Carbon balance components of a black locust-based agroforestry site under Mediterranean climate

Agroforestry systems (AFS) can provide many services, among which sequestering atmospheric carbon (C) dioxide (CO2) into both tree biomass and soil organic matter for mitigating climate warming. Such high performances were documented in several studies, but data are still scarse for covering the broad range of agrosystems – climate combinations. More particularly, data of the different C stocks and fluxes among the different components of the AFS needs to be documented for robust estimates of C sink strength. This study aims at providing values of C stocks and fluxes of a black locust (Robinia pseudoacacia L.)-based agroforestry site in Mauguio, Southern France. The different compartments of the AFS were investigated: the black locust rows, the herbaceous strip planted of various grassland species along the trees and the intercropping, constituted by a rotation cereals/legumes. The crop rotations comprised durum wheat, barley, chickpea and pea, but we presented the data for the barley planting year in 2021. A forest plantation and a pure crop planting systems were also studied as control modalities. The three planting systems were repeated in three independent blocks. Aboveground tree biomass growth was estimated for the agroforestry and the forestry plots from allometric models. Black locust litter fall was quantified also in the agroforestry and forestry plots. For each planting systems, root biomasses, root C contents and root growth were estimated . Aboveground herbaceous biomasses and C contents were also measured in 1m2 squared plots at different seasons. Soil microbial biomass and soil CO2 efflux were measured in all components and planting systems. All data currently under processing will be normalized per area unit. The effect of the planting system was assessed in order to determine the added value of the agroforestry system with respect to the pure planting systems

Monitoreo de servicios ecosistémicos en un observatorio de cafetales agroforestales. Recomendaciones para el sector cafetalero

Ocho años de estudio de la ecofisiología del café, a través de experimentación y de modelación y el monitoreo de los servicios del ecosistema (SE) en una gran finca cafetalera en Costa Rica, revelaron varias recomendaciones prácticas para los agricultores y los formuladores de políticas. El sistema de cultivo estudiado dentro de nuestro observatorio colaborativo (Coffee-Flux), corresponde a un sistema agroforestal (SAF) a base de café bajo la sombra de grandes árboles de Erythrina poeppigiana (16% de la cubierta del dosel). Una gran cantidad de SE y limitantes dependen de las propiedades locales del suelo (en este caso Andisoles), especialmente de la erosión/infiltración, el agua/carbono y la capacidad de almacenamiento de nutrientes. Por lo tanto, para la evaluación de SE, el tipo de suelo es crucial. Una densidad adecuada de árboles de sombra (bastante baja aquí por la condición de libre crecimiento), redujo la severidad de las enfermedades de las hojas con la posibilidad de reducir el uso de plaguicidas y fungicidas. Un inventario simple del área basal en el collar de las plantas de café permitió estimar la biomasa subterránea y la edad promedio de la plantación, para juzgar su valor de mercado y decidir cuándo reemplazarla. Las fincas de café probablemente estén mucho más cerca de la neutralidad de C que lo indicado en el protocolo actual de C-neutralidad, que solo considera árboles de sombra, no los cafetos ni el suelo. Se proponen evaluaciones más completas, que ncluyen árboles, café, hojarasca, suelo y raíces en el balance C del SAF. Los árboles de sombra ofrecen muchos SE si se gestionan adecuadamente en el contexto local. En comparación con las condiciones a pleno sol, los árboles de sombra pueden (i) reducir la erosión laminar en un factor de 2; (ii) aumentar la fijación de N y el % de N reciclado en el sistema, reduciendo así los requisitos de fertilizantes; (iii) reducir la severidad de enfermedades de las hojas; (iv) aumentar el secuestro de C; (v) mejorar el microclima y (vi) reducir sustancialmente los efectos del cambio climático. En nuestro estudio de caso, no se encontró ningún efecto negativo sobre el rendimiento del café

Neurological manifestations of COVID-19 in adults and children

Different neurological manifestations of coronavirus disease 2019 (COVID-19) in adults and children and their impact have not been well characterized. We aimed to determine the prevalence of neurological manifestations and in-hospital complications among hospitalized COVID-19 patients and ascertain differences between adults and children. We conducted a prospective multicentre observational study using the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC) cohort across 1507 sites worldwide from 30 January 2020 to 25 May 2021. Analyses of neurological manifestations and neurological complications considered unadjusted prevalence estimates for predefined patient subgroups, and adjusted estimates as a function of patient age and time of hospitalization using generalized linear models. Overall, 161 239 patients (158 267 adults; 2972 children) hospitalized with COVID-19 and assessed for neurological manifestations and complications were included. In adults and children, the most frequent neurological manifestations at admission were fatigue (adults: 37.4%; children: 20.4%), altered consciousness (20.9%; 6.8%), myalgia (16.9%; 7.6%), dysgeusia (7.4%; 1.9%), anosmia (6.0%; 2.2%) and seizure (1.1%; 5.2%). In adults, the most frequent in-hospital neurological complications were stroke (1.5%), seizure (1%) and CNS infection (0.2%). Each occurred more frequently in intensive care unit (ICU) than in non-ICU patients. In children, seizure was the only neurological complication to occur more frequently in ICU versus non-ICU (7.1% versus 2.3%, P < 0.001). Stroke prevalence increased with increasing age, while CNS infection and seizure steadily decreased with age. There was a dramatic decrease in stroke over time during the pandemic. Hypertension, chronic neurological disease and the use of extracorporeal membrane oxygenation were associated with increased risk of stroke. Altered consciousness was associated with CNS infection, seizure and stroke. All in-hospital neurological complications were associated with increased odds of death. The likelihood of death rose with increasing age, especially after 25 years of age. In conclusion, adults and children have different neurological manifestations and in-hospital complications associated with COVID-19. Stroke risk increased with increasing age, while CNS infection and seizure risk decreased with age

Fine Open Dendro: Un dendromètre automatique de précision adapté aux espèces tropicales

Source Agritrop Cirad (https://agritrop.cirad.fr/615053/)International audienc

Impact of trees on soil characteristics and root litter decomposition as a function of soil depth in a sub-sahelian agroforestry ecosystem dominated by Faidherbia Albida

International audienceAmong agroecological practices, the diversification of cropping systems with the introduction of trees is an adaptation solution to mitigate climate change (Bradshaw et al., 2004). Those combining trees and crops present functionally varied root systems that explore different soil depths. Moreover, while the production of aboveground biomass is recognized as one of the main levers to foster C storage in soils, the fate of root biomass has been less studied, especially in deep horizons. Deep roots from annual and perennial plants play a central role in the sustainable C sequestration through their turnover (Pradier et al., 2017), their exudation, and could become a determining criterion for plant selection. Indeed, root decomposition slows down with soil depth (Pries et al. 2018), and thus promote soil C storage.Our study aims to assess the contribution of roots to soil C sequestration, at different soil depth, under annual crops and trees in a sub-sahelian agroforestry ecosystem. The experiment was carried out in Sob village (Niakhar district, Senegal) in order to measure the root decomposition of two annual crops (pearl millet and cowpea) under the influence or not of a Legume tree (Faidherbia albida) and at different soil depth, down to 2m. Fine root decomposition of Faidherbia albida was also measured.Two pits of 2*2*2m were dug, one located at 1.5m from a Faidherbia albida tree of more than 80 year old (under the crown) and the second pit was located at 30m from the same tree, supposed with no tree influence. On three faces out of four of each pit, soil samples were collected at several depths and were analyzed (texture, C, N and P content, pH, bulk density). Soil humidity was monitored through TDR sensors from topsoil to 1.6m soil depth. The above- and belowground biomass of the annual crop (pear millet the year of sampling) was measured over the surface of each pit (4m²) including 4 plants. Pearl millet, Faidherbia and cowpea roots (from a juxtaposed field) were collected, washed and separated as a function of their diameter. Fine roots (Ø<2mm) were selected and 2g were put in litterbags of 2*2mm mesh size. Faidherbia medium root (2mm<Ø<10mm) decomposition was also monitored with 2.5g put in litterbags with the same mesh size. Litterbags were buried at 50cm from each pit face and at 20, 40, 90, 180cm soil depths. A total of 290 litterbags were buried with 3 replicates. At several sampling date (1.5, 3, 6, 9, 15 months) 50 to 70 litterbags were collected and roots litters were weighed to estimate the remaining mass.Results showed a tremendous effect of Faidherbia tree on soil fertility characteristics with higher mineral N and Olsen P content in topsoil under the tree. This trend was reversed under 30cm where the deep soil fertility seemed to be lower under the tree than far from it. The measurement of the crop aerial biomass at harvest showed an important increase (2 to 3 fold) under the tree compare to far from it. The belowground biomass was also increased but only in topsoil. Root to shoot ratio was higher far from the tree than under it. Fine and medium roots of Faidherbia albida were spread mainly in 40-100cm and 150-200cm soil layers. The root decomposition kinetics is currently under analyzes and would be further discussed in relation with C and N balance

Impact of trees on soil characteristics and root litter decomposition as a function of soil depth in a sub-sahelian agroforestry ecosystem dominated by Faidherbia Albida

International audienceAmong agroecological practices, the diversification of cropping systems with the introduction of trees is an adaptation solution to mitigate climate change (Bradshaw et al., 2004). Those combining trees and crops present functionally varied root systems that explore different soil depths. Moreover, while the production of aboveground biomass is recognized as one of the main levers to foster C storage in soils, the fate of root biomass has been less studied, especially in deep horizons. Deep roots from annual and perennial plants play a central role in the sustainable C sequestration through their turnover (Pradier et al., 2017), their exudation, and could become a determining criterion for plant selection. Indeed, root decomposition slows down with soil depth (Pries et al. 2018), and thus promote soil C storage.Our study aims to assess the contribution of roots to soil C sequestration, at different soil depth, under annual crops and trees in a sub-sahelian agroforestry ecosystem. The experiment was carried out in Sob village (Niakhar district, Senegal) in order to measure the root decomposition of two annual crops (pearl millet and cowpea) under the influence or not of a Legume tree (Faidherbia albida) and at different soil depth, down to 2m. Fine root decomposition of Faidherbia albida was also measured.Two pits of 2*2*2m were dug, one located at 1.5m from a Faidherbia albida tree of more than 80 year old (under the crown) and the second pit was located at 30m from the same tree, supposed with no tree influence. On three faces out of four of each pit, soil samples were collected at several depths and were analyzed (texture, C, N and P content, pH, bulk density). Soil humidity was monitored through TDR sensors from topsoil to 1.6m soil depth. The above- and belowground biomass of the annual crop (pear millet the year of sampling) was measured over the surface of each pit (4m²) including 4 plants. Pearl millet, Faidherbia and cowpea roots (from a juxtaposed field) were collected, washed and separated as a function of their diameter. Fine roots (Ø<2mm) were selected and 2g were put in litterbags of 2*2mm mesh size. Faidherbia medium root (2mm<Ø<10mm) decomposition was also monitored with 2.5g put in litterbags with the same mesh size. Litterbags were buried at 50cm from each pit face and at 20, 40, 90, 180cm soil depths. A total of 290 litterbags were buried with 3 replicates. At several sampling date (1.5, 3, 6, 9, 15 months) 50 to 70 litterbags were collected and roots litters were weighed to estimate the remaining mass.Results showed a tremendous effect of Faidherbia tree on soil fertility characteristics with higher mineral N and Olsen P content in topsoil under the tree. This trend was reversed under 30cm where the deep soil fertility seemed to be lower under the tree than far from it. The measurement of the crop aerial biomass at harvest showed an important increase (2 to 3 fold) under the tree compare to far from it. The belowground biomass was also increased but only in topsoil. Root to shoot ratio was higher far from the tree than under it. Fine and medium roots of Faidherbia albida were spread mainly in 40-100cm and 150-200cm soil layers. The root decomposition kinetics is currently under analyzes and would be further discussed in relation with C and N balance

Root litter decomposition in a Sub-Sahelian agroforestry parkland dominated by Faidherbia albida

International audienc

Impact of soil depth and plant species on root litter decomposition kinetics in a sub-sahelian agroforestry parkland

International audienceContent: Among agroecological practices, the diversification of cropping systems with the introduction of trees is an adaptation solution to mitigate climate change (Bradshaw et al., 2004). Those combining trees and crops present functionally varied root systems that explore different soil depths. Moreover, while the production of aboveground biomass is recognized as one of the main levers to foster C storage in soils, the fate of root biomass has been less studied, especially in deep horizons. Deep roots from annual and perennial plants play a central role in the sustainable C sequestration through their turnover (Pradier et al., 2017), their exudation, and could become a determining criterion for plant selection. Indeed, root decomposition slows down with soil depth (Pries et al. 2018), and thus promote soil C storage.Our study aims to assess the contribution of roots to soil C sequestration, at different soil depth, under annual crops and trees in a sub-sahelian agroforestry ecosystem. The experiment was carried out in Sob village (Niakhar district, Senegal) in order to measure the root decomposition of two annual crops (pearl millet and cowpea) under the influence or not of a Legume tree (Faidherbia albida) and at different soil depth, down to 180 cm. Fine root decomposition of Faidherbia albida was also measured.Two pits of 2 × 2 × 2 m were dug, one located at 1.5 m from a Faidherbia albida tree of more than 80 year old (under the crown) and the second pit was located at 30 m from the same tree, supposed with no tree influence. On three faces out of four of each pit, soil samples were collected at several depths and were analyzed (texture, C, N and P content, pH, bulk density). Soil humidity was monitored through TDR sensors at different depths. The above- and belowground biomass of the annual crop (pear millet the year of sampling) was measured over the surface of each pit (4 m²) including 4 plants. Pearl millet, Faidherbia and cowpea roots (from a juxtaposed field) were collected, washed and separated as a function of their diameter. Fine roots (Ø<2mm) were selected and 2 g were put in litterbags of 2 × 2 mm mesh size. Litterbags were buried at 50 cm from each pit face and at 20, 40, 90, 180cm soil depths. At several sampling date (1.5, 3, 6, 9, 15 months) 50 to 70 litterbags were collected and roots litters were weighed to estimate the remaining mass.Soil C :N content indicated a different microbial strategy with higher values under the tree than far from the tree in topsoils and lower values under the tree than far from the tree in depth. However, it was not related to root litter decomposition. Despite the higher tree root biomass under the legume tree, C and N stocks did not vary according to the location far or under the tree. Under the tree, C inputs in the soil were increased with higher pearl millet plant production and yield. It affected mainly aerial plant parts and shallow roots but not deep roots in accordance with the greater soil fertility in the 0 – 40 cm under the tree compared to deeper soil layers. Root litter decomposition was mainly impacted by soil moisture and thus soil depth. Root litter quality through plant species was another important driver of root decomposition. The main differences between root litter decomposition were mainly observed during the first 1.5 months of decomposition.Low root decomposition in depth suggested greater soil carbon storage than in topsoils. Tree root litters were more recalcitrant than annual crop root litters and thus participate in soil carbon storage. The presence of a tree did not seem to impact crop or tree root litter decomposition but further research should focus to this aspect with replicated trees and different distances to the tree according to a gradient to confirm the influence of the tree presence on root decomposition kinetics

Impact of trees on soil characteristics and root litter decomposition as a function of soil depth in a sub-sahelian agroforestry ecosystem dominated by Faidherbia Albida

International audienceAmong agroecological practices, the diversification of cropping systems with the introduction of trees is an adaptation solution to mitigate climate change (Bradshaw et al., 2004). Those combining trees and crops present functionally varied root systems that explore different soil depths. Moreover, while the production of aboveground biomass is recognized as one of the main levers to foster C storage in soils, the fate of root biomass has been less studied, especially in deep horizons. Deep roots from annual and perennial plants play a central role in the sustainable C sequestration through their turnover (Pradier et al., 2017), their exudation, and could become a determining criterion for plant selection. Indeed, root decomposition slows down with soil depth (Pries et al. 2018), and thus promote soil C storage.Our study aims to assess the contribution of roots to soil C sequestration, at different soil depth, under annual crops and trees in a sub-sahelian agroforestry ecosystem. The experiment was carried out in Sob village (Niakhar district, Senegal) in order to measure the root decomposition of two annual crops (pearl millet and cowpea) under the influence or not of a Legume tree (Faidherbia albida) and at different soil depth, down to 2m. Fine root decomposition of Faidherbia albida was also measured.Two pits of 2*2*2m were dug, one located at 1.5m from a Faidherbia albida tree of more than 80 year old (under the crown) and the second pit was located at 30m from the same tree, supposed with no tree influence. On three faces out of four of each pit, soil samples were collected at several depths and were analyzed (texture, C, N and P content, pH, bulk density). Soil humidity was monitored through TDR sensors from topsoil to 1.6m soil depth. The above- and belowground biomass of the annual crop (pear millet the year of sampling) was measured over the surface of each pit (4m²) including 4 plants. Pearl millet, Faidherbia and cowpea roots (from a juxtaposed field) were collected, washed and separated as a function of their diameter. Fine roots (Ø<2mm) were selected and 2g were put in litterbags of 2*2mm mesh size. Faidherbia medium root (2mm<Ø<10mm) decomposition was also monitored with 2.5g put in litterbags with the same mesh size. Litterbags were buried at 50cm from each pit face and at 20, 40, 90, 180cm soil depths. A total of 290 litterbags were buried with 3 replicates. At several sampling date (1.5, 3, 6, 9, 15 months) 50 to 70 litterbags were collected and roots litters were weighed to estimate the remaining mass.Results showed a tremendous effect of Faidherbia tree on soil fertility characteristics with higher mineral N and Olsen P content in topsoil under the tree. This trend was reversed under 30cm where the deep soil fertility seemed to be lower under the tree than far from it. The measurement of the crop aerial biomass at harvest showed an important increase (2 to 3 fold) under the tree compare to far from it. The belowground biomass was also increased but only in topsoil. Root to shoot ratio was higher far from the tree than under it. Fine and medium roots of Faidherbia albida were spread mainly in 40-100cm and 150-200cm soil layers. The root decomposition kinetics is currently under analyzes and would be further discussed in relation with C and N balance

Root litter decomposition in a Sub-Sahelian agroforestry parkland dominated by Faidherbia albida

International audienc