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LOSS OF BIODIVERSITY II

LOSS OF BIODIVERSITY II. ESC 556 week 10. Nature’s Last Stand. GDP vs. LPI Overpopulation & development  habitat loss. Hawaii. Polynesians 400 AD Introductions Ants, snakes, thorny pants etc. Pre-human Hawaii 125-145 endemic species Birds Now 35 species/24 endangered

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LOSS OF BIODIVERSITY II

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  1. LOSS OF BIODIVERSITY II ESC 556 week 10

  2. Nature’s Last Stand • GDP vs. LPI • Overpopulation & development  habitat loss

  3. Hawaii • Polynesians 400 AD • Introductions • Ants, snakes, thorny pants etc. • Pre-human Hawaii • 125-145 endemic species • Birds • Now 35 species/24 endangered • Hard to find • Many non-native species • Plants • 902/1935 species alien • 10,000 native animals & plants

  4. Hawaii Introduced Species • Human effects • Hunting • Clearing forests for agriculture • Introduction • Disruption of natural immigration processes • Aerial plankton • Natural rafts • Adaptive radiation • Polynesians increased the colonization rates • Pigs, rats, domestic plants • Birds, mammals, plants • Insects, spiders, mites • 35% of 8790 insect species alien, 4373/22070 species alien

  5. Introduced Species • Many species, few really damaging • Big-headed ant • Millions of workers • Destroy insects (pollinators) • Ripple up the food chain • vs. argentine ants • Not adapted to any such invader • Not adapted to ground-dwelling mammals • Hoary bat & Hawaiian monk seal • 42 mammal species • Common pig • 100,000 • Destroy understory forest cover, affect soil ecosystems, alien plants • Rats, mongooses, feral house cats • Goats and cattle

  6. HIPPO • Population • HIPPO vs. OPPIH • Various combinations of causes

  7. Vancouver Island marmot • Decline in late 20th Century • < 70 indivs by 2000 • Remote montane habitats • Clear-cutting

  8. Hawaii Land Snails • 1900s Giant land snails from Africa • 1950s predatory rosy wolfsnail • Rats, shell collectors, deforestation • 50-75% of 800 native species • 24/106 native species in Mauritus • Captive breeding and reintroductions

  9. Frog Decline • Gastric breeding frog, discovered & extinct in < one year • Golden toad of Costa Rica • 2%/year since 1960 • Habitat loss • Sierra Nevada – air pollution • Minnesota, chemical pollution • Oregon – increased UV light • Introduced trouts & bull frogs • Central America – fungus • Warning signal for environmental deterioration

  10. Small Population size • Inbreeding depression • Double dose of defective genes • Fritillary butterflies vs. cheetah • Vulnerable to stochastic events • Hurricane Andrew  Schaus’s swallowtail

  11. Habitat Destruction • Massive loss of species • Centineal Ridge in Ecuador  70 endemic plant species • Freshwater mussel fauna of United States • damming & river pollution • Clearing of forests • Maximum @ 6000-8000 years ago • Agriculture  50% remains • 30 % of conifer - 70% of tropical dry forests

  12. Species – Area Relationship • Species number proportional to area • 90% reduction in area – 50% species • Nature reserves • Bigger reserves more robust

  13. Tropical Rainforests • 7% area  50% species • Fragmentation • 1% deforestation / year • 15/25 hotspots: tropical rainforests • 1.4 %  44% plants; 1/3 of terrestrial animals • <10% cover • Hotspots: two sides of a coin • Frontier forests

  14. Amazon • 10 square km > Europe • Perception • Timber resource, agricultural land • 14% gone • 3-5% in reserves in Brazil – 10% goal • Not resilient • Biomass aboveground • Fast decomposition – quickly converted

  15. Synergism • Dry periods smoke  limit rainfall • Cutdown trees  reduce rainfall  lose more trees • Forest  dry scrubland • Indonesia • 80% committed • < rainfall  forest fires • Dipterocarp tree – El Nino relationship

  16. El Nino Southern Oscillation (ENSO) • El Nino, La Nina • Higher frequency & amplitude • Global warming • Industrial activity • Cutting and burning of forests • 1.3oC - 5.7oC • Storms, heat waves, forest fires, droughts, flooding • Sea level rises

  17. Global Warming & Biodiversity • Northward movement velocity of climatic zones • Tundra • Lichens, mosses, polar bears, rein deer • High mountain range species • Gondwana lands • Entrapment – e.g. southern Africa • Alien species • From Red Sea into the Mediterranean • 4500/200,000 alien in the US – starling • Removal of control mechanisms

  18. Conserving Populations • Various levels of conservation • Species  populations • 73% of 2290 plants in NA, < five populations • Informed action for conservation • Factors controlling population density • Identification of threats • Predict the effects of management actions

  19. What is a population? • Fixed geographic area • Convenience to the investigator • Scale • Populations description • Density • BIDE • Structure

  20. Monitoring Demographic Structure • States of development • Plants: juveniles, seedlings, reproductive, senescent • Marsh gentian • Invasive (bare soils), regressive (high ground cover percentage) • Individual counts

  21. Census data • Census data vs. survey data • Spider orchid • 80% decline in 50 years • Endangered in Britain • Chalk & limestone grassland • Cattle vs. sheep grazing

  22. What is rarity? • Some species naturally rare • Changes in population size • Classifying types of rarity • Size of geographic range • Habitat specificity • Local population size • Barn owl • Osprey

  23. Causes of Rarity • Anthropogenic effects • Patterns in the ecology of rare species • Poor dispersal abilities (sedentary species) • Plants, invertebrates • No migration to favorable habitats • Deterministic vs. stochastic process • External and Internal Influences

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