ABSTRACT
Leptospirosis is a zoonotic disease affecting most mammals and is distributed throughout the world. Several species of domestic and wild animals may act as reservoirs for this disease. The purpose of this study was to assess the exposure of free-ranging wild carnivores, horses and domestic dogs on a private reserve located in the northern Pantanal (Brazil) and the surrounding areas to Leptospira spp from 2002-2006, 75 free-ranging wild carnivores were captured in the Pantanal and serum samples were collected. In addition, samples from 103 domestic dogs and 23 horses in the region were collected. Serum samples were tested for the presence of Leptospira antibodies using the microscopic agglutination test. Thirty-two wild carnivores (42.7 percent) were considered positive with titres > 100, and 18 domestic dogs (17.5 percent) and 20 horses (74.1 percent) were also found to be positive. Our study showed that horses, dogs and several species of free-ranging wild carnivores have been exposed to Leptospira spp in the Pantanal, suggesting that the peculiar characteristics of this biome, such as high temperatures and an extended period of flooding, may favour bacterial persistence and transmission. In this region, wild carnivores and horses seem to be important hosts for the epidemiology of Leptospira species.
Subject(s)
Animals , Animals, Wild , Disease Reservoirs , Dogs , Horses , Leptospira/immunology , Antibodies, Bacterial/blood , Brazil , Carnivora , Disease Reservoirs , Disease Reservoirs/veterinary , SeasonsABSTRACT
Natural regeneration and structure and their relationship to environmental variables were studied in three sections of a gallery forest, in Eastern Mato Grosso, Brazil (14º43'S and 52º21'W). The assumption was that natural regeneration is constrained by environmental determinants at all stages of development of the tree community. The objective was to analyse the forest structure and to verify the relationship between species distribution and abundance at different stages of regeneration and environmental variables. In each section, 47 contiguous (10x10m) permanent plots were established to sample trees (gbh≥15cm), following a systematic design. Seedlings (0.01 to 1m height), saplings (1.01 to 2m) and poles (from 2.01m height to gbh<15cm) were sampled in sub-plots of 1x1m, 2x2m and 5x5m, respectively. In each plot, soil properties, gaps projection, bamboos, rocky cover, declivity and depth of ground watertable were determined. The relationships between the environmental variables with trees and seedling communities were assessed by canonical correspondence analysis. In spite of the sections being near to each other, they presented large differences in floristics, structure and site conditions. The forest soil presented a low cation exchange capacity and a high level of Al saturation. The occurrence of bamboos and gaps and the depth of ground watertable limited the occurrence of poles and trees. The high degree of structural heterogeneity for each regeneration category was related primarily to a humidity gradient; but soil fertility (Ca+Mg) was also a determinant of seedling and sapling communities.
Foi estudada a regeneração natural e a estrutura de três seções de uma floresta de galeria no leste de Mato Grosso, Brasil (14º43'S e 52º21'W). O objetivo foi analisar a estrutura da floresta e verificar a relação entre a distribuição e abundância das espécies nos diferentes estágios de regeneração e entre as variáveis ambientais. Em cada seção de floresta foram estabelecidas, sistematicamente, 47 parcelas (10x10m) contíguas e permanentes para amostrar as árvores (CAP≥15cm). As plântulas jovens (0,01 a 1m de altura), as plântulas maiores (1,01 a 2m) e as arvoretas (de 2,01m de altura a CAP≥15cm) foram amostradas em sub-parcelas de 1x1m, 2x2m e 5x5m, respectivamente. Para cada parcela foram determinadas as propriedades do solo, projeção das clareiras, cobertura de bambus, rochosidade, declividade e profundidade do lençol freático. A relação das variáveis ambientais com as árvores e comunidades de plântulas e arvoretas foi determinada a partir de uma análise de correspondência canônica. Apesar das seções de floresta serem próximas entre si, apresentaram diferenças importantes em relação à composição florística, estrutura e variáveis ambientais. Os solos apresentaram reduzida capacidade de troca catiônica e elevados níveis de saturação de alumínio. A ocorrência de bambus e clareiras e a profundidade do lençol freático limitam a ocorrência de arvoretas e árvores. A elevada heterogeneidade estrutural em cada categoria de regeneração esteve relacionada principalmente a um gradiente de umidade, mas a fertilidade do solo (Ca+Mg) também foi determinante nas diferentes comunidades de plântulas.