Ecosystems and CommunitiesChapter 4

4–1 The Role of Climate

Objectives• Identify the causes of climate

• Explain how Earth’s temperature is maintained

• Identify Earth’s three main climate zones

Weather

• The day to day condition of earth’s atmosphere at a particular time and place

Climate • The average, year after year

condition of temperature and precipitation in a particular region

• Caused by an interplay of many factors especially incoming sunlight

The Greenhouse Effect• Carbon dioxide, methane, water

vapor, and a few other atmospheric gases trap heat energy and maintain Earth’s temperature range.

• Just as the glass keeps the greenhouse plants warm, so these gases trap the heat energy of sunlight inside Earth’s atmosphere.

Greenhouse effect • The natural situation in which

heat is retained by this layer of greenhouse gases

Greenhouse effect

Infrared Radiation

Sun Rays

Atmosphere Containing Green House Gasses

The Sun

Temp within limits for life

Infrared Radiation

Sun Rays

Atmosphere Containing Extra Green House Gasses

*

The Effect of Latitude on Climate

• Because Earth is a sphere that is tilted on its axis, solar radiation strikes different parts of Earth’s surface at an angle that varies throughout the year.

The Effect of Latitude on Climate

The Effect of Latitude on Climate

• As a result of differences in latitude and thus the angle of heating, Earth has three main climate zones: polar, temperate, and tropical.

The more direct the rays are the ________________ an area of land will heat up.

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4–2 What Shapes an Ecosystem?

Objectives• Explain how biotic and abiotic

factors influence an ecosystem

• Identify the interactions that occur within communities

• Describe how ecosystems recover from a disturbance

biotic• Living factors of an environment

abiotic• The non-living factors of an

environment

Ex.) water, soil, air

• Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives

Habitat• Where an organism lives

Squirrel in tree

Fish in stream

Niche• The role an organism plays in its

environment

• A niche is the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions.

• No two species can share the same niche in the same habitat

Community Interactions• Community interactions, such as

competition, predation, and various forms of symbiosis, can powerfully affect an ecosystem.

Competition• Competition occurs when organisms

of the same or different species attempt to use an ecological resource in the same place at the same time

• Direct competition in nature often results in a winner and a loser—with the losing organism failing to survive

Competitive exclusion principle

• States that no two species can occupy the same niche in the same habitat at the same time

Predation• When one organism captures and

feeds on another organism

• The organism that does the killing and eating is called the Predator, and the food organism is the Prey.

Symbiosis• Any relationship in which two

species live closely together

• Biologists recognize three main classes of symbiotic relationships in nature

Mutualism

• When both members benefit

Ant – Acacia Tree

Commensalism• When one member benefits and

the other is neither helped nor harmed

Clownfish – Sea Anemone

Parasitism• When one member benefits and

the other is harmed

Humans - Tapeworms

Ecological Succession• Ecosystems are constantly changing

in response to natural and human disturbances. As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community.

• The series of predictable changes that occurs in a community over time

Primary Succession

• Succession that occurs on new land where no soil exists

Ex.) volcanic islands, bare exposed rock when glaciers melt

pioneer species

• The first species to populate an area

Ex.) lichen, algae, mosses

Secondary Succession

• When a disturbed area grows back to normal

Ex.) natural disaster areas

4–3 Land Biomes

Objectives• Identify the characteristics of

major land biomes

Biomes • Large geographical areas that

have similar climates and characteristics