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Chapter 15
15-1
•The biosphere is the portion of Earth that is inhabited by life.
•The biosphere includes all ecosystems.
–one of Earth’s systems
•There are three other Earth systems.
- hydrosphere – all of Earth’s water, ice, and water vapor
- atmosphere – the air blanketing the Earth’s solid and liquid surface
- geosphere – the features of Earth’s surface; continents, rocks, sea floor
•Biotic and abiotic factors interact in the biosphere.
•All four Earth systems are interconnected.
•The Gaia hypothesis considers Earth as a kind of living organism.
–Earth systems interact to yield a biosphere capable of supporting life.
–It was developed by James Lovelock and Lynn Margulis.
15-2
•Climate is the prevailing weather of a region.
•Climate is the long-term pattern of weather conditions.
–average temperature
–precipitation
–relative humidity
•Key factors shape an area’s climate.
–temperature
–sunlight
–water
–wind
•A microclimate is the climate of a small specific place within a larger area.
•Earth has three main climate zones.
•The three main zones are the polar, tropical, and temperate climates.
–polar climate: the far northern and southern regions of Earth
–tropical zone: surrounds the equator
–temperate zone: the wide area in between the polar and tropical zones
•The angle of the Sun’s rays help determine an area’s climate.
•Earth’s tilt on its axis plays a role in seasonal change.
–larger changes in temperatures
–less precipitation
•Oceans shape coastal climates.
–smaller changes in temperatures
–higher humidity
–more precipitation
15-3
•Earth has six major biomes. *p. 463
•Tropical rain forest biomes produce lush forests.
•Grassland biomes are where the primary plant life is grass.
–Temperate grasslands are dry and warm during the summer; most
precipitation falls as snow.
•Desert biomes are characterized by a very arid climate. Determined by rainfall
amounts.
•Temperate forest biomes include deciduous forests and rain forests.
–Deciduous trees (shed leaves during certain seasons )are the dominant plant
species.
–The temperate rain forests have a long wet season and relatively dry
summer.
–humus present – formed from dead and decaying materials
•The taiga biome is located in cooler northern climates.
•The tundra biome is found in the far northern latitudes with long winters.
- Permafrost is present all year round.
•Minor biomes, such as chaparral, occur globally on a smaller scale.
•Polar ice caps and mountains are not considered biomes.
•Polar ice caps have no soil, therefore no plant community.
•The climate and organisms found on mountains change as the elevation changes.
15-4
•The ocean can be divided into zones.
•Intertidal zone – between low and high tide
–neritic zone—from intertidal zone to continental shelf
–bathyal zone—from neritic zone to base of continental shelf
–abyssal zone –lies below 2000 m
•The neritic zone harbors more biomass than any other zone. Much of the biomass
is organisms called plankton. Zooplankton – animal plankton; Phytoplankton –
photosynthetic plankton.
•Coastal waters contain unique habitats.
•Coral reefs are found in warm waters.
–tropical climate zone
–great amount of biomass
•Kelp forests are found in cold, nutrient-rich waters.
15-5
•Estuaries are dynamic environments where rivers flow into the ocean.
•An estuary is a partially enclosed body of water.
–mixture of fresh water with salt water
–Chesapeake Bay
–Louisiana bayous
•Estuaries are highly productive ecosystems.
•Freshwater ecosystems include moving and standing water.
•A watershed is a region of land that drains into a body of water.
•Ecosystems may be different along a river’s course
•Wetlands are among the most productive ecosystems.
•Ponds and lakes share common features.
•Freshwater bodies are divided into three zones: littoral zone, limnetic zone,
benthic zone
•All lakes “turn over” periodically. Lake turnover brings nutrients from the bottom of
the lake to the top, where they are used by organisms.