Biological Dynamics of Forest Fragments Project - Study Area

Study Area

The BDFFP spans approximately 1,000 km² of the Brazilian Amazon region located 70 km north of Manaus, Brazil in South America. This particular area of South America is famous for its tropical forests and climate, as well as high levels of wildlife diversity.

On average, the Amazon Basin ranges from 1,900 to 2,500 millimeters of rainfall annually, while the mean annual temperature is 26°C with a prominent dry season from June through October (Bierregaard 2001). Another distinct feature of the forests in the BDFFP is the canopy, which can reach from 30 to 37 meters with some emergents reaching up to 55 meters (Bierregaard 2001). These forests, dominated primarily by palms in the understory, are home to over 1200 species of trees in at least 64 families (Bruna and Kress 2001).

The BDFFP reserves are found in non-flooded tropical lowland rainforest where soils are nutrient-poor and the topography ranges from 50 to 150 m in elevation (Bruna and Kress 2001). Although the area is relatively flat, it includes three large cattle ranges and contains 11 forest fragments, ranging from 1-100 hectares, surrounded by continuous forest that acts as an experimental controls (Laurance 2011).

For detailed images of the study area, visit the INPA maps

In the early 1980s, clearing and burning led to fragment isolation of about 80 – 650 meters from the surrounding intact forest, a procedure that was continued several times throughout the experiment due to successful regrowth of secondary forests (Laurance 2011). The final reserve isolation took place in 1990 with the successful felling and burning of a 200 meter-wide strip around the Dimona reserve (Bierregaard 2001).

An important characteristic of the diversity of the Amazon Basin is that many species are rare or distributed erratically throughout the Amazonian forest. This introduces an phenomenon known as the “sample effect”, which suggests that the absence of species from the experimental fragments may be due to the fact that they were not present during fragment creation rather than from vanishment (Laurance 2011). This effect is essential to understanding the effects of forest fragmentation because small fragments cannot sustain large populations due to competition for resources and habitat loss. Therefore, in the experiment, it is unlikely that species not present at the beginning of the experiment will appear in these smaller fragments. Some organisms, however, remain stable and even favor disturbed areas. Leaf bryophytes, wandering spiders and frogs are among the species that remain stable while gap-favoring species include hummingbirds, butterflies, and lianas. Because the matrix surrounding isolated fragments is not completely inhospitable to some species, it is important to understanding how native wildlife can use these human-altered habitats as corridors for dispersal or reproduction (Bierregaard 2001).