RESPONSE TO CHANGEWhat happens to an ecosystem when it is disturbed?

Ecosystem Changes

Ecological change is referred to as Succession the regular pattern of changes over time

in the types of species in a community

Interactions among living things results in these changes

First organisms to arrive, usually small plants, are called pioneers

The end result of these changes, if left undisturbed, is the climax community

What types of animals would you expect to inhabit each stage?

Animals in succession

As succession occurs, the animals correspond to the plants that are present

Small animals (insects, things that live in soil, small rodents) that eat the pioneer species appear first

Then larger animals that eat the smaller animals and/or the next plant species appear

This continues until you have the climax group of animals as well as plants

Types of Succession

Two types depending on how it starts:

Primary Succession – new land is created and succession begins Takes much longer (no soil!) Example: volcanic eruption creates

land; bare rock exposed from melted glacier

weathering plays a major role in creating soil

After Mount St. Helens erupted on May 18, 1980, the story most people heard was about violence and devastation. One of the greatest natural disasters of our time, the eruption killed 57 people, sheared 1,300 feet off the summit of the mountain, and turned a pristine forested landscape into a barren, lifeless wasteland.

Photo

credit: ©

Joel E

. Harv

ey

Its eruption in 1980 destroyed large areas of forest. In 1988 J. Alean documented the starting re-colonization of the terrain by plants, and in 2001 the photos were repeated.

Photos taken by Mrs.

McCurdy 1998

Photos taken by Ms.

McClure 2006

Types of Succession Secondary Succession – changes

occur on land where an existing ecosystem has been destroyed Happens faster Examples: Forest Fire, abandoned farm

fields, land left alone for many years

Succession in aquatic ecosystems called eutrophication the gradual change of an aquatic ecosystem

into a terrestrial (land) ecosystem as organisms die in the aquatic ecosystem,

they fall to the bottom and gradually fill in the pond/lake/river basin

different species of plants (like cattails or cottonwood trees) will start to grow on the edges, continuing the process

Eutrophication

humans GREATLY speed up this process by polluting the water ways with nitrogen and phosphorus found in many common products like

fertilizer, laundry detergent these elements cause increased plant

growth and more rapid animal death also speeds up with increased

temperatures

Three Categories of Human-Induced Environmental Problems

#1 Resource Depletion Natural resources become depleted

when a large part of it has been used up. Natural Resources can be either: Renewable - they are constantly being

replaced trees, water, crops, sun

Nonrenewable - they cannot be replaced (or replenish too slowly) animal and plant species, fossil fuels, minerals

Results of Resource Depletion

Deforestation: cutting large areas of trees for use in building products, fuel, etc. or to use the land for other purposes.

Desertification: destructive use of land results in the formation of desert conditions

Sustainable use can prevent both of these

Human-induced environmental problems

#2 Pollution Pollution is the introduction of harmful

levels of chemicals or waste material into the environment Pollution may be harmful to human health Pollution can occur in air, soil, or water Pollution can take the form of liquid, solid,

gas, or even energy

Results of Pollution

Acid Precipitation – rain/snow/ice that has a pH less than 7. Results from sulfur oxides and nitrogen

oxides in the atmosphere mixing with the water in the atmosphere to form sulfuric and nitric acid.

Dangerous to living things – pH in environment may become intolerable

Destructive to environment – acid dissolves certain types of stone

Results of pollution

Biomagnification – process by which a chemical moves through the food chain, becoming more concentrated. May be harmful/lethal

to organisms at the top of the food chain, reducing biodiversity.

Biomagnification video - MUST SEE

Human-induced environmental problems

#3 Extinction Extinction means the last individual

of a species has died and the species is gone forever Thousands of species are becoming

extinct each year Endangered species are those whose

extinction is very close, and will happen without some sort of intervention

A sustainable world In a sustainable world, human

populations can continue to exist with a high standard of living and health because Biodiversity is preserved Habitats are preserved Nonrenewable resource are used

sparingly and efficiently Renewable resources are used no faster

than they can be replaced There are enough resources for the next

generation

Biodiversity is preserved Biodiversity – all of the different forms of

life All living things are connected, and therefore

depend upon each other for survival.

Three Levels: Species diversity – all of the different species

in an area Genetic diversity – all of the different genetic

combinations in a particular species Ecosystem diversity – all of the different

biological, geological, chemical factors in an area

Habitats are preserved

Destruction of appropriate habitat can lead to extinction Habitat fragmentation – some living

things require large areas of land. Habitat can be come “fragmented” when human development separates areas.

Invasive species– occurs when a species is introduced to a habitat in which it is not naturally found. If there is no predator for that species, it

may increase in number at the expense of native species, who will now have to compete for resources

Invasive species

Global Changes occur when ecosystem is disrupted over long periods of time

1. Ozone Depletion – reduction in the thickness of the ozone layer

Ozone (O3) – located in the stratosphere, filters UVB light before it reaches the earth

Ozone is broken down into oxygen gas (O2) by CFC’s (chlorofluorocarbons)

Why does this matter? UVB has been linked to skin cancer,

cataracts, damage to materials like plastics, and harm to certain crops and marine organisms. Reduction in ozone means an increase in UVB!

Ozone “hole” September 2009

Global Changes (Continued)2. Global Warming: increase in the

average temperature of the Earth Dependent on the greenhouse effect –

the Earth is warmed because the gases in the atmosphere trap heat Greenhouse gases:

Carbon dioxide Methane Surface Ozone CFC’s Nitrous oxides

Temperature and Carbon Dioxide

In historical data, temperature and carbon dioxide levels have been closely connected

Greenhouse Effect

Results of Increased Global Temperatures Sea level rise

Loss of habitable land Coral bleaching Shoreline erosion

Changes in agriculture May be positive or negative Appropriate growing climate may shift

Changes in water resources Areas of drought/flooding as weather

patterns change

IF nonrenewable resource are used sparingly and efficiently

AND renewable resources are used no faster than they can be replaced

There will be enough resources for the next generation

Sustainable Use of Natural Resources: More efficient technology to produce

electricity Increase use of alternative energy

sources Increase fuel efficiency in automobiles Conservation: the act of reducing the

amount of resources one consumes. 3 R’s – reduce, reuse, recycle