The Biological Dynamics of Forest Fragments Project (BDFFP; or Projeto Dinâmica Biológica de Fragmentos Florestais, PDBFF, in Portuguese) is a large-scale ecological experiment looking at the effects of habitat fragmentation on tropical rainforest. The experiment which was established in 1979 is located near Manaus in the Brazilian Amazon rainforest. The project is jointly managed by the Amazon Biodiversity Center and the Brazilian Institute for Research in the Amazon (INPA).
The project was initiated in 1979 by Thomas Lovejoy to investigate the SLOSS debate. Initially named the Minimum Critical Size of Ecosystems Project,Quammen, p. 454 the project created forest fragments of sizes , , and . Data were collected prior to the creation of the fragments and studies of the effects of fragmentation now exceed 25 years.
As of April 2020, 785 scholarly journal articles and more than 150 graduate dissertations and theses had emerged from the project.
History The Biological Dynamics of Forest Fragments Project (BDFFP), was born out of the SLOSS (single large or several small reserves of equal area) debate in the mid 1970s about the application of the theory of island biogeography to conservation planning. The debate was triggered when Dan Simberloff and Larry Abele questioned the use of the theory of island biogeography to the design of nature reserves. The theory, developed by Robert MacArthur and E. O. Wilson predicted that the species richness of an island increases as the area of a reserve increases and distance to mainland colonizing sources decreases. It also determined that the shape of a reserve is very important to the species diversity. Reserves with a large edge to area ratio tend to be affected more by edge effects than reserves with a small edge to area ratio. The distance between reserves and the habitat surrounding the reserves (the matrix) can affect species richness and diversity as well. The concept was applied to planning nature preserves, which are effectively islands in a sea of human-generated or dominated habitat. Simberloff and Abele argued that even though smaller reserves will hold fewer species than larger reserves, a series of small reserves could theoretically hold (protect) as many species as a single large reserve.
Despite the seeming logic of these ideas, ecologists questioned the results of the SLOSS debate due to the lack of a critical body of evidence on the subject. Many ecologists began to conduct studies and experiments on fragmented ecosystems to fill this gap, including Tom Lovejoy, who designed a large-scale experiment that studied the effects of different sizes of fragmentation to animals, plants, and ecological processes. The original idea was conceived in 1977. Lovejoy’s objective throughout the experiment was to gain insight on the effects of habitat fragmentation on species in tropical rainforests. He called it the Minimum Critical Size of Ecosystems Project (the name was later changed to the Biological Dynamics of Forest Fragments Project).
In 1978, Lovejoy hired Rob Bierregaard to implement the project on the ground. In 1979 the National Institute of Amazonian Research (INPA) endorsed and Brazil's National Research Council approved Lovejoy’s experiment. As soon as the permits were granted, Bierregaard moved to Brazil to launch the project in the rainforests on the north of Manaus. The BDFFP began as a collaborative project between the Brazilian National Institute for Amazonian Research and the World Wildlife Fund. It is now a joint project between INPA and the Smithsonian Institution. The BDFFP became one of the most important studies of fragmentation in tropical forests because it is the only long-running study with data before fragments were created with the original data being from the continuous forest.
Project development and hypothesis
The study of habitat fragmentation found its roots early, with Aldo Leopold’s ideas on edge effect and Robert MacArthur and E. O. Wilson’s studies and models of island biogeography laying a foundation for the field (Laurance and Bierregaard 1997). These concepts offer potential applicable and hypothetico-deductive value for the study of forest fragmentation and have inspired debates about habitat reserve design.
Generally speaking, the theory of island biogeography represents a collection of interwoven ideas (Harris 1984), describing patterns of floral and faunal communities on marine islands. It models fundamental processes such as dispersal, diversity and population dynamics of islands with regards to their area and distance from other islands or the mainland. Theoretically, forest fragments take on the characteristics of habitat islands in proportion to their degree of and length of time of isolation (Harris 1984). Island biogeography theory and lessons learned from true-island biogeography provide a basis for developing a management strategy and addressing specific decision variables, such as reserve patch size, distribution, placement and protective measures (Harris 1984). Nevertheless, a notable difference between oceanic islands and terrestrial islands, or fragments, is the existence of land surrounding or between the fragments, referred to as the matrix. The impacts of use and management of this space is a continued subject of study.
Observations of edge effects on habitats are also important, if not integral, to the study of fragmentation effects. A slew of changes in habitat and trophic interactions have been observed to magnify as distance from habitat edge decreases, such as nest predation, decreased humidity and soil moisture, sunlight, decreased species richness and changes in species constitution. The degree of these impacts on fragments continues to be studied. Due to the generally high ratio of edge to habitat area in fragments, edges are presumed to have detrimental consequences for the organisms that inhabit forest fragments.
These concepts have largely inspired the SLOSS (single large or several small) reserve size debate, which the Minimal Critical Size of Ecosystem Project (now known as the BDFFP) attempts to address. The SLOSS debate is an ongoing interdisciplinary discussion in which the scientific community attempts to understand and weigh the pros and cons of different reserve size and distribution, for successful ecosystem conservation: single large reserve, or several small ones? Increasing and widespread habitat loss and fragmentation, along with the SLOSS debate, have led to the questions the BDFFP originally sought to answer. Overall, Lovejoy’s goal in establishing the project was to determine necessary reserve size and placement for successful habitat and species conservation, hence the original name of the project. According to Bierregaard's book, Lessons from Amazonia, Lovejoy worked off of the Island Biogeography Theory and asked three key questions:
What effect does fragment size have on the rate of species extinction? Would the local extinction rate eventually slow and halt, equalizing the number of species? How do species interactions and demography change as a result of reduced habitat?
Since then, studies conducted on the BDFFP site have varied enormously in terms of their principal goals and hypotheses (Laurance and Bierregaard 1997). Along with reserve size, placement and distribution, it is also important to understand and properly manage the links between habitat fragmentation and ecosystem persistence (Bierregaard 2001). Studies on edge effects, extinction rates, biotic and abiotic interactions, mortality factors, soil quality and more performed on this site address fragmentation effects on biodiversity and other ecological changes. Other dimensions influencing ecosystems are also studied, such as economic and human factors. Many studies in BDFFP also attempt to find ways to apply research to restoration, conservation and management practices of tropical forests. The original core question of minimum ecosystem reserve size has initiated an incredible variety of research that continues to grow and diversify.
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.
The BDFFP Area of Relevant Ecological Interest, which contains the study areas, is divided between the municipalities of Manaus (3.61%) and Rio Preto da Eva (96.39%). It has a total area of . The research area is about north of the city of Manaus.
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. 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. These forests, dominated primarily by palms in the understory, are home to over 1200 species of trees in at least 64 families.
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. 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.
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 a 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.
Example studies
There has been a broad scope of studies performed on the BDFFP site focusing on many elements of fragmentation effects on organisms and habitat conditions. Subjects from a range of biota are studied, including trees and other flora, microorganisms, and a variety vertebrate and invertebrates. Soil chemistry and development, as well as human and environmental factors in fragments have also been researched. Some notable studies performed on the BDFFP site are summarized below.
Edge effects