Biodiversity preserves three ecological systems -Genetic Diversity: the measure of the variety of different versions of the same genes with individual species -Species diversity: the number of different kinds of organisms (richness) -Ecological diversity: the richness and complexity of a biological community
Only 1.4 million species are known- a fraction of the total. 70% known species are invertebrates, only 10-15% species live in North America and Europe Hot Spots of the World: The centers of greatest biodiversity tend to be in the tropics, especially tropical rain forests and coral reefs.
How do we benefit from Biodiversity? -Food- 80,000 plants are edible to humans -Drugs and Medicines- more than half of prescription drugs come from natural products. ex. Madagascar periwinkle inhibits cancer growth! -Ecological Benefits-soil formation, waste disposal, air and water purification, nutrient cycling, etc. 95% of pests are controlled by other species that prey on them- better than chemicals! -Aesthetic and Cultural Benefits- nature as "church". Provides psychological and emotional rejuvenation. Ecotourism is big.
Loss of Biodiversity: -Extinction: the elimination of a species 99% of all species that have ever existed are now extinct! -Natural Causes of Extinction: in an undisturbed ecosystem. Mass extinctions (that wiped out dinosaurs at the end of the Cretaceous period and two thirds of all marine life at the end of the Permian period) were caused by climate changes, perhaps triggered when large asteroids struck the earth. Now we are losing species at thousands of times the natural background rate of extinction. 1/3 to 2/3 of all current species could go extinct by the MIDDLE of this century. :( -Habitat Destruction: The biggest reason for the current increase in extinction is habitat loss. Habitat Fragmentation: Habitat fragmentation divides populations into isolated groups that are vulnerable to catastrophic events. -Over harvesting (hunting and fishing) is responsible for depletion or extinction of many species. Ex. Passenger pigeon: 3 to 5 BILLION birds lived 200 years ago. In addition to over harvesting wild species for food, we also obtain a variety of valuable commercial products from nature. ex. Rhino horns. -Predator and Pest Control- some animals are killed off because they are deemed as dangerous. ex. coyotes
Exotic Species Introduction -Exotic organisms are aliens introduced into habitats where they are not native and they are one of the greatest threats to native biodiversity. Exotics can be thought of as biological pollution. There are now more than 4,500 alien species in the United States. ex. Kudzu vine, purple loosestrife, asian longhorn beetles. They have no natural predators in their new home and can often out compete native plants for food and space. -Diseases- pathogens (disease organisms) can become predators when natural checks and balances are lost.
Endangered Species Management -Hunting and Fishing Laws- 1890's most states authorized laws. ex. white tailed deer -The Endangered Species Act- ESA of 1973 prohibits the killing of a endangered species. The act has now expired. Endangered: considered in imminent danger of extinction Threatened: those that are likely to become endangered Vulnerable species: naturally rare or have become so because of human activities. Problems arose with lawsuits. What about saving Mrs. Furbisher's lousewort??? Area in US with most endangered species is Southwest. Characteristics of endangered species: large body size, large or very small territory requirement, long-lived, specialist species, low reproduction rate. Successful Comebacks: American alligator, Bald Eagle and California condor Some people want the economic cost of recovery to be included in the decision making process. ex. Snail darter and Northern Spotted Owl. 80% of the habitat for more than half of endangered species live on nonpublic property. Land owners are resistant. Over the past decade, growing numbers of scientists, land managers, policy makers, and developers have been making that case that it is time to focus on a rational, continent-wide preservation of ecosystems that support maximum biological diversity rather than a species-by-species battle for the rarest or most popular organisms.
-Minimum Viable Populations: small numbers of surviving species are more vulnerable to extinction. Island Biogeography. The smaller and farther away an "island" is from a continent, the faster the extinction rate. -International Wildlife Treaties Convention on International Trade in Endangered Species (CITES). Prohibits the trade of endangered species internationally. ex. Elephants -Captive Breeding and Species Survival Plans: zoo breeding can reintroduce endangered species back into the wild
Land Use: Forests and Range lands
Land Use Distribution of World: -32% Forest and wetlands, -31% Tundra, desert, wetlands, and urban areas, -26% Range and pasture, -11% Cropland Forests regulate climate, control water runoff, provide shelter and food and purify the air. Plus they are pretty to look at! 50 to 60% of the world depends upon wood or charcoal for heating and/or cooking. Forests in NE USA (Temperate) are rejuvenating! Tropical Forests are critically threatened. Jungles contain 2/3 of all plants and 1/2 of all animal life. There needs to be laws preventing deforestation in developing countries.
Forest management: Monoculture forestry is the most profitable but the most destructive to the health of the forest. -Temperate Forests: In the United States and Canada, the two main issues in timber management are (1) cutting the last remains of old-growth forest and (2) methods used in timber harvest. Clear cutting is when every tree in a given area is cut regardless of size. The concentration of nitrates in the runoff increases. Strip cutting entails harvesting all tress in a narrow corridor. Sustainable Forestry: In both temperate and tropical regions, scores and certification programs are being developed to identify sustainably produced wood products. Selective cutting is when only a small percentage of the mature tress are taken in each 10- or 20- year rotation. Increasingly, non-timber forest products are seen as an alternative to timber production. Range lands: Pasture (generally enclosed domestic meadows or managed grasslands) and open range (unfenced, natural prairie and open woodlands) occupy about 26% of the world's land surface. Overgrazing and Protection: About one-third of the world's range is severely degraded by overgrazing, making this the largest cause of soil degradation. The process of denuding and degrading a once-fertile land initiates a desert-producing cycle that feeds on itself and is called desertification. Rotational grazing; confining animals to a small area for a short time (often only for a day or two) before shifting them to a new location; stimulates the effects of wild herds. This allows the animals to trample and fertilize the ground without damaging it.
