1. Notes 4-1 What Is an Ecosystem?

2. An ecosystem includes a community of organisms and their physical environment.

3.  Community- a group of various species that live in the same habitat and interact with each other.  A web of relationships including predator-prey, parasitism, mutualism, etc.  Relationships between organisms are examples of biotic (living) factors that affect an ecosystem.  Ecosystem- a community of organisms and their abiotic (non-living) environment.

5.  The physical or nonliving factors of an environment are called abiotic factors (oxygen, water, rocks, sunlight, temperature).  Habitat- the place where an organism usually lives.

6.  The variety of organisms in a given area, the genetic variation within a population, the variety of species in a community, or the variety of communities in an ecosystem.  Physical factors can have a big influence on biodiversity.  High rainfall and warm temperatures  Low rainfall  Extremely low temperatures  When ecosystems have high biodiversity they are often better able to resist damage due to severe weather or human activities.  Systems with low biodiversity can be severely damaged easily.

7. The replacement of one type of community by another at a single location over a period of time.

14.  When a volcano forms a new island or a fire burns the vegetation of an area, new opportunities are made for organisms.  Pioneer species- the first organisms to appear in a newly made habitat; often make it possible for other species to live there.

15.  If a major disruption strikes a community, many of the organisms may be wiped out.  An ecosystem responds to change in such a way that the ecosystem is restored to equilibrium.

16. Two key factors of climate that determine biomes are temperature and precipitation.

17.  The average weather conditions in an area over a long period of time.  Temperature- most organisms are adapted to live within a particular range of temperatures and cannot survive at temperatures too far out of the range.  Precipitation- in biomes where precipitation is low, the vegetation is made up mostly of plants that need little water.  Biome- a large region characterized by a specific type of climate and certain types of plant and animal communities.

19. Earth’s major terrestrial biomes can be grouped by latitude into tropical, temperate, and high-latitude biomes.

20.  Because they are located at low latitudes near the equator, all are warm.  Rainfall determines different types:  Tropical rain forests- receive large amounts of rain and are warm all year.  Savannas- get less rain and have long dry seasons and shorter wet seasons.  Tropical deserts- get very little rain.

24.  Located at mid-latitudes, so have a wide range of temperatures throughout the year.  Types:  Temperate grasslands- have moderate precipitation and cooler temperatures than savannas; good for agriculture.  Temperate forests- grow in mild climates that receive plenty of rain; can have deciduous or evergreen trees.  Temperate deserts- receive little precipitation and have a wide range of temperatures throughout the year.

28.  Have very cold temperatures.  Types:  Taiga- coniferous forests in cold wet climates; winters are long and cold.  Tundra- gets very little rain, so plants are short; most water is unavailable to plants because it remains frozen in the soil most of the year.

31. Aquatic ecosystems are organized into freshwater ecosystems, wetlands, estuaries, and marine ecosystems.

32.  Located in bodies of fresh water, such as lakes, ponds, and rivers.  Have a variety of plants, fish, arthropods, mollusks, and other invertebrates.

35.  Provide a link between the land and fully aquatic habitats.  Water-loving plants dominate.  Support many species of birds, fishes, and plants.  Important because they moderate flooding and clean the water that flows through them.

38.  An area where fresh water from a river mixes with salt water from an ocean.  Productive ecosystems because they constantly receive fresh nutrients from the river and the ocean.

39.  Found in the salty waters of the oceans.  Kelp, seagrass, and coral reefs are found near land.  The open ocean has plankton and large predators, such as dolphins, whales, and sharks.