Communities and Biomes

Communities ► In communities there are various combinations of abiotic and biotic factors that result in conditions that are suitable for supporting certain forms of life but not others. ► Limiting Factors- are any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms. Pg. 66

Ranges of Tolerance ► Tolerance- The ability of an organism to withstand fluctuations in biotic and abiotic environmental factors.  The limits of an organism’s tolerance are reached when the organism receives too much or too little of some environmental factor. ► Populations respond by becoming smaller as conditions move toward either extreme.

Succession ► Primary Succession- The colonization of barren land by communities. It takes place on land where there are no living organisms. (Ex. Creating a community after a volcano erupts)  Climax Community- A stable mature community that undergoes little or no change. It may last for hundreds of years. ► Stability doesn't mean that it doesn't change at all. For example the numbers in a species might go up or down.

► Secondary Succession- is the sequence of changes that takes place after an existing community is severely disrupted in some way. (ex. The rebuilding of a community after a forest fire)  It takes place in areas that previously contained life and on land that still contains soil. ► Because soil already exist it may take less time for a secondary succession to reach a climax community.

Biomes ► Biome- a large group of ecosystems that share the same type of climax community.  These communities are adapted to the same types of conditions in their biome.

Aquatic Biomes ► Marine Biome- biome that is located in the ocean.  Photic zone- is the portion of the marine biome that is shallow enough for sunlight to penetrate. They are usually located around the coast lines. (Ex. Bays, rocky shores, sandy beaches, estuaries, and coral reefs)  Aphotic Zone- Is the deeper water that never receives sunlight and it is the least explored area of the ocean.

Estuaries – Mixed Waters ► Estuary- is a coastal body of water, partially surrounded by land, in which freshwater and salt water mix.  The salinity, or the amount of salt, in an estuary ranges between that of sea water and freshwater and depends on how much freshwater the river brings into the estuary. ► Plankton- are small organisms that drift and float in the waters of the photic zone. They are important because they form the base of all aquatic food chains.

Freshwater Biomes ► The shallow water around the shore line supports most of the life in freshwater. Most of the plants such as cattails grow here and creates a home for most of the aquatic life such as tadpoles, insects, and turtles.  Any dead organisms drift to the bottom of the water and bacteria use oxygen to bread them down and recycle the nutrients.

Terrestrial Biomes ► Tundra- located directly south of the north pole and is a treeless land with long summer days and short periods of winter sunlight.  It never rises above freezing for long and only the top most layer of soil thaws during the summer. ► Permafrost- lies directly underneath the top layer of soil and is permanently frozen. ► The types of organisms that can be supported are few due to a lack of nutrients. ► The plants are limited and consist of grasses and dwarf shrubs.

Taiga ► Located just south of the tundra and circles the north pole. ► It is almost a continuous belt of coniferous trees. Common trees are spruce, fir, and hemlock. ► This biome is warmer and wetter than the tundra but still have long severe winter and short mild summers. ► It stretches across much of Canada, Northern Europe, and Asia. ► Some animals include the caribou, lynx, hare, squirrels, deer, moose, and elk.

Desert ► It is the driest biome and has almost nonexistent plant life. ► The plants that do live in the desert have many adaptations to support life in such dry conditions. Such as photosynthetic stems, thick waxy coats, and leaves that curl up which are all ways to conserve water. ► Animals in the desert also have to have adaptations to survive in this dry biome. ► The kangaroo rat is a desert herbivore that does not have to drink water but gets the water that it needs from its food.

Grasslands ► A large community that is covered with rich soil, grasses, and similar plants. ► Grasslands occur in climates that experience a dry season where insufficient water exist to support forest. ► Grassroots survive throughout the winter and enlarge every year to form a continuous underground mat of roots called sod. ► Some grasslands are ideal for growing grains and each type of grain is a different species so the grasslands are known as the breadbasket of the world. ► Many animals graze in the grasslands and some examples are bison, deer, and elk. Other animals are rabbits and prairie dogs.

Temperate Forest ► Temperate forest or deciduous forest are dominated by broad leaved hardwood trees that lose their foliage annually. Examples are maple, oak, birch, elm, and ash. ► The soil is usually a top layer that is rich soil and a deeper layer of clay. ► Some of the animals are squirrels, mice, rabbits, deer, and bears. There are also many species of birds.

Rain Forest ► It is home to more species that any other biome. ► There are two types: Temperate and tropical.  Both have extensive amounts of moisture supplied by rainfall. ► Most of the nutrients in tropical rain forest are tied up in the living materials. There are very few nutrients held in the soil and are quickly recycled through complex food webs. Hot humid climate enables ants, termite, and other decomposes to break down dead plants and animals rapidly. ► Tropical rain forest support a wide variety of plants and animals. ► Pg. 82