Win-win opportunities combining high yields with high multi-taxa biodiversity in tropical agroforestry

Resolving ecological-economic trade-offs between biodiversity and yields is a key challenge when addressing the biodiversity crisis in tropical agricultural landscapes. Here, we focused on the relation between seven different taxa (trees, herbaceous plants, birds, amphibians, reptiles, butterflies, and ants) and yields in vanilla agroforests in Madagascar. Agroforests established in forests supported overall 23% fewer species and 47% fewer endemic species than old-growth forests, and 14% fewer endemic species than forest fragments. In contrast, agroforests established on fallows had overall 12% more species and 38% more endemic species than fallows. While yields increased with vanilla vine density and length, non-yield related variables largely determined biodiversity. Nonetheless, trade-offs existed between yields and butterflies as well as reptiles. Vanilla yields were generally unrelated to richness of trees, herbaceous plants, birds, amphibians, reptiles, and ants, opening up possibilities for conservation outside of protected areas and restoring degraded land to benefit farmers and biodiversity alike

Évaluation de la prolifération de la Jacinthe d’eau du lac Ravelobe Ankarafantsika et plan de restauration

The floating water hyacinth or Eichhornia crassipes invades Madagascar waters lotics and lentics. It’s the case of the lake Ravelobe, inside the national park of Ankarafantsika Mahajanga Madagascar, which, besides crocodiles, is very renowned by its wealth endemic in fishes, amphibians, aquatic turtle, and birds. In spite of the measures taken by the persons in charge of the park in 2007, by manual eradicated of the hyacinth by the villagers, the hyacinth proliferates in important scale. Regulation’s methods of the invasive species, besides quadrat and transects are applied to the plant, with the aim of estimating their ecology and the proliferation. Stable, the hyacinth invades almost half of the lake in wet season : it’s monospecific in many aquatics zones, or retained by the stalks of helophytes ; forms a nursery in the river which feds the lake. Entailed by the wind, it invades in a scattered way the entire free surface’s water. Ten plant groups were listed, all associated with Eichhornia crassipes. Three ecological factors are responsible in their distribution. Both maps of vegetations in wet and dry season represent the distribution of hyacinth with their species associate. The biomass as well as the density of hyacinth are important. The lake is filled because of the degraded basin hillsides’s erosion. The lake takes a convex aspect. The river which feds the lake searches an outcome deviant to feed the lake. The fragmentation of the ecosystem Ravelobe is felt. Human and birds have difficulties to fish within the water hyacinth proliferated. Recommendations are advanced to regulate water hyacinth and maintain the biodiversity

Évaluation de la prolifération de la Jacinthe d’eau du lac Ravelobe Ankarafantsika et plan de restauration

La jacinthe d’eau ou Eichhornia crassipes envahit les eaux lentiques de Madagascar. C’est le cas du lac Ravelobe du Parc National Ankarafantsika à l’ouest, qui, outre sa richesse en poissons, amphibiens, tortue, et oiseaux endémiques, est le château d’eau de la plaine du second grenier à riz de l’île. Malgré les mesures prises par les responsables du parc, la jacinthe prend une ampleur non négligeable, en occupant presque la moitié du lac alors qu’elle était absente il y a treize ans. Des quadrats et des transects, en plus des méthodes de régulation des espèces invasives ont été appliquées aux espèces végétales du lac, dans le but d’évaluer leur écologie et la prolifération la jacinthe. Toutes les espèces aquatiques du lac sont associées à la jacinthe. La biomasse ainsi que la densité de la jacinthe y sont importantes. La fragmentation de l’écosystème Ravelobe est sévèrement ressentie. L’homme comme les oiseaux ont des difficultés pour pêcher à cause de la prolifération de la jacinthe. Cependant, une quantité importante de biogaz pourrait être obtenue à partir des jacinthes d’eau du lac Ravelobe. Des recommandations sont avancées pour la réguler et maintenir la biodiversité de l’écosystème.The floating water hyacinth or Eichhornia crassipes invades Madagascar waters lotics and lentics. It’s the case of the lake Ravelobe, inside the national park of Ankarafantsika Mahajanga Madagascar, which, besides crocodiles, is very renowned by its wealth endemic in fishes, amphibians, aquatic turtle, and birds. In spite of the measures taken by the persons in charge of the park in 2007, by manual eradicated of the hyacinth by the villagers, the hyacinth proliferates in important scale. Regulation’s methods of the invasive species, besides quadrat and transects are applied to the plant, with the aim of estimating their ecology and the proliferation. Stable, the hyacinth invades almost half of the lake in wet season : it’s monospecific in many aquatics zones, or retained by the stalks of helophytes ; forms a nursery in the river which feds the lake. Entailed by the wind, it invades in a scattered way the entire free surface’s water. Ten plant groups were listed, all associated with Eichhornia crassipes. Three ecological factors are responsible in their distribution. Both maps of vegetations in wet and dry season represent the distribution of hyacinth with their species associate. The biomass as well as the density of hyacinth are important. The lake is filled because of the degraded basin hillsides’s erosion. The lake takes a convex aspect. The river which feds the lake searches an outcome deviant to feed the lake. The fragmentation of the ecosystem Ravelobe is felt. Human and birds have difficulties to fish within the water hyacinth proliferated. Recommendations are advanced to regulate water hyacinth and maintain the biodiversity

Évaluation de la prolifération de la Jacinthe d’eau du lac Ravelobe Ankarafantsika et plan de restauration

The floating water hyacinth or Eichhornia crassipes invades Madagascar waters lotics and lentics. It’s the case of the lake Ravelobe, inside the national park of Ankarafantsika Mahajanga Madagascar, which, besides crocodiles, is very renowned by its wealth endemic in fishes, amphibians, aquatic turtle, and birds. In spite of the measures taken by the persons in charge of the park in 2007, by manual eradicated of the hyacinth by the villagers, the hyacinth proliferates in important scale. Regulation’s methods of the invasive species, besides quadrat and transects are applied to the plant, with the aim of estimating their ecology and the proliferation. Stable, the hyacinth invades almost half of the lake in wet season : it’s monospecific in many aquatics zones, or retained by the stalks of helophytes ; forms a nursery in the river which feds the lake. Entailed by the wind, it invades in a scattered way the entire free surface’s water. Ten plant groups were listed, all associated with Eichhornia crassipes. Three ecological factors are responsible in their distribution. Both maps of vegetations in wet and dry season represent the distribution of hyacinth with their species associate. The biomass as well as the density of hyacinth are important. The lake is filled because of the degraded basin hillsides’s erosion. The lake takes a convex aspect. The river which feds the lake searches an outcome deviant to feed the lake. The fragmentation of the ecosystem Ravelobe is felt. Human and birds have difficulties to fish within the water hyacinth proliferated. Recommendations are advanced to regulate water hyacinth and maintain the biodiversity

Yield analysis as a function of stochastic plant architecture: case of Spilanthes acmella in the wet and dry season.

The number of organs produced by a plant varies among the individuals of a population. Taking these variations into account is an important step in understanding phenotypic variability. The aim of this study was to simulate stochastic development and growth in response to environmental change using GreenLab, an organ level functional-structural model. An annual herbaceous species, Spilanthes acmella L., was grown in pots in two climatic conditions corresponding to a wet and a dry season. Detailed records of plant development, plant architecture and organ growth were kept throughout the growing period. The concept of simple and compound organic series was introduced to target data for fitting. The model was calibrated using a mathematical model of stochastic plant development and growth. Here we describe (1) how a stochastic Functional Structural Plant Model is calibrated in two steps by first assessing the functioning parameters of meristems, and second the source-sink parameters of organs by fitting them on average organic series; (2) how dry conditions trigger the response of the plant both in the development of the inflorescence and in the allocation of biomass, quantified by model parameters. The calibration of a stochastic plant model opens a large window of opportunity to capture the common features of plant development and growth among stochastic individuals in a plant population, especially those with a branching structure. This extends the area of application of FSPM to analyzing food plants, or assisting breeding. (Résumé d'auteur

Implications of a local flora survey for pre‐human grass flora in north‐western Madagascar.

On apprend aux enfants de Madagascar que leurs ancêtres ont détruit la vaste forêt ancienne donnant naissance aux prairies modernes, un mythe trompeur qui continue à saper la relation des gens avec la nature. Remplacer ce mythe par un récit plus nuancé et précis sur les écosystèmes herbeux est fondamentale pour construire une relation positive entre la population et les écosystèmes de Madagascar, un processus nécessaire pour construire des pratiques modernes de conservation et de gouvernance environnementale. Les données que nous présentons sont cohérentes avec la flore herbacée pré‐humaine dans la région, suggérant que les écosystèmes herbacés locaux ne devraient pas être considérés comme anthropique et indésirables, mais qu'ils ont plutôt besoin d'être reconnus et d'une attention accrue de la recherche

Economic activities and their impacts on the ecosystem and biodiversity in Madagascar (Case of the Eastern region)

Extraction of wood for daily domestic use mainly for charcoal and construction are huge pressures on forests, even if restoration is carried out. Their impacts are considerably increased in the eastern region of Madagascar, due to unregulated and disproportionate economic activities mainly due to unemployment. The objective is to publicize the impacts of economic activities in the target sites. Socio-economic surveys were conducted followed by data analysis using econometric models. Questionnaires on the reasons for logging and / or forest conversion in relation to the activities of the inhabitants, the species of trees exploited in the forest restoration zone for the manufacture of charcoal, the quantity of trees felled, their diameter and the impacts on forest degradation were posed. Variances and standard deviations were calculated for the results obtained. Thus, the impacts of economic activities are significant. The use of fast-growing native species for forest restoration and the promotion of the use of efficient cook stoves or “fatana mitsitsy” were recommended