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Efeitos de borda sobre a comunidade de formigas da serrapilheira florestal na Amazônia Central
(Instituto Nacional de Pesquisas da Amazônia - INPA, 1998)
Carvalho, Keice Santana
Ecologia e modelagem da distribuição dos sítios de nidificação do jacaré-açu (Melanosuchus niger) em uma área de várzea da Amazônia Central, Brasil
(Instituto Nacional de Pesquisas da Amazônia - INPA, 2009)
Villamarín-Jurado, Francisco J.
The black caiman, Melanosuchus niger, is primarily an Amazonian species, its largest populations are associated mainly with interior várzea areas, but its nesting ecology related with these hydrologic dynamic environments is still poorly understood. The objectives of this study were related to the generation of information on the nesting ecology of this species as to the size and number of eggs per clutch and its relation with the size of the nesting female, the influence of flooding regimes on nests occurrence; egg mortality and its causes; and the creation of a model to predict nesting areas. The present research was developed in the southeastern-most portion of the Mamirauá Sustainable Development Reserve (the so-called focal area), a várzea region influenced by the annual flooding of the Solimões and Japurá rivers. We analyzed a sample of 231 nests of the species distributed in 67% of all 66 surveyed water bodies during two nesting seasons (2007 and 2008). Approximately 40% of the nests found were opened to measure and weight the eggs. The mean size of the eggs was comparable to that reported in other localities for the same species, but the size of the nesting female showed significant relations only with the volume, but not with the number of eggs per clutch, as opposed to other species. Occurrence of black caiman nests was positively related to the seasonal stability of lakes water mirror areas. Water bodies where nests occurred were often reached by the annual flooding between November and April, as opposed to other water bodies that were often flooded already in October. This reduces the risk of flooding of nests and provides enough time to finish the incubation of the eggs. A low proportion of nests (13%) were flooded, yet the eggs of almost 70% of the nests were taken by predators mainly by humans and the tegu lizard (Tupinambis teguixin), resulting in production of alive hatchlings in only 14% of the nests, one of the lowest proportions reported for crocodilians in natural conditions. The occurrence of nests in water bodies with the most stable water mirror areas aided the identification of nesting sites in the study area using the algorithms of the maximum entropy (Maxent) species distribution model. The models showed a good predictive performance, with AUC (Area Under the ROC Curve) values higher than 0.99. Nevertheless, it showed a low transferability (i.e. the ability to predict distributions in not sampled areas). The water bodies identified as suitable for nesting are key elements for population maintenance and should be considered as high-conservation value areas within sustainable management programs for the species.
Conectando biogeografia histórica e assembleias locais de aves de sub-bosque na Amazônia: áreas de endemismo, diversidade de espécies e proporcionalidade de guildas
(Instituto Nacional de Pesquisas da Amazônia - INPA, 2019)
Braga, Pilar Louisy Maia
The patterns of diversity in biological communities reflects historical and contemporaneous events that occurs at different spatial scales. In the Amazon, there is a consensus that historical processes related to the establishment of the drainage and the terra firme forests had triggered events of vicariance, speciation and dispersal, determining the regional pool of species. In addition, local ecological factors such as resource availability and species interactions are important in maintaining historically established patterns. The areas of endemism are units of interpretation of historical biogeography and investigating the assemblages in these areas can enhance our knowledge about the interaction between historical events and local diversity. We investigated patterns of diversity, composition, and structuring of understory bird assemblages from upland forests in seven Amazonian areas of endemism, using data from birds captured by mist nets, provided by several researchers. Our research sought to understand if the historical effect that resulted in the delimitation of the endemic areas could be extrapolated to the whole bird assemblage, besides the endemic species, acting in the current patterns of diversity and species composition. We find out which guilds predominate in each AE and if there is guilds substitution between the AE. We also tested if exists guild proportionality in each endemic area. The patterns of diversity and species composition were distinct among the seven areas of endemism studied, both in richness and in the assemblages intrinsic composition considering all the species studied, as in the relative abundances of species widely distributed in the Amazon. The insectivorous guild was predominant in all areas and the proportion of species and individuals in the guilds was constant between the areas of endemism. There is a prevalence of alpha guilds (guild proportionality) in almost all investigated areas. The species substitution between the endemic areas does not occur in a random way and it maintains the same ecological functions of the species, indicating a relative homogeneity in the resources availability of the upland forests. The prevalence of alpha guilds indicates that interspecific competition is a strong structuring factor of local assemblages, probably in a process of limiting similarity in the body size of the species. The congruence between the structuring of the understory bird assemblages and the areas of endemism evidence how much historical and evolutionary processes that acts on a large scale, along with local ecological processes, lead to the current patterns of diversity and species composition in the Amazon.
Dinâmica populacional de Podocnemis erythrocephala, no rio Ayuanã, Amazonas, Brasil
(Instituto Nacional de Pesquisas da Amazônia - INPA, 2010)
Bernhard, Rafael
Podocnemis erythrocephala is a species of turtle that inhabits black water rivers and lakes in the Rio Negro Basin and ventures into clear water habitats as well in the Tapajós and Trombetas rivers, in Brazil, as well as the extreme eastern tip of Colômbia and most of the states within the Venezuelan part of the Amazon Basin. As with all species in the family Podocnemididae their populations have suffered from the collection eggs and adults for human consumption. Even though this species is an important item in the food of the local population of river people where ever P. erythrocephala occurs, there are no studies documenting the natural size of these turtle populations nor monitoring programs. The existing information concerning the decline of natural populations of Podocnemididae are scarce, and not well studied, therefore the monitoring studies are needed for all of the species in this family utilizing methods that can measure the size of adult populations, size structure within populations, and sex ratios. The objective of this study was to characterize aspects of the population dynamics of P. erythrocephala in the Ayuanã River, middle Rio Negro, Amazonas State. The size at reproductive maturity in a population of turtles is important to determine such that the adult sex ratio of the population can be calculated. For this reason it was necessary to study growth and sexual maturity using the gonads, external dimorphic features, gravid females, growth rates of individuals between captures, and the model of von Bertalanffy with Fabens adjustment. The size at sexual maturity in males and females was 161 and 218 mm in straight line maximum carapace length, respectively. Juveniles growth faster than adults and have a negative linear relationship between the growth rate and the carapace length in males and females. Sexual maturity in both males and females was estimated to be nine years, however in the case of males this needs to be examined more extensively. In order to characterize the population structure, sex ratio, and proportion of juveniles in the population, as well as relative abundance of P. erythrocephala in the Ayuanã River, I marked 4.111 individual turtles from 2003 to 2008 in a section of 148.5 km of the Ayuanã River, a small lake in an island in the channel of Rio Negro and the Jurubaxi River. These population parameters differ between the capture methods used. Trammel nets proved to be more efficient than free diving for turtles. The capture index between turtles caught in trammel nets with mesh size of 18 and 21 were greater than for trammel nets with the mesh size of 11 cm. The corrected sex ratio for the population in the Ayuanã River was (0,41♂:1♀). The proportion of juveniles was corrected to be 40% for the population studied. The frequency of recaptures suggests that only a small part of this population was captured during this study. The study concerning movement patterns (defined as the linear distance between the points of capture) of P. erythrocephala indicates that this species disperses along the entire Ayuanã River, without having a small fixed area of use. The linear distance moved by females was greater than that observed for males. The longest linear distances moved were greater than 27.000 m, including the movements between Ayuanã River and a lake in the middle of the Rio Negro or to the next river entering the Rio Negro, Jurubaxi River.
Germinação de sementes e conservação de plântulas de pupunha (Bactris gasipaes Kunth)
(Instituto Nacional de Pesquisas da Amazônia - INPA, 2009)
Vilcarromero, Anita Rocio Jarama
This study aimed to assess the seed germination and conservation of seedlings of peach palm (Bactris gasipaes Kunth) under different conditions. The study was conducted in three independent tests: a) Germination depending on the type and condition of the substrate - a completely randomized design in factorial 5 (substrates: wood sawdust, expanded vermiculite, rice hulls; Plantmax®, and fiber coconut crushed) X 4 (proportions of water: 50%, 60%, 70% and 80% on the mass of dry substrate) x 2 (temperature: 26ºC and 20ºC) with four replicates; b) Germination in function of pre-treatment with acetylene - fully randomized experimental design, in factorial 4 (concentrations of acetylene: 10, 20, 30 and 40 g/m3 of CaC2) X 3 (incubation periods: 6, 12 and 24 hours) plus an additional treatment (control, without pre-treatment) with four replicates; c) Conservation of seedlings in terms of substrate and temperature - a completely randomized design in factorial 3 (stages of seedling: germinative button; ligule and first sheath) x 3 (substrates: wood sawdust, expanded vermiculite, coconut fiber crushed) x 3 (temperature: 26°C, 20°C and 15°C) with four replicates. Seed germination peachpalm had better performance in sealed plastic bags, where the vermiculite was used as substrate, this containing around 58.9% of moisture, under environmental conditions (26ºC). The use of calcium carbide (acetylene) has not provided satisfactory results as to speed up the germination of peach palm, to promote some degree of abnormalities in the seedlings obtained. Seedlings of peachpalm retained best when the stage of "first sheath" in vermiculite and wood sawdust, each with a moisture content of 40% under a temperature of 15ºC.