Faidherbia albida

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  • Root litter decomposition in a sub-Sahelian agroforestry parkland dominated by Faidherbia albida
    'Elsevier BV', 2022
    Co-Authors: Siegwart Lorène, Roupsard Olivier, Bertrand Isabelle, Duthoit Maxime, Jourdan Christophe
    Abstract:

    International audienceIn agroforestry systems, fine roots grow at several depths due to the mixture of trees and annual crops. The decomposition of fine roots contributes to soil organic carbon stocks and may impact soil fertility, particularly in poor soils, such as those encountered in sub-Sahelian regions. The aim of our study was to measure the decomposition rate of root litter from annual and perennial species according to soil depth and location under and far from trees in a sub-Sahelian agroforestry parkland.Soil characteristics under and far from the trees were analysed from topsoil to 200 cm depth. Faidherbia tree, pearl millet and cowpea root litter samples were buried in litterbags for 15 months at 20, 40, 90 and 180 cm depths.Root litter decomposition was mainly impacted by soil moisture and soil depth. Faidherbia decomposed more slowly (36 ± 12% remaining mass after 15 months) than cowpea and pearl millet roots (23 ± 7% and 29 ± 11% respectively). Pearl millet aboveground biomass, at harvesting time, was twice as high under (9918 g m-2) than far (4332 g m-2) from the tree, and belowground biomass (0–200 cm of depth) was 89 g m-2 and 64 g m-2 under and far from the tree, respectively. Faidherbia fine roots contributed slightly (p-value < 0.1) to higher stocks of C under the tree (7761 ± 346 g m-2) than far from it (5425 ± 558 g m-2) and from 0 cm down to 200 cm depth

  • More C uptake during the dry season? The case of a semi-arid agro-silvo-pastoral ecosystem dominated by Faidherbia albida, a tree with reverse phenology (Senegal)
    'Copernicus GmbH', 2020
    Co-Authors: Roupsard Olivier, Do, Frédéric C., Rocheteau Alain, Jourdan Christophe, Orange Didier, Tall Laure, Sow Sidy, Faye W., Diongue, Djim M.l., Diouf Khalisse
    Abstract:

    Agro-silvo-pastoralism is a highly representative Land Use in Africa, often presented as a strategical option for ecological intensification of cropping systems towards food security and sovereignty. We set up a new long-term observatory (“Faidherbia-Flux”) to monitor and model microclimate, energy and C balance in Niakhar (central Senegal, rainfall ~ 500 mm), dominated by the multipurpose tree Faidherbia albida (12.5 m high; 7 tree ha-1; 5% canopy cover). Faidherbia is an attractive agroforestry tree species in order to partition fluxes, given that it is on leaf during the dry season (October-June) and defoliated during the wet season, just when crops take over. Pearl-millet and groundnut crops were conducted during the wet season, following annual rotation in a complex mixed mosaic of ca. 1 ha fields. Early 2018, we installed an eddy-covariance (EC) tower above the whole mosaic (EC1: 20 m high). A second EC system was displayed above the crop (EC2: 4.5 m if pearl-millet, 2.5 m if groundnut) in order to partition ecosystem EC fluxes between tree layer and crop+soil layers. Sap-flow was monitored from April 2019 onwards in 5 Faidherbia trees (37 sensors). The ecosystem displayed moderate but significant daily CO2 and H2O fluxes during the dry season, when Faidherbia (low canopy cover) was in leaf and the soil was evaporating. At the onset of the rainy season, the soil bursted a large amount of CO2. Just after the growth of pearl-millet in 2018, CO2 uptake by photosynthesis increased dramatically. However, this was largely compensated by high ecosystem respiration. Surprisingly in 2019, although the crop was turned to groundnut, the fluxes behaved pretty much the same as with pearl millet in 2018: comparing annual balances between 2018 and 2019 we obtained [454, 513] for rainfall (P: mm yr-1), [3500, 3486] for potential evapotranspiration (ETo: mm yr-1), [0.13, 0.15] for P/ETo, [470, 497] for actual evapotranspiration (E: mm yr-1), [2809, 2785] for net radiation (Rn: MJ m-2 yr-1), [1686, 1645] for sensible heat flux (H: MJ m-2 yr-1), [-3.2, -2.8] for net ecosystem exchange of C (NEE: tC ha-1 yr-1), [-11.8, -11.1] for gross primary productivity (GPP: tC ha-1 yr-1) and [8.6, 8.3] for ecosystem respiration (Re: tC ha-1 yr-1). The energy balance (Rn-H-LE) was nearly nil indicating that the EC system behaved reasonably. E was very close to P, indicating that little or no water would recharge the deep soil layers.Now comparing the dry (2/3 of the year) and wet (1/3) seasons: surprisingly, NEE was more effective during the dry season [-3.9, -1.7]. This was the result of Re being much lower on a daily basis as well as cumulated over the entire seasons [57, 84], whereas GPP was similar [-10.8, -12.1]. We found a good match between E measured above the whole ecosystem (EC1), and the sum of tree transpiration (T, measured by sapflow) + E measured just above crops + soil (EC2) throughout the wet and dry seasons. The “Faidherbia-Flux” observatory is registered in FLUXNET as SN-Nkr and is widely open for collaboration

  • “Faidherbia-Flux”: adapting crops to climate changes in a semi-arid agro-sylvo-pastoral open observatory (Senegal)
    HAL CCSD, 2019
    Co-Authors: Roupsard Olivier, Rocheteau Alain, Jourdan Christophe, Orange Didier, Clermont-dauphin Cathy, Audebert Alain, Sanou J., Koala J., Do Frédéric, Bertrand Isabelle
    Abstract:

    National audienceThe adaptation of semi-arid crops to climate changes is theoretically possible through agroforestry, provided that the trees exert little competition, or even increase the multifunctional LER (LER_M). We monitored microclimate, net primary productivity (NPP), CO2 and H2O fluxes in a semiarid agro-sylvo-pastoral system (Niakhar, Senegal), dominated by the multipurpose Faidherbia albida (FA) tree. Undercrops were mainly millet and peanut, under annual rotation. We scanned a 1.24 ha millet under FA plot with UAV photogrammetry in RGB, thermal infrared and multispectral bands. At harvest, we collected 12 subplots of 15 millet holes each, distributed either below the crown of FA, or at 2.5 x crown radius, or at 5 x crown radius. We separated all organs. The whole millet root system (0-200 cm) was sampled also in 2 m trenches, totalizing 4 millet holes, where all roots were sorted by layer. The whole plot harvest will allow extrapolating yield from subplots, through UAV images. Millet yield per unit ground area was about 3 times higher below FA, with still a positive influence at 2.5 x crown radius and less impacts of pests close to FA. In the trenches, we noted higher soil humidity and SOC close to the FA trunks. This observatory is open for collaboration

  • "Faidherbia-Flux": an open observatory for GHG balance and C stocks in a semi-arid agro-sylvo-pastoral system (Senegal)
    HAL CCSD, 2019
    Co-Authors: Roupsard Olivier, Jourdan Christophe, Duthoit Maxime, Cournac Laurent, Tall L., Kergoat Laurent, Timouk Franck, Grippa Manuela, Li A., Lardy Laurent
    Abstract:

    International audienceThe mitigation of climate change by agro-sylvo-pastoral systems is complex to assess or model, owing to high spatial and temporal heterogeneities. We set a new long-term observatory up for the monitoring and modelling of microclimate, GHG and deep SOC in a semi-arid agro-sylvo-pastoral system (Niakhar, Sénégal), dominated by the multipurpose Faidherbia albida tree. Crops were mainly millet and peanut, under annual rotation. Transhumant livestock contributed largely to manure, SOM and soil fertility. Early 2018, we installed 3 eddy-covariance towers above (i) the whole mosaic, (ii) millet and (iii) peanut and monitored energy, CO2 balance and evapotranspiration for one full year. The mosaic ecosystem displayed low but significant CO2 and H2O fluxes during the dry season, owing to Faidherbia in leaf (Fig. 1). When rains resumed, the soil bursted a large amount of CO2. Just after the raising of millet, CO2 uptake by photosynthesis increased dramatically, then stabilized before harvest. However, this was compensated by large ecosystem respiration. The annual ecosystem CO2 balance was close to nil. This observatory is currently installing soil chambers for GHG fluxes, studying the horizontal variability of SOC by Vis-NIR and of deep soil roots and C using wells. Microclimate (land surface temperature, energy balance and gas exchanges) and light-use-efficiency will be mapped through 3D modelling (Charbonnier et al., 2017; Vezy et al., 2018). This observatory is open for collaboration

  • Ecophysiologie et diversité génétique de Faidherbia albida (Del.) A. Chev. (syn. Acacia albida Del.), un arbre à usages multiples d'Afrique semi-aride. Fonctionnement hydrique et efficience d'utilisation de l'eau d'arbres adultes en parc agroforestier et de juvéniles en conditions semi-contrôlées. Tome 1 : Partie synthèse
    HAL CCSD, 1997
    Co-Authors: Roupsard Olivier
    Abstract:

    Faidherbia albida (Del.) A. Chev. (syn. Acacia albida, Del.) is a multipurpose tree of the legume family, widespread in Africa. Its strategy in the face of drought appears very original: it is present in semi-arid zones but its phenology is reversed in relation to the rains: it buds at the end of the rainy season, bears fruit and grows during the dry season, then loses its leaves at the beginning of the new rainy season. Very little is known about its hydrous functioning. We conducted seasonal monitoring of the water functioning of adult trees in agroforestry parks (Burkina Faso, West Africa; 920 mm rainfall). The basic water potential remained high throughout the dry season, indicating that the trees were permanently accessing soil horizons with very good water supply. Roots were down to the vicinity of the water table (-7 to -15 m depending on the site). The isotopic oxygen content of the soil water, groundwater and raw sap indicated that the trees absorbed mainly in the vicinity of the water table, except during the rainy season, when they tilted towards the surface. The trees transpired intensely, especially at the beginning of the dry season (about 400 l/day for a 65 cm diameter tree, measured by a sap flow method). But stem density was low, and annual transpiration of the tree component of the plots remained below 5% of the rainfall. During the dry season, the soil moisture stress increased moderately (slight decrease in base water potential, 50% reduction in total soil-leaf specific hydraulic conductance). The edaphic and atmospheric components of water stress probably contributed to the closure of stomata during the dry season. We tracked changes in intrinsic water use efficiency (ratio of net assimilation to stomatal conductance, A/g) using leaf carbon isotopic composition. A/g decreased during the dry season despite stoma closure. The photosynthetic capacity could therefore be affected, and we looked for a nutritional cause. Foliar nitrogen content actually fell by 50% during the dry season: F. albida absorbed and probably fixed nitrogen only within a narrow "window" corresponding to leaf initiation, when the surface horizons are still moist and surface nitrogen remains mobilized. Radial growth stopped early in the dry season, before leaf fall, and may also have been dependent on reduced photosynthetic capacity. Leaf fall started after the new rains, and would therefore be independent of the edaphic drought: on the other hand, the narrow "window" of assimilation and fixation would predispose to leaf senescence during the dry season, and could explain their abscission. The strategy of using water from juveniles that have not yet reached the water table is certainly very critical, and could explain why some fast-growing sources show low survival rates in dryland trials. We used pan-African provenances with contrasting initial growth patterns to describe the diversity of ecophysiological characters of F. albida at the seedling stage. We tested the factors: provenance, soil water availability and experimental site (in a greenhouse in Nancy-France or in a nursery in Ouagadougou-Burkina Faso), factors that are likely to affect the efficiency of integrated water use (W: ratio of dry biomass produced to water consumed). Nitrogen fixation can also modulate W, playing either on A or on the carbon allocation for symbiosis. Nitrogen fixation was estimated by the natural abundance of nitrogen 15, and modulated by phosphorus input. Vigorous provenances had more leaf area and transpiration and invested less in root growth. Differences in vigour between provenances were very small at the more restrictive Ouagadougou site: vigorous provenances lost much of their initial growth advantage, showing less hardiness. These elements seem essential to interpret their poor survival in the dry zone. Inter-provenance differences in W, A/g and carbon isotope discrimination were significant but moderate. A/g was better for the most vigorous provenances, a fact confirmed by carbon isotope discrimination. But the relationship between W and carbon isotope discrimination differed between provenances, probably due to differences in non-photosynthetic processes. Vigorous provenances, which fixed more nitrogen, had lower W values for the same carbon isotope discrimination value. Carbon losses, perhaps related to the requirements of symbiosis, could explain this. The relationship between W and carbon isotope discrimination, tested at the two sites, differed mainly because of differences in air saturation deficits. The relationship between A/g and carbon isotope discrimination seemed to be maintained on the contrary. We conclude that there was a close relationship between A/g and carbon isotope discrimination, demonstrating the relevance of using carbon 13 in the field to estimate A/g, but not W. Faidherbia albida ultimately appears to be a phaetophyte species in the adult state, which makes it relatively free of edaphic water stress. Its very late bud burst has little impact on its water functioning, but greatly affects nutrition, and probably photosynthesis and growth. In the juvenile stage, the stomata close very rapidly in response to moderate edaphic drought, showing a drought "avoidance" strategy. We conclude that F. albida represents an excellent plant model for studying the impact of drought at different physiological stages.Faidherbia albida (Del.) A. Chev. (syn. Acacia albida, Del.) est un arbre a usages multiples de la famille des légumineuses, très répandu en Afrique. Sa stratégie face à la sécheresse apparaît très originale : il est présent en zone semi-aride mais sa phénologie est inversée par rapport aux pluies : il débourre en fin de saison des pluies, fructifie et croît en cours de saison sèche, puis perd ses feuilles au début de la nouvelle saison des pluies. Son fonctionnement hydrique est très peu connu. Nous avons mené des suivis saisonniers du fonctionnement hydrique d'arbres adultes en parc agroforestier (Burkina Faso, Afrique de l'Ouest ; 920 mm de pluies). Le potentiel hydrique de base est reste élevé tout au long de la saison sèche, indiquant que les arbres accédaient en permanence à des horizons de sol très bien pourvus en eau. Les racines descendaient jusqu'au voisinage de la nappe (-7 à -15 m selon les sites). La teneur isotopique en oxygène de l'eau du sol, de la nappe et de la sève brute indiquait que les arbres absorbaient essentiellement au voisinage de la nappe, sauf au moment des pluies, où ils opéraient un basculement vers la surface. Les arbres transpiraient intensément, notamment au début de la saison sèche (environ 400 l/jour pour un arbre de 65 cm de diamètre, mesuré par une méthode de flux de sève). Mais la densité des tiges était faible, et la transpiration annuelle de la composante arbre des parcelles est restée inférieure à 5 % des pluies. En cours de saison sèche, la contrainte hydrique édaphique a augmenté modérément (légère diminution des potentiels hydriques de base, réduction de 50 % de la conductance hydraulique totale spécifique sol-feuilles). Les composantes édaphique et atmosphérique de la contrainte hydrique ont probablement contribué à la fermeture des stomates en cours de saison sèche. Nous avons suivi les variations de l'efficience intrinsèque d'utilisation de l'eau (rapport de l'assimilation nette à la conductance stomatique, A/g) à l'aide de la composition isotopique en carbone des feuilles. A/g a diminué en cours de saison sèche malgré la fermeture de stomates. La capacité photosynthétique a donc pu être affectée, et nous avons recherché une cause nutritionnelle. La teneur en azote foliaire a effectivement chuté de 50 % en cours de saison sèche : F. albida n'absorbait et ne fixait probablement l'azote que dans une étroite " fenêtre " correspondant à l'initiation foliaire, lorsque les horizons de surface sont encore humectés et que l'azote de surface reste mobilisable. La croissance radiale s'est arrêtée précocement en cours de saison sèche, avant la chute des feuilles : elle était peut-être aussi tributaire de la réduction de la capacité photosynthétique. La chute des feuilles a commencé après les nouvelles pluies, elle serait donc indépendante de la sécheresse édaphique : en revanche, l'étroite " fenêtre " d'assimilation et de fixation prédisposerait à la sénescence des feuilles en cours de saison sèche, et pourrait expliquer leur abscission. La stratégie d'utilisation de l'eau de juvéniles qui n'ont pas encore atteint la nappe est certainement très critique, et pourrait expliquer pourquoi certaines provenances à croissance rapide montrent de faibles taux de survie dans les essais pratiqués en zone sèche. Nous avons utilisé des provenances panafricaines à croissance initiale contrastée pour décrire la diversité des caractères écophysiologiques de F. albida au stade jeune plant. Nous avons testé les facteurs : provenance, disponibilité en eau du sol et site expérimental (en serre à Nancy-France ou en pépinière à Ouagadougou-Burkina Faso), facteurs qui sont susceptibles d'affecter I'effïcience d'utilisation de l'eau intégrée (W : rapport biomasse sèche produite sur eau consommée). La fixation de l'azote peut également moduler W, en jouant soit sur A, soit sur l'allocation de carbone pour la symbiose. La fixation de l'azote a été estimée par l'abondance naturelle de l'azote 15, et modulée par l'apport de phosphore. Les provenances vigoureuses présentaient une surface foliaire et une transpiration plus importantes et investissaient moins dans la croissance racinaire. Les écarts de vigueur entre provenances étaient très réduits sur le site plus contraignant de Ouagadougou : les provenances vigoureuses perdaient une grande partie de leur avantage de croissance initiale, montrant une moindre rusticité. Ces éléments semblent essentiels pour interpréter leur médiocre survie en zone sèche. Les différences inter-provenances de W, A/g et de discrimination isotopique du carbone, étaient significatives mais modérées. A/g était meilleur pour les provenances les plus vigoureuses, un fait confirmé par la discrimination isotopique du carbone. Mais la relation entre W et la discrimination isotopique du carbone différait entre provenances, probablement en raison de différences dans les processus non-photosynthétiques. Les provenances vigoureuses, qui fixaient davantage d'azote, présentaient des valeurs de W plus faibles pour une même valeur de la discrimination isotopique du carbone. Des pertes de carbone, liées peut-être aux exigences de la symbiose pourraient expliquer ceci. La relation entre W et la discrimination isotopique du carbone, testée sur les deux sites, différait principalement à cause des différences de déficit de saturation de l'air. La relation entre A/g et la discrimination isotopique du carbone semblait conservée au contraire. Nous en concluons qu'il existait un lien étroit entre A/g et la discrimination isotopique du carbone, démontrant la pertinence de l'utilisation du carbone 13 sur le terrain pour estimer A/g, mais pas W. Faidherbia albida apparaît en définitive comme une espéce phréatophyte à l'état adulte, ce qui I'affranchit relativement de la contrainte hydrique édaphique. Son débourrement très tardif a peu d'impact sur son fonctionnement hydrique, mais affecte grandement la nutrition, et probablement la photosynthèse et la croissance. Au stade juvénile, les stomates se ferment très rapidement en réponse à une sécheresse édaphique modérée, montrant une stratégie " d'évitement " de la sécheresse. Nous concluons que F. albida représente un excellent modèle végétal pour l'étude de l'impact de la sécheresse à différents stades physiologiques

Technical Centre For Agricultural And Rural Cooperation - One of the best experts on this subject based on the ideXlab platform.

  • Faidherbia albida
    Technical Centre for Agricultural and Rural Cooperation, 2015
    Co-Authors: Technical Centre For Agricultural And Rural Cooperation
    Abstract:

    La technique de sylviculture du Faidherbia albida, plus connu sous le nom d Acacia albida, est désormais au point et peut être facilement appliquée par les agriculteurs qui connaissent déjà la richesse de cet arbre. Les graines récoltées de janvier à avril sont décortiquées, triées puis séchées pendant quelques jours, on les immerge ensuite dans l'eau bouillante, où on les laisse macérer une journée avant de les semer. Les semis sont effectués dans des sachets de polyéthylène étroits et hauts arrosés deux fois par jour. La plantation s'effectue en saison des pluies, lorsque les plants ont atteint 15 à 30 cm, dans des trous de 30 cm de profondeur. Il faut alors protéger les jeunes arbres du bétail, du feu et des mauvaises herbes. Lorsque les arbres ont un développement suffisant, on les taille afin qu'ils ne gênent pas les cultures. Favoriser la plantation de cet arbre est un facteur important de lutte contre la désertification dans les zones soudaniennes et sahéliennes. En effet, en remontant l'eau des nappes phréatiques grâce à son pivot très profond, cet arbre sécrète un micro-climat favorable aux cultures, et il améliore la fertilité des sols en perdant ses feuilles juste avant la saison de pluies. Outre ces avantages, il fournit un fourrage de qualité (fruits et gousses) au bétail en saison sèche. Pour en savoir plus, contacter le : CTFT 45 bis av. de la Belle Gabrielle 94130 Nogent-sur-Marne FranceLa technique de sylviculture du Faidherbia albida, plus connu sous le nom d Acacia albida, est désormais au point et peut être facilement appliquée par les agriculteurs qui connaissent déjà la richesse de cet arbre. Les graines récoltées de..

  • A wide range of benefits
    Technical Centre for Agricultural and Rural Cooperation, 2015
    Co-Authors: Technical Centre For Agricultural And Rural Cooperation
    Abstract:

    A wide range of benefits Cue: While agroforestry, as a science, is quite new, in fact farmers have been enjoying the benefits of having trees on their farms for generations. Some trees, for example, produce nutrient-rich leaves which, when they fall on the soil, act as a natural fertilizer. In the lakeshore areas of Malawi, Faidherbia albida trees, known locally as msangu, are often left by farmers, who recognise the fertility benefit they give. But agroforestry is about more than just increasing soil fertility. Carefully chosen trees and shrubs, if planted on farms, can provide a huge range of benefits, from building materials to insecticides. Excello Zidana recently spoke to Dr Henry Phombeya, Project Co-ordinator for Malawi?s Land Resource Centre, about the many advantages of having trees on farms. IN: ?There are several and normally I like dividing them.? OUT: ?. agroforestry really can help to boast crop yields.? DUR?N 5?29? BACK ANNOUNCEMENT: Dr Henry Phombeya of Malawi?s Land Resource Centre, talking to Excello Zidana. Transcript Phombeya There are several and normally I like dividing them in two categories. We?ve got some technologies that are dealing with soil fertility improvement and for these we use shrubs like Tephrosia vogelii, Sesbania sesban, and trees like Faidherbia albida locally known as msangu or mtete. And then there are some technologies that are to do more with afforestation. And here we have trees like the Sennas, Senna spectabilis, Senna siamea. Zidana What are the other forms of agroforestry that you have been using or that you know? Phombeya There are other forms yes of agroforestry technologies. For example we can talk of biomass transfer. These are instances where you?ve got trees that are planted say as boundaries around your farm. You can at times prune the branches, take the biomass that you realise from there and apply it to your field. That has proved to be a very important technology and crops have improved under such systems. And then when you get the leaves like that you have the branches and of course the tree you can use for fuel wood. So you have got two benefits here. Not even two, three. You are improving soil fertility, you have the trees that are demarcating your boundaries to avoid conflict with your neighbours and then you?ve got the fuel wood which is a very important factor now that there is rampant deforestation. Zidana When we look around in the villages in Malawi we have discovered that a number of farmers have taken up the technology of using Tephrosia vogelii. What are the specific advantages regarding this shrub? Phombeya Tephrosia it?s a very important shrub in that first and foremost it has got a very good biomass that when we incorporate in the soil it helps to build up organic matter. And at the same time it?s a legume, it fixes nitrogen. That?s contributing to soil fertility. But up and above that Tephrosia vogelii has got some insecticidal properties. If you crush the leaves of Tephrosia vogelii and you?ve got maize stalk borer, you put it in the maize funnel the maize stalk borer goes away. So it has got that insecticidal property that is a very important component. Zidana You also talked about the tree which is locally known as msangu in Malawi. Phombeya Faidherbia albida, that is the scientific name. Zidana Faidherbia albida. Now if we talk about the lake shore areas, these trees are numerous, they are all over. Do the farmers realise the importance of retaining or keeping these trees? Phombeya Yes I did research on Faidherbia albida specifically. And in the survey that we conducted it showed that people value these trees and they deliberately leave them on their farms. And asking them about why they leave them there their answers were, if you plant maize underneath a Faidherbia albida tree it does very well and you?ve got a variety of crops that can be grown underneath it. So in a way they know it?s an important tree. Zidana So they are convinced that if you are using these trees definitely the fertility of the soil may be improved in one way or the other? Phombeya Yes, they are aware of that, only that they don?t know exactly what happens for that fertility to come about and that?s the work of the scientist. Zidana You have been talking about the trees like Leucaena but now we haven?t seen you doing much on the Leucaena. Is there any problem? Phombeya Yes Leucaena leucocephala was a very important tree in those old days when agroforestry just came into the picture. But as we were working with it a terrible pest attacked it. That pest is called psyllid; it?s a pest that attacks the leaves, the tender leaves of Leucaena and it devastates the whole tree. A very dangerous pest. Zidana But the animals enjoyed consuming or eating the leaves from the Leucaena tree? Phombeya It was a very good fodder, highly nutritive. But all is not lost because breeders are looking at other species of Leucaena, like Leucaena pallida, Leucaena esculenta. They are looking at Leucaena that have resistance to psyllid attack. Zidana How do you look at farming if many people adopted this concept? Phombeya If people adopted agroforestry, like others have already done, productivity of their farms will be very high. We compared fields where we had just maize growing on its own and a plot where we had maize and then the agroforestry species and a bit of chemical fertiliser. The differences in yields were just too high, over 200%. So agroforestry really can help to boost crop yields. End of track.Henry Phombeya of Malawi?s Land Resource Centre outlines the benefits of various popular agroforestry species, including those offering soil fertility improvement

  • Monographie sur l’ACACIA albida
    Technical Centre for Agricultural and Rural Cooperation, 2015
    Co-Authors: Technical Centre For Agricultural And Rural Cooperation
    Abstract:

    Dans un ouvrage collectif du CTFT-CIRAD (Centre Technique Forestier Tropical) consacré au Faidherbia albida, encore appelé Acacia albida ou gao ou kad en fonction des pays, se trouve une description minutieuse de cet arbre étonnant. Bien connu pour son rythme phénologique inversé -c'est à- dire qu'il possède la particularité de perdre ses feuilles en début de saison des pluies et d'être feuillé en saison sèche-, les agriculteurs le préservent sur leurs champs. Ce ne sont pas tous les arbres qui, non seulement ne gênent pas l'agriculture, mais au contraire, présentent d'inestimables avantages quant à la fertilisation des sols et à l'alimentation du bétail en saison sèche. Fort de ces caractéristiques et de ces mérites bien connus, cet arbre qui vit à contre temps fait l'objet de recherches détaillées et est reconnu comme l'une des essences les plus importantes pour le maintien de l'équilibre du milieu en zones semi-arides. Dans cet excellent ouvrage magnifiquement illustré qui lui est consacré, est abordé de façon très approfondie tout ce qui le concerne : répartition géographique, variabilité génétique, écologie, étude de son rythme de feuillaison, croissance, reproduction... Puis quelques chapitres sont consacrés aux applications sur le terrain de la 'culture ' de cet arbre : son impact sur l'agriculture, sur l'élevage, sa production de bois, son utilisation en pharmacopée... Enfin, la dernière partie traite de sa sylviculture : régénération artificielle et naturelle, plantation, description des ennemis de cette culture, amélioration génétique... Pour se procurer ce livre : CTFT CIRAD 45bis, av.Belle Gabrielle 94736 - Nogent/Marne FranceDans un ouvrage collectif du CTFT-CIRAD (Centre Technique Forestier Tropical) consacré au Faidherbia albida, encore appelé Acacia albida ou gao ou kad en fonction des pays, se trouve une description minutieuse de cet arbre étonnant.Bien connu..

  • Green fertilizer at planting time
    Technical Centre for Agricultural and Rural Cooperation, 2015
    Co-Authors: Technical Centre For Agricultural And Rural Cooperation
    Abstract:

    Green fertilizer at planting time Cue: Normally, when the rains end and the dry months begin, we expect trees to drop their leaves and for the landscape to become increasingly brown. But in the lakeshore areas of Malawi, one species of tree is breaking the rules. The African winterthorn is very unusual; it is covered with green leaves throughout the dry season, but sheds them at planting time, when the rains arrive. This characteristic makes it a very useful species for farmers, and as a result, this African tree has now been successfully introduced in Asia and South America. Grown together with cereal crops such as sorghum, millet and maize- and even in flooded rice fields - the tree is able to improve soil fertility and provide much needed shade for people and livestock during the hot months. To find out more about this unusual tree, Patrick Mphaka visited Salima district, an area where for generations farmers have been leaving these trees to grow in their fields. He sent us this report. IN: ?It is not the most beautiful.? OUT: ?. fast growing tree here in Salima, than to other places.? DUR?N 5?10? BACK ANNOUNCEMENT: Robin Mlolo ending that report from Salima district in Malawi. The African winterthorn, Faidherbia albida is in fact able to grow well in many different environments, from low lying areas to high savannahs and woodlands. Transcript Mphaka It is not the most beautiful of trees when you look at it. It has thorns. It sheds its leaves with the rains and is green during the dry season. When fully grown, it is a large deciduous tree to 30 metres high, crown wide and rounded. The list of its uses is endless. Welcome to the African winterthorn, also known as Acacia albida, or Faidherbia albida. Here, it is locally known as Msangu. Now that agroforestry, and Faidherbia albida in particular, is being promoted country-wide by the Ministry of Agriculture, this district has become a demonstration district. I came over to see what I never saw of the tree, and know what I never knew. I chatted with Mr. Robin Mlolo, a local farmer in Traditional Authority Maganga in the district. I found him working in his field. Mlolo These trees are most useful here. We use them as soil fertility trees. And in most times in our gardens, we don?t apply fertilizer. These trees act as fertilizer in our fields. Mphaka For other trees, we avoid the cover which the leaves of trees do give to the crops because sunlight does not reach the crops. What happens with these big trees, do you tolerate them to hinder sunlight from reaching the crops? What happens? Mlolo In other trees, there is a shading effect to our crops. But to this tree, which is Msangu, it is a special tree. This is how God has created it. In the beginning of the rains, is the time when it is shedding its leaves. Mphaka So it sheds the leaves, it doesn?t have the leaves? Mlolo Yes, during the cropping period, it doesn?t have leaves. Mphaka But the leaves are there when people have harvested? Mlolo Yes after harvesting, that is when it starts producing the leaves. Mphaka And you use the leaves as fertilizers? Mlolo As fertilizers. Mphaka These are very big trees and they are very old indeed. Is there anything which the people here are doing to make sure that these trees do not finish as we know that most people use the trees for firewood as well as for making charcoal? Mlolo Yes, there are many projects which are going on here in Salima, mainly in replanting this tree to other fields or other gardens. These projects are helping us also to maintain these species in our gardens. We know the usefulness of these trees, mainly the leaves. It?s hard for a farmer like me to cut down this big tree, Msangu. If I want, I can just cut the branches and leave the whole tree. Mphaka You do that because you know the usefulness of the trees? Mlolo Yes, the usefulness of the tree. Mphaka What are other uses which these trees are used for? Mlolo These trees are mainly useful to us, we can use it as a medicinal tree. And also we can use it as a shade to people like us, and our animals mainly during the hot season, it?s when it gives the leaves while other trees are shedding off the leaves. We can also use this tree for poles, building our houses, whatsoever. Firewood, and also the pods of this tree, if they fall down, it can be as feed to our livestock. Mphaka Oh I see. Like when I was coming over here, I saw that one of the big trees there has got a hole, and I found that there were some bees. Mlolo Okay, okay, I forgot. We can also harvest honey in our trees. That is my honey. We can also put some beehives on these trees. You can see one over there. But do not go near, because bees sting. Mphaka You use Msangu as we have seen, do you apply any amount of fertilizer in these fields? Mlolo No, no, no. We don?t apply any fertilizers. The funny thing is that when we are using these Msangu trees, we can raise our crop production from 50%-250%, which is similar to fertilizer application. Mphaka And maybe we can say higher because for the fertilizer, you have to buy and you use some money there? Mlolo Yes, yes, yes. Mphaka Whereas this one is almost free? Mlolo It?s almost free, yes. We do not use fertilizer here. Mphaka How easy or difficult is it to propagate or to plant Faidherbia albida in other areas other than this lakeshore area? Mlolo Here in our area, it?s a hot area. These trees favour hot areas. And you can see the soils are almost sandy. So it is a fast growing tree here in Salima, than to other places. End of trackRobin Mlolo, a farmer from Malawi?s lakeshore area, describes the many benefits to be gained from Faidherbia albida, the African winterthorn

  • Relève assurée
    Technical Centre for Agricultural and Rural Cooperation, 2015
    Co-Authors: Technical Centre For Agricultural And Rural Cooperation
    Abstract:

    Relève assurée Mamadou Faye, du secteur Eaux et Forêts de Mbacké, au Sénégal, décrit les résultats de la bonne collaboration entre l'ONG SOS Sahel, les services gouvernementaux et les villageois. « La zone où nous vivons est une savane arborée très déboisée, on n'y trouve que des espèces fourragères (Faidherbia albida, Acacia spp., Balanites aegyptiaca) ; presque toutes les espèces à valeur industrielle ont disparu. L'ONG a tenu des séances de causerie et de sensibilisation pour amener les populations à planter et entretenir de jeunes plants. Des groupements ont été formés aux techniques de pépinière. Et chaque année, de petites parcelles (0, 5-1 ha) de plantations clôturées à base d'Euphorbia balsamifera ont été plantées. » M. Faye mentionne aussi le forage de deux puits, la création de parcelles maraîchères, l'achat d'un moulin à mil et la construction de cases de santé. Et de conclure : « La fin du projet en 1994 n'a pas empêché les responsables des villages de continuer les actions de plantation, sous la houlette de Mme Cazaty qui continue de se battre avec l'aide du secteur Eaux et Forêts de Mbacké pour le bien-être de nos populations rurales. »Mamadou Faye, du secteur Eaux et Forêts de Mbacké, au Sénégal, décrit les résultats de la bonne collaboration entre l'ONG SOS Sahel, les services gouvernementaux et les villageois. « La zone où nous vivons est une savane arborée très..

Jourdan Christophe - One of the best experts on this subject based on the ideXlab platform.

  • Root litter decomposition in a sub-Sahelian agroforestry parkland dominated by Faidherbia albida
    'Elsevier BV', 2022
    Co-Authors: Siegwart Lorène, Roupsard Olivier, Bertrand Isabelle, Duthoit Maxime, Jourdan Christophe
    Abstract:

    International audienceIn agroforestry systems, fine roots grow at several depths due to the mixture of trees and annual crops. The decomposition of fine roots contributes to soil organic carbon stocks and may impact soil fertility, particularly in poor soils, such as those encountered in sub-Sahelian regions. The aim of our study was to measure the decomposition rate of root litter from annual and perennial species according to soil depth and location under and far from trees in a sub-Sahelian agroforestry parkland.Soil characteristics under and far from the trees were analysed from topsoil to 200 cm depth. Faidherbia tree, pearl millet and cowpea root litter samples were buried in litterbags for 15 months at 20, 40, 90 and 180 cm depths.Root litter decomposition was mainly impacted by soil moisture and soil depth. Faidherbia decomposed more slowly (36 ± 12% remaining mass after 15 months) than cowpea and pearl millet roots (23 ± 7% and 29 ± 11% respectively). Pearl millet aboveground biomass, at harvesting time, was twice as high under (9918 g m-2) than far (4332 g m-2) from the tree, and belowground biomass (0–200 cm of depth) was 89 g m-2 and 64 g m-2 under and far from the tree, respectively. Faidherbia fine roots contributed slightly (p-value < 0.1) to higher stocks of C under the tree (7761 ± 346 g m-2) than far from it (5425 ± 558 g m-2) and from 0 cm down to 200 cm depth

  • More C uptake during the dry season? The case of a semi-arid agro-silvo-pastoral ecosystem dominated by Faidherbia albida, a tree with reverse phenology (Senegal)
    'Copernicus GmbH', 2020
    Co-Authors: Roupsard Olivier, Do, Frédéric C., Rocheteau Alain, Jourdan Christophe, Orange Didier, Tall Laure, Sow Sidy, Faye W., Diongue, Djim M.l., Diouf Khalisse
    Abstract:

    Agro-silvo-pastoralism is a highly representative Land Use in Africa, often presented as a strategical option for ecological intensification of cropping systems towards food security and sovereignty. We set up a new long-term observatory (“Faidherbia-Flux”) to monitor and model microclimate, energy and C balance in Niakhar (central Senegal, rainfall ~ 500 mm), dominated by the multipurpose tree Faidherbia albida (12.5 m high; 7 tree ha-1; 5% canopy cover). Faidherbia is an attractive agroforestry tree species in order to partition fluxes, given that it is on leaf during the dry season (October-June) and defoliated during the wet season, just when crops take over. Pearl-millet and groundnut crops were conducted during the wet season, following annual rotation in a complex mixed mosaic of ca. 1 ha fields. Early 2018, we installed an eddy-covariance (EC) tower above the whole mosaic (EC1: 20 m high). A second EC system was displayed above the crop (EC2: 4.5 m if pearl-millet, 2.5 m if groundnut) in order to partition ecosystem EC fluxes between tree layer and crop+soil layers. Sap-flow was monitored from April 2019 onwards in 5 Faidherbia trees (37 sensors). The ecosystem displayed moderate but significant daily CO2 and H2O fluxes during the dry season, when Faidherbia (low canopy cover) was in leaf and the soil was evaporating. At the onset of the rainy season, the soil bursted a large amount of CO2. Just after the growth of pearl-millet in 2018, CO2 uptake by photosynthesis increased dramatically. However, this was largely compensated by high ecosystem respiration. Surprisingly in 2019, although the crop was turned to groundnut, the fluxes behaved pretty much the same as with pearl millet in 2018: comparing annual balances between 2018 and 2019 we obtained [454, 513] for rainfall (P: mm yr-1), [3500, 3486] for potential evapotranspiration (ETo: mm yr-1), [0.13, 0.15] for P/ETo, [470, 497] for actual evapotranspiration (E: mm yr-1), [2809, 2785] for net radiation (Rn: MJ m-2 yr-1), [1686, 1645] for sensible heat flux (H: MJ m-2 yr-1), [-3.2, -2.8] for net ecosystem exchange of C (NEE: tC ha-1 yr-1), [-11.8, -11.1] for gross primary productivity (GPP: tC ha-1 yr-1) and [8.6, 8.3] for ecosystem respiration (Re: tC ha-1 yr-1). The energy balance (Rn-H-LE) was nearly nil indicating that the EC system behaved reasonably. E was very close to P, indicating that little or no water would recharge the deep soil layers.Now comparing the dry (2/3 of the year) and wet (1/3) seasons: surprisingly, NEE was more effective during the dry season [-3.9, -1.7]. This was the result of Re being much lower on a daily basis as well as cumulated over the entire seasons [57, 84], whereas GPP was similar [-10.8, -12.1]. We found a good match between E measured above the whole ecosystem (EC1), and the sum of tree transpiration (T, measured by sapflow) + E measured just above crops + soil (EC2) throughout the wet and dry seasons. The “Faidherbia-Flux” observatory is registered in FLUXNET as SN-Nkr and is widely open for collaboration

  • "Faidherbia-Flux": adapting crops to climate changes in a semi-arid agro-sylvo-pastoral open observatory (Senegal)
    HAL CCSD, 2019
    Co-Authors: Rouspard Olivier, Rocheteau Alain, Jourdan Christophe, Didier Orange, Clermont-dauphin Cathy, Audebert Alain, Sanou Josias, Koala Jonas, Do F. C., Bertrand Isabelle
    Abstract:

    International audienceThe adaptation of semi-arid crops to climate changes is theoretically possible through agroforestry, provided that the trees exert little competition, or even increase the multifunctional LER (LER_M). We monitored microclimate, net primary productivity (NPP), CO2 and H2O fluxes in a semiarid agro-sylvo-pastoral system (Niakhar, Senegal), dominated by the multipurpose Faidherbia albida (FA) tree. Undercrops were mainly millet and peanut, under annual rotation. We scanned a 1.24 ha millet under FA plot with UAV photogrammetry in RGB, thermal infrared and multispectral bands. At harvest, we collected 12 subplots of 15 millet holes each, distributed either below the crown of FA, or at 2.5 x crown radius, or at 5 x crown radius. We separated all organs. The whole millet root system (0-200 cm) was sampled also in 2 m trenches, totalizing 4 millet holes, where all roots were sorted by layer. The whole plot harvest will allow extrapolating yield from subplots, through UAV images. Millet yield per unit ground area was about 3 times higher below FA, with still a positive influence at 2.5 x crown radius and less impacts of pests close to FA. In the trenches, we noted higher soil humidity and SOC close to the FA trunks. This observatory is open for collaboration

  • “Faidherbia-Flux”: adapting crops to climate changes in a semi-arid agro-sylvo-pastoral open observatory (Senegal)
    HAL CCSD, 2019
    Co-Authors: Roupsard Olivier, Rocheteau Alain, Jourdan Christophe, Orange Didier, Clermont-dauphin Cathy, Audebert Alain, Sanou J., Koala J., Do Frédéric, Bertrand Isabelle
    Abstract:

    National audienceThe adaptation of semi-arid crops to climate changes is theoretically possible through agroforestry, provided that the trees exert little competition, or even increase the multifunctional LER (LER_M). We monitored microclimate, net primary productivity (NPP), CO2 and H2O fluxes in a semiarid agro-sylvo-pastoral system (Niakhar, Senegal), dominated by the multipurpose Faidherbia albida (FA) tree. Undercrops were mainly millet and peanut, under annual rotation. We scanned a 1.24 ha millet under FA plot with UAV photogrammetry in RGB, thermal infrared and multispectral bands. At harvest, we collected 12 subplots of 15 millet holes each, distributed either below the crown of FA, or at 2.5 x crown radius, or at 5 x crown radius. We separated all organs. The whole millet root system (0-200 cm) was sampled also in 2 m trenches, totalizing 4 millet holes, where all roots were sorted by layer. The whole plot harvest will allow extrapolating yield from subplots, through UAV images. Millet yield per unit ground area was about 3 times higher below FA, with still a positive influence at 2.5 x crown radius and less impacts of pests close to FA. In the trenches, we noted higher soil humidity and SOC close to the FA trunks. This observatory is open for collaboration

  • "Faidherbia-Flux": an open observatory for GHG balance and C stocks in a semi-arid agro-sylvo-pastoral system (Senegal)
    HAL CCSD, 2019
    Co-Authors: Roupsard Olivier, Jourdan Christophe, Duthoit Maxime, Cournac Laurent, Tall L., Kergoat Laurent, Timouk Franck, Grippa Manuela, Li A., Lardy Laurent
    Abstract:

    International audienceThe mitigation of climate change by agro-sylvo-pastoral systems is complex to assess or model, owing to high spatial and temporal heterogeneities. We set a new long-term observatory up for the monitoring and modelling of microclimate, GHG and deep SOC in a semi-arid agro-sylvo-pastoral system (Niakhar, Sénégal), dominated by the multipurpose Faidherbia albida tree. Crops were mainly millet and peanut, under annual rotation. Transhumant livestock contributed largely to manure, SOM and soil fertility. Early 2018, we installed 3 eddy-covariance towers above (i) the whole mosaic, (ii) millet and (iii) peanut and monitored energy, CO2 balance and evapotranspiration for one full year. The mosaic ecosystem displayed low but significant CO2 and H2O fluxes during the dry season, owing to Faidherbia in leaf (Fig. 1). When rains resumed, the soil bursted a large amount of CO2. Just after the raising of millet, CO2 uptake by photosynthesis increased dramatically, then stabilized before harvest. However, this was compensated by large ecosystem respiration. The annual ecosystem CO2 balance was close to nil. This observatory is currently installing soil chambers for GHG fluxes, studying the horizontal variability of SOC by Vis-NIR and of deep soil roots and C using wells. Microclimate (land surface temperature, energy balance and gas exchanges) and light-use-efficiency will be mapped through 3D modelling (Charbonnier et al., 2017; Vezy et al., 2018). This observatory is open for collaboration

Duponnois Robin - One of the best experts on this subject based on the ideXlab platform.

  • L'introduction d'acacias australiens pour réhabiliter des écosystèmes dégradés est-elle dépourvue de risques environnementaux ? = Australian acacia introduction to rehabilitate degraded ecosystems is it free of environmental risks ?
    2013
    Co-Authors: Duponnois Robin, Thioulouse J., Prin Y., Galiana A., Baudoin Ezékiel, Sanguin H., Le Roux C., Tournier E., Dreyfus Bernard
    Abstract:

    The use of exotic tree species and especially fast-growing trees (acacias, pines or eucalypts) has been frequently recommended to rehabilitate and restore in short term degraded areas resulting from natural events or human activities. The consequences on the environment of the introduction of these species, as the case invasive, are generally evaluated on their impact on plant biodiversity and soil physico-chemical characteristics but rarely on the composition of microbial communities. The soil microbiota, especially mycorhizal fungi, plays a key role vis-a-vis biological mechanisms governing the chemical soil fertility, productivity and stability of plant terrestrial ecosystems. Chosen approach was to describe the impact of exotic species on soil biological characteristics and the consequences of the recovering of vegetation cover composed of native species from the previous stand. After pointing out importance of the use of acacias worldwide, two case studies implemented in Senegal and Algeria, have shown that two Australian acacias, Acacia holosericea and Acacia mearnsii, induce deep changes in the functional diversity of soil microorganisms and in the structure of symbiotic microorganisms communities (mycorhizal fungi and rhizobia). These acacias inhibit the growth of two native tree species, Quercus suber and Faidherbia albida. These results confirm the need to identify the biological processes related to the actions of introducing exotic species in order to modulate their use. And this knowledge will prevent risks and ensure the performance of afforestation including rehabilitation of degraded land

  • Controlled ectomycorrhization of an exotic legume tree species Acacia holosericea affects the structure of root nodule bacteria community and their symbiotic effectiveness on Faidherbia albida, a native Sahelian Acacia
    2009
    Co-Authors: Faye A., Krasova-wade T., Thiao M., Thioulouse J., Neyra Marc, Prin Y., Galiana A., Dreyfus Bernard, Duponnois Robin
    Abstract:

    Many fast growing tree species have been introduced to promote biodiversity rehabilitation on degraded tropical lands. Although it has been shown that plant productivity and stability are dependent on the composition and functionalities of soil microbial communities, more particularly on the abundance and diversity of soil symbiotic micro-organisms (mycorrhizal fungi and rhizobia), the impact of tree introduction on soil microbiota has been scarcely studied. This research has been carried in a field plantation of Acacia holosericea (Australian Acacia species) inoculated or not with an ectomycorrhizal fungus isolate, Pisolithus albus IR100. After 7 year's plantation, the diversity and the symbiotic properties of Bradyrhizobia isolated from the plantation soil or from the surrounding area (Faidherbia albida (Del.) a. Chev. parkland) and able to nodulate E albida, a native Sahelian Acacia species, have been studied. Results clearly showed that A. holosericea modified the structure of Bradyrhizobia populations and their effectiveness on F albida growth. This negative effect was counterbalanced by the introduction of an ectomycorrhizal fungus, P albus, on A. holosericea root systems. In conclusion, this study shows that exotic plant species can drastically affect genotypic and symbiotic effectiveness of native Bradyrhizobia populations that could limit the natural regeneration of endemic plant species such as E albida. This effect could be counterbalanced by controlled ectomycorrhization with P albus. These results have to be considered when exotic tree species are used in afforestation programs that target preservation of native plants and soil ecosystem rehabilitation

  • Controlled ectomycorrhization of an exotic legume tree species Acacia holosericea affects the structure of root nodule bacteria community and their symbiotic effectiveness on Faidherbia albida, a native sahelian Acacia
    'Elsevier BV', 2009
    Co-Authors: Faye Aliou, Neyra Marc, Dreyfus Bernard, Krasova-wade Tatiana, Thiao Mansour, Thioulouse Jean, Prin Yves, Galiana Antoine, Ndoye Ibrahima, Duponnois Robin
    Abstract:

    Many fast growing tree species have been introduced to promote biodiversity rehabilitation on degraded tropical lands. Although it has been shown that plant productivity and stability are dependent on the composition and functionalities of soil microbial communities, more particularly on the abundance and diversity of soil symbiotic micro-organisms (mycorrhizal fungi and rhizobia), the impact of tree introduction on soil microbiota has been scarcely studied. This research has been carried in a field plantation of Acacia holosericea (Australian Acacia species) inoculated or not with an ectomycorrhizal fungus isolate, Pisolithus albus IR100. After 7 year's plantation, the diversity and the symbiotic properties of Bradyrhizobia isolated from the plantation soil or from the surrounding area (Faidherbia albida (Del.) a. Chev. parkland) and able to nodulate F. albida, a native Sahelian Acacia species, have been studied. Results clearly showed that A. holosericea modified the structure of Bradyrhizobia populations and their effectiveness on F. albida growth. This negative effect was counterbalanced by the introduction of an ectomycorrhizal fungus, P. albus, on A. holosericea root systems. In conclusion, this study shows that exotic plant species can drastically affect genotypic and symbiotic effectiveness of native Bradyrhizobia populations that could limit the natural regeneration of endemic plant species such as F. albida. This effect could be counterbalanced by controlled ectomycorrhization with P. albus. These results have to be considered when exotic tree species are used in afforestation programs that target preservation of native plants and soil ecosystem rehabilitation. (Résumé d'auteur

  • Controlled ectomycorrhization of an exotic legume tree species Acacia holosericea affects the structure of root nodule bacteria community and their symbiotic effectiveness on Faidherbia albida, a native sahelian Acacia
    CBBC, 2008
    Co-Authors: Faye Aliou, Neyra Marc, Dreyfus Bernard, Krasova-wade Tatiana, Thiao Mansour, Thioulouse Jean, Prin Yves, Galiana Antoine, Ndoye Ibrahima, Duponnois Robin
    Abstract:

    In the 400-700 mm rainfall zone, Acacia holosericea was found to be one of the best-adapted exotic tree showing excellent survival rate and rapid early growth (Harwood, 1994). In addition to rhizobial symbiosis, this tree species can form arbuscular mycorrhiza (AM) andlor ectomycorrhiza (De La Cruz & Garcia. I991 , Founoune et al ., 2002) and controlled mycorrhizal inoculation could improve its performance in glasshous e conditions (Duponnois et al ., 2000a, 2001, 2003) &Id also after outplanting into the field (Duponnois et al ., 2005, 2007). The impact of the establishment of exotic plant on the structure and function of native microbial communities was mainly unknown. Hence a study was conducted in a field experiment carried out in Senegal with A. holosericea, inoculated or not with an ectomycorrhizal strain Pisolithus albus IR 100 (Duponnois et al ., 2005, 2007) in order to evaluate the influence of this exotic fast growing leguminous tree on the native soi l microbiota and the potential consequences on soil revegetalisation with native plant species. Among the targeted native species, the leguminous tree Faidherbia albida has been selected since it plays a major role in the agrosylvo-pastoral balance of the Sahelian regions of Africa . Our study shows that exotic plant species can drastically affect the genotypic and symbiotic effectiveness of native bradyrhizobia populations which could limit the natural regeneration of endemic plant species such as F. albida. But this field-base experimental research outlights the role of mycorrhizal symbiosis in afforestation programmes with exotic tree species that target preservation of native plants. (Texte intégral

Bertrand Isabelle - One of the best experts on this subject based on the ideXlab platform.

  • Root litter decomposition in a sub-Sahelian agroforestry parkland dominated by Faidherbia albida
    'Elsevier BV', 2022
    Co-Authors: Siegwart Lorène, Roupsard Olivier, Bertrand Isabelle, Duthoit Maxime, Jourdan Christophe
    Abstract:

    International audienceIn agroforestry systems, fine roots grow at several depths due to the mixture of trees and annual crops. The decomposition of fine roots contributes to soil organic carbon stocks and may impact soil fertility, particularly in poor soils, such as those encountered in sub-Sahelian regions. The aim of our study was to measure the decomposition rate of root litter from annual and perennial species according to soil depth and location under and far from trees in a sub-Sahelian agroforestry parkland.Soil characteristics under and far from the trees were analysed from topsoil to 200 cm depth. Faidherbia tree, pearl millet and cowpea root litter samples were buried in litterbags for 15 months at 20, 40, 90 and 180 cm depths.Root litter decomposition was mainly impacted by soil moisture and soil depth. Faidherbia decomposed more slowly (36 ± 12% remaining mass after 15 months) than cowpea and pearl millet roots (23 ± 7% and 29 ± 11% respectively). Pearl millet aboveground biomass, at harvesting time, was twice as high under (9918 g m-2) than far (4332 g m-2) from the tree, and belowground biomass (0–200 cm of depth) was 89 g m-2 and 64 g m-2 under and far from the tree, respectively. Faidherbia fine roots contributed slightly (p-value < 0.1) to higher stocks of C under the tree (7761 ± 346 g m-2) than far from it (5425 ± 558 g m-2) and from 0 cm down to 200 cm depth

  • "Faidherbia-Flux": adapting crops to climate changes in a semi-arid agro-sylvo-pastoral open observatory (Senegal)
    HAL CCSD, 2019
    Co-Authors: Rouspard Olivier, Rocheteau Alain, Jourdan Christophe, Didier Orange, Clermont-dauphin Cathy, Audebert Alain, Sanou Josias, Koala Jonas, Do F. C., Bertrand Isabelle
    Abstract:

    International audienceThe adaptation of semi-arid crops to climate changes is theoretically possible through agroforestry, provided that the trees exert little competition, or even increase the multifunctional LER (LER_M). We monitored microclimate, net primary productivity (NPP), CO2 and H2O fluxes in a semiarid agro-sylvo-pastoral system (Niakhar, Senegal), dominated by the multipurpose Faidherbia albida (FA) tree. Undercrops were mainly millet and peanut, under annual rotation. We scanned a 1.24 ha millet under FA plot with UAV photogrammetry in RGB, thermal infrared and multispectral bands. At harvest, we collected 12 subplots of 15 millet holes each, distributed either below the crown of FA, or at 2.5 x crown radius, or at 5 x crown radius. We separated all organs. The whole millet root system (0-200 cm) was sampled also in 2 m trenches, totalizing 4 millet holes, where all roots were sorted by layer. The whole plot harvest will allow extrapolating yield from subplots, through UAV images. Millet yield per unit ground area was about 3 times higher below FA, with still a positive influence at 2.5 x crown radius and less impacts of pests close to FA. In the trenches, we noted higher soil humidity and SOC close to the FA trunks. This observatory is open for collaboration

  • “Faidherbia-Flux”: adapting crops to climate changes in a semi-arid agro-sylvo-pastoral open observatory (Senegal)
    HAL CCSD, 2019
    Co-Authors: Roupsard Olivier, Rocheteau Alain, Jourdan Christophe, Orange Didier, Clermont-dauphin Cathy, Audebert Alain, Sanou J., Koala J., Do Frédéric, Bertrand Isabelle
    Abstract:

    National audienceThe adaptation of semi-arid crops to climate changes is theoretically possible through agroforestry, provided that the trees exert little competition, or even increase the multifunctional LER (LER_M). We monitored microclimate, net primary productivity (NPP), CO2 and H2O fluxes in a semiarid agro-sylvo-pastoral system (Niakhar, Senegal), dominated by the multipurpose Faidherbia albida (FA) tree. Undercrops were mainly millet and peanut, under annual rotation. We scanned a 1.24 ha millet under FA plot with UAV photogrammetry in RGB, thermal infrared and multispectral bands. At harvest, we collected 12 subplots of 15 millet holes each, distributed either below the crown of FA, or at 2.5 x crown radius, or at 5 x crown radius. We separated all organs. The whole millet root system (0-200 cm) was sampled also in 2 m trenches, totalizing 4 millet holes, where all roots were sorted by layer. The whole plot harvest will allow extrapolating yield from subplots, through UAV images. Millet yield per unit ground area was about 3 times higher below FA, with still a positive influence at 2.5 x crown radius and less impacts of pests close to FA. In the trenches, we noted higher soil humidity and SOC close to the FA trunks. This observatory is open for collaboration

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