Biology Chapter 52: An Introduction to Ecology

Ecology and the Biosphere

• Ecology is the scientific study of the interactions between organisms and the living and nonliving components of their environment.
• There are four levels of ecological study: population ecology, community ecology, ecosystem ecology, and biosphere ecology.

Climate and Biomes

• Climate has four major components: temperature, precipitation, sunlight, and wind.
• Biomes are major life zones characterized by vegetation type or physical environment.
• There are two main types of biomes: terrestrial and aquatic.

Terrestrial Biomes

• Tropical rain forests: high temperature and rainfall, vertically layered, and intense competition for light.
• Deserts: low and variable precipitation, plants adapted for heat and desiccation tolerance, and animals adapted for water conservation.
• Savannas: warm year-round, dominated by grasses and forbs, and large herbivores such as wildebeests and zebras.
• Chaparral: highly seasonal precipitation, dominated by shrubs, and many plants adapted to fire and drought.
• Temperate grasslands: highly seasonal precipitation, mammals include grazers and small burrowers.
• Coniferous forests: dominant vegetation includes evergreen conifers, and animals include large mammals and migratory birds.
• Temperate forests: significant precipitation, dominant plants are deciduous trees, and many mammals hibernate and birds migrate.
• Tundra: cold winters, permafrost restricts plant root growth.

Aquatic Biomes

• Oceans: 75% of the Earth's surface, 3% salt concentration, and two types of aquatic biomes: marine and freshwater.
• Marine biomes: estuaries, intertidal zones, ocean pelagic zones, coral reefs, and marine benthic zones.
• Estuaries: nutrient-rich and productive transition zones between rivers and seas.
• Intertidal zones: periodically submerged and exposed by the tides.
• Ocean pelagic zones: expansive open water, vulnerable to overfishing, pollution, ocean acidification, and global warming.
• Coral reefs: formed from calcium carbonate skeletons of corals, highly diverse species.
• Marine benthic zones: consist of the seafloor below surface waters, including deep-sea hydrothermal vents.
• Freshwater biomes: salt concentration less than 0.1%, influenced by soil and biotic components.
• Lakes: undergo mixing of waters called turnover in spring and autumn.
• Wetlands: inundated by water, support plants adapted to water-saturated soil.
• Streams and rivers: water flow from headwater to downstream, vulnerable to pollution and damming.

Other Ecological Concepts

• Convergent evolution: two evolutionarily unrelated species may live in the same type of biome on different continents.