Abstract: Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models. © 2015 2015 Macmillan Publishers Limited.

Abstract: The impact of a road crossing a continuous Guyana primary forest was studied through the analysis of qualitative and quantitative changes in a frugivorous and nectarivorous bat community at different distances from forest edge. Bats were captured along three 3-km forest transects perpendicular to the edge, and at the Nouragues Station located 150 km in the interior of the primary forest block, in an uninhabited area. Along the 3-km transects, we caught over seven times more individuals than in primary forest, this value decreasing according to the distance from the edge. Moreover, at the very edge, species richness was higher than along transects, probably due to exchanges between primary forest and the open habitats. On the contrary, diversity values at forest edges were lower than in primary forest, with a demographic explosion of a few opportunistic phyllostomid species such as Carollia perspicillata and Artibeus jamaicensis. Species restricted to degraded habitat like Glossophaga soricina and Artibeus cinereus were still present 3 km away from the edge, where the proportion of C perspicillata was seven times higher than in primary forest at Nouragues. These changes in the community of bats have important consequences on seed and pollen dispersal. So edge effects may significantly affect both faunal and floral assemblage. We conclude that changes in bat community occur up to at least 3 km from forest edge, i. e. at a greater distance than that found for all other vertebrates previously studied. By their implications our results should be considered in habitat and species conservation management plans.

Abstract: In rain forests, sapling survival is highly dependent on the regulation of trunk slenderness (height/diameter ratio): shade-intolerant species have to grow in height as fast as possible to reach the canopy but also have to withstand mechanical loadings (wind and their own weight) to avoid buckling. Recent studies suggest that mechanosensing is essential to control tree dimensions and stability-related morphogenesis. Differences in species slenderness have been observed among rainforest trees; the present study thus investigates whether species with different slenderness and growth habits exhibit differences in mechanosensitivity. Recent studies have led to a model of mechanosensing (sum-of-strains model) that predicts a quantitative relationship between the applied sum of longitudinal strains and the plant's responses in the case of a single bending. Saplings of five different neotropical species (Eperua falcata, E. grandiflora, Tachigali melinonii, Symphonia globulifera and Bauhinia guianensis) were subjected to a regimen of controlled mechanical loading phases (bending) alternating with still phases over a period of 2 months. Mechanical loading was controlled in terms of strains and the five species were subjected to the same range of sum of strains. The application of the sum-of-strain model led to a dose-response curve for each species. Dose-response curves were then compared between tested species. The model of mechanosensing (sum-of-strain model) applied in the case of multiple bending as long as the bending frequency was low. A comparison of dose-response curves for each species demonstrated differences in the stimulus threshold, suggesting two groups of responses among the species. Interestingly, the liana species B. guianensis exhibited a higher threshold than other Leguminosae species tested. This study provides a conceptual framework to study variability in plant mechanosensing and demonstrated interspecific variability in mechanosensing.

Abstract: The relationship between ants and Philodendron insigne, a trash-basket epiphyte abundant along streams, was studied in French Guiana. Only a few (3%) of the young plants sheltered ants, whereas 90% of the mature individuals did. The most frequent associate was Odontomachus hastatus (Fabricius), an arboreal ponerine ant, and its nests were almost entirely (94.4%) located in P. insigne root clusters. Experimental choice tests conducted on O. hastatus workers confirmed their preference for P. insigne. We propose that the interactions between P. insigne and ants may be intermediate between non-obligatory, reward-based interactions and obligatory, specific ant-myrmecophyte interactions because (1) almost all mature P. insigne individuals are associated with ants; (2) O. hastatus is the most frequent when diverse ants nest in its root clusters; (3) ants colonize mature P. insigne, but rarely young individuals; (4) ants, particularly O. hastatus, protect the foliage of their host; and (5) at least one ant species, O. hastatus, prefers P. insigne over other host plants. The latter relationship is asymmetrical because P. insigne is inhabited by diverse ants whereas O. hastatus nests almost exclusively in P. insigne. (c) 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 341-346.

Abstract: This study is an assessment of the chemical quality and evaluation of antibacterial and antifungal activity of rosemary’s essential oils from three regions of Morocco (Rchida and Berkine/Eastern Morocco and Aknoul/North East of Morocco. The essential oils obtained by hydrodistillation of the leaves and young twigs of rosemary, were analyzed by GC / FID and GC/ MS. These essential oils are characterized by the presence of α and β-pinene, camphene, 1,8-cineole and camphor compounds. The quality of these essential oils met the AFNOR NF ISO 4730 rosemary Morocco kind (1,8-cineole). The evaluation of the antimicrobial activity of essential oils of Rosmarinus officinalis showed low efficacy against microorganisms tested which were all inhibited from 1/100 v/v except for Penicillium expansum whose growth was stopped at the concentration 1/250 v/v.