Chapter 3 Communities, Biomes and Ecosystems 3.1 Community Ecology

Communities All the interacting populations in an ecosystem A biological community is a group of interacting populations that occupy the same area at the same time. Abiotic and biotic factors interact and result in condition that are suitable for life for some organisms and unsuitable for other organisms

Limiting Factors Environmental factors (abiotic or biotic) that restricts existence, numbers, reproduction or distribution of organisms Food, predators, temperature, light…

Limiting Factors Factors that limit one organism may indirectly limit others What happens when the number of grasshoppers is reduced?

Tolerance Ability of an organism to withstand fluctuation in biotic and abiotic factors

Range of Tolerance

Ecological Succession Orderly, natural changes and species replacement that take place in the communities of an ecosystem Primary Succession After volcano or avalanche Start with rock (no soil) Secondary Succession After forest fire or abandoned farmland Start with soil

Primary Succession

Primary Succession Pioneer Species: first species on bare land/rock is lichen or moss Breakdown of rock and decay of moss will build up the soil so other plants can survive Overtime additional habitats develop

Primary Succession Producers are always present before consumer Ends with climax community Stable, mature community which undergoes little or no change in species Can take hundreds of years to develop a climax community starting with rock

Secondary Succession

Secondary Succession Sequence of community changes that take place after a community is disrupted by natural disasters or human actions Occurs in places that previously contained life On land that contains soil, so takes less time than primary succession to reach climax community

Primary or Secondary Succession?

Chapter 3 Communities, Biomes and Ecosystems 3.2 Terrestrial Biomes

Effects of Latitude and Climate Weather is the condition of the atmosphere at a specific place and time. One of the keys to understanding these communities is to be aware of latitude and climatic conditions.

Effects of Latitude and Climate The distance of any point on the surface of Earth north or south from the equator is latitude.

Effects of Latitude and Climate The average weather conditions in an area, including temperature and precipitation, describe the area’s climate. The graph shows how temperature and precipitation influence the communities.

Effects of Latitude and Climate Biomes are classified by their plants, temperature, and precipitation.

Biomes Large group of ecosystems that share the same type of climax community Identified by climax community of plants rather than animals because plants don’t migrate. Plants are a better indicator of long term characteristics of a biome

Major Biomes of the World

Terrestrial Biomes From the North Pole Tundra Taiga Temperate Forest Grassland Desert Tropical Rain Forest Each have characteristic abiotic and biotic factors

Aquatic Ecosystems Temperature and precipitation reflect its associated terrestrial biome Freshwater biomes Lakes, streams, rivers, ponds Marine Biomes Oceans and seas Study by amount of sunlight Specialty biomes: estuary and intertidal zone Intertidal zone

Freshwater Ecosystems Only about 2.5 percent of the water on Earth is freshwater.

Freshwater Ecosystems The characteristics of rivers and streams change during the journey from the source to the mouth.

Freshwater Ecosystems Fast-moving rivers and streams prevent much accumulation of organic materials and sediment. Usually, there are fewer species living in the rapid waters. In slow-moving water, insect larvae are the primary food source for many fish, including American eel, brown bullhead catfish, and trout.

Freshwater Ecosystems The temperature of lakes and ponds varies depending on the season.

Transitional Aquatic Ecosystems Areas of land such as marshes, swamps, and bogs that are saturated with water and that support aquatic plants are called wetlands

Marine Ecosystems The intertidal zone is a narrow band where the ocean meets land. Communities are constantly changing in this environment as a result of disturbance.

Open Ocean Systems The photic zone is shallow enough that sunlight is able to penetrate. Below the photic zone lies the aphotic zone—an area where sunlight is unable to penetrate. The benthic zone is an area along the ocean floor that consists of sand, silt, and dead organisms.