Historique de la colonisation du milieu de la presqu'île d'Ampasindava : transformations du paysage et système de conservation

In the northwest of Madagascar, the Ampasindava peninsula is home to the essential part of what remains of the forests of the Sambirano phytogeographic domain. The area has great importance in terms of biogeography, ecology, and socio-cultural aspects. The first documented human presence dates back to the tenth century, during the development of the maritime trade in Madagascar, before becoming the first headquarters of the Sakalava kingdom in the northwest of Madagascar. Several facts contributed to the degradation of the landscape, like the practice of the tavy and the war between Bemihisatra and Merina. In the peninsula, the western part was the most affected, on contrary to the eastern part where are located the forest massifs which served as refuges during the tribal wars. After the annexion by France, of an important territory including the peninsula (August 6th, 1 896), the Merina left the region, and these forest massifs acquired a sacred status and as such were protected against destruction, preserving the characteristics of the primary forests of Sambirano. Elsewhere, a process of natural reconstruction of the vegetation started. These historic facts lead us to conclude that the forests of Dypsis spp. (Arecaceae) and Sarcolaenaceae are not primary resulting from a difference in substrate or climate, but are to be interpreted as old secondary forest, deriving from the long-term process of reconstruction of the vegetation. For several years, the analysis of satellite imagery demonstrates that the rhythm of the tavy has dramatically increased in the region. This increase stems not only from a population growth, but also from a growing pressure for land to generate income for the purchase of manufactured products. The practice of the tavy represents a major threat to forests and different types of residual natural habitats. Secondary forests are the most sensitive and most suitable for rice production. Primary sacred forests have remained so far untouched. Their traditional protection is however recently shaken by the influx of immigrants, who show little respect to traditional ban. RÉSUMÉ Dans le Nord-ouest de Madagascar, la presqu’île d’Ampasindava abrite une partie essentielle des restes des forêts du domaine du Sambirano. La région possède une grande importance tant biogéographique et écologique, que socio-culturelle. Elle a connu au Xe siècle sa première implantation humaine et il est vraisemblable que l’Homme l’ait parcourue et utilisée régulièrement à l’époque du développement du réseau maritime à Madagascar, avant que le Sambirano ne devienne le premier siège du royaume Sakalava dans le Nord-ouest de l’île. Plusieurs faits ont contribué à la déstructuration du paysage écologique initial, comme la pratique de l’abattis sur brûlis ou tavy et les guerres entre les Bemihisatra de la région et l’armée du royaume Merina. Si la zone Ouest de la région a été la plus touchée, celle de l’Est où se trouvent les grands massifs forestiers a servi de refuges durant ces guerres. Après l’annexion par la France, le 6 août 1 896, d’un important territoire comprenant la presqu’île, les Merina ont quitté la région, et ces massifs forestiers acquirent un caractère sacré et furent ainsi protégés contre la destruction et le défrichement en conservant les caractéristiques des forêts climaciques intactes du Sambirano. Ailleurs, un processus de reconstitution naturelle de la végétation se mit en route. Ces divers aspects historiques permettent d’avancer que les forêts à Sarcolaenaceae et à Dypsis spp (Arecaceae), avec leurs caractéristiques physionomiques, structurales et floristiques, ne découlent pas tant de caractéristiques du substrat ou du climat, mais seraient plutôt des forêts secondaires âgées, issues du long processus d’évolution progressive du dynamisme de la succession végétale. Depuis quelques années, l’analyse des images satellite montre que le rythme auquel le tavy est pratiqué s’intensifie dans la région. Cet accroissement découle non seulement de la croissance démographique, mais aussi d’un besoin accru en terres pour générer les revenus nécessaires à l’achat de produits manufacturés. La pratique du tavy représente une des principales menaces pour les forêts et les différents types d’habitats naturels résiduels. Les forêts secondaires âgées qui sont situées hors des zones traditionnellement protégées sont les plus sensibles car elles sont les plus propices à la production de riz. Les forêts des massifs sacrés, en revanche, ne semblent pas encore réellement menacées mais leur protection traditionnelle est quelque peu ébranlée depuis par l’arrivée récente et massive d’immigrants qui respectent peu les interdits traditionnels

A DNA metabarcoding study of a primate dietary diversity and plasticity across its entire fragmented range

In tropical regions, most primary ecosystems have been replaced by mosaic landscapes in which species must cope with a large shift in the distribution of their habitat and associated food resources. Primates are particularly vulnerable to habitat modifications. Most species persist in small fragments surrounded by complex human-mediated matrices whose structure and connectivity may strongly influence their dispersal and feeding behavior. Behavioral plasticity appears to be a crucial parameter governing the ability of organisms to exploit the resources offered by new matrix habitats and thus to persist in fragmented habitats. In this study, we were interested in the dietary plasticity of the golden-crowned sifaka (Propithecus tattersalli), an endangered species of lemur, found only in the Daraina region in north-eastern Madagascar. We used a DNA-based approach combining the barcoding concept and Illumina next-generation sequencing to (i) describe the species diet across its entire range and (ii) evaluate the influence of landscape heterogeneity on diet diversity and composition. Faeces from 96 individuals were sampled across the entire species range and their contents were analyzed using the trnL metabarcoding approach. In parallel, we built a large DNA reference database based on a checklist of the plant species of the Daraina region. Our results suggest that golden-crowned sifakas exhibit remarkable dietary diversity with at least 130 plant species belonging to 80 genera and 49 different families. We highlighted an influence of both habitat type and openness on diet composition suggesting a high flexibility of foraging strategies. Moreover, we observed the presence of numerous cultivated and naturalized plants in the faeces of groups living in forest edge areas. Overall, our findings support our initial expectation that P. tattersalli is able to cope with the current level of alteration of the landscape and confirm our previous results on the distribution and the dispersal ability of this species

Results of a biological inventory of the Nosy Ankao island group, Parc National de Loky-Manambato, northeastern Madagascar

International audienceUn inventaire biologique a été réalisé du 3 au 14 mars 2016 dans quatre îles de la commune d'Apisikinana, district de Vohémar: Nosy Ankao (365ha), Nosy Manampao (29ha), Nosy Ratsy (6ha) et Nosiborona (6ha). Ces îles font partie du Parc National de Loky-Manambato. Chacune des îles se distingue par sa superficie et sa distance à la côte malgache. L'investigation menée sur le terrain et présentée ici inclut les groupes suivants: plantes ligneuses, moustiques, fourmis, reptiles, amphibiens, oiseaux et petits mammifères. En outre, des informations sur d'autres groupes, tels que les escargots terrestres, ont été collectées et sont présentées

Quemere_gh_sequence_data

This file contains all unique sequences produced by G/H primers and occurring more than once. The sequences have been produced by the Illumina technology (GA IIx platform)

Quemere_gh_final

This file contains the filtered sequences produced by G/H primers. The sequences have been produced by the Illumina technology (GA IIx platform)

Quemere_gh_final_data

This file contains the filtered sequences produced by G/H primers. The sequences have been produced by the Illumina technology (GA IIx platform)

Taxonomic resolution of the golden-crowned sifaka diet.

<p>Panel (a) presents the results base on the EMBL reference database only. Panel (b) presents the results using both EMBL and customized local reference database. Panel (c) uses the final results integrating the final validation by taxonomic experts. The proportions correspond to the number of sequences assigned to each taxonomic rank compared to the total number of identified sequences from DNA Barcoding (N = 130).</p

Plant richness rarefaction curve.

<p>The solid line represents the cumulated number of MOTUs (a) and food plant genera (b) as a function of the number of sampled individuals. The dashed lines are the 95% confidence intervals.</p

Faeces and plant sampling schemes.

<p>Faeces and plant sampling schemes.</p