Les mammifères frugivores arboricoles nocturnes d'une forêt guyanaise : inter-relations plantes-animaux

The relationships between a community of nine nocturnal frugivorous mammal species and the plants on which they feed were studied during 14 consecutive months in a secondary forest near Cayenne, French Guiana. Two major trophic groups can be defined : 1. - The seed eaters, which open unripe fruits to eat their seeds. All are rodents : Coendou prehensilis (average adult weight 4 000 g), Echimys armatus (400 g) and Oryzomys concolor (35 g). 2. - The pulp eaters, which specialize in ripe fruits. They eat the pulp and swallow most of the seeds which are disseminated with their feces. Five of them are marsupials : Didelphis marsupialis (1 000 g), Philander opossum (400 g), Caluromys philander (300 g), Marmosa cinerea (80 g) and Marmosa murina (45 g). The sixth species is a Procyonid Carnivore : Potos flavus (3 000 g). These differing types of feeding strategies are discussed in relation to the morphology of the teeth and digestive tract of the species. Species with a similar diet and comparable body size generally live in different forest layers. The population density and biomass of these nocturnal frugivorous mammals were estimated on the basis of direct counts along forest trails at night, trapping results and radio-tracking. Out of the 127 plant species listed, 26 play a major role as a food source for the mammals studied. The trunk diameter (DBH) of the 13 most common species was measured, and the distribution of these trees mapped in the 8.5 ha study area. These 13 tree species account for approximately half of the total basal area, which is considered here as an index of standing crop biomass. The same 13 species account for 25 % of the total number of individual trees. Fruit production was measured during 13 months by weighing all fallen fruits along 1 200 m of trails. Fruit production and consumption of the same species were also estimated by the use of fruit collectors located under fruiting trees. Special attention was given to the phenological cycles of trees. Three types of fruiting cycles could thus be related to three different foraging strategies of the sympatric frugivorous mammals : 1. - Species with a low fruit production spread over an extended time period. Only a few fruit ripen at the same time, but fruiting takes place almost all year long. Such trees are early - or late - pionneer species ; their fruits have tiny seeds which are mainly eaten by small vertebrates which scatter them more or less homogeneously. 2. - Species with synchronous, but irregular cycles of fruit production. Such trees have rather large seeds which are very attractive to seed-eating rodents. These animals even destroy part of the fruit crop before ripening. The massive, irregular, and unpredictable fruiting cycles of these species may reduce seed predation by rodents . The few trees belonging to this category which do not bear fruit synchronously with their conspecifics may have their crop totally destroyed by rodents. 3. - Species with synchronous and regular cycles of fruit production. Such trees have rather large seeds, which are ingested by large frugivorous vertebrates and spread through their feces. Chemical or physical deterrents are generally present in such fruits before ripening. The tree species belonging to this category have successive and partly overlapping periods of fruit production. In this way, food is made available for pulp-eaters during most of the year. This pattern of fructification is presumably the end-result of a long lasting mutual interaction between plants and seed-scattering vertebrales. Frugivorous mammals apparently need two different kinds of fruit in their diet, sorne rich in sugar and others rich in fat. Trees producing these two categories of fruit produce their crop successively, so that the necess ary nutrients are made available throughout the year. A definite decrease in fruit production takes place in our study are ajust before the beginning of the dry season. The marsupial pulp-eaters have adapted to this temporary food shortage by storing fat during the season of plenty. However, their production of young is strongly affected by this seasonal food shortage, as shawn by an increased mortality rate of pouch young

Les fruits et les graines des espèces végétales pionnières de Guyane Française

Quantitative data are provided on the fruits and seeds of 90 pioneer species of plants characteristic of the young secondary forests in French Guyana : size of the fruits, number of seeds per fruit, size of the seeds. The dispersal mechanisms of the species are described. Most pioneer species produce berries (51/90), drupes (15/90) or capsules (13/90). The greatest diameter of most (72 %) of the fruits is less than 2 cm ; 60 per cent of the fruits contain more than 50 seeds each, and the greatest diameter of 84 per cent of the seeds is smaller than 5 mm. The seeds of most species (93 %) are dispersed by animals. The variation of the number of seeds per fruit was studied in 11 species of Solanum and two Passiflora ; the number can vary by a factor of two to four. The production of seeds per individual plant was estimated in the short-lived pioneer Solarium rugosum ; it can reach 2.3 millions of seeds per individual plant during its average life-span of 4 years.Prévost M.F. Les fruits et les graines des espèces végétales pionnières de Guyane Française. In: Revue d'Écologie (La Terre et La Vie), tome 38, n°2, 1983. pp. 121-145

Les plantes colorantes utilisées en Guyane française

This paper is a synthesis of the ethnobotanical data on the colouring plantes used by the Amerindians populations of French Guiana and surrounding countries. Bibliography has been reviewed and confronted with our proper field observations. Finally, compared uses and diffusion of the species known in French Guiana are treated at the Amazonian scale.Ce travail est une synthèse des connaissances ethnobotaniques sur les plantes colorantes de Guyane Française et des régions voisines, utilisées par les populations amérindiennes. La bibliographie a été analysée et confrontée avec de récentes observations in situ. Enfin, utilisations comparées et diffusion des espèces connues en Guyane sont envisagées à l'échelle du bassin amazonien.Grenand Pierre, Prévost Marie-Françoise. Les plantes colorantes utilisées en Guyane française. In: Journal d'agriculture traditionnelle et de botanique appliquée, 36ᵉ année, bulletin n°1,1994. pp. 139-172

Zoochorie et premiers stades de la régénération naturelle après coupe en forêt guyanaise

Processes leading to forest regeneration in a mature rain forest of French Guiana were studied on six plots representing initial stages of regeneration, from 2 to 10 years following clear-cutting. The first woody species to appear in plots after tree felling are light demanding species growing from seeds remaining dormant in the rain forest soil. Such a «seed bank» is very heterogeneous, its composition being strongly influenced by the proximity of forest gaps and tree falls. Burning and increased soil compaction can prevent dormant seeds from germinating. Other seeds are disseminated by frugivorous bats and birds, yet other by wind. A few other regenerating plants are sucker shoots from cut stumps of shade tolerant species of the undergrowth, which grow easily beneath the canopy of pioneers. The pioneer vegetation (Table I) is characterized by a low species richness : no more than 15 species (out of a grand total of 113 found 3.5 years after clear cutting), contribute to 85 % of the woody community. The seeds of these pioneer species are dispersed by bats and birds. Twenty species of frugivorous bats were observed in the study area, out of which only 4 (Table II) were abundant in the regenerating forest. Forty species of birds (Table III) also contribute to seed dispersal, out of which 16 species are restricted to second-growth. Some of these birds have a limited flight range and tend to disperse seeds more or less evenly around feeding trees. Other birds, particularly «lek» forming species (Pipridae), tend to defecate mainly around their traditional display grounds and generate a more aggregative dispersal of seeds. Some generalist species with a mixed insectivorous and frugivorous diet (Turdus albicollis and Ramphocelus carbo) are the first birds to colonize newly formed gaps in the forest. The «seed rain» generated by bats during the night and by birds during the day, was measured (Table IV) both in the open and under the trees, using plastic collecting sheets. Only bats defecate in the open in a 50 metre wide belt bordering the forest edge. Seed rain generated by birds was observed only under isolated trees used as perches in the open, and to a lesser extent in the undergrowth of the mature forest.Foresta H. de, Charles-dominique P., Erard Ch., Prévost M.F. Zoochorie et premiers stades de la régénération naturelle après coupe en forêt guyanaise. In: Revue d'Écologie (La Terre et La Vie), tome 39, n°4, 1984. pp. 369-400

Hypobaric hypoxia-related impairment of pulmonary surfactant proteins A and D did not favour Pneumocystis carinii Frenkel 1999 growth in non-immunocompromised rats

It has been suggested that patients with pulmonary surfactant impairment are more susceptible to Pneumocystis infection than healthy controls. Owing the fact that most patients with pulmonary surfactant impairment also suffer from hypoxia, we explored the effect of intermittent hypobaric hypoxia conditions on the ability of non-immunocompromised rats infected by endotracheal route with P. carinii to clear the infection from their lungs. Control rats, inoculated or not with P. carinii, were maintained in normobaric normoxic conditions, and were submitted or not to dexamethasone administration. It was found that even if hypobaric hypoxia weakened host immune mechanisms and impaired significantly the surfactant composition, mainly of surfactant proteins A and D, these changes were not enough to favour the Pneumocystis growth or to inhibit the clearing of Pneumocystis organisms from the lungs of non-immunocompromised rats. The potential influence of surfactant protein changes on Pneumocystis infection is discussed

Les mammifères frugivores arboricoles nocturnes d’une forêt guyanaise : inter-relations plantes-animaux

The relationships between a community of nine nocturnal frugivorous mammal species and the plants on which they feed were studied during 14 consecutive months in a secondary forest near Cayenne, French Guiana. Two major trophic groups can be defined : 1.-The seed eaters, which open unripe fruits to eat their seeds. All are rodents : Coendou prehensilis (average adult weight 4 000 g), Echimys armatus (400 g) and Oryzomys concolor (35 g). 2.-The pulp eaters, which specialize in ripe fruits. They eat the pulp and swallow most of the seeds which are disseminated with their feces. Five of them are marsupials : Didelphis marsupialis (1 000 g), Philander opossum (400 g), Caluromys philander (300 g), Marmosa cinerea (80 g) and Marmosa murina (45 g). The sixth species is a Procyonid Carnivore : Potos flavus (3 000 g) . These differing types of feeding strategies are discussed in relation to the morphology of the teeth and digestive tract of the species. Species with a similar diet and comparable body size generally live in different forest layers. The population density and biomass of these nocturnal frugivorous mammals were estimated on the basis of direct counts along forest trails at night, trapping results and radio-tracking. Out of the 127 plant species listed, 26 play a major role as a food source for the mammals studied. The trunk diameter (DBH) of the 13 most common species was measured, and the distribution of these trees mapped in the 8.5 ha study area. These 13 tree species account for approximately half of the total basal area, which is considered here as an index of standing crop biomass. The same 13 species account for 25 % of the total number of individual trees. Fruit production was measured during 13 months by weighing all fallen fruits along 1 200 m of trails. Fruit production and consumption of the same species were also estimated by the use of fruit collectors located under fruiting trees. Special attention was given to the phenological cycles of trees. Three types of fruiting cycles could thus be related to three different foraging strategies of the sympatric frugivorous mammals : 1.-Species with a low fruit production spread over an extended time period. Only a few fruit ripen at the same time, but fruiting takes place almost all year long. Such trees are early- or late-pionneer species ; their fruits have tiny seeds which are mainly eaten by small vertebrates which scatter them more or less homogeneously. 2.-Species with synchronous, but irregular cycles of fruit production. Such trees have rather large seeds which are very attractive to seed-eating rodents. These animals even destroy part of the fruit crop before ripening. The massive, irregular, and unpredictable fruiting cycles of these species may reduce seed predation by rodents. The few trees belonging to this category which do not bear fruit synchronously with their conspecifics may have their crop totally destroyed by rodents. 3.-Species with synchronous and regular cycles of fruit production. Such trees have rather large seeds, which are ingested by large frugivorous vertebrates and spread through their feces. Chemical or physical deterrents are generally present in such fruits before ripening. The tree species belonging to this category have successive and partly overlapping periods of fruit production. In this way, food is made available for pulp-eaters during most of the year. This pattern of fructification is presumably the end-result of a long lasting mutual interaction between plants and seed-scattering vertebrates. Frugivorous mammals apparently need two different kinds of fruit in their diet, some rich in sugar and others rich in fat. Trees producing these two categories of fruit produce their crop successively, so that the necessary nutrients are made available throughout the year. A definite decrease in fruit production takes place in our study area just before the beginning of the dry season. The marsupial pulp-eaters have adapted to this temporary food shortage by storing fat during the season of plenty. However, their production of young is strongly affected by this seasonal food shortage, as shown by an increased mortality rate of pouch youngs.Charles-Dominique Pierre, Atramentowicz Martine, Charles-Dominique M., Gérard H., Hladik Annette, Hladik C.M., Prévost M.F. Les mammifères frugivores arboricoles nocturnes d’une forêt guyanaise : inter-relations plantes-animaux. In: Revue d'Écologie (La Terre et La Vie), tome 35, n°3, 1981. pp. 341-435

Hypobaric hypoxia-related impairment of pulmonary surfactant proteins A and D did not favour

It has been suggested that patients with pulmonary surfactant impairment are more susceptible to Pneumocystis infection than healthy controls. Owing the fact that most patients with pulmonary surfactant impairment also suffer from hypoxia, we explored the effect of intermittent hypobaric hypoxia conditions on the ability of non-immunocompromised rats infected by endotracheal route with P. carinii to clear the infection from their lungs. Control rats, inoculated or not with P. carinii, were maintained in normobaric normoxic conditions, and were submitted or not to dexamethasone administration. It was found that even if hypobaric hypoxia weakened host immune mechanisms and impaired significantly the surfactant composition, mainly of surfactant proteins A and D, these changes were not enough to favour the Pneumocystis growth or to inhibit the clearing of Pneumocystis organisms from the lungs of non-immunocompromised rats. The potential influence of surfactant protein changes on Pneumocystis infection is discussed