Chapter 50 ~ An Introduction to Ecology and the Biosphere

Ecology

Components:

•abiotic~nonliving chemical & physical factors

•biotic~living factors

Population ~group of individuals of the same species in a particular geographical area

Community ~assemblage of populations of different species

Ecosystem ~all abiotic factors and the community of species in an area

Rachel Carson, 1962, Silent Spring

Biosphere~the sum of all the planet’s ecosystems

Biome~ areas of predominant flora and fauna

Abiotic factors

Temperature

Water

Sunlight

Wind

Rocks & Soil

Periodic disturbances

Global climate

Seasons

Lake stratification & turnover

Thermal stratification ~ vertical temperature layering

Biannual mixing ~ spring and fall

Turnover ~ changing water temperature profiles; brings oxygenated water from the surface to the bottom and nutrient rich water form the bottom to the surface

Aquatic biomes

Vertical stratification:

•photic zone~ photosynthetic light

•aphotic zone~ little light

•thermocline~ narrow stratum of rapid temperature change

•benthic zone~ bottom substrate

Benthos~ community of organisms at the bottom

Detritus~ dead organic matter; food for benthic organisms, planktonic organisms, or filter feeders

Freshwater biomes

Littoral zone ~ shallow, well-lit waters close to shore

Limnetic zone ~ well-lit, open water farther from shore

Profundal zone ~ deep, aphotic waters

Lake classification : •oligotrophic~ deep, nutrient poor •eutrophic~ shallow, high nutrient content •mesotrophic~ moderate productivity

Wetland ~ area covered with water

Estuary ~ area where freshwater merges with ocean

Marine biomes

Intertidal zone ~ area where land meets water

Neritic zone ~ shallow regions over continental shelves

Oceanic zone ~ very deep water past the continental shelves

Pelagic zone ~ open water of any depth

Benthic zone ~ seafloor bottom

Abyssal zone ~ benthic region in deep oceans

Terrestrial biomes

Savanna ~ tropical grassland with scattered trees; occasional fire and

drought; large herbivores

Tropical forests ~ equator; most complex; constant temperature and rainfall; canopy, most productivity in the organisms, little fertile potential

Desert ~ sparse rainfall (<30cm/yr)

Chaparral ~ spiny evergreens at midlatitudes along coasts

Temperate grassland ~ all grasses; seasonal drought, occasional fires; large mammals