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Section 4-1: The Role of Climate
Carbon dioxide, methane, water vapor, and a few other atmospheric gases trap heat energy and maintain Earth's temperature range.
As a result of differences in latitude and thus the angle of heating, Earth has three main climate zones: polar, temperate, and tropical.
Section 4-2: What Shapes an Ecosystem?
Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives.
Community interactions, such as competition, predation, and various forms of symbiosis, can powerfully affect an ecosystem.
Ecosystems are constantly changing in response to natural and human disturbances. As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community.
Section 4-3: Land Biomes
The world's major land biomes include tropical rain forest, tropical dry forest, tropical savanna, temperate grassland, desert, temperate woodland and shrubland, temperate forest, northwestern coniferous forest, boreal forest, and tundra. Each of these biomes is defined by a unique set of abiotic factors—particularly climate—and has a characteristic ecological community.
Section 4-4: Aquatic Ecosystems
Aquatic ecosystems are determined primarily by the depth, flow, temperature, and chemistry of the overlying water.
Freshwater ecosystems can be divided into two main types: flowing-water ecosystems and standing-water ecosystems.
In addition to the division between the photic and aphotic zones, marine biologists also divide the ocean into zones based on the depth and distance from shore: the intertidal zone, coastal ocean, and the open ocean.