Wild mammals in a man-made heterogeneous landscape in Low Tibagi River
Forest fragmentation has been identified as one of the main causes of the global biodiversity decline, which is even more serious in countries with mega-diversity, such as Brazil. The process of biotic integrity loss occurs more rapidly in smaller forest remnants and it is often possible to see degraded areas for human activities becoming ecologically vulnerable.
Habitat loss can be specially rough on species that occur at low density and/or have lower adaptive plasticity, and lead to local disappearance of biodiversity and impair the maintenance of a genetically viable population. The so-called edge effects alter the microclimate conditions (reduced moisture, increased solar radiation and wind), resulting in changes in species composition on the edge of a forest and its predation interactions, herbivory, competition, seed dispersal and pollination.
The appearance of landscape "mosaics", which are formed by forest remnants and a set of altered areas (matrix) such as pastures, crops, roads and reforestation, directly interferes in the displacement and dispersal of species, acting as a selective filter, where the dispersal and colonization may be limited and the exposure and vulnerability to predators, increased.
The areas of this study are located by the river Congonhas, in the region of Low Tibagi river, which integrates the Paraná River Basin. Likewise all the northern Paraná state, Brazil, the region has suffered massive deforestation due to increasing agricultural and logging in the early 20th century, which resulted in a landscape made up of only 2 to 4% of its original forests. The research sought to investigate the richness and diversity of species of medium and large terrestrial mammals in a legal reserve of native forest, in a reforested area with native pioneer and secondary species located near the remnant forest, and in the matrix surrounding these areas. Furthermore, the study aimed to identify which species dispersed more often by the matrix and explored areas beyond the native forest remnant. Field methodologies (transect, sand plots for footprints and active search of trace elements, ex. feces) were applied in the research. Other studies were conducted simultaneously, investigating the diversity and abundance of bats in these areas and the structure of the community and resource partition by non-volant mammals. We identified 23 species of medium and large mammals belonging to 8 orders, and 14 species of bats from 10 different genera. Generalist species, such as the omnivores nine-banded armadillo and common zorro, exhibit greater adaptive plasticity and dispersal, exploiting different environments of the matrix, when compared to specialist species such as tapeti or the crab-eating raccoon.
Any forest fragment capable of harboring wild species plays a role in maintaining local biodiversity and should be preserved. The studied area, despite the small size, is home to many species, and although it may not sustain viable populations of specialist larger mammals, still can provide important resources for the survival of these species, as for example for cougars. The presence of reforestation and orchard areas near the forest remnant minimize the loss of diversity and fragmentation impacts for some species and also increase connectivity between this and other forest remnants.
This research was part of a Master in Biological Sciences and had the support of the Graduate Program in Biological Sciences at the Universidade Estadual de Londrina (UEL). The studies were published as chapters in ecology books and presentations in scientific events.