1 August 2012 Environmental Science Ch # 11 Biodiversity 11 -1. Biodiversity Issues. Biodiversity is described in terms of Genes, Species and Ecosystems. Its loss results from Extinction and Human Domination. Extinction is normal. Cause of Extinction is primarily due to Habitat Destruction. Most likely to become extinct are those animals with: Small populations, Restricted habitats, Specialized, Low rates of reproduction, and which feed at higher trophic levels Extinction due to human activities, such as: Modification of the ecosystem to benefit man, leads to displaced organisms. Killing for food. 11-2 Describing Biodiversity Genetic diversity. In a society with many different individuals, structures and abilities, there is a high biodiversity. The factors which influence genetic biodiversity are: Mutations – modifying genes already present Migration – entering another population. Increasing numbers Sexual reproduction – new combinations Population size – smaller populations have less diversity Selective breeding – eliminate some characteristics. Species diversity is a measurement of the number of species present in an area. They are influenced by: Evolutionary and geologic history of the region Climate change Migration Area size Human activity such as: converting biomes , introducing species (Nelgay) , killing species. Ecosystem diversity is a measure of the number of ecosystems in the region. That is a function of “local regions” – microhabitats – (Climate, topo, vegetation.). 2 Value of Biodiversity. Value can be assigned after we understand an Organism role, its economic impact and take into consideration ethical considerations. Organisms’ role. ( Biological and Ecosystem Services Values). Services provided by the ecosystem must be assigned a $ value, because each organism is interdependent on others. When decisions are to be made, services are not to be overlooked. Example: Trees clean the air, produce food on which we depend. If trees are allowed to become extinct, genes are lost. Direct Economic Values. ( Agriculture, forestry and fisheries) in undeveloped countries, income may never enter the formal economy. Services may have significant value. For example: Nutrient cycling done by Nitrogen fixing bacteria; Cultural uses; water regulations and supply; disturbance regulations and soil erosion; waste treatment; food and raw materials; Atmospheric and climate services; Recreation; Biological Control services and soil formation. Ethical Values. All species have an intrinsic value and a fundamental right to life, without being needlessly eliminated. One’s values are developed as a result of experiences. Threats to Biodiversity. The value of an exploited resource can be measured in economic terms, but not so for the preservation of biodiversity. Human threats to biodiversity result from: Habitat loss – conversion to agriculture; Conversion to Agriculture alters the biotic nature of an area. As human population increases, space requirements increase. Forestry practices in deforestation – Forested areas change climate, reduces run off, protect against soil erosion, silt accumulation in streams, water temp. lowered, less hunting . Logging practices are clear cutting, patch work clear cutting, and selective harvesting. Concerns about tropical deforestation. Here is the largest biodiversity of all terrestrial biomes. It requires harvesting techniques significantly different from those used in temperate forests. Harvesting large tracks reduce biodiversity, alters climate and affects global warming. It is a Carbon Sink. Plantation forestry – single species , hybrid is planted. It is fast growing but does not support diverse wild life. 3 Range land and grazing practices in a region too arid to support agriculture. Used to raise domesticated animals. Has a major impact on biodiversity. Indigenous plants are removed and animals driven off. Overgrazing and harvesting fuel wood leads to desertification. Habitat loss in an aquatic Ecosystem. – Shallow water, marine bottom dwellers are harvested, 25% of which have no commercial value. Rivers and lakes are dammed , which prevents up stream migration . Conversion to Urban and Industrial usage. 4.3% /year natural ecosystems are destroyed. Trend is towards urbanization. Over exploitation is responsible for 30% endangered species, 8% plants. Poaching nets $ 2 to 30 Billion /year Overfishing – 70% marine fishing grounds are over exploited. Reduced catches have caused the sale of previously regarded unacceptable fish. Aquaculture causes pollution, possible genetic alteration. It is becoming an increasingly important food source. 60% salmon sold is farmed. Unsustainable harvesting of wild life and plants – Bush meat used for food and as a source of income. Introduction of Exotic species, accidental or deliberate. Results in the native species die off. Diseases change the nature of the forest. Can be controlled by destroying infected trees Control of pest organisms. i.e the systematic killing of predators as Passenger pigeons or Bald Eagles. Climate change may affect amphibians, corals and Arctic species. 11 – 4. WHAT IS BEING DONE TO PRESERVE BIODIVERSITY ? Legal Protection – Treaties (Biodiversity treaties 168 of 191 nations signed). Habitats established Legislation (Endangered species Act). Legislation . set up a classification as: Endangered (unlikely to survive). Vulnerable (decreasing population). Rare (Small population worldwide). Indeterminate (believed to be endangered). Education programs. Purchase of sensitive habitats. 4 Sustainable management of Wild life populations; requires habitat analysis and management (Cover, food, protection); Population assessment (Carrying Capacity and hunting); Special issues concerning migratory birds and animals. Sustainable Management of Fish Populations – whose habitat is shallow waters. 200 Nautical miles. Claimed 300 Km. Designate non-fishing areas. Presently researching the best fishing methods. EEZ is 350km. .