Carolina C. Blanco

Population ecology of Tupinambis merianae (Squamata, Teiidae): home-range, activity and space use

The activity and space parameters (home range and use of space) for a population of Tupinambis merianae was recorded through 640 h of observation during nine months, and by monitoring 56 marked individuals. There was a significant difference in activity in the periods stipulated in this study throughout the months. Active lizards were not registered before 7:30 a.m., nor after 6:00 p.m. The greatest level of activity by the individuals occurred during November and December. Fluctuations in the population size and in the activity of the different age classes were recorded throughout the studied months. We recorded the minimum home-range of three males and two females, which varied from 0.05 to 26.44 ha. We also observed agonistic interactions. The utilization area of the animals did not vary during the studied months, but it was possible to observe gregarious behavior in spatial use. The highest daily activity occurred at the hours of higher temperatures. The positive correlation between seasonal activity and the maximum temperature (air and substrate) showed a unimodal distribution and was identical to the records from a tropical area (southeastern Brazil). It is possible that temperature is not the only environmental variable/factor that influences the seasonal activity cycle of the species. Although teiids are not considered territorial, some of our results could suggest territoriality in the studied population.

South Brazilian Forest-Grassland Ecotones: Dynamics Affected by Climate, Disturbance, and Woody Species Traits

The southernmost part of Brazil is characterized by extended grasslands—the southern Campos. In some parts of the region, these grasslands occur in close contact with different forest types of the Atlantic forest biome or riparian forests, forming mosaics. Otherwise, they form large and continuous areas toward south and southwest, where they reach the Pampa grassland of Uruguay and Argentina. Throughout this region, forest expansion and/or shrub encroachment can be observed and have been related both to site conditions (abiotic variables and disturbance regimes) and climatic changes. We know today, based on studies of pollen records from peat profiles, that expansion of woody vegetation throughout the past centuries was driven by changes in the climatic conditions towards a climate increasingly favorable for forest development, and evidence exists that this process is halted or at least slowed down as consequence of land use and disturbances. Current vegetation dynamics in forest-grassland ecotones thus likely are linked both to climatic changes (on the regional scale) and vegetation management and/or disturbance regime (on the local scale).

Interação comportamento de pastejo ´ dinâmica de tipos funcionais em pastagem natural na depressão central do Rio Grande do Sul

This study aimed to describe the feeding and spatial behavior of beef heifers under rotational stocking, in response to the dynamics of the morphological functional types (TFs) in natural grassland. Stocking rate was adjusted to keep an average of 12% (12 kg DM/100 kg BW) of forage allowance. Animal activity was registered from 12 to 27 February 2003 using the Ethosys automatic device. Thirty permanent field sampling units comprised by five adjacent 0.20 x 0.20 m squares were used to determine pasture attributes. Results showed the existence of an optimum subset of two attributes to describe pasture plant community: the aerial and the lignified (woody) forage biomasses, which defined eight morphological functional types that had a 0.43 congruency value with the variable degree-day. The evolution of grazing activity showed that grazing time increased as the frequency of preferred functional types decreased. Thus, the morphological characterization of functional type-based attribute definition can bring more contributions for the interactive response between the vegetation and the animal behavior than the one realized using only the taxonomic identification. Therefore, in a simultaneous action, as the vegetation change, the animals modulate the behavior adjusting their rhythm of activity in time and space, determining, in a continuous process, differential impacts in the vegetation, which evolves with time.