“Land Biomes of the World” Mrs. Hartge’s Science Class

The biosphere is the total of all of Earth's ecosystems The global ecosystem is called the biosphere It is the sum of all the Earth's ecosystems The biosphere is the most complex level in ecology Figure 34.2A

The biosphere is self-contained except for energy obtained from the sun and heat lost to space Each habitat has a unique community of species Figure 34.2B

Abiotic Factors Abiotic factors are those non-living physical and chemical factors which affect the ability of organisms to survive and reproduce.   

Abiotic Factors Abiotic factors vary in the environment and determining the types and numbers of organisms that exist in that environment. light intensity temperature range type of soil or rock pH level (acidity or alkalinity) water availability dissolved gases level of pollutant

Physical and chemical factors influence life in the biosphere The most important abiotic factors that determine the biosphere's structure and dynamics include solar energy water temperature

Disturbances such as fires, hurricanes, and volcanic eruptions are also abiotic factors Figure 34.4

Biotic Factors Biotic factors are all the living things or their materials that directly or indirectly affect an organism in its environment.   This would include organisms, their presence, parts, interaction, and wastes.  Factors such as parasitism, disease, and predation (one animal eating another) would also be classified as biotic factors.

Natural selection adapts organisms to abiotic and biotic factors Organisms are adapted to abiotic and biotic factors by natural selection The presence and success of a species in a particular place depends upon its ability to adapt Natural selection adapts organisms to abiotic and biotic factors Biotic factors include predation and competition Figure 34.5

Regional climate influences the distribution of biological communities Climate often determines the distribution of communities Earth's global climate patterns are largely determined by the input of solar energy and the planet's movement in space

Most climatic variations are due to the uneven heating of Earth's surface This is a result of the variation in solar radiation at different latitudes North Pole 60º N Low angle of incoming sunlight 30º N Tropic of Cancer Sunlight directly overhead 0º (equator) Tropic of Capricorn 30º S Low angle of incoming sunlight 60º S Atmosphere South Pole Figure 34.6A

The seasons of the year result from the permanent tilt of the plant on its axis as it orbits the sun MARCH EQUINOX (equator faces sun directly) JUNE SOLSTICE (Northern Hemisphere tilts toward sun) DECEMBER SOLSTICE (Northern Hemisphere tilts away from sun) SEPTEMBER EQUINOX Figure 34.6B

What is a Biome? Plants and animals don't live in isolation, but they live together with other plants and animals in an interdependent group called an ecological community. If you think about it for a moment, you will realize that all of the plants and animals in a particular ecological community must be adapted to the same climate so that they can all live in the same location.

A distinct ecological community of plants and animals living together in a particular climate is called a "biome." Scientists have divided the broad spectrum of climates and ecological communities found on Earth into biomes in different ways - some with many divisions, some with only a few.

Major terrestrial biomes 30º N Equator 30º S Tropical forest Polar and high-mountain ice Temperate deciduous forest Savanna Chaparral Coniferous forest Desert Temperate grassland Tundra (arctic and alpine) Figure 34.9

Tropical forests cluster near the equator Several types of tropical forests occur in the warm, moist belt along the equator Tropical Rainforest Figure 34.10

Savannas are grasslands with scattered trees Drier, tropical areas and some nontropical areas are characterized by the savanna Tropical Savannah Figure 34.12

Deserts are defined by their dryness Deserts are the driest of all terrestrial biomes They are characterized by low and unpredictable rainfall Desert Desertification is a significant environmental problem Figure 34.13

Temperate grasslands include the North American prairie Temperate grasslands are found in the interiors of the continents, where winters are cold Drought, fires, and grazing animals prevent trees from growing Farms have replaced most of North America's temperate grasslands Figure 34.15

Deciduous trees dominate temperate forests Temperate deciduous forests grow where there is sufficient moisture to support the growth of large trees Deciduous Forest Nearly all of the original deciduous forests in North America have been drastically altered by agriculture and urban development Figure 34.16

Coniferous forests are often dominated by a few species of trees The northern coniferous forest, or taiga, is the largest terrestrial biome on Earth Taiga Figure 34.17

The taiga is characterized by long, cold winters and short, wet summers Coastal coniferous forests of the Pacific Northwest are actually temperate rain forests

Long, bitter-cold winters characterize the tundra The arctic tundra lies between the taiga and the permanently frozen polar regions Arctic Tundra It is a treeless biome characterized by extreme cold, wind, and permafrost Permafrost is continuously frozen subsoil Figure 34.18