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

Temperate and tropical terrestrial living planet indices Reason for loss: Conversion for agriculture WWF 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 Spills More on this later… Global Climate Change –Changing ice/water –Increased range for disease More on this later…

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.species Largest conservation agreement in existence. Voluntary participation. Requires each nation to draft laws as to how they implement CITES

Spix’s Macaw

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