Ecosystems and Communities Chapter 20

The role of Climate  What is climate? –Temperature, precipitation, other environmental factors combine to produce weather and climate.

Greenhouse Effect  This is a natural situation!!  Carbon dioxide, methane, water vapor and other gases trap heat energy and maintain the Earth ’ s temperature range

The Effect of Latitude on climate  How does the position of the sun in the sky effect climate? (see the next slide for the answer) The Earth has three main climate zones: polartemperatetropical

Different latitudes have different angles of heating, affecting climate

Heat Transport in the Biosphere  Unequal heating and cooling drives winds and ocean currents.

What Shapes an Ecosystem?  Key concept: Biotic and abiotic factors determine the survival and growth of and organism and the productivity of the ecosystem in which the organism lives.

 Biotic Factors –All living things in an ecosystem  Abiotic Factors –Temperature, –Precipitation –Humidity –Wind –Nutrient availability –Soil type –Sunlight

The Niche  An organisms occupation in its environment is it ’ s niche.  This includes the following factors –Type of food –How it obtains food –Which other species use the organism as food –Physical conditions.

WARNING WARNING No two species can share the same niche in the same habitat.

Community Interactions  Community interaction, such as competition, predation and various forms of symbiosis can powerfully affect an ecosystem

 Competition –Happen when two organisms try to use the same resource in the same place at the same time –A Resource is: water, nutrients, light food, or space.  Competitive Exclusion Principle –No two species can occupy the same niche in the same habitat at the same time!!!

Predation  An interaction in which one organism captures and feeds on another.

Symbiosis: Living together closely  Mutualism: both species benefit  +/+

Commensalism  One member benefits and the other is neither helped nor harmed  +/0

Parasitism  One organism lives on or inside another organisms and harms it.  +/-

Patterns in Communities  Species richness –The number of species in the community –A simple count of the species in a community  Species evenness –The relative abundance of each species. –How common each species is.

Latitude and species richness  Species richness varies with distance from equator—closer to equator = more species

 Habitat size: greater the area will contain more species than a small area.  Species interactions will affect species richness  Species richness influences how a community responds to a disturbance.

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 occur in a community over time.  Primary succession –Succession that occurs on surfaces where no soil exists.

Primary succession  Occurs on the surfaces formed as volcanic activity builds new islands or covers the land with lava or volcanic ash.  Also occurs on bare rock exposed when glaciers melt.  The first species to populate an area: pioneer species

Secondary Succession  A disturbance of some kind that changes an existing community without removing the soil.  Caused by farming, wildfires  The series of predictable changes ends with a mature, stable community called a climax community

Climax community

Secondary Succession

Biomes  There are at least 10 different biomes.  Each of these biomes is defined by a unique set of abiotic factors and has a characteristic ecological community

What is this biome?

What biome is this?

Name That Biome!!

What biome is this?

Last but not least…

Water, water everywhere…  Aquatic ecosystems are determined primarily by the depth, temperature, flow, and chemistry of the overlying water.

Freshwater ecosystems  Flowing water: rivers and streams  Standing water: lakes and ponds  Wetlands: marshes and swamps  Estuaries: where rivers meet the sea. –Contain a mixture of fresh and salt water –Salt marshes and mangrove swamps are examples.

Marine Ecosystems  Divided into two zones based on the amount of light penetration. –Photic zone: well-lit upper layer down to about 200 meters. Photosynthesis possible. –Aphotic zone: permanently dark. Only producers in this zone are chemoautotrophs.

Marine ecosystems continued.  Scientists also divide the ocean into zones based on the depth and distance from shore. –Intertidal: subject to tides –Coastal ocean: from the low tide mark to the edge of the continental shelf. Contain coral reefs in tropical areas.

Marine ecosystems cont.  Open Ocean: from the continental shelf and extends outward –Largest marine zone –Organisms in the deep open ocean have adapted to great pressure, freezing temperatures and no light Benthic Zone: the ocean floor.