Dinâmicas temporais de populações em resposta a mecanismos estruturadores da comunidade: uma avaliação preliminar da sincronia em pequenos mamíferos não-voadores

Abstract

The present study sought to understand the population dynamics of the species of a community of small tropical forest mammals and to carry out a first approach in a long-term data series in order to evaluate the synchrony of the species responses to factors that structure a community. The study was carried out in the Serra dos Órgãos National Park, in a hillside forest belonging to the Atlantic Forest, southeastern Brazil. I used capture-mark-recapture data from a 20-year monitoring program of small mammal populations to estimate time series of population size and biomass of the nine most captured species, accounting for the imperfect detection of individuals. I applied the autocorrelation function in the time series generated for each species in order to detect population cycles and to detect the nature of the mechanisms that govern them (endogenous and / or exogenous). In addition, I correlated temporal series with each other and with climatic factors of local and global scale. A combination of endogenous and exogenous factors seems to govern the temporal dynamics of the populations studied. The species presented specific dynamics, where different cycles could be observed among the species, even if for some a defined cycle has not been clearly identified. Species also varied with respect to the responses to the environmental mechanisms tested, either in the direction of the response (positive or negative), as well as in the delay time. Additionally, few significant correlations were found among the studied species, so that most of the correlations were positive, but were either weak or very weak. Therefore, this preliminary assessment suggests that the temporal dynamics of the species in that community are not in synchrony. It is possible that this occurs due to the fact that the area is influenced by anthropic activities, so that the impact of these can be favoring some species to the detriment of others. In addition to this, demographic stochasticity may also be influencing, since it affects mainly the small populations and is known to diminish the synchrony of the population dynamics