Bellringer Jot down some of the factors that could influence the number of organisms in an area. Try to get at least 5.

Chapter 3: Communities and Biomes

Community A group of interacting populations that live in the same place at the same time.

Limiting Factors Any biotic or abiotic factor that limits the number of organisms in a given area. Sunlight Climate Atmospheric gases (Carbon Dioxide, oxygen, nitrogen, etc.) Temperature Water Availability of food Fire Soil chemistry Space Other organisms

How do limiting factors influence communities? Drought Plants need water Herbivores need plants Carnivores need herbivores Other carnivores need carnivores and herbivores Decomposers need all of the above These factors may influence an individual, a population, and all the way up to a community

Ranges of Tolerance Tolerance=an organism’s ability to withstand changes in environmental conditions.

Succession Orderly, natural changes and species replacements that take place in the communities of an ecosystem. Occurs in stages and is gradual. First, some species move in. These species change conditions so that they are suitable for other species. This in turn brings further species in. What will The Cities look like after humans?

Primary Succession The colonization of barren land by communities of organisms Example: After a Volcano eruption, plants begin to grow on the barren land

Pioneer species 1st to move in during Primary Succession Example: Lichens (bacteria and fungus) As these pioneer species die, they decompose and build a layer of soil From this layer of soil, plants can grow. These also contribute to soil. Seeds blown in the wind grow, and bring in the heterotrophs that eat them.

Climax community A stable, mature community that undergoes little change in species. After some time of primary succession, the ecosystem stabilizes and change stops happening as much. The area has become a climax community. May last hundreds of years. Change still happens, just not as drastic.

Secondary Succession Series of changes that takes place after an existing community is severely disrupted. Fire, hurricane, humans Soil already exists, and other organisms can move in more quickly. If Primary succession is an empty house for sale, secondary succession would be a furnished house that is move-in ready. Takes much less time to reach climax community. See “An example of secondary succession” on pg. 69 for a real-life example.

Biomes Large group of ecosystems that share the same type of climax community. Not necessarily identical, but very similar. 2 Types: Aquatic and Terrestrial These are then broken down into smaller biomes

Aquatic Biomes Most of the Earth (Earth > 75% water) Broken into 2 Biomes Marine and Freshwater

Marine Biomes These are the oceans and other saltwater bodies Oceans contain a huge amount of the Earth’s biomass Ecologists often separate the bodies into zones based on amount of light that gets to a certain depth

Photic and Aphotic Zones Photic Zone=Shallow water that light penetrates Aphotic Zone=Deep water that no light passes through.

Estuaries Coastal body of water where fresh water and salt water mix

Freshwater Biomes Lakes. Ponds, rivers, ,etc Limiting factors: Temperature of water (warmer near surface, colder near bottom) Amount of light (more near surface, less below) Where would we find the greatest biodiversity?

Other Aquatic Biomes Wetlands-where water meets land Swamps-have trees Marshes-Do not have trees Bogs-water comes from rain, but does not flow.

Terrestrial Biomes Latitude and Climate

By the way, what causes the seasons?

Biome Characteristics Main 2 that we look at are Temperature and Rainfall

Tundra

Tundra Characteristics