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Chapter 5: Biomes and Biodiversity

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Relative abundance of plant life

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Part 1: Biomes

Biomes

• Broadly defined life zones

• Environments with similar climates, topographies, soil conditions, and biological communities

• Distribution mainly dependent on temperature and precipitation

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ADD FIG. 5.1

157”

118

79

39

86 68 50 32 14 F

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Biomes of the World

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ADD FIG. 5.4

(note that hotter months more representative of northern hemishpere)

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Tropical rainforest savannah

Desert

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Grasslands Temperate forest

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Temperate rainforest

Tundra

Boreal forest

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Coral reefs – warm, shallow water with little suspended material (not a great photo of a reef)

- colonial animals living symbiotically w/algae- high biological productivity; coral structures shelter fish, worms, crustaceans, etc.

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Mangroves – salt-tolerant trees along warm, shallow, tidal mudflats - stabilize shorelines, take force of storms, trap sediments & organic matter; nurseries for young fish, crab, etc. - many being cleared for fish & shrimp farms

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Estuaries – where rivers enter the ocean; mixed fresh & salt waterSalt marshes – shallow wetlands regularly flooded by salt waterAbout 2/3 all marine fish & shellfish rely on these areas for spawning & juvenile development

Estuaries near Boston, New York, & Baltimore once provided extensive oyster beds & clam banks

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Tidal pools – depressions in rocky shorelines; flooded at high tide, some water retained at low tide

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Lake environments

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Wetlands

Shallow ecosystems whose surface is saturated or submerged for at least part of the year

Generally high biologic productivity; abundant & varied life

Types defined by vegetation

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Swamp – wetland with trees

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Marsh – wetland with no trees

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Bogs/fens – water-saturated ground, which is usually made of layers of accumulated, undecayed vegetation (peat).

bog – water from precipitationfen – water fed by groundwater

Often nutrient-poor; some plants adapted to get nutrients from captured insects (sundews, pitcher plants, Venus fly traps)

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Part 2: Biodiversity

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

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

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

Biodiversity - the variety of living things - three types:

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How many species are there?

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Biodiversity Hotspots

Most of the world's biodiversity concentrations are near the equator (tropical rainforests, coral reefs).

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Part 3: How do we benefit from biodiversity?

• Foods

• Drugs and medicines

• Ecological benefits– 95%potential pests & disease-carrying

organisms controlled by natural predators

• Aesthetic and cultural benefits

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Aesthetic and CulturalBenefits (ecotourism)

Bird watching and other wildlife observationcontribute more than $29 billion each year to the U.S. economy.

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Part 4: What Threatens Biodiversity?

Extinction - the elimination of a species

• Natural process - one species lost every 10 years

• Process been accelerated by human impacts on populations and ecosystems

• E.O. Wilson - we are currently losing thousands of species a year

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Part 5: Human-Caused Reductions in Biodiversity

• Habitat destruction and fragmentation– Clear cutting of forests– Converting grasslands to croplands

• Hunting and fishing• Commercial products and live specimens• Predator and pest control• Exotic species introduction

• Diseases• Pollution• Genetic assimilation• Surface mining – removes land cover• Dam construction - floods stream environments

& adjacent habitat

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

Population: 3-5 billion

Over hunting and habitat destruction caused its extinction.

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Trade in Products from Endangered Species

Collection of hides & skins, horns, cacti, exotic pets

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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 (both practices kill the coral).

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Part 6: Protecting Biodiversity

• Hunting and fishing laws• The Endangered Species Act (ESA)• Recovery plans• Reintroductions• Minimum viable population• Private land and critical habitat• Reauthorization of the ESA• International wildlife treaties

• Endangered Species Act (ESA)– Enacted 1973, officially expired 1992 but

still very much a force– Covers all species (animals & their

habitats), not just “game” species– Regulates the “taking” (by any means,

accidental or on purpose), import/export, possession, transport, selling, shipping

– Prohibitions on live organisms, body parts, products made from them

– Violations: fines, prison, confiscation of vehicles & equipment used

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• Types of critters involved– Endangered – in imminent danger of

extinction– Threatened – likely to become endangered

(at least locally) in the near future– Vulnerable – naturally rare or locally

depleted by human activity

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5416

9917

8163

5743

28,500

1,190,200

259,630

Total endangered/threatened: only 1% (so, no big deal, right?)