The Decline of Biodiversity. US Species Animal Extinctions Since 1600.
24
The Decline of Biodiversity
-
Upload
jason-bond -
Category
Documents
-
view
214 -
download
1
Transcript of The Decline of Biodiversity. US Species Animal Extinctions Since 1600.
The Decline of Biodiversity
US Species
Animal Extinctions Since 1600
Biodiversity: Variety of Life
• 1.75 million species known (2003)
• Many more than that number exist
• Existence vs. Population
Decline of Biodiversity: North America
WWF Living Planet Index http://www.panda.org/about_our_earth/all_publications/living_planet_report/living_planet_index/
an indicator of the state of global biological diversity, based on trends in vertebrate populations of species from around the world. Loss of tropical species is the main reason for this overall loss, due to conversion of habitat loss to cropland and pastures. This loss is about 55% of species.
Decline of Biodiversity: Global
• Rate: 20-25/100 years• Background Rate:
– Mammal 1/400 years– Bird 1/800 years
• 24% of mammals and 12% of birds are “threatened”
• Most recent extinctions occurred on islands• Where is biodiversity richest? Tropical Forest!
Why? HIPPO
• Habitat Conversion:– Forest to farm, housing, shopping,
factory– Proportional reduction in wildlife
populations
Why? Habitat Alteration
• Fragmentation:– Natural – connectedness– Human – “patchwork”– Will population fall below critical
number?– Bad year -> population eliminated
Why? Habitat Alteration
• Simplification– Human use often simplifies– Ex: removal of dead trees, underbrush– Ex. Hiking trail– Ex: Management for timber
Simplification of Habitat = Simplification of Species
Why? Habitat Alteration
• Intrusion:– Towers intrude on bird “airspace”– Other examples?
Why? Human Population Growth
• Competition for same resources
• Increased population – increases in the four other factors
• Population growth highest in most
sensitive areas!
Why? Other Human Factors:
• Excess Agricultural Runoff
• Oil SpillsMore on this later…
• Global Climate Change– Changing ice/water– Increased range for disease
Why? Introduced Species
Why? Overuse
• Obvious• Responsible for about ¼ of recent
extinctions• Food• Trade
Consequences
• Ecosystems can lose some rarer (non-dominant) species and still function
• Loss of Keystone Species = Trouble
• Or, introduction of new dominant
• Loss of Biodiversity will eventually lead to consequences
Biological Hotspots – there are 25
• A hotspot:– Ecologically distinct– Contains at least 0.5% (1500) of the
world’s vascular plants– Has suffered loss of at least 70% original
vegetation
CITES Treaty
• Convention on International Trade in Endangered Species of Wild Flora and Fauna (aka Washington Convention)
• Its aim is to ensure that international trade in specimens of wild animals and plants does not threaten the survival of the species in the wild, and it accords varying degrees of protection to more than 33,000 species of animals and plants.
• Largest conservation agreement in existence. Voluntary participation. Requires each nation to draft laws as to how they implement CITES
Spix’s Macaw
King of Sushi
• http://www.youtube.com/watch?v=dsbx6dQuRhQ
