Introduction to Environmental Studies

• Ecology

the study of how plants, animals, and microbes interact with each other and with their physical environment

• Environmental Science

the study of how humans impact natural ecosystems

The First Principle of Ecology: everything is connected to

everything else

What are the implications of this principle?

History of Environmentalism

• Thoreau and Emerson

• John Muir

• Gifford Pinchot

• Theodore Roosevelt

• Rachel Carson

• 1960’s

• Earth Day

Most famous for his book, Walden, which details simple

living in Nature

• A. Ralph Waldo Emerson

• B. John Muir

• C. Aldo Leopold

• D. Henry David Thoreau

• E. Gifford Pinchot

In the late 1800’s, he started the Sierra Club, an

environmental organization still going strong today

• A. Ralph Waldo Emerson

• B. John Muir

• C. Aldo Leopold

• D. Henry David Thoreau

• E. Gifford Pinchot

In the book Silent Spring, this author and scientists warned of

the dangers of pesticides• A. Aldo Leopold

• B. Gifford Pinchot

• C. Thoreau

• D. Rachel Carson

• E. Robert Underwood Johnson

Creator of the U.S. Forest Service

• A. Theodore Roosevelt

• B. Franklin Roosevelt

• C. Aldo Leopold

• D. Ronald Reagan

• E. Henry David Thoreau

Changing Worldviews

• Expansionist Worldviewnatural resources are unlimited and for our use

• Ecological Worldviews– Conservationwise use and management of natural resources

today will insure use for future generations– Preservationminimal use of nature – nature should not be

thought of as just here to serve humans – nature deserves to exist for its own sake

Deep Ecology

Sustainable development – a pattern of resource use that aims to meet human needs while preserving the environment so that these needs will always be met in the future

Principles of Ecology

To understand environmental issues and foster sustainable development,

humans should take lessons form how ecosystems function …

Ecosystem – a group of plants, animals, and microbes interacting with each other and the physical environment in a sustainable way

ecosystem size …

• very small … a small pond … your back yard

or very large …

http://www.pbase.com/logios/sahara

http://www.pbase.com/serenab/serengeti

biomes – large terrestrial ecosystems

biosphere – the earth’s “super-ecosystem” … includes all life

forms and the physical environments supporting life

ecotone – transitional region between adjacent ecosystems

Categories of Organisms

(common to every ecosystem)

autotrophs – (producers) “self-feeding” – typically, green plants

heterotrophs – consumers and detritivores and decomposers

types of consumers …

herbivores (primary consumers)

carnivores (secondary or tertiary consumers)

omnivores (primary, secondary or tertiary, depending on the meal)

decomposers (bacteria and fungi)

break down organic material recycling nutrients in the process

detritivores and scavengers –exploit the available energy in recently dead organisms

Feeding Relationships

http://www.alamy.com/search-results.asp?qt=stock%2Bphotos%2Bsa%2Blion&go=1&a=-1&lic=1&lic=6

http://www.pbase.com/captain04/glacier&page=2

food chainsshow the direction of energy flow

between organisms in an ecosystem

food weba more comprehensive model showing all feeding pathways

trophic levels – steps on a food chain

biomass – total mass of biological material (living) – usually refers to specific trophic level

Fig. 3-18, p. 49

Secondaryconsumers

(perch)

10

100

1,000

10,000Usable energy

available ateach tropic level(in kilocalories)

Heat

Heat

Heat

Heat

Heat

Producers(phytoplankton)

Tertiaryconsumers

(human)

Primaryconsumers

(zooplankton)

Pyramid of Energy Flow

Decomposers

biomass pyramid – shows the relative proportions of biomass at each trophic level

• in the most efficient ecosystems, there is only about 10% of food energy available for the next higher trophic level – what happened to the other 90%?

• food chains in most terrestrial ecosystems rarely go higher than four trophic levels

Fig. 9-16, p. 197

DDT in fish-eatingbirds (ospreys)

25 ppm

DDT in largefish (needle fish)2 ppm

DDT in smallfish (minnows)0.5 ppm

DDT in water0.000003 ppm,or 3 ppt

DDT inzooplankton0.04 ppm

Biomagnification of DDT

Toxins in Food Chains

• bioaccumulation: the storing of toxins in an organism over time

• biomagnification: an increase in the concentration of toxins as you move higher in a food chain

Non-feeding Ecological Relationships

symbiosis – a close physical relationship between two different

species

commensalism – one organism benefits while the other is

unaffected

mutualism – beneficial to both organisms

competition

• intraspecific – competition between members of the same species – a major force in Natural Selection

• interspecific – competition for limited resources between different species

Abiotic factors – physical and chemical environmentalconditions that determine the types of plants and animals in an ecosystem … examples?

optimum conditions – for every abiotic factorthere exists a certain level at which a speciesdoes best

limiting factor – an environmental factor thatrestricts the success of a species

range of tolerance – acceptable range of environmental conditions for each species

Lower limitof tolerance

Upper limitof tolerance

TemperatureLow High

Abundance of organismsFew

organismsFew

organismsNo

organismsNo

organisms

Zone ofintoleranceZone of

physiological stress

Zone ofintolerance Zone of

physiological stress

Optimum range

Po

pu

lati

on

Siz

e

Fig. 3-11, p. 43

Range of Tolerance

habitat and niche – the place where organism is found and the role it plays

Ecosystem Sustainability

Energy – life depends on producer’s ability to convert solar energy to chemical energy in the form of organic molecules that consumers can utilize

cellular respiration – the breakdown of glucose to release energy for cell activity

energy flows “one way” through an ecosystem,it can not be recycled

Solarenergy

Chemical energy(photosynthesis)

Chemicalenergy(food)

Mechanicalenergy

(moving,thinking,

living)

Wasteheat

Wasteheat

Wasteheat

Wasteheat

Fig. 2-11, p. 32

Second Law of Thermodynamics

continuity of life depends upon an unending supply of nutrients

CHONPS – the “elements of life”

Nutrient Cycling

carbon cycle

nitrogen cycle

Ecological Succession

Succession- a series of regular predictable changes occurring to an ecosystem after a disturbance

climax community- the end result of succession

characteristics- stable, sustainable

primary succession- begins with soil formation, occurs after major disturbance

secondary succession- more common, faster

Seven Major Terrestrial Biomes

Fig. 5-8, p. 84

Precipitation and Temperature Affects Biome Type

Polar

Subpolar

TropicalChaparral

Grassland

Desert

Desert

Scrubland

SavannaDry

Cold

Tundra

Coniferous forest

Decreasing

Temperate

precipitation

Dec

reas

ing

Deciduousforest

Tropicalseasonal

forest

Wet

Ho

t

Rain forest

tem

pera

ture

• climatographs – a graph showing average precipitation and temperature for a given region

• net primary productivity – the amount of energy available for consumers resulting from photosynthesis

how is NPP related to temperature and precipitation?

Fig. 3-20, p. 50

Swamps and marshes

Tropical rain forest

Temperate forest

Northern coniferous forest

(taiga)

Savanna

Agricultural land

Woodland and shrubland

Temperate grassland

Tundra (arctic and alpine)

Desert scrub

Extreme desert

Aquatic EcosystemsEstuaries

Lakes and streams

Continental shelf

Open ocean

Terrestrial Ecosystems

800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600

Average net primary productivity (kcal/m2/yr)

Net Primary Productivity in Major Life Zones and Ecosystems