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Rio de Janeiro, Brazil

Ferreira R.N.C.,National Institute of Amazonian Research | Franklin E.,INPA | de Souza J.L.P.,National Institute of Amazonian Research | de Moraes J.,National Institute of Amazonian Research
Journal of Natural History | Year: 2012

We recorded species abundance and richness of oribatid mites along 16 plots established in semi-deciduous forest fragments in Amazonia. The results were compared with a published dataset consisting of an inventory carried out in 38 plots in the surrounding savanna. Totals of 143 and 91 species were recorded in the forest fragments and savanna, respectively. Sørensen similarity index between both environments was 0.44. Ordination of sites according to oribatid mite species composition showed a clear separation between forest fragments and savanna. Rostrozetes ovulum, Archegozetes longisetosus and Eohypochthonius (Eohypochthonius) becki were abundant and frequent in the forest fragments but exceedingly rare in the savanna. Neoppia (Neoppia) schauenbergi, Pseudoppia sp. C, Microppia sp. A and Cosmochthonius sp. A were limited to the savanna. This study also represents an early step toward knowing which groups of species are exclusive to one or another vegetation type or are sensitive to their inherent environmental conditions. © 2012 Copyright Taylor and Francis Group, LLC. Source

Background: Previous work has shown that Amazonian tropical forests have experienced two widespread changes in dynamics over recent decades, increases in both tree stem turnover and above-ground biomass. However, data from an Amazonian monodominant forest dominated by Peltogyne gracilipes have shown that the above-ground biomass of this forest type has declined slightly (<5%) over an 11-year period. Aims: To determine whether the tree communities in three types of forest, with or without Peltogyne gracilipes (Peltogyne-rich forest (PRF), Peltogyne-poor (PPF) and forest without Peltogyne (FWP)) on Maracá Island, Roraima, have experienced a change in structure and floristic composition over a 20-year period. Methods: We have quantified the variation in the occurrence and abundance of tree species, the above-ground biomass (AGB) and change in total stand biomass from mortality, recruitment and growth for trees, palms and large lianas, ≥10 cm diameter at breast height, in three plots of 0.25 ha in each of the three forest types. Results: Floristic composition showed little change, with no shift in the rank abundance amongst the 10 most important tree species, although in FWP there was a reduction in species richness from 51 to 43. Recruitment is shown to offset the losses caused by mortality in PRF and FWP. The annual mean mortality rates were low, at around 1%. In 2011 AGB in the three forest types varied from 434 Mg ha-1 (PPF) to 363 Mg ha-1 (FWP). PRF experienced an AGB decline of 4.1%, associated with the death of large trees, while FWP showed a slight increase in biomass (2.6%). Conclusions: Over the last 20 years Maracá forest stands appear to have been stable in terms of their floristic composition and structure, some showing a persistent monodominance by Peltogyne gracilipes. © 2014 Copyright 2013 Botanical Society of Scotland and Taylor & Francis. Source

Boubli J.P.,Wildlife Conservation Society | Couto-Santos F.R.,INPA | Strier K.B.,University of Wisconsin - Madison
Ecotropica | Year: 2011

This study presents results from the first systematic botanical investigation of the RPPN Feliciano Miguel Abdala (RPPN-FMA, formerly Caratinga Biological Station), a semi-deciduous forest fragment in southeastern Brazil that supports nearly a third of the remaining population of the critically endangered northern muriqui (BrachyteUs hypoxanthus). Here we describe the structure, diversity, and floristic composition of this forest. Our goal was to provide the scientific basis for a management plan that will take into consideration the factors involved in the unusually high muriqui carrying capacity in this fragment. Our sample comes from six 500 × 10 -m plots, totaling 3 ha. We marked and identified all trees with DBH ≥ 10 cm in all of the plots, and all trees of 5 ≤ DBH < 10 cm in half of the plots (1.5 ha). Forest structure was consistent with secondary forest characteristics, inasmuch as large trees were rare, total basal area was small, canopy was discontinuous, average tree height was low, and liana load was heavy. Top-ranking families, based on Importance Value, were Fabaceae, Euphorbiaceae, Annonaceae, Rubiaceae, and Moraceae. Compared with other forests where northern muriquis occur, the RPPN-FMA forest was more floristically diverse (H' = 4.6) and even (J = 0.85). In addition, top- ranking species were known muriqui foods. These factors might contribute to the unusually high density of the primate found at this site. © Society for Tropical Ecology. Source

Mendes K.R.,National Institute of Amazonian Research | Marenco R.A.,National Institute of Amazonian Research | Magalhaes N.S.,INPA
Revista Arvore | Year: 2013

In the Amazon Rainforest, photosynthesis and tree growth may be limited by the availability of nutrient. Thus, the objectives of this study were to determine the effect of leaf N and P content on photosynthesis, and to assess plant growth in response to understory light in ten tree species in Central Amazonia. Data were collected in January 2008. The photosynthetic capacity (Apot) of leaves positively increased with foliar N and P content, but it was only responsive to P use efficiency. The contents of N and P increased as understory irradiance increased. In addition, we found a positive relationship between N content and the N/P ratio. On the contrary, the relationship between P content and the N/P ratio was negative. Specific leaf area was negatively correlated with N and P. N use efficiency declined with increases with the N/P ratio, but the N/P ratio had no significant effect on P use efficiency. Growth in diameter increased with understory light. In conclusion, saplings were highly sensitive to variations in light intensity, and P was used with high efficiency in studied species. Source

Slugs of the genus Omalonyx d'Orbigny, 1837 are hermaphrodites, herbivorous, distributed on Neotropical regions, living on aquatic plants, moist soil and terrestrial vegetation close to freshwater systems. The present paper reports the atypical occurrence of O. pattersonae Tillier, 1981 and Omalonyx sp. in an upland area far from any aquatic environment. Both species reported here are sympatric and due to the high populations density and damages caused on leaves of elephant-grass Pennisetum purpureum Schumach, they are recognized as agricultural pests. During the night, the slugs feed on the grass leaves and at the daylight they stayed hidden in the base of stems, near the moist soil surface. The use of hydrated lime distributed over the aggregations of Omalonyx spp. showed to be an effective method to control the populations. The environmental changes in the Amazonian ecosystems for agricultural or urban purposes have promoted the increase of populations of native species that adapt in the new habitat and usually become pests that are difficult to control. Source

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