Biodiversity: Fragile Ecosystems

Image of land being slashed and burned The rate at which species are becoming extinct today has become more accelerated than in the past. Humans are altering the environment to such a degree that many animals cannot adapt - therefore they die. Other species are being illegally hunted or trapped at a rate that is also causing extinction. Oil spills, pesticides, acid rain, and solid wastes are finding their way into animals' digestive tracts and skin, which is still another reason animals are disappearing from our earth. If, in fact, wildlife is an "environmental barometer", the human species is also in trouble.

Essential Questions

What is the inherent value of biological diversity?
How does the conservation of biological diversity involve an understanding of the intricate relationships among species and between species and their environments?
What are the ecological functions of biological diversity?
What major problems are associated with biological diversity and what impact does human activity have?
How do species interact?
What limits the growth of populations?
How do communities and ecosystems respond to changing environmental conditions?
How do species replace one another in ecological succession?
Why should we protect certain species and not others?

Key Terms

Aesthetic value: the beauty or appreciation of nature as in its artistic quality, or beauty as a value or aspect of worth.
Amensalism: an association between organisms of two different species in which one is inhibited or destroyed and the other is unaffected. There are two basic modes: competition, in which a larger or stronger organism excludes a smaller or weaker one from living space or deprives it of food, and antibiosis, in which one organism is unaffected but the other is damaged or killed by a chemical secretion.
Biogeographical Area: An entire self-contained natural ecosystem and its associated land, water, air, and wildlife resources.
Boreal Forest: Also called taiga, vegetation composed primarily of cone-bearing, needle-leaved, or scale-leaved evergreen trees, found in regions that have long winters and moderate to high annual precipitation. The boreal (meaning northern) forest region occupies about 17 percent of the Earth's land surface area in a circumpolar belt of the far Northern Hemisphere.
Chaparral: a biome with a Mediterranean climate (mild, moist winters and hot, dry summers). Chaparral vegetation is characterized by small-leaved evergreen shrubs and small trees.
CITES Legislation: (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) is an international agreement between governments to ensure that international trade of wild animals and plants does not threaten their survival. CITES became law on July 1, 1975.
Clear-cutting: A forest management technique that involves the removal of all trees from an area at a single time.
Climate Diagrams (climatographs): A climate graph is a single graph that often depicts the overall weather for a specified location. Data included in the depiction usually shows annual precipitation and temperatures graphed on a scale.
Commensalism: A type of symbiosis in which one organism benefits and the other one is neither harmed nor helped
Competition: The interaction among organisms that vie for the same resources in an ecosystem (such as food, living space, or other resources).
Conservation: The sensible and careful management of natural resources
Desert: A fragile ecosystem in which lack of precipitation limits plant growth. Arid lands are found in both temperate and tropical regions.
Ecotones: The transitional zone where two ecosystems or biomes intergrades
Ecological Restoration: The field of science in which the principles of ecology are used to help return a degraded environment as close as possible to its former, undisturbed state
Endangered Species Act: U.S. federal law passed in 1973 that obligates federal and state governments to protect all species threatened with extinction that fall within the borders of the United States and its outlying territories. The U.S. Fish and Wildlife Service (USFWS) of the Department of the Interior and the National Oceanic and Atmospheric Administration (NOAA) of the Department of Commerce is responsible for the conservation and management of fish and wildlife resources and their habitats, including endangered species.
Existence value: The importance we place on just knowing that a particular species or a specific organism exists
Extirpate: To destroy totally: extinction caused by direct human action, such as hunting, trapping, etc.
Fundamental Niche: The potential ecological niche that an organism could have If there was no competition from other species.
Habitat Corridor: A protected zone that connects unlogged or undeveloped areas; wildlife corridors are thought to provide escape routes and allow animals to disperse so they can interbreed.
Invasive Species: Foreign species whose introduction causes economic or environmental harm.
Keystone Species: A species that is crucial in determining the nature and structure of the entire ecosystem in which it lives; other species of a community depend on or are greatly affected by the keystone species, whose influence is much greater than would be expected by its relative abundance.
Mutualism: A symbiotic relationship in which both partners benefit from the association.
Parasitism: A symbiotic relationship in which one member (the parasite) benefits and the other (the host) is adversely affected.
Pioneer Community: The first organisms (such as lichens or mosses) to colonize an area and begin the first state of ecological succession.
Predation: The consumption of one species (the prey) by another (the predator; includes both animals eating other animals and animals eating plants.
Primary Succession: An ecological succession that occurs on land that has not previously been inhabited by plants; no soil is present initially.
Realized Niche: The lifestyle that an organism actually pursues, including the resources that it actually uses. An organism's realized niche is narrower than its fundamental niche because of competition from other species.
Restoration Ecology: The field of science in which the principle of ecology is used to help return a degraded environment as close as possible to its former, undisturbed state.
Riparian Area: The thin patch of vegetation along the bank of a stream or river that interfaces between terrestrial and aquatic habitats; protects the habitat of salmon, trout, and other aquatic species from sedimentation caused by soil erosion.
Savannas: A tropical grassland with widely scattered trees or clumps of trees; found in areas of low rainfall with prolonged dry periods.
Secondary Succession: An ecological succession that takes place after some disturbance destroys the existing vegetation; the soil is already present.
Succession: The sequence of changes in a plant community over time.
Symbiosis: An intimate relationship between two or more organisms of different species.
Temperate Deciduous Forest: A forest biome that occurs in temperate areas where annual precipitation ranges from about 7.5 cm to 125 cm.
Temperate Grasslands: A grassland characterized by hot summers, cold winters, and less rainfall than is found in a temperate deciduous forest biome.
Temperate Rain Forest: A coniferous biome characterized by cool weather, dense fog, and high precipitation.
Trophic Level: Each level in a food chain. All producers belong to the first trophic level; all herbivores belong to the second tropic level, and so on.
Tropical Dry Forest: A tropical forest where enough precipitation falls to support trees but not enough to support the lush vegetation of a tropical rain forest. Many tropical dry forests occur in areas with pronounced raining and dry seasons.
Tropical Rain Forest: A lush, species-rich forest biome that occurs in tropical areas where the climate is moist throughout the years. Tropical rain forests tend to be characterized by old, infertile soils.
Tundra: The treeless biome in the far north that consists of boggy plains covered by lichens and small plants such as mosses. The tundra is characterized by harsh cold winters and extremely short summers.
US Wilderness Act of 1964: Signed into law by President Lyndon B. Johnson. It created a way for Congress to protect pristine wildlands by designating them as protected wilderness. It created the National Wilderness Preservation System, which manages the nation's protected wilderness areas and it immediately put 9.1 million acres of wild American lands into the National Wilderness Preservation System, protecting them as designated wilderness.

RESOURCES IN THIS MODULE ARE OPEN EDUCATIONAL RESOURCES (OER) OR CREATED BY GAVS UNLESS OTHERWISE NOTED. SOME IMAGES USED UNDER SUBSCRIPTION.