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Soil organic carbon as an indicator of land use impacts in life cycle assessment
No full textInternational audiencePurpose Anthropogenic activities are a major driver of soil and land degradation. Due to the spatial heterogeneity of soil properties and the global nature of most value chains, the modelling of the impacts of land use on soil quality for application in life cycle assessment (LCA) requires a regionalised assessment with global coverage. This paper proposes an approach to quantify the impacts of land use on soil quality, using changes in soil organic carbon (SOC) stocks as a proxy, following the latest recommendation of the Life Cycle Initiative.Methods An operational set of SOC-based characterisation factors for land occupation and land transformation were derived using spatial datasets (1 km resolution) and aggregated at the national and global levels. The developed characterisation factors were tested by means of a case study analysis, investigating the impact on soil quality caused by land use activities necessary to provide three alternative energy supply systems for passenger car transport (biomethane, ethanol, and solar electricity). Results obtained by applying characterisation factors at local, regional, and national levels were compared, to investigate the role of the level of regionalisation on the resulting impacts.Results and discussion Global maps of characterisation factors are presented for the 56 land use types commonly used in LCA databases, together with national and global values. Urban and industrial land uses present the highest impacts on SOC stocks, followed by severely degraded pastures and intensively managed arable lands. Instead, values obtained for extensive pastures, flooded crops, and urban green areas often report an increase in SOC stocks. Results show that the ranking of impacts of the three energy systems considered in the case study analysis is not affected by the level of regionalisation of the analysis. In the case of biomethane energy supply, impacts assessed using national characterisation factors are more than double those obtained with local characterisation factors, with less significant differences in the other two cases.Conclusions The integration of soil quality aspects in life cycle impact assessment methods is a crucial challenge due to the key role of soil conservation in ensuring food security and environmental protection. This approach allows the quantification of land use impacts on SOC stocks, taken as a proxy of soil quality. Further research needs to improve the assessment of land use impacts in LCA are identified, such as the ability to reflect the effects of agricultural and forestry management practices
Timescale of radium and alkaline earth cations ascent in the trees: Use of isotopic (228Ra/226Ra) ratio
No full textInternational audienceDue to its short-lived progeny, including gaseous radon isotopes that can be inhaled and its significant transfer into vegetation, radium poses a substantial concern in radiation risk assessment. Although the transfer of Ra from soil to plants has been previously documented, the distribution and speciation of radium within the plant tissues, particularly within trees, remain unclear. The temporal dimension of Ra transfer is also poorly known. Therefore, the transfer of radium and others alkaline earth cations in beech trees was investigated through the analysis of fine (<2 mm) roots and leaves corresponding to tree organs with a life cycle limited to one season. This study was conducted at the experimental Montiers (INRAE-Andra site, France) and Strengbach watershed (OHGE site, France) beech-forested site. The activity of 226Ra and the isotopic ratio (228Ra/226Ra) were measured in roots and leaves using gamma spectrometry. Additionally, the concentration of alkaline earth cations (Mg, Ca, Sr, and Ba) was measured, to better constraint the mechanism of alkaline earth cation transfer through the xylem. The retention of these cations within the trees increases with the mass of the element, following the order Mg < Ca < Sr ≈ Ba < Ra, i.e.: light alkaline earth cations are more efficiently transferred from roots to leaves than heavy one. Our results suggest that these cations maintain their hydration shell during their ascent in stems and a low pH ion-exchange process rather than a complexation process with carboxylic group occurs.The decay of the (228Ra/226Ra) isotopic ratio over time during transfer within the trees allows us to quantify the slow Ra translocation from roots to the leaves, ranging from 1 to more than 16 years. This duration increases with the age of the trees. Hence, radioactive decay of Ra provides particularly valuable timescale information that is usually difficult to assess for Ca or other alkaline earth cations
The private management of plant disease epidemics: infection levels and social inefficiencies
No full textInternational audiencePlant disease control is often implemented at the private property level, and problems of cooperation and coordination between landowners can lead to social inefficiencies. Drawing on the private management problem of sharka on Prunus trees, we analyse an epidemic game and its outcomes according to initial infection levels. We show that, depending on the infection level in each farm, the nature of strategic interactions changes drastically, and a wide range of games can occur, including games with multiple or without pure strategy equilibria and games with coordination or anti-coordination patterns. We characterise the epidemic conditions for which private management produces social inefficiency and analyse the properties of uniform and differentiated subsidy schemes to solve it. We conclude with a discussion of the policy implications of the ongoing deregulation of sharka management in France
Combining modelling and participation to build transformational water management & agricultural adaptation scenarios in water stressed areas
No full textInternational audienceIn the Mediterranean area, climate change increases significantly the water needs by crops while water resources are getting scarce because of reduced and distributional shifts of rain patterns. The need for methods to identify and assess robust adaptation strategies are urgent. Combining a multistakeholder dialogue and agro‐hydro‐economic modelling we aim at addressing this question. Based on an experiment conducted in one of the most overexploited water basins in France, the Aude catchment, we propose an approach to co‐construct strategies for climate change adaptation of the farming sector and water management with a multi‐stakeholder dialogue and modelling. Local scenarios derived from Socio‐economic pathways (SSPs) are co‐constructed as narratives that detail context, local economy, agricultural development and, water management and governance. The quantification – partly done by stakeholders and partly enabled by agronomic modelling ‐ enables to state that the difference in the effect of land use changes (socio‐economic scenarios) are much higher than the ones associated to alternative climate scenarios. This work is still in progress, but already shows a very good and active level of participation of key stakeholders
Effects of Leaf Size and Defensive Traits on the Contribution of Soil Fauna to Litter Decomposition
No full textInternational audienceLeaf litter quality has been acknowledged as a crucial determinant affecting litter decomposition on broad spatial scales. However, the extent of the contribution of soil fauna to litter decomposability remains largely uncertain. Nor are the effects of leaf size and defensive traits on soil fauna regulating litter decomposability clear when compared to economics traits. Here, we performed a meta-analysis of 81 published articles on litterbag experiments to quantitatively evaluate the response ratio of soil fauna to litter decomposition at the global level. Our results revealed that soil fauna significantly affected litter mass loss across diverse climates, ecosystems, soil types, litter species, and decomposition stages. We observed significantly positive correlations between the response ratio of soil fauna and leaf length, width, and area, whereas the concentrations of cellulose, hemicellulose, total phenols, and condensed tannins were negatively correlated. Regarding economic traits, the response ratio of soil fauna showed no relationship with carbon and nitrogen concentrations but exhibited positive associations with phosphorus concentration and specific leaf area. The mean annual temperature and precipitation, and their interactions were identified as significant moderators of the effects of soil fauna on litter decomposition. We evidenced that the contribution of soil fauna to litter decomposability is expected to be crucial under climate change, and that trait trade-off strategies should be considered in modulating litter decomposition by soil fauna
The importance of mountain-block recharge in semiarid basins: An insight from the High-Atlas, Morocco
No full textInternational audienceMountain-block recharge (MBR), consisting of groundwater inflows from the mountain block into adjacent alluvial aquifers, can be an important source of recharge for groundwater in (semi)arid areas. The present study examined Mountain-Block Recharge (MBR) from the Marrakech High-Atlas Mountain to the adjacent Haouz alluvial aquifer in Morocco, using environmental tracers and endmember mixing analysis (EMMA). The influence of the isotopic altitude effect on rainfall (−0.18 ‰ per 100 m for δ18O) in the mountains allows a distinction between groundwater originating from rainfall recharged at different altitudes. Mean δ18O values are heavier at lower altitudes (−5.1 ‰; 2000 m.a.s.l). Stable isotopes suggest a mountain-aquifer connectivity via two MBR flow pathways: a regional MBR from lower-medium altitudes, and a localised MBR from the foothills. In addition, chloride highlighted a potential origin via regional groundwater flowpath from the lower-medium altitudes where important evaporite deposits are present. Furthermore, samples dominated by lower-medium altitude recharge displayed lower 3H content, suggesting longer residence times typical of MBR, where mountain front recharge prevails. EMMA illustrated MBR contributions ranging from under 1 % to 98 %, varying by proximity to irrigated areas and streams. Eastern areas showed more significant regional MBR influence than the western due to existing faults, acting as hydrogeologic barriers to MBR. These findings are crucial in defining groundwater recharge origins for protection strategies in water-stressed semi-arid regions. Understanding MBR dynamics and connectivity between mountain blocks and aquifers is pivotal for sustainable groundwater resource management
Analyser la transition nutritionnelle à travers l’offre et la demande alimentaires : approches croisées en économie, gestion et nutrition
No full textVoir aussi la version anglaise du livre : Sustainable Food Systems for Food Security. Need for combination of local and global approaches :https://www.quae.com/produit/1787/9782759235766/sustainable-food-systems-for-food-securityInternational audienc
A single changing hypernetwork to represent (social-)ecological dynamics
No full textA preprint peer-reviewed and recommended by PCI Network ScienceTo understand and manage (social-)ecological systems, we need an intuitive and rigorous way to represent them. Recent ecological studies propose to represent interaction networks into modular graphs, multiplexes and higher-order interactions. Along these lines, we argue here that non-dyadic (non-pairwise) interactions are common in ecology and environmental sciences, necessitating fresh concepts and tools for handling them. In addition, such interaction networks often change sharply, due to appearing and disappearing species and components. We illustrate in a simple example that any ecosystem can be represented by a single hypergraph, here called the ecosystem hypernetwork. Moreover, we highlight that any ecosystem hypernetwork exhibits a changing topology summarizing its long term dynamics (e.g., species extinction/invasion, pollutant or human arrival/migration). Qualitative and discrete-event models developed in computer science appear suitable for modeling hypergraph (topological) dynamics. Hypernetworks thus also provide a conceptual foundation for theoretical as well as more applied studies in ecology (at large), as they form the qualitative backbone of ever-changing ecosystems
Dataset documenting prevalence and counts of pine processionary moth tents on local host trees in 3 regions of France with different climatic environments
No full textInternational audienceThe pine processionary moth Thaumetopoea pityocampa is a defoliating lepidopter that develops during winter. The larvae are gregarious and bear urticating setae that are harmful to humans and vertebrates. They shelter in conspicuous silk tents that are easy to detect. We here present a dataset comprising tree characterization and tent counts from 3 agglomerations in France located in regions with different climatic environments. The studied trees belong to various conifer species that are potential hosts for the caterpillars. In each site, we defined clusters as one target tree and its 10–62 nearest neighbors, and surveyed each tree within the clusters by informing: tree species, coordinates, size, number of tents. We characterized a total of 3690 trees, including 2009 trees in Orléans (grouped in 68 clusters), 359 trees in La Baule (18 clusters) and 1322 trees in Montpellier (52 clusters). We provide the raw data characterizing each individual tree, graphs showing the prevalence and mean number of tents for the tree species included in the survey, and maps allowing to locate each tree. This dataset brings information about host preference of the pine processionary moth and will be useful as a baseline to study spatio-temporal variability of host-insect relationships. It can also be informative for decision-makers and managers of urban greenings to avoid trees that are likely to be heavily infested for plantation in proximity to vulnerable people