Chapter 50

An Introduction to Ecology and the Biosphere

I am the Lorax. I speak for the trees. I speak for the trees, for the trees have no tongues.

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biosphere

ecosystem

community

population

Studying organisms in their environment

organism

Components Abiotic = nonliving chemical & physical

factor

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

Abiotic factors Temperature

Water

Sunlight

Wind

Rocks & Soil

Periodic disturbances

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A large, relatively distinct terrestrial region with characteristic Climate

Soil

Plants

Animals

Interacting landscapes

Biome

Terrestrial biomes

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Using

precipitation

and

temperature

to identify

biomes

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Northernmost biome Frozen layer of subsoil (permafrost)

Low-growing vegetation adapted to extreme cold/short growing season

Tundra

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Taiga

•Coniferous trees dominate the taiga, or

boreal forest

•Cold winters, short growing season, and

acidic, mineral-poor soil

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Large conifers

High precipitation

Temperate rain forest

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Temperate deciduous forest

Precipitation relatively high

Soils rich in organic matter

Broad-leaf trees that lose their leaves

seasonally dominate

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Deep, mineral-rich soil

Moderate but uncertain precipitation

Well suited to growing grain crops

Temperate Grassland

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Chaparral

Thickets of small-leaf evergreens

Climate of wet, mild winters and

dry summers

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Significance of precipitation in temperate

biomes

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Cold deserts in temperate climates

Warm deserts in subtropical or tropical regions

Low levels of precipitation

Organisms with specialized water-conserving adaptations

Desert

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Tropical grassland

Widely scattered trees interspersed with grassy areas

Occurs in topical areas with low or seasonal rainfall

Savanna

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Mineral-poor soil

High rainfall evenly distributed throughout the year

High species richness and high productivity

Tropical rain forest

Aquatic biomes

Vertical stratification: photic zone = photosynthetic light

aphotic zone = little light

thermocline= narrow stratum of

rapid temperature change

benthic zone = bottom substrate

Aquatic life divided into

Plankton

Free-floating organisms

Nekton

Strongly swimming organisms

Benthos

Bottom-dwelling organisms

Detritus

dead organic matter; food for benthic organisms

Freshwater ecosystems include Flowing-water ecosystems

Streams and rivers

Standing-water ecosystems

Ponds and lakes

Freshwater wetlands

Freshwater ecosystems include Streams and rivers

Ponds and lakes

Freshwater wetlands

Estuaries Coastal body of water with access to both the

ocean and fresh water from rivers

Features

of a

typical

river

Lake Classification

Oligotrophic~ deep, nutrient poor

Eutrophic~ shallow, high nutrient content

Mesotrophic~ moderate productivity

Lake stratification & turnover Thermal stratification = vertical

temperature layering

Biannual mixing = spring and summer

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

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

Zones in the

ocean

Ecotone Transition zone where two communities meet

and overlap

Provide habitat diversity

Often inhabited by a greater variety and density of organisms than either adjacent community