in the upper part of the catena. Low values of stemflow were associated with potatoes and maize annual short-cycle crops while high values were associated with the natural vegetation. For cultivated crops rainwater interception by stemflow delayed the soil surface crusting and runoff process. This study shows that rainwater interception by vegetation is of great importance for soil water recharge in these Andisols. © 2015 IWA Publishing.


Rufat S.,Cergy-Pontoise University | Ter Minassian H.,CNRS Cities, Territories, Environment and Societies | Coavoux S.,Ecole Normale Superieure de Lyon
Espace Geographique | Year: 2014

Geographical approaches to leisure and cultural participation are often restricted to sports and outdoor activities. They do not address the micro-scale of individual homes. In our study of the environment and the practice of video gaming in a national population, we aim to shed new light on the spatial analyses of domestic leisure. A survey was conducted in 2012 on a representative sample of the French population aged 11 and over (n = 2,542). It explored the diversity of uses of video games and contextualized video gaming at the social, cultural, and spatial level. This article shifts the focus from video games to the players themselves; analyzing gaming as a socially and spatially situated experience. The survey showed that while many inhabitants of France play video games, their practices are not homogeneous; the diversity in gaming should thus be understood in relation to life cycles and lifestyles. © Belin. Tous droits réservés pour tous pays.


Minassian H.T.,CNRS Cities, Territories, Environment and Societies
Annales de Geographie | Year: 2016

Video games are today a major cultural practice, present in many parts of society. Nevertheless, we still lack precise studies on the place they occupy in everyday life. A study of the various publics and practices of video games, based upon a questionnaire by phone and semi-structured interviews, shows that the place of video games in the spaces of everyday life varies, according to the commitment of videogame players. Taking here the example of domestic places, this study gives an indication on the importance of this leisure in everyday life of the players and, at the same time, shows the capacity of individuals to produce and appropriate their home. Thus, domestic space appears as a topological, appropriated and negotiated space. © Armand Colin.


Marquet J.-C.,CNRS Cities, Territories, Environment and Societies | Seronie-Vivien M.-R.,CNRS Cities, Territories, Environment and Societies
Quaternaire | Year: 2016

The excavation undertaken by M.-R. Seronie-Vivien in Pradayrol cave has allowed the discovery of many rodents remains including Lagurus lagurus, the grey lemming of the steppe, Allocricelus bursae, a currently extinct hamster, and probably two species of Pliomys: P. lenki and P. episcopalis. The morphological characteristics of Terrícola vaufreyi or metrical characteristics of Arvícola cantiana/terrestris indicate quite old ages for the assemblages discovered in the different levels of the excavation. Base on the principle of actualism, the bottom of the excavation might correspond with a climatic phase characterized by a strong dryness and temperature that might have been very low in winter. The upper part of the excavation corresponds to wetter climatic conditions. The quite large biodiversity observed in the different levels can be explained by the geographical location of the cave near the edge of the limestone plateau ("causse") dominating a large irrigated lowland. Characteristics of Allocricelus, Terrícola and Arvicola led to correlate the age of this sequence with an early phase of marine isotope stage 6.


In the cities of the Maghreb, informal settlements are proving to be a privileged observatory of the relations between institutional policies and social dynamics. The focus here is put on the subtle links between the processes of marginalization and informalization and forms of domination of the populations concerned. The segregation and injustice that characterize the legalization policy undertaken by the State in the late 1980s had disgruntled the aspirations of empowerment and affirmation of the urbanity of the inhabitants of Cherarba. The government lost its legitimacy among residents and the neighborhood then passed into the hands of radical Islamist opposition who had to turn to informal channels to finance its activities. People’s expectations and hopes of change this time encountered aggressive Islamist authoritarianism and the situation passed from a symbolic kind of violence to deadly violence that was probably the cause of the change in position of a large part of the population : a change in position and disaffection which she paid for by amassacre. The suppression of terrorismand the “pacification” that followed were accompanied by a desire of the government to reconquer the territory, through the revival of housing programs and development of several amenities. Residents of the area want only one thing : turn the page of the Civil War and delete the terrorist image of Cherarba. The government’s relations with the populations of informal settlements are forged with a form of government whose purpose is primarily political, which even more strongly raises the democratic question, especially in the current context of Arab countries. © Armand Colin.


Bonthoux S.,École Nationale Supérieure de la Nature et du Paysage | Bonthoux S.,CNRS Cities, Territories, Environment and Societies | Brun M.,CNRS Cities, Territories, Environment and Societies | Di Pietro F.,University of Tours | And 5 more authors.
Landscape and Urban Planning | Year: 2014

Urbanisation leads to natural habitats being fragmented with various effects according to the species and their ecological characteristics. Paradoxically, the urbanisation process creates relatively unused environments, wastelands, habitats which could contribute to biodiversity conservation in urban regions. In this review we examined the role of wastelands in maintaining biodiversity in the city and assessed the different factors responsible for wasteland biodiversity. 37 articles were suitable for our aim. Most of the studies have been conducted in large cities in Western and Central Europe. A wasteland is defined as an abandoned site with spontaneous vegetation (i.e. wild grown vegetation). In most cases, wastelands harbour more species than other urban green spaces. The processes which affect the biodiversity of wastelands operate on two different levels. Locally, the area size, age, soil, microclimate and the vegetation structure are the dominant factors. As in other environments, the species richness increases with the size of the wasteland. Wastelands of different ages include different stages of vegetation, ranging from pioneer to pre-forest stages, and consequently harbour different communities of plants and animals. The diversity of anthropogenic soil substrates leads to different plant communities. At the landscape scale, matrix composition and geographic connectivity between wastelands influence the biodiversity of wastelands, although to a lesser extent than the local features. We show that wastelands have a real potential to contribute to biodiversity conservation in urban regions. At the city scale, they represent habitats which urban planners need to take into account and include in dynamic urban planning. © 2014 Elsevier B.V.

Loading CNRS Cities, Territories, Environment and Societies collaborators
Loading CNRS Cities, Territories, Environment and Societies collaborators