Chapter 5 - Topics

• Biomes

• Biodiversity

• How Do We Benefit from Biodiversity?

• What Threatens Biodiversity?

• Human-Caused Reductions in Biodiversity

• Protecting Biodiversity1

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Dry, thorn-shrubland, Africa

SAVANNASerengeti National Park

Impalas in African savannas http://www.summitelgin.org/grassland_web/Tropical%20Grasslands/Animals.html

http://www.summitelgin.org/grassland_web/Tropical%20Grasslands/Plants.html

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Deserts. The Encroaching Wilderness. Ed. Allan and Warren. 1993 Oxford University Press

Tranvsvaal, South AfricaSudan

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Deserts. The Encroaching Wilderness. Ed. Allan and Warren. 1993 Oxford University Press

West Africa

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Joshua Tree National Park

•Low rain

•Deep roots

•Lots insects

•Plants store water

•Adapted to higher soil salt levels

•Plants, animals adapted = heat, low HOH, repel enemies

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Chaco Canyon, San Juan Basin, New Mexico

http://www.ratical.com/southwest/ChacoCanyon.html 7

Okefenokee Swamp, Georgia

WETLANDS

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Freshwater ecosystems are influenced by surrounding terrestrial ecosystems. In turn, riparian areas are productive because of nutrient deposition by the river. Can also have pollutants transported by river to terrestrial areas.

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Freshwater ecosystems are impacted by anything that happens uphill or upstream from them.

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Coastal wetlands – salt marsh ecosystems

One most productive systems in the world

Major breeding, nesting habitat for waterfowl, shorebirds

Highly human impacted -Burn easily

WETLANDS

Coral reefs - Most productive ecosystems in world in terms of energy cycling; strongly impacted by land uses from land (sewage wastes)

Tolerance Limits

Biosphere 2

Biodiversity

• Genetic diversity - variety of different versions of the same genes within a species

• Species diversity - number of different kinds of organisms within an ecosystem

• Ecological diversity - complexity of a biological community (number of niches, trophic levels, etc.)

Biodiversity - the variety of living things - three types essential:

Generally the greater the biodiversity in an ecosystem the more resistant/resilient the system is to a disturbance.

How many species are there?

??? 50 million???

Biodiversity Hot Spots – rare and potentially endangered species. Many hot spots contain

endemic species (species are found only in that region)

Most of the world’s biodiversity - concentrated near the equator (tropical rainforests, coral reefs), islands, coastal areas, mountain tops

How do we benefit from biodiversity?Where do we collect most of these species?

Food,Drugs & MedicineEcological benefits,Aesthetic & Cultural

benefits Mangosteens, Indonesia

Costa Rica, taxonomists identifying all insects in the country

Human Activities That Reduce Biodiversity

• Habitat destruction and fragmentation• Hunting and fishing• Commercial products and live specimens• Predator and pest control• Exotic species introduction• Diseases• Pollution• Genetic assimilation

What Threatens Biodiversity?

Human Disturbance Map

IcelandPhoto: B Hecht

Degraded grasslands with sheep, TUNDRA

About 200 years ago, the American passenger pigeon was the world’s most abundant bird.

Population: 3-5 billion

Overhunting and habitat destruction caused its extinction.

Trade in Products from Endangered Species

Trade in Wildlife

About 75% of all saltwater tropical aquarium fish sold come from coral reefs of the Philippines and Indonesia, where they are commonly caught with dynamite or cyanide.

Live in a human ecosystem where humans are the top predator!

SO Humans eliminated or drastically reduced the population of top predators that might hunt or harm us, or eat our food

http://www.sel.barc.usda.gov/acari/index.html, http://www.dfwpest.com/scorpion.htm

cockroaches

Introduction of Exotic Species

Most species do not survive when introduced into different habitats because they have specialized habitat requirements. Others do well and most of our invasive species are very effective in competing for limited resources with native species.

OPTIMUM ENVIRONMENT

Species absent

Species absent

Optimal rangeAbundant species

Stress zone

Stress zone

Fewer species

Fewer species

Classic example of an invasive species – considered by some to be the biggest threat to biodiversity conservation (this is a western world view)

• Endangered species – considered in imminent danger of extinction

• Threatened species – likely to become endangered (at least locally)

• Vulnerable species – naturally rare or have been depleted by human activities to a level that puts them at risk

Species Status?

Protecting Biodiversity• Hunting and fishing laws• The Endangered Species Act (ESA) 1973• Recovery plans (rebuild pop)• Minimum viable populations• Private land and critical habitat (HCPs)• Reauthorization of the ESA-exp’d in 1992.

plants & animals above humans? what now???• International wildlife treaties

(eg, Convention on International Trade in Endangered Species-CITES, 1975)

Only 40 Florida panthers remain in the Everglades. We spend millions of dollars to protect them, but the population may be too small to be viable.

Recovery Plans

Pet parrots, Amazon Brazil, TROPICAL FORESTS Photo: K Vogt

Protecting biodiversity conflicts with indigenous community’s needs to survive and

obtain sufficient food for themselves

Biomes & Biodiversity• Biomes – life zones w similar climatic, soil, etc

conditions• Biodiversity – variety of organisms• Biodiversity hot spots – regions of threatened &

potentially endangered species• Benefits of biodiversity – food, drugs/medicines,

ecological & aesthetic & cultural benefits• Human-Caused Reductions in Biodiversity –

habitat destruction, fragmentation, hunting/fishing, products, predator/pest control, exotic species intro, diseases, pollution, genetic assimilation

• Protecting Biodiversity – laws, Endangered Species Act, recovery & conservation plans, reintroductions, minimum viable populations, international treaties