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Principles of

Environmental ScienceInquiry and Applications

Third EditionThird Edition

Cunningham • Cunningham

Chapter 5

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

PICK-UP LINES

• DESERT ka ba?

kasi you’re so hot eh!

• GRASSLAND ka ba?

kasi you’re so green eh!

• TUNDRA ka ba?

kasi nag freeze ang time when I’m with you eh!

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Biomes and Biodiversity

Chapter 5

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Outline:

• Terrestrial Biomes• Aquatic Ecosystems• Biodiversity and Species Definitions

Benefits of Biodiversity Threats to Biodiversity

- Human Caused Reductions• Biodiversity Protection

ESA- Recovery Plans- Minimum Viable Populations

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BIOMES

• Biomes - Areas sharing similar climate, topographic and soil conditions, and roughly comparable communities. Temperature and precipitation are among

the most important determinants in biome distribution.

- Evapotranspiration Influenced by prevailing landforms.

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Biomes

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World Biomes

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Deserts

• Characterized by low moisture levels and precipitation that is infrequent and unpredictable from year to year.

• Wide daily and seasonal temperature fluctuations.

• Soils are easily disturbed by human activities, and slow to recover.

• Plants exhibit water conservation characteristics.

Figure 05.04

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Grasslands

• Communities of grasses, seasonal herbaceous flowering plants, and open savannas.

• Few trees due to inadequate rainfall.• Large daily and seasonal temperature

fluctuations.• Frequent grass fires.

Figure 05.05

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Tundra

• Short growing season.• Cold, harsh winters.• Water locked up much of the year.• Most animals migrate south or downhill in

winter.• Low biological productivity, low diversity, and

low resilience.

Figure 05.06

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Conifer Forests

• Cone-bearing trees. Needle-like leaves with waxy coatings.

- Minimize water loss.• Boreal Forests

Northern coniferous forests.• Taiga

Northernmost edge of boreal forest.• Temperate Rainforests

Pacific Northwest

Figure 05.07

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Broad-Leaved Deciduous and Evergreen Forests

• Occur throughout the world where rainfall is plentiful.

• Deciduous trees shed leaves when water is scarce or ground is frozen.

• Rich variation of tree species. Forest canopy covers diverse understory.

Figure 05.09

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Mediterranean

• Hot, dry summers and cool, moist winters.• Dominated with small, leathery, waxy leaves.• Fires common component of landscape.

California - Chaparral Africa - Thorn Scrub

Figure 05.10

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Tropical Moist Forests

• Cloud Forests - High mountains with heavy fog and mist.

• Tropical Rainforests - More than 200 cm annual rainfall with warm-hot temperatures year-round. Rapid decomposition and nutrient cycling. Thin soil cannot support continued cropping,

and cannot resist erosion.

Figure 05.11

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Tropical Seasonal Forests

• Characterized by distinct wet and dry seasons instead of uniform heavy rainfall year-around. Tend toward open woodlands and grassy

savannas.

Figure 05.08

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Freshwater Ecosystems

• Include standing waters of ponds and lakes, as well as flowing waters of rivers and streams.

• Cover relatively little total area, but biologically distinctive.

• Extremely varied due to individual site influences.

Figure 05.12

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Critical Aquatic Characteristics

• Dissolved Substances• Suspended Matter• Depth• Temperature• Flow Rate• Bottom Characteristics• Internal Convective Currents• Connectivity to Other Aquatic Ecosystems

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Vertical Component

• Vertical stratification is an important aspect of many aquatic ecosystems. Organisms tend to form distinctive vertical

sub-communities.- Benthos - Bottom sub-community.

Low oxygen levels- Thermocline - Distinctive temperature

transition zone that separates warm upper layer and deeper cold layer.

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Water Gradients

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Wetlands

• Land surface is saturated or covered with water at least part of the year. Swamps - Wetlands with trees. Marshes - Wetlands without trees. Bogs and Fens - Waterlogged soils that

tend to accumulate peat.• Water usually shallow enough to allow full

sunlight penetration.• Trap and filter water, and store runoff.

Figure 05.18

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Estuaries

• Estuaries - Bays or semi-enclosed bodies of brackish water that form where rivers enter the ocean. Usually carry rich sediments.

- Fan-shaped sediment deposit (delta) formed on shallow continental shelves.

Figure 05.14

Figure 05.16

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Marine Ecosystems

• Marine ecosystems have as much variability as those on land. Food webs and communities off-shore are

intricately connected to those onshore.• Coral Reefs - Accumulated calcareous

skeletons of colonial organisms (coral). Depth limited by light penetration. Among most endangered communities.

Figure 05.13

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BIODIVERSITY

• Biodiversity - Variety of living things. Genetic Diversity - Measures variety of

different versions of same genes. Species Diversity - Measures number of

different kinds of organisms within a community.

Ecological Diversity - Measures richness and complexity of a community.

Table 05.01

Figure 05.19

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How Many Species

• Currently 1.7 million species identified.• Estimates range between 3-50 million.

May be 30 million insect species. Invertebrates make up 70% of all known

species, and probably most of yet to be discovered species.

• Tropical rainforests and coral reefs are biodiversity hotspots. North America and Europe only contain

10-15%.

Figure 05.20

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BENEFITS OF BIODIVERSITY

• Food As many as 80,000 edible wild plant

species could be utilized by humans.• Drugs and Medicines

More than half of all prescriptions contain some natural product.

Pharmaceutical products derived from developing world, plants, animals, and microbes to be more than $30 billion/year.

Figure 05.21

Table 05.02

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BENEFITS OF BIODIVERSITY CONT’D

• Ecological Benefits Soil formation, waste disposal, air and

water purification, nutrient cycling, solar energy absorption, and food production and hydrological cycles all depend on biodiversity.

- At least $33 Trillion annual benefit. Can a system function without all its

integral parts?

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BENEFITS OF BIODIVERSITY CONT’D

• Aesthetic and Cultural Benefits Cultural diversity inextricably linked to

biodiversity. USFWS estimates Americans spend $104

billion annually on wildlife-related recreation.

Ecotourism can be an important form of sustainable economic development.

Existence (intrinsic) value.

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THREATS TO BIODIVERSITY

• Extinction - Elimination of a species. Normal Process

- In undisturbed ecosystems, background rate appears to be one species per decade.

In this century, human impacts have accelerated that rate, causing perhaps hundreds to thousands of extinctions annually.

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Natural Causes of Extinction

• Fossil record suggests more than 99% of all species ever in existence are now extinct. Most went extinct before humans arrived.

- End of Cretaceous period - Dinosaurs and 50% of existing genera disappeared.

- Permian period - Two-thirds of all marine species and nearly half of all plant and animal families died out.

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Human-Caused Reductions in Biodiversity

• Habitat Destruction Biggest reason for current increase in

extinction is habitat loss.- Habitat fragmentation divides

populations into isolated groups vulnerable to catastrophic events.

Island Biogeography Species diversity is a balance

between colonization and extinction.

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Habitat Fragmentation - Cadiz Township, WI

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Human-Caused Reductions in Biodiversity Cont’d

• Hunting and Fishing Overharvesting of game species.

- American Passenger Pigeon- American Bison- Whales- Atlantic Cod

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Human-Caused Reductions in Biodiversity Cont’d

• Commercial Products and Live Specimens Wildlife smuggling is very profitable.

- 50 deaths for every live arrival at market. U.S. Annual pet trade in wild species:

2 million reptiles 1 million amphibians and mammals 500,000 birds 128 million tropical fish - often

caught with cyanide above coral reefs.

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Endangered Species Parts

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Predator and Pest Control

• Many animal populations have been greatly reduced or exterminated because they are regarded as dangerous to humans or livestock. Animal control costs $20 million in federal

and state funds annually.- 700,000 birds and mammals annually.

100,000 coyotes

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Predator and Pest Control Cont’d

• Exotic Species Introductions Exotic organisms - Organisms introduced

into habitats where they are not native.- Biological Pollution

Kudzu Vine Leafy Spurge Purple Loosestrife Zebra Mussels Asian Long-Horned Beetles

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Predator and Pest Control Cont’d

• Diseases When a disease is introduced into a new

environment, natural balance may be tipped, leading to an epidemic.

- Chestnut Blight, Whirling Disease• Pollution

Toxic Pollutants- Pesticides, Lead , DDT

• Genetic Assimilation

Figure 05.29

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BIODIVERSITY PROTECTION

• Hunting and Fishing Laws By 1890’s, most states had enacted some

hunting and fishing laws.- General idea was pragmatic, not

aesthetic or moral preservation. White-tailed deer Wild turkeys Wood ducks

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Endangered Species Act

• Established in 1973. Endangered are those considered in

imminent danger of extinction. Threatened are those likely to become

endangered, at least locally, in the near future.

- Vulnerable are those that are naturally rare or have been locally depleted to a level that puts them at risk.

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Endangered Species Act Cont’d

• ESA regulates a wide range of activities involving Endangered Species: Taking (harassing, harming, pursuing,

hunting, shooting, killing, capturing, or collecting) either accidentally, or on purpose.

Selling Importing into or Exporting out of the U.S. Possessing Transporting or Shipping

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Endangered Species Act Cont’d

• Currently, the U.S. has 1,300 species on its endangered and threatened lists, and 250 candidate species waiting for consideration. Number reflects more about human

interests than actual status.- Invertebrates make up 75% of all

species, but only 9% worthy of protection.

Listing process is extremely slow.

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Recovery Plans

• Once a species is listed, USFWS is required to propose a recovery plan detailing the rebuilding of the species to sustainable levels. Total cost of all current plans = $5 billion.

• Opponents have continually tried to require economic costs and benefits be incorporated into planning.

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Minimum Viable Populations

• Minimum Viable Population is the minimum population size required for long-term viability of a species.

Table 05.03

Figure 05.24

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Minimum Viable Populations Cont’d

• Diversity Loss in Small Populations: Founder Effect

- Few individuals start a new population. Demographic Bottleneck

- Few individuals survive catastrophe. Genetic Drift

- Random reduction in gene frequency. Inbreeding

- Mating between related individuals.

Figure 05.25

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Private Land and Critical Habitat

• Private land is essential in endangered species protection. Eighty percent of habitat for more than half

of all listed species is on nonpublic property.

• Habitat Conservation Plans (HCP) Landowners are allowed to harvest

resources or build on part of their land as long as the species benefits overall.

Figure 05.26

Figure 05.27

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Reauthorizing ESA

• ESA officially expired in 1992. Proposals for new ESA generally fall into

two general categories:- Versions that encourage ecosystem and

habitat protection rather than individual species.

- Safe Harbor policies that allow exceptions to critical habitat designations.

(Economic Considerations)

Figure 05.30

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International Wildlife Treaties

• Convention on International Trade In Endangered Species (CITES) - 1975. Regulated trade in living specimens and

products derived from listed species.

Table 05.04

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Summary:

• Terrestrial Biomes• Aquatic Ecosystems• Biodiversity and Species Definitions

Benefits of Biodiversity Threats to Biodiversity

- Human Caused Reductions• Biodiversity Protection

ESA- Recovery Plans- Minimum Viable Populations

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