5 environmental status-biodiversity


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5 environmental status-biodiversity

  1. 1. Biodiversity
  2. 2. Biodiversity • Biodiversity or Biological diversity, is the term used to describe the variety of plants and animals and other living things found on Earth. • Biodiversity is the variability among terrestrial, marine and other aquatic living organisms and their ecosystems. This includes diversity within species (genetic diversity), between species and of ecosystems. • For example, desert plants and animals have different characteristics and needs than those in the mountains. Also the desert and mountain ecosystems are different from each other with different weather, vegetation etc. •
  3. 3. Benefits of Biodiversity • Biodiversity has led to the development of drugs that come from plants, animals, or microbes. Around half of all drugs on the market in the United States are derived from plants, animals, or microbial organisms. Biodiversity also helps humans in the agricultural, business, and industrial sectors. • In agriculture, diversity among crops helps to reduce weakness to disease and to improve overall crop performance. One of the reasons biodiversity is important is because it helps to keep the environment in a natural balance. An ecosystem which is species-rich is more strong and adaptable to external pressures than one in which the range of species is limited. In a system where species are limited, the loss or temporary reduction of any one could disrupt a complex food chain with serious effects on other species in that same system.
  4. 4. Threats to Biodiversity • Habitat loss and degradation • Overexploitation • Alien invasive species • Climate change and • Pollution
  5. 5. Habitat loss • Habitat loss in the terrestrial domain has been caused mainly by the expansion of agriculture: more than 30% of land has been converted for agricultural production. • Wetlands in particular have faced a 50 per cent loss in the 20th century. • Freshwater ecosystems are severely affected by fragmentation • Bottom habitats have been degraded as a consequence of bottom fishing with nets and other destructive fishing methods.
  6. 6. Overexploitation • Overexploitation of wild species to meet consumer demand threatens biodiversity, with unregulated overconsumption contributing to declines in terrestrial, marine and freshwater ecosystems. • major exploited groups include • plants for timber, food and medicine • mammals for wild meat and recreational hunting • birds for food and the pet trade; and • amphibians for traditional medicine and food • The threat to vertebrates from overexploitation is particularly severe, especially due to demand for wildlife and wildlife products from East Asia. • Globally, utilized vertebrate populations have declined by 15 per cent since 1970 • Similarly, the extinction risk of utilized bird species increased during 1988–2008, partly due to overexploitation. • In the marine systems, capture fisheries more than quadrupled their catch from the early 1950s to the mid-1990s. • Overfishing is also a problem in freshwater wetlands
  7. 7. Invasive alien species • Invasive alien species threaten native biodiversity and are spreading through both deliberate and unintentional introductions as a consequence of increasing levels of global travel and trade. • Poorly planned economic introductions, air transport, water from ships, trade in pets, garden plants and aquarium species, are significant pathways for the dispersal of invasive species. • Invasive alien species affect native species principally through predation, competition and habitat modification. • Data from Europe show that the number of alien species has increased by 76 per cent since 1970 • In another study, invasive alien species were a factor in more than 50 per cent of vertebrate extinctions where the cause was known, and were the sole cause of 20 per cent of extinctions
  8. 8. Climate change • Climate change is an increasingly important threat to species and natural habitats. There is widespread evidence that changes in phenology, including the timing of reproduction and migration, physiology, behaviour, morphology, population • density and distributions of many diferent types of species are driven by climate change.
  9. 9. Pollution • Pollutants such as pesticide and fertilizer effluents from agriculture and forestry, industry including mining and oil or gas extraction, sewage plants, run-of from urban and suburban areas, and oil spills, harm biodiversity directly through mortality and reduced reproductive success, and also indirectly through habitat degradation Additional threats • Additional threats to biodiversity include changes in fire regimes, problematic native species (Figure 5.1) and negative influences from human activities.