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Mèze, France

Conti G.,National University of Cordoba | Kowaljow E.,National University of Cordoba | Baptist F.,Biotope | Rumpel C.,French National Institute for Agricultural Research | And 3 more authors.
Plant and Soil | Year: 2016

Background and aims: Subtropical seasonally dry forests from South America are now experiencing one of the highest rates of forest-cover change globally. These changes may affect the dynamics of soil organic carbon (SOC) including long-term stabilization processes, with profound consequences for the fertility and carbon storage of these ecosystems. Methods: In order to explore the effect of different land-use regimes on SOC dynamics, we determined the amount and quality of plant litter, the amount and quality (lignin and carbohydrate content) of SOC, and the soil basal respiration rates across seasonally dry Chaco forests of Argentina. Results: Changes in land-use regimes significantly reduced the amount of litter but not its quality. As a consequence, the SOC content was also reduced together with SOC quality. Unexpectedly, we found a higher CO2 release per SOC unit in soils with lower amount and quality of SOC. Conclusions: The results presented here show a clear effect of different land-use regimes on SOC dynamics through a reduction in the amount and quality of SOC. Additionally, we found that potential microbial activity is somehow disconnected from substrate quantity and quality, suggesting that the molecular structure of SOC is not significantly affecting long-term soil stabilization processes across these seasonally-dry ecosystems. © 2016, Springer International Publishing Switzerland. Source

Penone C.,CNRS Science Conservation Center | Le Viol I.,CNRS Science Conservation Center | Pellissier V.,CNRS Science Conservation Center | Julien J.-F.,CNRS Science Conservation Center | And 2 more authors.
Conservation Biology | Year: 2013

Biodiversity monitoring at large spatial and temporal scales is greatly needed in the context of global changes. Although insects are a species-rich group and are important for ecosystem functioning, they have been largely neglected in conservation studies and policies, mainly due to technical and methodological constraints. Sound detection, a nondestructive method, is easily applied within a citizen-science framework and could be an interesting solution for insect monitoring. However, it has not yet been tested at a large scale. We assessed the value of a citizen-science program in which Orthoptera species (Tettigoniidae) were monitored acoustically along roads. We used Bayesian model-averaging analyses to test whether we could detect widely known patterns of anthropogenic effects on insects, such as the negative effects of urbanization or intensive agriculture on Orthoptera populations and communities. We also examined site-abundance correlations between years and estimated the biases in species detection to evaluate and improve the protocol. Urbanization and intensive agricultural landscapes negatively affected Orthoptera species richness, diversity, and abundance. This finding is consistent with results of previous studies of Orthoptera, vertebrates, carabids, and butterflies. The average mass of communities decreased as urbanization increased. The dispersal ability of communities increased as the percentage of agricultural land and, to a lesser extent, urban area increased. Despite changes in abundances over time, we found significant correlations between yearly abundances. We identified biases linked to the protocol (e.g., car speed or temperature) that can be accounted for ease in analyses. We argue that acoustic monitoring of Orthoptera along roads offers several advantages for assessing Orthoptera biodiversity at large spatial and temporal extents, particularly in a citizen science framework. © 2013 Society for Conservation Biology. Source

Viard-Cretat F.,IRSTEA | Viard-Cretat F.,CNRS Alpine Ecology Laboratory | Viard-Cretat F.,Joseph Fourier University | Baptist F.,Biotope | And 3 more authors.
Plant Ecology | Year: 2013

Allelopathy is recognized as an important process in plant-plant interactions, but how it affects plant communities growing in competitive conditions has not been assessed. This article investigates whether the allelopathic effect of Festuca paniculata is modified by competition between target plants in subalpine grasslands. We hypothesized that plants growing in mixed stands will be more affected by allelochemicals than the same species in monoculture. At Lautaret pass (Northern French Alps), a pot experiment was designed. We used leachates from donor pots (Treatments: 1. Bare soil, 2. F. paniculata clipped, and 3. F. paniculata unclipped) to water target pots (Treatments: 1. Control (soil only), 2. Dactylis glomerata, 3. Agrostis capillaris, and 4. D. glomerata and A. capillaris). Target plants were cultivated during one growing season. The effects of leachates from donor pots and interspecific competition in target pots were evaluated by measuring the final biomass of plants. Soil fertility was controlled in all target pots by measuring NO3 -, NH4 +, N, and C % of the soil. Effect of target treatment under: Both D. glomerata and A. capillaris grew better in monocultures than in mixture. Effect of donor treatment on monocultures: Under bare soil, D. glomerata grew better than under F. paniculata leachates. By contrast, A. capillaris did not respond to donor pot treatment. Effect of donor treatment on mixtures: However, when both species were cultivated together under F. paniculata leachates, the biomass of D. glomerata was similar to that in monoculture under bare soil. Differences in sensitivity to allelopathy reversed the impact of interspecific competition: A. capillaris facilitated D. glomerata under allelopathy, which made allelopathy of F. paniculata on D. glomerata inefficient. The complexity of overlapping mechanisms of plant-plant interactions are highlighted by this semi-natural experiment. In subalpine grasslands, allelopathy not only limits the growth of neighboring plants, but it may also modify community assembly by affecting other plant-plant interactions such as competition. This study contributes to explore the way allelopathy interacts with other plant-plant interactions in natural systems. © 2012 Springer Science+Business Media Dordrecht. Source

van Teeffelen A.J.A.,VU University Amsterdam | van Teeffelen A.J.A.,Wageningen University | Opdam P.,Wageningen University | Watzold F.,TU Brandenburg | And 8 more authors.
Landscape and Urban Planning | Year: 2014

Protected areas are a cornerstone of current biodiversity policy. The continued loss of biodiversity, however, as well as the limited scope to extend protected area networks necessitates a conservation perspective that encompasses both protected areas and the wider landscape. This calls for policy instruments that can govern land use dynamics, simultaneously meeting demands for conservation (i.e. no net loss of biodiversity) and economic development. Conservation banking could be such an instrument, but only when certain criteria are met. Building on the theory of ecological networks, we combine ecological, economic and institutional perspectives on conservation banking to identify when and where conservation banking could be feasible. Economic prerequisites include sufficient market activity to match demand and supply. Adequate regulatory capacity is needed to design and enforce trading rules. From an ecological perspective, habitat turnover is least detrimental in large and well-connected networks. For many ecosystem types, those prerequisites will be rarely met in practice: sufficient market activity implies sufficient habitat turnover, but most ecological networks are not robust enough to buffer frequent habitat turnover. Therefore, banking is best limited to common and fast-regenerating ecosystem types (e.g. certain coastal systems, wetlands, nutrient-rich grasslands). Furthermore, conservation banking could be applied to a subset of the network only, i.e. the wider landscape, as a complementary instrument to protected area policy. With appropriate trading rules and institutional arrangements, the loss and gain of habitat could be governed to improve the spatial cohesion and size of ecological networks and the capacity of landscapes to support biodiversity. © 2014 Elsevier B.V. Source

Quetier F.,Biotope | Quetier F.,CNRS Alpine Ecology Laboratory | Regnery B.,French Natural History Museum | Levrel H.,French Research Institute for Exploitation of the Sea
Environmental Science and Policy | Year: 2014

French regulations concerning the mitigation of development impacts have been progressively strengthened with offsets now required for impacts on forests, wetlands, and protected species, among others. In 2012, following a national consultative process called Grenelle de l'Environnement, legal requirements in terms of monitoring and effective implementation of measures aimed at avoiding, reducing and offsetting impacts were strengthened. This has created strong "demand" for offsets.The workability of these new requirements has come under scrutiny, not least because of their strong legal and financial implications for developers. In this context, official government guidance on implementing the mitigation hierarchy was published in 2012. Under this guidance, the aim of the mitigation hierarchy is to achieve no net loss (NNL) of biodiversity, and preferably a net gain for currently threatened biodiversity and ecosystems. We discuss what NNL means in this context, and highlight some of the technical and governance issues raised by the French approach to NNL.Our analysis shows that the French guidance, in spite of its laudable ambition, does not address the institutional arrangements and science base needed to reach the policy's objective of NNL. The burden of designing and building adequate institutional arrangements is shifted down to local and regional permitting authorities, and even developers themselves. Consequently, and in spite of the increasing demand for offsets, the result is a highly variable and often ineffective project by project approach to offset supply, with minimal commitments. Unless the institutional and scientific challenges are tackled, the likely outcome will be an expansion of "paper offsets". © 2013 Elsevier Ltd. Source

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