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LOSS OF SPECIES FOR FOREST REGENERATION A fully functioning forest has a great capacity to regenerate. Exhaustive hunting of tropical rainforest species can reduce those species necessary to forest continuance and regeneration. For example, in Central Africa, the loss of species like gorillas, chimps, and elephants reduces the ability of seed dispersal and slows the recovery of damaged forest. Loss of habitat in the tropics also affects the regeneration of temperate species. North American migratory birds, important seed dispersers of temperate species, declined 1-3 percent annually from 1978-1988. INCREASE OF TROPICAL DISEASES The emergence of tropical diseases and outbreaks of new diseases, including nasty hemorrhagic fevers like ebola and lassa fever, are a subtle but serious impact of deforestation. With increased human presence in the rainforest, and exploiters pushing into deeper areas, man is encountering "new" microorganisms with behaviors unlike those previously known. As the primary hosts of these pathogens are eliminated or reduced through forest disturbance and degradation, disease can break out among humans. Although not unleashed yet, someday one of these microscopic killers could lead to a massive human die-off as deadly for our species as we have been for the species of the rainforest. Until then, local populations will continue to be menaced by mosquito-borne diseases like dengue fever, Rift Valley fever, and malaria, and water-borne diseases like cholera. Many emergent and resurgent diseases are directly linked to land alterations which bring humans in closer contact with such pathogens. For example, malaria and snailborne schistosomiasis have escalated because of the creation of artificial pools of water like dams, rice paddies, drainage ditches, irrigation canals, and puddles created by tractor treads. Malaria is a particular problem in deforested and degraded areas, though not in forested zones where there are few stagnant ground pools for mosquito breeding. These pools are most abundant in cleared regions and areas where tractors tear gashes in the earth. Malaria is already a major threat to indigenous peoples who have developed no resistance to the disease nor any access to antimalarial drugs. Malaria alone is cited as being responsible for killing an estimated 20 percent of the Yanomani in Brazil and Venezuela. Malaria—caused by unicelluar parasites transferred in the saliva of mosquitoes when they bite—is an especially frightening disease for its drug-resistant forms. Thanks to poor prescribing techniques on the part of doctors, there are now strains in Southeast Asia reputed to be resistant to more than 20 anti-malarial drugs. There is serious concern that global climate change will affect the distribution of malaria, which currently infects roughly 270 million people worldwide and kills 1-2 million a year— 430,000-680,000 children in sub-Saharan Africa alone. According to the Centers for Disease Control (CDC) in Atlanta, deaths from infectious disease are on the rise. Infectious disease is the leading cause of death worldwide and the third leading cause of death in the United States. Though AIDS death rates are declining in wealthier countries, this infectious disease is still killing millions around the globe. Demographers predict several African countries may achieve zero population growth within a generation partly due to the toll from AIDS. Of even greater concern, according to the CDC, in 1994 10 percent of people who died before 50 did so suddenly and mysteriously, probably from some unidentified infection. Strangely, the U.S. invests only $42 million a year in infectious-disease surveillance, yet spends $225 million maintaining marching bands for the military (Crenson 1997). The times may be changing, though: in the fall of 1997, Congress allocated funds for the establishment of a world monitoring system to detect emerging infectious-disease outbreaks. Infectious disease have had a major role in human mortality throughout history. At least one-third of human deaths during World War I came from an infectious disease: influenza. In 1919, between 20 million and 100 million died from the flu—more than the number of total casualties from the war. Review questions:
[full photo version] Continued: Loss of Renewable Resources, Wildlife Conflict Bibliographic citation for this page Other pages in this section:
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