The Layout Of Life

(from

BIG

to small )

Biosphere

(planet earth: water, land and sky)

Biomes

( Tundra, Taiga, Dessert , Ocean, Lake )

Ecosystem

( all of the plants and animals in a community that live together in a particular biome )

Biomes of the World

• • • A

biome

is a large biogeographical unit of the biosphere that has a particular mix of plants and animals that are adapted to living under certain environmental conditions.

Terrestrial

: Tundra, Taiga, Coniferous and Deciduous Forests, Temperate Rain Forests, Grasslands, Shrublands (Chaparrel), Desert,

Aquatic

: Freshwater (lakes), Saltwater (Ocean), Estuaries (salt and fresh combined)

• Ecology is the study of these ecosystems!

• Ecology is not just about plants, animals and their environmets…… ………………..it’s also about the humans!

(our lives tend to affect all other lives

disproportionately

!)

Population Growth and Density

(one is dependent on the other) • When the population reaches

carrying capacity

, the population stops growing because environmental resistance opposes biotic potential.

• If the population does not stop growing, it will demolish its resources, thereby killing itself.

Human Population Growth

• The human population is expanding

exponentially

– it is not known how much longer the earth will be able to support our population at the current rate of exhausting natural resources -- but it doesn’t look good. 

Chapter 34: Ecosystems and Human Interferences

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

The Nature of Ecosystems

• An

ecosystem

contains components and

abiotic biotic

(living) (nonliving) components. • The biotic components of ecosystems are the populations of organisms.

• The abiotic components include inorganic nutrients, water, temperature, and prevailing wind.

Biotic Components of an Ecosystem

• •

Autotrophs

are

producers

that produce food for themselves and for consumers. • Most are photosynthetic organisms but some chemosynthetic bacteria are autotrophs.

Heterotrophs

are preformed food.

consumers

that take in

Biotic components

• • • • • • Consumers may be:

Herbivores

– animals that eat plants,

Carnivores

animals, – animals that eat other

Omnivores

, such as humans, that eat plants and animals, or

Decomposers

, bacteria and fungi, that break down dead organic waste.

Detritus

is partially decomposed organic matter in the soil and water; beetles, earthworms, and termites are

detritus feeders

.

Consumers

Energy Flow and Chemical Cycling

• Every ecosystem is characterized by two phenomena:

1) Energy flows

in one direction from the sun to producers through several levels of consumers, and

2) Chemicals cycle

when inorganic nutrients pass from producers through consumers and returned to the atmosphere or soil.

Nature of an ecosystem

• Only a small portion of energy and nutrients made by autotrophs is passed on to heterotrophs, and only a small amount is passed to each succeeding consumer; much energy is used at each level for cellular respiration and much is lost as heat.

• Ecosystems are dependent on a continual supply of solar energy.

• The laws of thermodynamics support the concept that energy flows through an ecosystem.

Energy balances

Energy Flow

• The feeding relationships in an ecosystem are interconnected in a

food web

.

• Generally, the upper portion of a food web is a

grazing food web

, based on living plants, and the lower portion is a

detrital food web

, based on detritus and the organisms of decay.

Forest food webs

Trophic Levels

• A

trophic level

is all the organisms that feed at a particular link in a food chain . • A diagram that link organisms together by who eats whom is called a

food chain

.

• A grazing food chain: • Leaves → caterpillars → tree birds → hawks • A detrital food chain: • Dead organic matter → soil microbes → worms

Food chain

Ecological Pyramids

• The shortness of food chains can be attributed to the loss of energy between trophic levels.

• Generally, only about 10% of the energy in one trophic level is available to the next trophic level.

• This relationship explains why so few carnivores can be supported in a food web.

• The flow of energy with large losses between successive trophic levels can be depicted as an

ecological pyramid

that shows trophic levels stacked one on the other like building blocks. • Usually a pyramid shows that biomass and energy content decrease from one trophic level to the next, but an inverted pyramid occurs where the algae grow rapidly and are consumed by long-lived aquatic animals.

Ecological pyramid

Global Biogeochemical Cycles

• All organisms require a variety of organic and inorganic nutrients.

• Since pathways by which chemicals cycle through ecosystems involve both biotic and abiotic components, they are known as

biogeochemical cycles

.

• Biogeochemical cycles often contain

reservoirs

, such as fossil fuels, sediments, and rocks that contain elements available on a limited basis to living things.

•

Exchange pools

are components of ecosystems like the atmosphere, soil, and water —which are ready sources of nutrients for the biotic community that uses the chemicals. • Nutrients cycle among the members of the biotic component of an ecosystem and may never enter an exchange pool. • Nutrients flow between terrestrial and aquatic ecosystems.

Model for chemical cycling

The Water Cycle

• In the

water

, or

hydrologic cycle

, the sun’s rays cause fresh water to evaporate from the oceans, leaving the salts behind. • Vaporized fresh water rises into the atmosphere, cools, and falls as rain over oceans and land.

• Precipitation, as rain and snow, over land results in bodies of fresh water plus groundwater, including

aquifers

.

• Water is held in lakes, ponds, streams, and groundwater. • Evaporation from terrestrial ecosystems includes transpiration from plants.

• Eventually all water returns to the oceans.

• Groundwater “mining” in the arid West and southern Florida is removing water faster than underground sources can be recharged.

The water cycle

The Carbon Cycle

• • In the

carbon cycle

, a gaseous cycle, organisms exchange carbon dioxide with the atmosphere. • Shells in ocean sediments, organic compounds in living and dead organisms, and fossil fuels are all reservoirs for carbon.

Fossil fuels

were formed during the Carboniferous period, 286 to 360 million years ago.

The carbon cycle

Carbon Dioxide and Global Warming

• The

transfer rate

, the amount of a nutrient that moves from one compartment of the environment to another, can be altered by human activities, allowing more carbon dioxide to be added to the atmosphere. • Atmospheric carbon dioxide has risen from 280 ppm to 350 ppm due to burning of fossil fuels and forests. • Besides CO 2 , nitrous oxide and methane are also

greenhouse gases

.

• Similar to the panes of a greenhouse, these gases allow the sun’s rays to pass through but hinder the escape of infrared (heat) wavelengths. • Buildup of more of these “

greenhouse gases

” could lead to more

global warming

. • The effects of global warming could include a rise in sea level, affecting coastal cities, and a change in global climate patterns with disastrous effects.

Earth’s radiation balances

The Nitrogen Cycle

• Nitrogen makes up 78% of the atmosphere but plants are unable to make use of this nitrogen gas and need a supply of

ammonium

or

nitrate

. • The

nitrogen cycle,

a gaseous cycle, is dependent upon a number of bacteria. • During

nitrogen fixation

, nitrogen-fixing bacteria living in nodules on the roots of legumes convert atmospheric nitrogen to nitrogen-containing organic compounds available to a host plant.

•

Cyanobacteria

in aquatic ecosystems and

free-living bacteria

nitrogen gas. in the soil also fix • Bacteria in soil carry out

nitrification

when they convert ammonium to nitrate in a two step process: first,

nitrite-producing bacteria

convert ammonium to nitrite and then

nitrate-producing bacteria

nitrate. convert nitrite to • During

denitrification

,

denitrifying bacteria

in soil convert nitrate back to nitrogen gas but this does not quite balance nitrogen fixation.

The nitrogen cycle

Nitrogen and Air Pollution

• Human activities convert atmospheric nitrogen to

fertilizer

which when broken down by soil bacteria adds nitrogen oxides to the atmosphere at three times the normal rate. • Humans also burn fossil fuels which put nitrogen oxides (NOx) and sulfur dioxide (SO 2 ) in the atmosphere.

•

Nitrogen oxides

and

sulfur dioxide

with water vapor to form acids that contribute to

acid deposition

. react • Acid deposition is killing lakes and forests and also corrodes marble, metal, and stonework. • Nitrogen oxides and hydrocarbons (HC) react to form

photochemical smog

, which contains

ozone

and

PAN

(

peroxyacetylnitrate

), oxidants harmful to animal and plant life.

Acid deposition

• A

thermal inversion

, where these pollutants are trapped under warm, stagnant air concentrates pollutants to dangerous levels. • Nitrous oxide is not only a greenhouse gas, but contributes to the breakdown of the ozone shield that protects surface life from harmful levels of solar radiation.

Thermal inversion

The Phosphorus Cycle

• The

phosphorus cycle

is a

sedimentary cycle

. • Only limited quantities are made available to plants by the weathering of sedimentary rocks; phosphorus is a limiting inorganic nutrient.

• The biotic community recycles phosphorus back to the producers, temporarily incorporating it into ATP, nucleotides, teeth, bone and shells, and then returning it to the ecosystem via decomposition.

The phosphorus cycle

Phosphorus and Water Pollution

• Phosphates are mined for fertilizer production; when phosphates and nitrates enter lakes and ponds,

eutrophication

occurs.

• Many kinds of wastes enter rivers which flow to the oceans; oceans are now degraded from added pollutants. • If pollutants are not decomposed, they may increase in concentration as they pass up the food chain, a process called

biological magnification

.

Chapter Summary

• An ecosystem includes autotrophs that make their own food and heterotrophs that take in preformed food.

• Solar energy enters biotic communities via photosynthesis, and as organic molecule pass from one organism to another, heat is returned to the atmosphere.

• Chemicals cycle within and between ecosystems in global biogeochemical cycles.

• Biogeochemical cycles are gaseous (carbon cycle, nitrogen cycle) or sedimentary (phosphorus cycle).

• The addition of carbon dioxide (and other gases) to the atmosphere is associated with global warming.

• The production of fertilizers from nitrogen gas is associated with acid deposition, photochemical smog, and temperature inversions.

• Fertilizer also contains mined phosphate; fertilizer runoff is associated with water pollution.

• Certain pollutants undergo biological magnification as they pass through the food chain.

Chapter 36: Conservation of Biodiversity

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

Conservation Biology and Biodiversity

•

Conservation biology

studies all aspects of biodiversity with the goal of conserving natural resources.

• A primary

goal

of conservation biology is the management of biodiversity for

sustainable use

by humans.

• Conservation biology supports these ethical principles: 1. Biodiversity is desirable for all living things.

2. Extinctions, due to human actions, are undesirable.

3. Complex interactions in ecosystems support biodiversity.

4. Biodiversity resulting from evolutionary change has value in and of itself.

Biodiversity

•

Biodiversity

is the variety of life on earth.

• There are between 5 to 15 million species in existence.

• Important aspects of biodiversity are: •

Genetic diversity

• •

Community diversity Landscape diversity

Number of described species

Distribution of Diversity

• Biodiversity is not evenly distributed across the biosphere.

•

Biodiversity hotspots

contain large concentrations of species but may cover only small portions of the earth.

• Rain forest canopies and the deep-sea benthos are so diverse they are considered

biodiversity frontiers

.

Value of Biodiversity

•

• Biodiversity is a resource of immense value.

Direct values

include:

•

Medicinal value

•

Agricultural value

•

Consumptive use value

Medicinal Value

• Most of the

prescription drugs

used in the U.S. were derived from living things.

• For example, many lives have been saved from cancer with medicine made from the tropical plant, rosy periwinkle.

• It is likely that an additional 328 types of drugs will be found in tropical rain forests, with a value to society of $147 billion.

Agricultural Value

• Certain wild plants serve as a

source of genetic variation

for related crop species.

• Biodiversity can also provide

biological pest controls

that reduce the need for chemical pesticides.

• Wild bees are resistant to mites that have wiped out the honeybee population that pollinates many important crops.

Consumptive Use Value

• Much of the

freshwater and marine harvest

of organisms used for food depends on natural ecosystems rather than aquaculture.

• •

Wild fruits and vegetables

, fibers, beeswax, and seaweed are important economically.

• Wood, rubber, and latex are

tree products

economic importance.

Sustained production

destruction, will ensure that these products are available indefinitely.

of great , rather than ecosystem

Indirect Value of Biodiversity

• Indirect value of biodiversity includes: •

Biogeochemical cycles (simply: LIFE!)

•

Waste disposal

•

Provision of fresh water

•

Prevention of soil erosion

•

Regulation of climate

•

Ecotourism

Biodiversity and Natural Ecosystems

• Scientific studies have shown that ecosystem performance improves with

increasing species richness

.

• Rates of photosynthesis also increases as diversity increases.

• It remains to be determined whether more diverse ecosystems are better able to withstand environmental change.

!!! WARNING !!!

• Between 10-20% of living species will go

extinct

in 20 to 50 years unless immediate steps are taken to protect them.

• It is important to understand the: •

Concept of biodiversity

•

Value of biodiversity

•

Causes of present-day extinctions

•

How to prevent extinctions from occurring

Causes of Extinction

• Causes of extinction include: •

Habitat loss

•

Alien species

•

Pollution

•

Overexploitation

• Most threatened and endangered species are imperiled for more than one reason.

Habitat Loss

•

Habitat loss

has occurred in all ecosystems.

• Habitat loss in tropical rain forests and coral reefs is of great concern because of the great diversity of species living in these ecosystems.

• Loss of habitat also affects freshwater and marine biodiversity.

Habitat loss

Road construction in Brazil

Alien Species

•

Alien species

(exotics) are nonnative species that migrate into new ecosystems or are

introduced

there by humans.

• Introduction of alien species by humans has been due to: •

Human colonization of new areas

•

Horticulture and agriculture

•

Accidental transport

• Alien species disrupt food webs.

Exotics on Islands

• Because islands have unique assemblages of native species that are closely adapted to one another, introduction of exotic species is especially disruptive.

• Examples: •

Myrtle trees in Hawaii

•

Brown tree snake in Guam

•

Black rats in the Galapagos Islands

Alien species

Pollution

•

Pollution

is any environmental change that adversely affects the lives and health of living things. • Categories include: •

Acid deposition

•

Eutrophication

•

Ozone depletion

•

Organic chemicals

•

Global warming

Global warming

Overexploitation

•

Overexploitation

occurs when too many individuals are taken and population size is severely reduced.

• Overexploitation occurs in: •

Decorative plants

•

Exotic aquarium fish

•

Colorful parakeets and macaws

•

Oceanic fishing areas

Trawling

Conservation Techniques

• To preserve species, it is necessary to preserve their habitat.

• Preserving

biodiversity hotspots

will help save greater numbers of species.

• The preservation of a

keystone species

can preserve biodiversity in a habitat.

• Saving

metapopulations

, including the

source population

and

sink population

, is important in species preservation.

Habitat preservation

Landscape Dynamics

• A

landscape

encompasses different types of ecosystems.

• Landscape protection for one species often benefits other wildlife sharing the same space.

• When preserving landscapes, the

edge effect

must be considered because it can have a serious impact on population size.

Edge effect

Computer Analyses

•

Gap analysis

uses the computer to find gaps in preservation, places where biodiversity is high outside of preserved areas.

• A

population viability analysis

helps researchers determine the amount of habitat a species requires to maintain itself.

Habitat Restoration

•

Restoration ecology

is a subdiscipline of conservation biology that seeks scientific ways to return ecosystems to their former state.

• A restoration plan has been developed for the Everglades that will sustain the Everglades ecosystem while maintaining flood control.

Restoration of the Everglades

• Three principles of restoration ecology have emerged: 1. It is best to begin as soon as possible before remaining fragments of habitat are lost.

2. It is best to use biological techniques that mimic natural processes to bring about restoration.

3. The goal is sustainable development, the ability of the ecosystem to maintain itself while serving human beings.

Chapter Summary

• Conservation biology is the scientific study of biodiversity and its management for sustainability.

• Biodiversity must be preserved as genetic, community, and landscape diversity.

• Biodiversity has direct and indirect values.

• Researchers have identified the major causes of extinction, including habitat loss, alien species introduction, pollution, and overexploitation.

• To preserve species, habitat must be preserved.

• Sometimes habitat must be restored before sustainable development is possible.