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Vol. 2: Coviability Questioned by a Diversity of Situations Chapitre 40 La version en français sera publiée ultérieurement aux éditions Matériologiques en co-édition avec les éditions IRD; International audience; The babassu palm tree (Attalea speciosa Mart. ex Spreng.) is a species native to the Amazonian rainforest. The invasive nature of this palm tree results in a high density of babassu palm trees with a subsequent decrease in forage crop production. This is a serious problem for local farmers who have tried to resolve it by removing mature palms, seedlings and young individuals. Within these conditions, is coviability between the babassu palm tree and society possible? Our work consisted in developing tools and methods with the aim of producing knowledge and providing answers to this issue within a given territory. To understand the eco-socio-system, we have explored the available knowledge in the literature, produced specific field data, tools and methods such as mathematical modeling (dynamics of the palm tree population) and remote sensing (land use analysis thanks to Landsat high-resolution images and automatic detection of mature palm trees using Pleiades and GeoEye very high-resolution images). This multidisciplinary research in progress has already given us a good overview of the current situation of this eco-socio-system, enabling us to consider the best way to ensure its sustainability.

The babassu palm tree (Attalea speciosa Mart. ex Spreng.) is an endemic species of Amazon forests, and has social and economical impact/utility. Deforestation highlights this palm tree in anthropogenic open areas (pastures and cultivated fields). Simultaneously, knowledge concerning the sustainable functioning of the species within these manmade environments is sorely lacking: its life cycle is not well known, and its population dynamics remains unstudied. In this study, our objective was to generate a model of the population dynamics of the babassu palm tree, validated by in situ analysis, to understand how babassu, a forest species, adapts to pastureland and, under certain conditions, becomes invasive. We propose a random matrix model with aggregated variables based on the biological stages of the species as the input. The probabilities of the between-stage transition matrix were modelled using a Dirichlet-multinomial model with a hierarchy taking geographical organization, i.e. transect level, into account. The integration of prior information was formulated through a Bayesian approach. This Bayesian hierarchical matrix model enabled us to demonstrate a bottleneck in the population dynamics and a high year-dependent mortality rate at an early stage.

Na microrregião de Marabá, PA, as pastagens dos agricultores familiares apresentam alta diversidade de árvores e palmeiras que têm papel importante tanto para limitação da degradação da biodiversidade quanto para suas utilidades. O trabalho foi realizado em 26 propriedades, onde 62 pastagens foram visitadas junto com o agricultor. Em cada pastagem foram repertoriadas todas as árvores e palmeiras presentes. Setenta e uma espécies foram encontradas, pertencentes a 32 famílias, das quais nove se destacaram com maior número de espécies: Caesalpiniaceae (11), Mimosaceae (10), Arecaceae (4), Lecythidaceae (4), Bignoniaceae (3), Fabaceae (3), Moraceae (3), Sapotaceae (3) e Sterculiaceae (3); 20 famílias apresentaram uma única espécie. Vinte e quatro espécies (34% do total) pertenceram às três famílias Leguminosae (Fabaceae, Caesalpiniaceae e Mimosaceae). As espécies arborescentes são conservadas principalmente em razão dos usos diversos na propriedade. Das 21 espécies, indicadas para arborização de pastagens de agricultores desta e de outras comunidades, nove espécies são particularmente recomendadas pela resistência ao fogo e para muitos anos de pastagem, pelo fato de ter dois usos ou mais: Caryocar villosum (Aubl.) Pers., Bertholletia excelsa H. B. K., Attalea speciosa Mart. ex Spreng., Oenocarpus distichus Mart., Astrocaryum tucuma Mart., Swartzia flaemingii Raddi, Apeiba tibourbou Aubl., Cenostigma tocantinum Ducke e Spondias mombin L. In the microregion of Marabá - Pará, the cattle pastures of the family farmers present a high diversity of trees and palm trees which have an important role in limiting biodiversity degradation and for its utilities. The study was carried out in 26 properties, where 62 cattle pastures were visited with the farmer. In each cattle pasture, it was listed all trees and palm trees present in the area. Seventy-one species were found, belonging to 32 families of which 9 were stood out with the greatest number of species: Caesalpiniaceae (11), Mimosaceae (10), Arecaceae (4), Lecythidaceae (4), Bignoniaceae (3), Fabaceae ( 3), Moraceae (3), Sapotaceae (3) and Sterculiaceae (3); twenty families present one single species. Twenty-four species (34% of total) belonged to 3 Leguminosae families (Fabaceae, Caesalpiniaceae and Mimosaceae). The tree species are held mainly because of the various uses on the property. Out of the 21 species, suitable for afforestation of cattle pasture of farmers of this and other communities, 9 species are particularly recommended because of their fire resistance and for many years of grazing, and because they have two or more uses: Caryocar villosum (Aubl.) Pers., Bertholletia excelsa H. B. K., Attalea speciosa Mart. ex Spreng., Oenocarpus distichus Mart., Astrocaryum tucuma Mart., Swartzia flaemingii Raddi, Apeiba tibourbou Aubl., Cenostigma tocantinum Ducke, Spondias mombin L.