Beyond infrared spectroscopy and spatial analysis : SOC stocks mapping in volcanic soils of Reunion island.

As high carbon content soils with high human carrying capacity, volcanic soils of Reunion island highlight the importance of “carbon hotspots” to face the challenges of climate change and food security trough carbon sequestration. In addition, the '4 per mille' initiative demonstrated that agricultural soils can play a crucial role for these global issues but knowledge on soil organic carbon (SOC) stocks of agricultural soils is still needed in tropical areas. Reunion is a young tropical volcanic island in the Indian Ocean, 700km east of Madagascar, with three major agricultural land uses (sugarcane crops, pastures and gardening) on a volcanic rock weathering gradient from Andosols to Ferralsols. A stratification method has been used to map SOC stocks in Reunion. First, 1000 soil samples (0-30cm depth) on the major agricultural land uses across the island from a huge database containing more than 45 000 soil analyses since 1993, have been selected. Mid-infrared spectra were acquired on these dried and thieved 1000 soil samples using a portable spectrophotometer. Spatially homogenous soil units have been defined by a clustering method (K-means) from laboratory analyses (SOC content, CEC, N, …) and mid-infrared spectra of these 1000 soil samples. Secondly, since 2016, soil samples have been collected in the field on the major agricultural land uses per spatially homogenous soil units to developed a mid- and near- infrared (MIR and NIR) spectroscopy method, both in the field (fresh soil samples) and in the laboratory (dried and thieved samples) to predict SOC stocks on 0-30 cm depth. Overall, SOC stocks can be predicted with satisfactory accuracy and directly by NIR and MIR spectroscopy in volcanic soils. In order to spatialize these results, an average SOC stock has been calculated for each combination of soil unit and agricultural land use. Then, each average SOC stock has been attributed to every agricultural field to map SOC stocks of the whole agricultural area in Reunion. The proposed methodology will produce a strong spatial baseline that will enable simulations of impacts of land use changes on SOC stocks at the island scale

Évaluation par spectroscopie infra-rouge des stocks en carbone des sols agricoles réunionnais. Mesures in-situ et construction de modèles de prédictions

Dans le contexte actuel de réchauffement climatique, les recherches effectuées sur les facteurs de diminution des gaz à effet de serre de l'atmosphère se multiplient. Une des solutions pourrait se trouver dans le stockage de carbone par les sols, puisque ceux-ci constituent un réservoir de carbone 2,6 fois plus important que l'atmosphère. C'est en partant de ce constat qu'est né le programme de recherche " 4 pour 1 000 ", basé sur l'estimation qu'une augmentation de 4 pour 1 000 par an des stocks de matière organique des sols suffirait à compenser l'ensemble des émissions de gaz à effet de serre de la planète. Ce programme a pour but de développer la recherche agronomique afin de favoriser le stockage de carbone des sols cultivés. La dynamique de cette séquestration reste cependant mal connue, puisque les mesures des stocks sont longues et coûteuses, donc difficilement reproductibles géographiquement et temporellement. L'étude tente de trouver une alternative à ces méthodes contraignantes, en proposant une méthode de détermination des stocks de carbone, in situ, rapide et peu chère à long terme, afin de démocratiser ces mesures. Cette méthode porte sur l'utilisation conjointe d'un carottier, et d'un spectromètre proche infrarouge de terrain. L'étude est réalisée dans le cadre du projet CARUN, dont l'objectif d'évaluation des fonctions temporelles et spatiales du stockage de carbone dans les sols, sous cultures annuelles de la Réunion, s'inscrit tout à fait dans le programme 4 pour 1 000. La méthodologie proposée est élaborée à partir de sols prélevés à La Réunion, incluant donc la variabilité et la particularité des propriétés de ces sols. Au regard des résultats obtenus, ce dernier aspect semble avoir une influence prépondérante sur la précision des stocks de carbone par SPIR. Cette étude, en parallèle à la proposition d'un protocole de terrain efficace et reproductible, tente d'interpréter l'influence des types de sols dérivés de matériaux volcaniques sur la prédiction par SPIR de leurs stocks de carbone

Addressing climate change with behavioral science: a global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions’ effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior—several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people’s initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors

Addressing climate change with behavioral science:A global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors.</p

Addressing climate change with behavioral science:A global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors.</p

Addressing climate change with behavioral science: A global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors

Temporalités d'un géosystème soudanien. : Géomorphologie et enregistrements sédimentaires de la moyenne vallée du Bao Bolon (Région de Wanar, site du Patrimoine Mondial, Sénégal)

The study focuses on the middle valley of the Bao Bolon River, in Sudanian domain in Senegal, in order to reconstruct the evolution of the environment at different time scales. The region is characterized by human presence for at least two millennia, as evidenced by the megalithic World Heritage Site of Wanar. In the second half of the 20th century, the local environment experienced major upheavals linked with the agricultural intensification of the groundnut basin and the great Sahelian drought. First, a detailed analysis of the geomorphological forms and dynamics of the region is carried out, and highlights the key stages of the genesis of current landscapes. Secondly, the sedimentary archives of Bao Bolon and its tributaries are studied, in particular those of the Khour, whose watershed drains the area of the megalithic site of Wanar. The numerous profiles studied (cores, sections, transects) reveal a richness and consistency of fluvial sedimentary records at the Holocene scale, rare in West Africa. The approach is intended to be multi-proxy and associates field surveys and laboratory analyzes (laser grain size, morphoscopy of quartz grains, carbon analyzes, palynofacies, diatoms, geochemistry). The combination of geomorphological study and sedimentary records allows reconstructing different stages of the evolution of the middle Bao Bolon valley during the Holocene, under the influence of climatic and anthropogenic parameters.L’étude porte sur la moyenne vallée du Bao Bolon, en domaine soudanien au Sénégal, afin d’en reconstituer l’évolution de l’environnement à différentes échelles de temps. La région est marquée par la présence humaine depuis au moins deux millénaires, comme en témoigne le site mégalithique de Wanar, inscrit au Patrimoine Mondial. Dans la deuxième moitié du XX° siècle, l’environnement local a connu des bouleversements majeurs en lien avec l’intensification agricole du bassin arachidier et la grande sécheresse au Sahel. Dans un premier temps, une analyse détaillée des formes et des dynamiques géomorphologiques de la région est réalisée, et met en lumière les étapes-clefs de la genèse des paysages actuels. Dans un second temps, les archives sédimentaires du Bao Bolon et de ses marigots affluents sont étudiées, en particulier celui du Khourdont le bassin versant draine la zone du site mégalithique de Wanar. Les nombreux profils étudiés (carottages, coupes, transects) dévoilent une richesse et une cohérence des enregistrements sédimentaires fluviatiles à l’échelle de l’Holocène, rares en Afrique de L’Ouest. L’approche se veut multi-proxy et associe relevés de terrain et analyses de laboratoire (granulométrie laser, morphoscopie des grains de quartz, analyses de carbone, palynofaciès, diatomées, géochimie). La combinaison de l’étude géomorphologique et des enregistrements sédimentaires permet de reconstituer différentes étapes de l’évolution de la moyenne vallée du Bao Bolon au cours de l’Holocène, sous l’influence des paramètres climatiques et anthropiques

Temporalités d’un géosystème soudanien. Géomorphologie et enregistrements sédimentaires de la moyenne vallée du Bao Bolon (Région de Wanar, site du Patrimoine Mondial, Sénégal).

The study focuses on the middle valley of the Bao Bolon river, in Sudanian domain in Senegal, in order to reconstruct the evolution of the environment at different time scales. The region is characterised by human presence for at least two millennia, as evidenced by the megalithic World Heritage Site of Wanar. In the second half of the 20th century, the local environment experienced major upheavals linked with the agricultural intensification of the groundnut basin and the great Sahelian drought.First, a detailed analysis of the geomorphological forms and dynamics of the region is carried out, and highlights the key stages of the genesis of current landscapes. Secondly, the sedimentary archives of Bao Bolon and its tributaries are studied, in particular those of the Khour, whose watershed drains the area of the megalithic site of Wanar. The numerous profiles studied (cores, sections, transects) reveal a richness and consistency of fluvial sedimentary records at the Holocene scale, rare in West Africa. The approach is intended to be multi-proxy and associates field surveys and laboratory analyses (laser granulometry, morphoscopy of quartz grains, carbon analyses, palynofacies, diatoms, geochemistry). The combination of geomorphological study and sedimentary records allows to reconstruct different stages of the evolution of the middle Bao Bolon valley during the Holocene, under the influence of climatic and anthropogenic parameters.L’étude porte sur la moyenne vallée du Bao Bolon, en domaine soudanien au Sénégal, afin d’en reconstituer l’évolution de l’environnement à différentes échelles de temps. La région est marquée par la présence humaine depuis au moins deux millénaires, comme en témoigne le site mégalithique de Wanar, inscrit au Patrimoine Mondial. Dans la deuxième moitié du XX° siècle, l’environnement local a connu des bouleversements majeurs en lien avec l’intensification agricole du bassin arachidier et la grande sécheresse au Sahel.Dans un premier temps, une analyse détaillée des formes et des dynamiques géomorphologiques de la région est réalisée, et met en lumière les étapes-clefs de la genèse des paysages actuels. Dans un second temps, les archives sédimentaires du Bao Bolon et de ses marigots affluents sont étudiées, en particulier celui du Khour dont le bassin versant draine la zone du site mégalithique de Wanar. Les nombreux profils étudiés (carottages, coupes, transects) dévoilent une richesse et une cohérence des enregistrements sédimentaires fluviatiles à l’échelle de l’Holocène, rares en Afrique de L’Ouest. L’approche se veut multiproxy et associe relevés de terrain et analyses de laboratoire (granulométrie laser, morphoscopie des grains de quartz, analyses de carbone, palynofaciès, diatomées, géochimie). La combinaison de l’étude géomorphologique et des enregistrements sédimentaires permet de reconstituer différentes étapes de l’évolution de la moyenne vallée du Bao Bolon au cours de l’Holocène, sous l’influence des paramètres climatiques et anthropiques