de Thoisy B.,Association Kwata Study and Conservation of French Guianan Wildlife |
Richard-Hansen C.,British Petroleum |
Goguillon B.,WWF France |
Joubert P.,Office National des Forets |
And 3 more authors.
Biodiversity and Conservation | Year: 2010
Although there is an extensive literature demonstrating the impact of human activities on both species extinction risk and local ecological processes, the methodological tools that allow for the visualization and quantification of the intensity of the observed and forthcoming impacts are lacking. Here we propose a Footprint index for French Guiana, (northern Atlantic coast of South America) which sums up the expected and proven disturbances on biodiversity. The index was developed by superimposing geographical and human data, including human population densities, land use, settlements and camps, mining and forest activities, tracks, roads and rivers. The relevance of the index as a general measure of anthropic impact on large terrestrial fauna was estimated by investigating the structure of the large terrestrial vertebrate assemblages, including primates, large frugivorous birds, rodents and ungulates, in relation to the extent of disturbances. The abundance of large terrestrial fauna was assessed using the line-transect sampling method in 34 forest sites facing different disturbance levels, including hunting, logging and fragmentation, and consequently different footprint scores. A Self Organizing Map was used to combine species abundances and disturbance scores. It allowed us to rank species in accordance to their sensitivity towards disturbances, identifying the response of fauna to different concomitant threats. The index provided correct identification of sites with similar threats which proves it is a relevant estimator of human disturbance. In addition, the richness of animal communities and abundances of several seed dispersers and predators were negatively correlated to the index (e. g. large monkeys and frugivorous birds, r2 = 0. 49, P <0. 0001 and r2 = 0. 48, P <0. 0001, respectively), indicating its reliability in identifying areas where animal communities are disturbed. The index could, therefore, constitute a useful tool to identify areas where ecological processes supported by those species are expected to be disrupted, and where they are already disrupted. Furthermore, the footprint index can deal with lack of field data or with only partially valid information, and so may directly help land managers forecast and, hopefully, mitigate forthcoming impacts resulting from the development of human activities. © 2010 Springer Science+Business Media B.V.
Plot V.,University of Strasbourg |
Plot V.,French National Center for Scientific Research |
de Thoisy B.,Kwata Association |
de Thoisy B.,Institute Pasteur Of La Guyane |
And 11 more authors.
Journal of Animal Ecology | Year: 2012
The assessment of species extinction risk has been well established for some time now. Assessing the potential for recovery in endangered species is however much more challenging, because complementary approaches are required to detect reliable signals of positive trends. This study combines genetics, demography and behavioural data at three different time-scales to assess historical and recent population changes and evidence of reproductive synchrony in a small population of olive ridley sea turtle Lepidochelys olivacea. Lepidochelys is considered as the most extraordinary example of reproductive synchrony in reptiles, yet to date, it has only been reported in large populations. Using Bayesian coalescent-based models on microsatellite nuclear DNA variability, we demonstrate that effective population size in olive ridleys nesting in French Guiana has dramatically declined by 99% over the last 20 centuries. This low current population size is further illustrated by the absence of genetic mitochondrial DNA diversity in the present nesting population. Yet, monitoring of nesting sites in French Guiana suggests a possible recovery of the population over the last decade. Satellite telemetry shows that over the first 14days of their 28-days inter-nesting interval, i.e. when eggs maturation is likely to occur, gravid females disperse over the continental shelf. They then gather together with a striking spatiotemporal consistency close to the nesting site, where they later emerge for their second nesting event. Our results therefore suggest that reproductive synchrony also occurs in small populations. Olive ridleys may ensure this synchrony by adjusting the duration of the second half of their inter-nesting interval prior to landing, possibly through social mediation. Such reproductive synchrony may be related to the maintenance of some species-specific strategy despite former collapse and may contribute to the present population recovery. The gregarious behaviour of reproductive individuals close to shore where human-induced perturbations occur is however a cause for conservation concern for this still poorly known species. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society.
Ibanez T.,Aix - Marseille University |
Ibanez T.,French National Center for Scientific Research |
Borgniet L.,IRSTEA |
Mangeas M.,CIRAD - Agricultural Research for Development |
And 4 more authors.
Austral Ecology | Year: 2013
Stable forested environments can be converted to savanna in response to changes in environmental disturbances. New Caledonia is a biodiversity hotspot; significant ecological and economic resources would be lost if forests were turned into savanna by anthropogenic environmental changes. On the landscape scale, systems that have undergone shifts of this kind are characterized by sharp forest-savanna boundaries and mosaic-like distributions of savanna and forest. Understanding the locations and the dynamics of such boundaries is a challenge for ecologists and is critical for landscape management and biodiversity conservation. Using a time series of aerial photographs (1955-2000) and a forest habitat suitability map, we tested the hypothesis that topography and spatial processes, especially those relating to fire spread and seed dispersal, are the main determinants of the spatial distribution of rainforest and savanna in a New Caledonian landscape covering 24km2. Within the studied landscape, the overall forest coverage decreased by 24% between 1976 and 2000. This was primarily due to the contraction of forests on west-facing slopes, which accounted for about 90% of the total loss. Conversely, the east-facing forests seemed to have contracted extensively prior to the studied period, and were confined to refuges. A habitat suitability index calculated from the landscape's topographical features using generalized additive models accurately predicted both the presence of forests and the probability of forest expansion/contraction. We also provide evidence that spatial processes such as fire spread and seed dispersal limit the expansion and contraction of forests. Our results suggest that rainforests on west-facing slopes in New Caledonia will be progressively destroyed by fire until they are restricted to refuges along thalwegs and creeks, as appears to have already happened for their east-facing counterparts. © 2012 The Authors. Austral Ecology © 2012 Ecological Society of Australia.
Mansourian S.,Environmental Consultant |
Vallauri D.,WWF France
Environmental Management | Year: 2014
Forest restoration at large scales, or landscapes, is an approach that is increasingly relevant to the practice of environmental conservation. However, implementation remains a challenge; poor monitoring and lesson learning lead to similar mistakes being repeated. The World Wildlife Fund (WWF), the global conservation organization, recently took stock of its 10 years of implementation of forest landscape restoration. A significant body of knowledge has emerged from the work of the WWF and its partners in the different countries, which can be of use to the wider conservation community, but for this to happen, lessons need to be systematically collected and disseminated in a coherent manner to the broader conservation and development communities and, importantly, to policy makers. We use this review of the WWF's experiences and compare and contrast it with other relevant and recent literature to highlight 11 important lessons for future large-scale forest restoration interventions. These lessons are presented using a stepwise approach to the restoration of forested landscapes. We identify the need for long-term commitment and funding, and a concerted and collaborative effort for successful forest landscape restoration. Our review highlights that monitoring impact within landscape-scale forest restoration remains inadequate. We conclude that forest restoration within landscapes is a challenging yet important proposition that has a real but undervalued place in environmental conservation in the twenty-first century. © 2013 Springer Science+Business Media New York.
Hackradt C.W.,University of Murcia |
Garcia-Charton J.A.,University of Murcia |
Harmelin-Vivien M.,University of Toulon |
Perez-Ruzafa A.,University of Murcia |
And 7 more authors.
PLoS ONE | Year: 2014
Groupers species are extremely vulnerable to overfishing and many species are threatened worldwide. In recent decades, Mediterranean groupers experienced dramatic population declines. Marine protected areas (MPAs) can protect populations inside their boundaries and provide individuals to adjacent fishing areas through the process of spillover and larval export. This study aims to evaluate the effectiveness of six marine reserves in the Western Mediterranean Sea to protect the populations of three species of grouper, Epinephelus marginatus, Epinephelus costae and Mycteroperca rubra, and to understand in which circumstances MPAs are able to export biomass to neighbouring areas. All the studied MPAs, except one where no grouper was observed, were able to maintain high abundance, biomass and mean weight of groupers. Size classes were more evenly distributed inside than outside MPAs. In two reserves, biomass gradients could be detected through the boundaries of the reserve as an indication of spillover. In some cases, habitat structure appeared to exert a great influence on grouper abundance, biomass and mean individual weight, influencing the gradient shape. Because groupers are generally sedentary animals with a small home range, we suggest that biomass gradients could only occur where groupers attain sufficient abundance inside MPA limits, indicating a strongly density-dependent process. © 2014 Hackradt et al.