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The pan-African Great Green Wall (GGW) is an initiative that was initially meant to involve the planting of a 15 km wide transcontinental forest belt running from Dakar to Djibouti. This major project is designed to combat desertifi... more
The pan-African Great Green Wall (GGW) is an initiative that was initially meant to involve the planting of a 15 km wide transcontinental forest belt running from Dakar to Djibouti. This major project is designed to combat desertifi cation. The band of vegetation is to be as continuous as possible, but it may be rerouted if necessary to skirt around obstacles (streams, rocky areas, mountains) or to link inhabited areas (see grandemurailleverte.org).
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Adoption of no-till management on croplands has become a controversial approach for storing carbon in soil due to conflicting findings. Yet, no-till is still promoted as a management practice to stabilize the global climate system from... more
Adoption of no-till management on croplands has become a controversial approach for storing carbon in soil due to conflicting findings. Yet, no-till is still promoted as a management practice to stabilize the global climate system from additional change due to anthropogenic greenhouse gas emissions, including the 4 per mille initiative promoted through the UN Framework Convention on Climate Change. We evaluated the body of literature surrounding this practice, and found that SOC storage can be higher under no-till management in some soil types and climatic conditions even with redistribution of SOC, and contribute to reducing net greenhouse gas emissions. However, uncertainties tend to be large, which may make this approach less attractive as a contributor to stabilize the climate system compared to other options. Consequently, no-till may be better viewed as a method for reducing soil erosion, adapting to climate change, and ensuring food security, while any increase in SOC storage...
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What challenges for the South? A After being excluded, agriculture is gradually gaining a position in climate policy negotiations. The IPCC Fifth Assessment Report assessed the potential reduction of GHG at between 20 and 60% in... more
What challenges for the South? A After being excluded, agriculture is gradually gaining a position in climate policy negotiations. The IPCC Fifth Assessment Report assessed the potential reduction of GHG at between 20 and 60% in land-based sectors (agriculture, forestry and other land use) by 2030. The challenge to the sector is enormous. Greenhouse gas emission must be reduced in agriculture. The latter must also adapt to climate change while responding to food security imperatives. According to the FAO, agricultural production should at least double by 2050 to match population growth.
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Quels défis pour le Sud ? A près en avoir été exclue, l’agriculture se fait progressivement une place dans les négociations sur les politiques climatiques. Le 5e rapport du Giec a évalué entre 20 et 60 % le potentiel de réduction des... more
Quels défis pour le Sud ? A près en avoir été exclue, l’agriculture se fait progressivement une place dans les négociations sur les politiques climatiques. Le 5e rapport du Giec a évalué entre 20 et 60 % le potentiel de réduction des émissions de GES par le « secteur des terres » (agriculture, forêt et sols) d’ici 2030. Le défi posé au secteur est gigantesque. L’agriculture doit réduire ses émissions de gaz à effet de serre. Elle doit aussi s’adapter au changement climatique, tout en répondant aux impératifs de sécurité alimentaire. Or, selon la FAO, la production agricole devrait au moins doubler d’ici 2050 pour faire face à la croissance démographique.
In the current context of climate change, oil palm plantations are much criticized because they replace large areas of tropical forests. In Benin Republic, located in the Sudano-Guinean region, smallholder's oil palm plantations do... more
In the current context of climate change, oil palm plantations are much criticized because they replace large areas of tropical forests. In Benin Republic, located in the Sudano-Guinean region, smallholder's oil palm plantations do not replace forests but old and unproductive croplands. In some of these palm plantations, pruned leaves from the palm trees are deposited to the soil for recycling. A study was conducted in southeastern Benin to evaluate the effect of the input of pruned leaves on soil carbon sequestration in smallholders' plantations. The study area is characterized by a mean annual precipitation in the range 1300-1400 mm. Soils are slightly desaturated ferralsols. Young palm plantations (4-6 year-old), pre-adults (7-12 year-old) and adults (13-20 year-old) were selected. In the young plantations, the leaves pruning is not occurring yet. In the pre-adults and adults plantations, the leaves have been cut down and recycled during respectively 4 years and 10 years,...
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Land degradation and regeneration are complex processes that greatly impact climate regulation, ecosystem service provision, and population well‐being and require an urgent and appropriate response through land use planning and... more
Land degradation and regeneration are complex processes that greatly impact climate regulation, ecosystem service provision, and population well‐being and require an urgent and appropriate response through land use planning and interventions. Spatially explicit land change models can greatly help decision makers, but traditional regression approaches fail to capture the nonlinearity and complex interactions of the underlying drivers. Our objective was to use a machine learning algorithm combined with high‐resolution data sets to provide simultaneous and spatial forecasts of deforestation, land degradation, and regeneration for the next two decades. A 17,000‐km2 region in the south of Madagascar was taken as the study area. First, an empirical analysis of drivers of change was conducted, and then, an ensemble model was calibrated to predict and map potential changes based on 12 potential explanatory variables. These potential change maps were used to draw three scenarios of land chan...
Research Interests: Earth Sciences, Environmental Science, Urban Regeneration, Environmental Sciences, Environmental Resource Management, and 10 moreMadagascar, Land Use, Scenarios, CHEMICAL SCIENCES, Land use change modelling, Land Degradation, Déboisement, conservation du paysage, Apprentissage machine, and Ensemble Method
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Abstract In the context of climate change, studies have focused on the temperature dependence of soil CO 2 emissions. Although calcareous soils cover over 30% of the earth's land surface, few studies have considered calcareous soils... more
Abstract In the context of climate change, studies have focused on the temperature dependence of soil CO 2 emissions. Although calcareous soils cover over 30% of the earth's land surface, few studies have considered calcareous soils where soil inorganic carbon (SIC) makes the analysis of the C fluxes at the soil to air interface more complex. This study tested how temperature could affect the contributions of soil organic carbon (SOC) and SIC to the CO 2 emitted from a calcareous soil. The soil pH, CO 2 emissions and δ 13 C signatures of CO 2 were measured after soil incubations at 4 temperatures (20 °C, 30 °C, 40 °C and 50 °C). The CO 2 emissions and the δ 13 C signature of the emitted CO 2 increased with temperature. The proportion of SIC-derived CO 2 in these emissions seemed to be stimulated by temperature. Three processes were discussed: (1) isotopic fractionations, (2) temperature impacts on SIC- and SOC-derived CO 2 , and (3) isotope exchanges between SIC- and SOC-derived CO 2 . The use of δ 13 C signature analysis to determine the contribution of SIC and SOC to the total CO 2 emissions from soil is not straightforward. An increase in the SIC signature of emitted CO 2 does not directly imply an increase in SIC as a source of CO 2.
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Carbon dioxide and methane integrate biogeochemical cycles of C and constitute, together with nitrous oxide, the main trace gases responsible for the greenhouse effect. Increasing interest in the global consequences of climate change has... more
Carbon dioxide and methane integrate biogeochemical cycles of C and constitute, together with nitrous oxide, the main trace gases responsible for the greenhouse effect. Increasing interest in the global consequences of climate change has prompted the global scientific community to deepen their studies about the global C stocks and the interrelations among its different compartments. As main compartments, soils and phytomass (living and nonliving) have received special attention. Many authors proposed a quantification of C stored in soils and proposed to study their role as both a source and sink of carbon (Post et al. 1982, Eswaran et al. 1993, Sombroek et al. 1993, Batjes 1996). The world’s mineral soils are estimated to contain about 1500 Pg C (Post et al. 1982, Eswaran et al. 1993, Batjes 1996), while the biomass of plants is estimated to be comprised between 560 and 835 Pg C (Whittaker and Likens 1975, Bouwman 1990). Tropical forests account for between 20 and 25% of the world terrestrial C (Brown and Lugo 1982, Dixon et al. 1994). The Amazon contains the largest expanse of native tropical ecosystems and has a direct influence on global biogeochemical cycles, especially the C cycle. The C stored in phytomass is of importance because of its quantity and its potential to be released easily. Carbon in soil is proved to be important because soil organic carbon (SOC) is intimately involved in virtually all biological processes, and organic matter (OM), even when present in small amounts, is an extremely important soil constituent. Two Brazilian soil classes, Latossolos and Podzólicos, make up 73% of the total area of the Legal Amazon Basin of Brazil (Prado 1996, Jacomine and Camargo 1996). More precisely, only three dystrofic soil types, Podzólico Vermelho Amarelo (Acrisol), Latossolo Amarelo (xanthic Ferralsol), and Latossolo Vermelho Amarelo (orthic Ferralsol) cover approximately 60% of the total, and are therefore of prime interest. The remainder is distributed between 13 additional classes. Only 6, however, represent more than one percent, and only 2 of which are more than 5%: Plintossolos (Inceptisols, Oxisols, and Alfisols) and Gleissolos (Entisols and Inceptisols).
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The Brazilian Cerrado is a large and expanding agricultural frontier, representing a hotspot of land‐use change (LUC) from natural vegetation to farmland. It is known that this type of LUC impacts soil organic matter (SOM) dynamics,... more
The Brazilian Cerrado is a large and expanding agricultural frontier, representing a hotspot of land‐use change (LUC) from natural vegetation to farmland. It is known that this type of LUC impacts soil organic matter (SOM) dynamics, particularly labile carbon (C) pools (living and non‐living), decreasing soil health and agricultural sustainability, as well as increasing soil greenhouse gas (GHG) emissions, and accelerating global climate change. In this study, we quantified the changes in the quantity and quality of SOM and GHG fluxes due to changes in land use and cropland management in the Brazilian Cerrado. The land uses studied were native vegetation (NV), pasture (PA) and four croplands, including the following management types: conventional tillage with a single soybean crop (CT), and three no‐tillage systems with two crops cultivated in the same year (i.e., soybean/sorghum (NTSSo), soybean/millet (NTSMi) and maize/sorghum (NTMSo)). Soil and gases were sampled in the rainy season (November, December and January) and dry season (May, July and September). The highest soil C and nitrogen (N) stocks (6.7 kg C m−2 and 0.5 kg N m−2, 0–0.3‐m layer) were found under NV. LUC reduced C stocks by 25% in the CT and by 10% in the PA and NT. Soil N stocks were 30% lower in the PA and NTMSo and 15% lower in the croplands with soybean compared to NV. δ13C values clearly distinguished between the C‐origin from NV (−25‰) and that from other land uses (−16‰). Soil (0–0.1 m) under NV also presented higher labile‐C (625 g C m−2), microbial‐C (70 g C m−2) and microbial‐N (5.5 g N m−2), whereas other land uses presented values three times lower. GHG emissions (expressed as C‐equivalent) were highest in the NV (1.2 kg m−2 year−1), PA (1.3 kg m−2 year−1) and NTMSo (0.9 kg m−2 year−1) and were positively related to the higher SOM turnover in these systems. Our results suggest that in order to maintain SOM, it is necessary to adopt “best” management practices, that provide large plant residue inputs (above‐ and belowground). This can be seen as a pathway to achieving high food production with low GHG emissions.
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Measurement, Reporting and Verification (MRV) of soil carbon. International Scientific Conference Our under Common Climate Future Chang
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To respect the Paris agreement targeting a limitation of global warming below 2°C by 2100, and possibly below 1.5°C, drastic reductions of greenhouse gas emissions are mandatory but not sufficient. Large‐scale deployment of other climate... more
To respect the Paris agreement targeting a limitation of global warming below 2°C by 2100, and possibly below 1.5°C, drastic reductions of greenhouse gas emissions are mandatory but not sufficient. Large‐scale deployment of other climate mitigation strategies is also necessary. Among these, increasing soil organic carbon (SOC) stocks is an important lever because carbon in soils can be stored for long periods and land management options to achieve this already exist and have been widely tested. However, agricultural soils are also an important source of nitrous oxide (N2O), a powerful greenhouse gas, and increasing SOC may influence N2O emissions, likely causing an increase in many cases, thus tending to offset the climate change benefit from increased SOC storage. Here we review the main agricultural management options for increasing SOC stocks. We evaluate the amount of SOC that can be stored as well as resulting changes in N2O emissions to better estimate the climate benefits of ...
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Agroforestry is a land use type where crops and trees are grown together in the same place and at the same time. Agroforestry systems have the advantage of providing multiple products (e.g. wood, fruits) or services (e.g. biodiversity... more
Agroforestry is a land use type where crops and trees are grown together in the same place and at the same time. Agroforestry systems have the advantage of providing multiple products (e.g. wood, fruits) or services (e.g. biodiversity enhancement, erosion control) whilst maintaining agricultural production. If they are known to store carbon into the biomass of the trees, they could also increase soil organic carbon (SOC) stocks. However their impact has rarely been studied under temperate conditions and has mostly concerned superficial soil layers. Our objectives were (i) to quantify and spatialize SOC stocks in an agroforestry system and in an adjacent agricultural plot, (ii) to assess what SOC fractions are responsible for possible additional carbon storage, and (iii) to quantify all organic inputs entering the soil. The trial was established in 1995 in southern France. Hybrid walnut trees are intercropped with durum wheat. SOC stocks were measured on 200 soil cores down to 2 m so...