Empty forest is a term coined by Kent H. Redford's article "The Empty Forest" (1992), which was published in BioScience . An "empty forest" refers to an ecosystem that is void of large mammals. Empty forests are characterized by an otherwise excellent habitat, and often have large, fully grown trees, although they lack large mammals as a result of human impact. Empty forests show that human impact can destroy an ecosystem from within as well as from without. [1]
Many of the large mammals that are disappearing, such as deers and tapirs, [2] are important for seed dispersion. Many tree species that are very localized in their dispersion rely on mammals rather than the wind to disperse their seeds. [3] Furthermore, when seed predation is down, trees with large seeds begin to completely dominate those with small seeds, changing the balance of plant life in an area. [4]
Predatory large mammals are important for increasing overall biodiversity by making sure that smaller predators and herbivores do not become overabundant and dominate. An absence of large predators seems to result in uneven densities of prey species. [5] Even though certain animals may not have become completely extinct, they may have lowered in numbers to the point that they have suffered an ecological extinction. The animals that have most likely suffered an ecological extinction in neotropical forests are the ones who are the most important predators, large seed dispersers, and seed predators. [6]
The defaunation of large mammals can be done by direct or indirect means. Any type of human activity not aimed at the animals in question that results in the defaunation of those animals is indirect. The most common means of indirect defaunation is habitat destruction. However, other examples of indirect means of defaunation of large mammals would be the over-collection of fruits and nuts or over-hunting of prey that large mammals need for food. Another example of an indirect means of the defaunation of large mammals is through the by-products of modern human activities such as mercury and smoke, or even noise pollution. [1]
There are two categories of direct defaunation. They include subsistence hunting and commercial hunting. The most common species of animals hunted are typically the largest species in their area. The large mammals in an area are often represented by only a few species, but make up a major part of the overall biomass. In areas with only moderate hunting, the biomass of mammalian game species decreases by 80.7%. In areas with heavy hunting, the biomass of mammalian game species can decrease by 93.7%. [7]
The Oceanian realm is one of the eight biogeographic realms and is unique in not including any continental land mass. It has the smallest land area of any of the WWF realms.
A duiker is a small to medium-sized brown antelope native to sub-Saharan Africa, found in heavily wooded areas. The 22 extant species, including three sometimes considered to be subspecies of the other species, form the subfamily Cephalophinae or the tribe Cephalophini.
The Atlantic Forest is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and the Misiones Province of Argentina, where the region is known as Selva Misionera.
Insular biogeography or island biogeography is a field within biogeography that examines the factors that affect the species richness and diversification of isolated natural communities. The theory was originally developed to explain the pattern of the species–area relationship occurring in oceanic islands. Under either name it is now used in reference to any ecosystem that is isolated due to being surrounded by unlike ecosystems, and has been extended to mountain peaks, seamounts, oases, fragmented forests, and even natural habitats isolated by human land development. The field was started in the 1960s by the ecologists Robert H. MacArthur and E. O. Wilson, who coined the term island biogeography in their inaugural contribution to Princeton's Monograph in Population Biology series, which attempted to predict the number of species that would exist on a newly created island.
The bald uakari or bald-headed uakari is a small New World monkey characterized by a very short tail; bright, crimson face; a bald head; and long coat. The bald uakari is restricted to várzea forests and other wooded habitats near water in the western Amazon of Brazil and Peru.
The red-rumped agouti, also known as the golden-rumped agouti, orange-rumped agouti or Brazilian agouti, is a species of agouti from the family Dasyproctidae.
The southern Amazon red squirrel, is a squirrel species from South America where it inhabits forests in much of north-western South America east of the Andes. Three subspecies are currently recognised. It is a dark red colour, or a dark brown grizzled with ochre, has whitish underparts and grows to a total length of 48 to 63 cm, including a very long tail. It spends much of its time on the ground in the undergrowth and feeds largely on nuts. Little is known of its breeding habits, but it is a sociable species, several individuals often feeding together in one tree. This squirrel faces no particular threats, has a wide range and is relatively common, and the International Union for Conservation of Nature lists it as a "least-concern species".
Sloths are a Neotropical group of xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their lives hanging upside down in the trees of the tropical rainforests of South America and Central America. Sloths are considered to be most closely related to anteaters, together making up the xenarthran order Pilosa.
Cocha Cashu Biological Station is a tropical biological research station located at 11° 54'S and 71° 22'W in Manú National Park, Peru. It was established in 1969-70, predating the founding of its containing national park. Though only 10 km2 in area, the site has provided valuable research. The station is situated on the shore of an oxbow lake, from which it takes its name. "Qucha" is the Quechua word for lake. "Cashu" is derived from the English word "cashew" and refers to the shape of the lake.
An ecological cascade effect is a series of secondary extinctions that are triggered by the primary extinction of a key species in an ecosystem. Secondary extinctions are likely to occur when the threatened species are: dependent on a few specific food sources, mutualistic, or forced to coexist with an invasive species that is introduced to the ecosystem. Species introductions to a foreign ecosystem can often devastate entire communities, and even entire ecosystems. These exotic species monopolize the ecosystem's resources, and since they have no natural predators to decrease their growth, they are able to increase indefinitely. Olsen et al. showed that exotic species have caused lake and estuary ecosystems to go through cascade effects due to loss of algae, crayfish, mollusks, fish, amphibians, and birds. However, the principal cause of cascade effects is the loss of top predators as the key species. As a result of this loss, a dramatic increase of prey species occurs. The prey is then able to overexploit its own food resources, until the population numbers decrease in abundance, which can lead to extinction. When the prey's food resources disappear, they starve and may go extinct as well. If the prey species is herbivorous, then their initial release and exploitation of the plants may result in a loss of plant biodiversity in the area. If other organisms in the ecosystem also depend upon these plants as food resources, then these species may go extinct as well. An example of the cascade effect caused by the loss of a top predator is apparent in tropical forests. When hunters cause local extinctions of top predators, the predators' prey's population numbers increase, causing an overexploitation of a food resource and a cascade effect of species loss. Recent studies have been performed on approaches to mitigate extinction cascades in food-web networks.
Ecological extinction is "the reduction of a species to such low abundance that, although it is still present in the community, it no longer interacts significantly with other species".
Defaunation is the global, local, or functional extinction of animal populations or species from ecological communities. The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient exploitation of the environment. This has resulted in the depletion of large vertebrates from ecological communities, creating what has been termed "empty forest". Defaunation differs from extinction; it includes both the disappearance of species and declines in abundance. Defaunation effects were first implied at the Symposium of Plant-Animal Interactions at the University of Campinas, Brazil in 1988 in the context of Neotropical forests. Since then, the term has gained broader usage in conservation biology as a global phenomenon.
Island ecology is the study of island organisms and their interactions with each other and the environment. Islands account for nearly 1/6 of earth’s total land area, yet the ecology of island ecosystems is vastly different from that of mainland communities. Their isolation and high availability of empty niches lead to increased speciation. As a result, island ecosystems comprise 30% of the world’s biodiversity hotspots, 50% of marine tropical diversity, and some of the most unusual and rare species. Many species still remain unknown.
Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term applies to natural resources such as water aquifers, grazing pastures and forests, wild medicinal plants, fish stocks and other wildlife.
Igapó is a word used in Brazil for blackwater-flooded forests in the Amazon biome. These forests and similar swamp forests are seasonally inundated with freshwater. They typically occur along the lower reaches of rivers and around freshwater lakes. Freshwater swamp forests are found in a range of climate zones, from boreal through temperate and subtropical to tropical. In the Amazon Basin of Brazil, a seasonally whitewater-flooded forest is known as a várzea, which is similar to igapó in many regards; the key difference between the two habitats is in the type of water that floods the forest.
The Afi Mountain Wildlife Sanctuary in Cross River State in southern Nigeria covers 104 km2 (40 sq mi). The wildlife sanctuary was founded in 2000 to provide refuge for endangered animal species, including the Cross River gorilla, the Nigeria-Cameroon chimpanzee, the drill and the gray-necked rockfowl.
Seabirds include some of the most threatened taxa anywhere in the world. For example, of extant albatross species, 82% are listed as threatened, endangered, or critically endangered by the International Union for Conservation of Nature. The two leading threats to seabirds are accidental bycatch by commercial fishing operations and introduced mammals on their breeding islands. Mammals are typically brought to remote islands by humans either accidentally as stowaways on ships, or deliberately for hunting, ranching, or biological control of previously introduced species. Introduced mammals have a multitude of negative effects on seabirds including direct and indirect effects. Direct effects include predation and disruption of breeding activities, and indirect effects include habitat transformation due to overgrazing and major shifts in nutrient cycling due to a halting of nutrient subsidies from seabird excrement. There are other invasive species on islands that wreak havoc on native bird populations, but mammals are by far the most commonly introduced species to islands and the most detrimental to breeding seabirds. Despite efforts to remove introduced mammals from these remote islands, invasive mammals are still present on roughly 80% of islands worldwide.
Victoria Forest Park, is situated on the West Coast of the South Island of New Zealand. At 2,069 square kilometres (799 sq mi) it is New Zealand's largest forest park. The park is administered by the Department of Conservation (DOC).
Mauro Galetti. is a Brazilian ecologist and conservation biologist. He is a full professor in the Department of Biodiversity at the Universidade Estadual Paulista, Rio Claro, São Paulo and has worked at Stanford University (USA), Aarhus University (Denmark) and the University of Miami (USA). He also holds a position as a Courtesy Associated Professor at Florida International University, Miami, FL. Galetti's work has centered on the analysis of the ecological and evolutionary consequences of defaunation. He was awarded by WWF in 1998 and was a Tinker Fellow at Stanford University and a visiting professor at Aarhus Universitet, Denmark in 2017.
Rodolfo Dirzo is a professor, conservationist, and tropical ecologist. He is a Bing Professor in environmental science at Stanford and a senior fellow at the Stanford Woods Institute for the Environment. His research interests mainly focus on plant-animal interactions, evolutionary ecology, and defaunation in the tropics of Latin America, Africa, and the Central Pacific. He was a member of the Committee on A Conceptual Framework for New K-12 Science Education Standards, co-authoring the framework in 2012, and continues to educate local communities and young people about science and environmental issues.