Tropical Forests Tropical forests have, for the most part, evolved in stable environments over a period of millions of years, untouched by the recent Ice Ages. The oldest forests on Earth may be in Borneo where the same species of towering trees have been growing for 250 million years. Climates in tropical forests tend to be uniformly warm year-round, with half the year rainy, and the other half dryer but not without rain. Tropical trees generate enormous amounts of moisture. In some parts of the world, the climate has changed over the ages, resulting in islands of forests surrounded by grassland or other habitats. Many scientists theorize that some forests, including the Amazon and African rainforests, went through such climatic changes during the Ice Ages (Collins 1990). Isolation might explain the evolution of a great number of endemic species in these regions, which today are continuous forest. These tropical forests are showcases of evolution.
Tropical forests vary greatly according to altitude, region and species of trees. Each has a different micro-climate, soil type, fauna and flora. They grow in tropical latitudes 30 degrees to the north and south of the Equator (Collins 1990). Among the many types of tropical forests are evergreen wet forests, deciduous dry forests, mountain cloud forests, and mixed lowland rainforests. In general, lowland rainforests are the most biologically diverse, as well as the most endangered. Covering only 7 percent of the Earth's surface, rainforests harbor half its species (Lean and Hinrichsen 1992). Biological research in tropical forests has consistently shown that this great diversity helps stabilize ecosystems and the very life support systems of the planet.
Some tropical forests have been characterized as "hotspots," having exceptionally high diversity of endemic species that are found nowhere else on Earth. All are threatened by deforestation. Two studies by ecologist Norman Myers in 1988 identified 10 highly endangered and biologically diverse tropical forest hotspots in the world; in 1990, he revised that number to 18 (Myers 1988, 1990; McNeely et al. 1990, Mittermeier et al. 1999a). Myers pointed out that the 10 hotspots named covered only 0.2 percent of the land surface of the world, but contained 27 percent of the plants and also a high percentage of endemic species. Hotspots, a book by Russell Mittermeier, President of Conservation International, and other biologists and ecologists, describes 15 tropical forest hotspots throughout the world among a total of 25 hotspots of all types of ecosystems. The high diversity in tropical forests is reflected in the fact that these hotspots covered 61 percent of the land area of all hotspots identified in the study. Many have lost 90 percent or more of their original forests and continue to decline. Originally, these extremely diverse tropical forests covered 10,635,513 square kilometers; at present, only 1,246,538 square kilometers remain, a loss of 86 percent (Mittermeier et al. 1999a). These tropical forest hotspots cover only 0.08 percent of Earth, but harbor 205,789 plant species and 21,903 vertebrate species other than fish (Mittermeier et. al. 1999a), a large percentage of the some 248,428 named vascular plants and 23,524 non-fish vertebrates (Wilson 1988). One can only wonder what diversity these areas had prior to their near-destruction. Such astounding facts should result in strong programs to preserve these regions, all of which are being degraded.
The tropical forest hotspots include the Caribbean, Central America, Brazil's Atlantic Rainforest, western Ecuador's Choco region, Andean tropical forests, Indo-Burma, the Philippines, Indonesia and Peninsular Malaysia, the Western Ghats of India, Madagascar, New Caledonia, Polynesia and Micronesia, Guinean Forests of West Africa, and mountains and coastal forests of Tanzania and Kenya (Mittermeier et al. 1999).
The richest and most diverse hotspot on Earth is found in the tropical Andes, stretching from western Venezuela to Chile and Argentina (Mittermeier et al. 1999a). This area has innumerable isolated valleys, slopes, and peaks in many altitudes, all physical characteristics that contribute to the evolution of a great array of plants and animals. Covering 1,258,000 square kilometers, these forests are interspersed with alpine vegetation and grassland. Between 45,000 and 50,000 kinds of plants are found here, 20,000 of which are found nowhere else (Mittermeier et al. 1999a). Birdlife is prolific, with 1,666 species, 41 percent of which are endemic. Andean Cock-of-the-Rocks (Rupicola peruviana), threatened Toucan Barbets (Semnornis ramphastinus), the giant Andean Condor (Vultur gryphus), also a threatened species, and the greatest variety of hummingbirds in the world are resident (Mittermeier et al. 1999a). The critically endangered Yellow-tailed Woolly Monkey (Lagothrix flavicauda) is native to a few Peruvian cloud forests, and the Spectacled Bear (Tremarctos ornatus) and Mountain Tapir (Tapirus pinchaque) are other endangered species of the region. Deforestation has destroyed much of the region through slash-and-burn farming and extensive cultivation of opium poppies, which are controlled with herbicides that poison rivers and streams, suspected to cause declines in frogs and toads (Mittermeier et al. 1999a). Several national parks have been set aside, including the Madidi and Tambopota National Parks on the Peru-Bolivia border, covering some 2,225,000 hectares.
The Atlantic forest of southeastern Brazil, another hotspot, has been reduced by 92 percent, yet it has been found to contain the greatest diversity of trees in the world: 476 species in a plot of only 2.5 acres, including 104 previously unknown tree species. By contrast, a plot of similar size in a North American temperate forest has only about 20 species of trees. A much larger plot, totaling 129 acres, in an old-growth forest in Malaysia's Lambir Hills National Park has an astounding 1,175 tree species (NGS 1997). This site is surrounded by farms, and nearby forests have been logged to the forest's boundaries. Both sites are tropical forest hotspots.
Africa's tropical forests once stretched in a wide band from Sierra Leone east through Zaire to Uganda and Kenya, and south to Angola. Of the original 3,620,000 square kilometers, less than half, or about 1,760,000 square kilometers, remained in the early 1990s (Martin 1991). The worst damage has occurred in West Africa where logging and clearance for plantations and villages have destroyed at least 85 percent of its rainforests (Collins 1990, Mittermeier et al. 1999a). Even the now-extensive forests of the Democratic Republic of the Congo and neighboring countries are being logged so rapidly that, outside reserves, they will have disappeared in 50 years, according to a 1997 study. A primate anthropologist, John F. Oates, researched the destruction of West African forests and the role played by international loan agencies such as the World Bank and the Ford Foundation. His book, Myth and Reality in the Rain Forest. How Conservation Strategies Are Failing in West Africa (Oates 1999), carefully documents the establishment of forest sanctuaries that did not protect forests and their wildlife, but encouraged logging, farming and bushmeat hunting. Almost no forest or sanctuary in West Africa is protected from logging, wildlife killing or capture, or other destruction. The rainforests stretching from Sierra Leone east to western Cameroon and the Gulf of Guinea islands of Equatorial Guinea comprise one of the world's most endangered hotspots for biological diversity (Mittermeier et al. 1999a). They covered 1,265,000 square kilometers a few hundred years ago, but have been reduced to only 182,348 square kilometers, or 14.4 percent of the original; of the remaining forests, only about 126,500 square kilometers are pristine forest, a scant 10 percent of the original (Mittermeier et al. 1999a). These forests are fragmented and largely unprotected. Some 9,000 species of plants exist in this region, of which 2,250 are endemic (Mittermeier et al. 1999a).
Some of the world's most fascinating and unusual wildlife species can be found here as well, including the world's largest frog, the threatened, 3.3 kilogram Goliath Frog (Conraua goliath), which inhabits mountain streams in Cameroon. The Western Chimpanzee (Pan troglodytes verus) of these forests is highly endangered by forest clearance and killing for the meat trade. Like the Chimpanzees of Kenya studied by Jane Goodall, they are tool-using, employing stones to crack open hard nuts on logs. They may be a completely different species of chimpanzee (Mittermeier et al. 1999a). Forest Elephants (Loxodonta africana cyclotis) are vital to forest ecosystems as seed dispersers and to open up forest glades for wildlife, such as the threatened White-breasted Guineafowl (Agelastes meleagrides) (Kingdon 1989). They also dig waterholes which provide a lifeline for a host of animals. Unfortunately, they are endangered as a result of deforestation and poaching. These forests also harbor many species of little forest antelope known as duikers, all less than 3 feet tall, which dart about the undergrowth in the Guinean forests. Sixteen of the 17 species are listed in the 2000 IUCN Red List Species, declining from forest loss and intense hunting. The rarest is Jentink's Duiker (Cephalophus jentinki), of which only a few hundred remain. There are no individuals of this species in captivity, and no photo has ever been published of this little antelope (Martin 1991).
In spite of these extraordinary treasures, there are few national parks in the Guinean forests, and almost all remaining forests are being commercially logged. In Sierra Leone, the only protected area is Tiwai Island, a 12-square-kilometer, primate-rich area (Mittermeier et al. 1999a). The parks that have been set aside, such as the Tai National Park, an extremely important and biologically rich forest in the Ivory Coast, are under siege from illegal hunters, and farmers whittling away at the forest. Kakum National Park in Ghana has been aided by Conservation International in promoting ecotourism over the past six years; a new canopy walk and aid in tourist promotion helped attract 40,000 tourists in 1997 (Mittermeier et al. 1999a). Few of the existing preserves are large enough to preserve the diversity of wildlife and plants of the region. Unless dramatic action is taken, many extinctions will take place in the near future.
In Gabon, to the south of Cameroon, recent progress has been made in protecting a large block of forest in the center of the country. Lope Reserve covers 1,900 square miles of Equatorial jungle coveted by loggers. An agreement signed in July 2000 between logging companies, the government and a variety of environmental organizations permanently prohibited logging in this sizeable area (Revkin 2000a). A compromise included the removal of 400 square miles of the reserve area with valuable Okoume Tree (Aucoumea klaineana) in order to add 200 square miles of extremely important habitat for primates, elephants and other wildlife (Revkin 2000a). Since 1957 when only a small percentage of Gabon's forests were open for logging, to the present when almost all the country is logged, wildlife has been driven from many areas by logging noise, roads that open up the forest to hunters and loss of habitat (Revkin 2000a). Dr. Lee J.T. White of the Wildlife Conservation Society has documented this phenomenon and has convinced the government to approve a country-wide forest inventory to identify other areas to protect for a network of national parks (Revkin 2000a).
The Lope Reserve, according to zoologist Jonathan Kingdon, does not include the Bee Forest, home to a very beautiful and rare primate, the Sun-tailed Guenon (Cercopithecus solatus), first classified and named in 1984. Dramatically patterned in dark gray with white facial markings and long reddish tails, these monkeys were photographed in the mid-1990s lying dead on tables at a market in Libreville, Gabon, offered for sale as meat (Bohan et al. 1996). Known only from this forest, this monkey is threatened by heavy logging in the forest by Isoroy, a French company acquired by Glunz Corporation of Germany (Bohan et al. 1996). The species is classified as Vulnerable in the 2000 IUCN Red List Species (Hilton-Taylor 2000). Isoroy cuts about 140,000 cubic meters of logs per year from a 300,000-hectare (741,300-acre) concession in the Bee Forest, exporting logs to plywood factories in Europe (Bohan et al. 1996). The prime wood sought by the loggers is from the Okoume Tree, and a four-year study has found major damage being done to the forest in the process. On average, 8.5 trees were destroyed for every Okoume log harvested, and 49 percent of the forest canopy has been disrupted (Bohan et al. 1996).
The Sun-tailed Guenon is one of 26 species of guenons considered "refugia" species of African rainforests. During the Ice Ages, these forests shrank into islands, where many different primates evolved in isolation in these forest fragments. Each has brightly marked facial and body patterns (Kingdon 1989, 1997). These "masked monkeys," many of which were photographed in the spectacular PBS Nature film of that name, are often highly restricted in their ranges and considered threatened by the IUCN. Kingdon, who has studied these primates for decades, believes that they have brightly colored markings in order to see and identify one another in the dark forest foliage (Kingdon 1989).
A close relative of the Sun-tailed Guenon is the endangered Diana Monkey (Cercopithecus roloway), endemic to the Guinean region. This lovely primate's jet black face contrasts with its white chest and legs; its back is russet red and gray, and its long tail is black. Its fur seems to have been painted on, so silky and lustrous is its texture. The majority of Americans know little about this species and other endangered African monkeys. This was dramatically illustrated in the summer of 2000 when New York state authorities ordered the confiscation of a pet Diana Monkey kept by an immigrant family. This animal had been bought in a Long Island pet store in 1995, long after its listing on the US Endangered Species Act and New York's endangered species legislation, yet no one seemed to notice when it was offered for sale illegally. The new owners immediately had a veterinarian spay and remove the canine teeth from this female monkey, named her "Cookie" and dressed her in tutus as a family pet. They said they had no idea that she was an endangered species and refused to give her to the state, which planned to place her in the Detroit Zoo with a male of the species. She can never be part of a breeding program, however, and is a genetic loss to the species. Had the plight of these beautiful primates been better recognized and the species better known, this unfortunate incident would never have happened.
Another "masked monkey" native to Ghana and the Ivory Coast has recently been declared extinct, the first primate extinction in several centuries (Revkin 2000b). Known as Miss Waldron's Red Colobus (Procolobus badius waldroni), this monkey had colorful, reddish-brown legs and head, and charcoal body. Last seen in the 1970s, deforestation and hunting caused its extinction; thorough searches over seven years within its habitat proved fruitless (Revkin 2000b). Had it been protected in a forest reserve, this colorful monkey would have avoided extinction (Revkin 2000b). This extinction is likely to be followed in the near future by those of many other critically endangered primates as a result of logging and hunting.
The deforestation of Central and West Africa also presents dangers for people. Many scientists warned that an inevitable consequence of opening up Africa's tropical rainforest through logging was the eruption of ebola virus and other diseases carried by native mammals. Such warnings went unheeded, and several outbreaks of the highly contagious and nearly always fatal ebola virus have occurred. Meat hunting of Chimpanzees in Gabon was a source of this virus, which has killed hundreds of people (French 1996).
The number of threatened vertebrates native to tropical forests of all types has grown astronomically in the past 20 years, concurrent with their widespread destruction. Indonesia, Brazil, Peru, Ecuador, India, Madagascar and Mexico are among the countries with the greatest number of endangered species, enormous diversity, and significant losses of tropical forest cover.
Among the hardest hit of tropical mammals are the primates. Ninety percent of all species inhabit tropical forests, and recent surveys have found that 204 species, or one-third of the world's 650 taxa (taxonomic listing including subspecies), are in high degrees of threat; 103 are critically endangered or endangered (Mittermeier et al. 1999b). In Southeast Asia, 90 percent of primates are either threatened or near-threatened, an amazingly high rate of endangerment. Primates are in rapid decline as a result of forest loss, killing for the pet trade, hunting for meat, and capture for zoos, the pet trade and research (Mittermeier et al. 1999b). The combination of all these factors has pushed some species so close to extinction that some primate species and subspecies have total world populations of fewer than 100 animals (Mittermeier et al. 1999).