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Intro to Ecology & the Biosphere
Chapter 52
Ecology
• scientific study of the interactions between
organisms and the environment
• an organism’s environment includes:
– abiotic (non-living) components
– biotic (living) components)
• focuses on 4 levels of biological organization:
– populations
– communities
– ecosystems
– biosphere
Subfields of Ecology
• organismal ecology
– how an organism′s structure, physiology, and behavior
meet the challenges posed by the environment
• population ecology
– how factors affect the number of individuals of a
particular species live in an area
• community ecology
– how interactions such as predation, competition, &
disease, as well as abiotic factors like disturbance, affect
community structure & organization
Subfields of Ecology cont.
 ecosystem ecology
 focuses on energy flow and chemical cycling among the
various biotic and abiotic components
 landscape ecology
 deals with arrays of ecosystems & how they are arranged
in a geographic region
 focuses on the factors controlling exchanges of energy,
materials, and organisms among the ecosystem patches
making up a landscape or seascape
Global Distribution of Organisms
 a major factor contributing to the global distribution
of organisms is dispersal:
 movement of individuals away from centers of high
population density or from their area of origin
 limits to distribution include:
 accessibility of an area (ie: dispersal)
 behavior (ie: habitat selection)
 biotic factors (ie: predation, competition, parasitism,
disease)
 abiotic factors (ie: temperature, water, sunlight, wind, soil
structure/nutrients, fire, oxygen, salinity, etc.)
Climate
 major components: temperature, water, sunlight, &
wind
 temperature & water have a major influence on the
distribution of organisms
 climate patterns can be described on 2 scales:
 macroclimate = patterns on the global, regional, & local
level
 microclimate = very fine patterns, such as those
encountered by the community of organisms underneath
a fallen log
Macroclimate
• Earth′s global climate patterns are determined largely by the
input of solar energy & the planet′s movement in space
– the sun′s warming effect on the atmosphere, land, & water
establishes the temperature variations, cycles of air movement, and
evaporation of water that are responsible for dramatic latitudinal
variations in climate
• proximity to bodies of water, mountain ranges, & other
topographic features affect regional & local climatic
variations
– contributes to the patchiness of the biosphere
• changing angle of the sun over the course of the year also
affects local environments
Sun Intensity: Latitude Variations
Sun Intensity: Seasonal Variations
Air Circulation & Precipitation Patterns
Wind Patterns
Water Moderates Climate
warm summer day
Mountains Affect Rainfall
Microclimate
• many features in the environment influence
microclimates by casting shade, affecting
evaporation from soil, & changing wind patterns
Biomes
• major types of ecological associations that
occupy broad geographic regions of land or
water
Aquatic Biomes
account for the largest part of the biosphere in
terms of area
• freshwater
& marine
–
Aquatic Biomes cont.
• many aquatic biomes are
physically & chemically
stratified
• communities are distributed
according to depth of the
water, degree of light
penetration, distance from
shore, and open water
versus bottom
Terrestrial Biomes
• because there are
latitudinal patterns of
climate over Earth′s
surface, there are also
latitudinal patterns of
biome distribution
• the impact of climate
on the distribution of
organisms can be seen
in a climograph
Terrestrial Biomes
• most terrestrial biomes are named for major physical
or climatic features and for their predominant
vegetation
– vertical stratification of vegetation provides many
different habitats for animals
– terrestrial biomes usually grade into each other,
without sharp boundaries at an area called an
ecotone
Major Terrestrial Biomes
AQUATIC BIOMES
Distribution of life is affected by:
•
•
•
•
•
LIGHT
Temperature
Oxygen
Salinity
Turbulence
Zones in lake- affect distribution of organisms
FRESHWATER BIOMES
Eutrophic Lake
Oligotrophic Lake
River
Wetlands (top) and estuaries (bottom)
Zonation in the marine environment
Examples of marine biomes
CORAL REEF
TIDE POOL: Intertidal
DEEP SEA VENT: Benthos
Black smoker
The distribution of major terrestrial biomes
Temperate grassland
Distribution: mid-latitudes, mid continents
Precipitation: seasonal, dry season/wet season
Temperature: cold winters/hot summers
Characteristics: Prairie grasses, fire-adapted, drought tolerant
plants; many herbivores; deep fertile soil
Temperate grassland
Temperate deciduous forest
Distribution: mid-latitudes, northern hemisphere
Precipitation: adequate; summer rains, winter snow
Temperature: moderate warm summer, cool winter
Characteristics: many mammals, insects, birds, etc.
deciduous trees; fertile soil
Temperate deciduous forest
Coniferous forests
Distribution: high-latitude, northern hemisphere
Precipitation: adequate to dry (temperate rain forest on coast)
Temperature: cool year round
Characteristics: conifers;diverse mammals, birds, insects, etc.
Coniferous forests
Tundra
Distribution: arctic, high-latitude, northern hemisphere
Precipitation: dry
Temperature: cold year round
Characteristics: permafrost, lichens and mosses, migrating
animals & resident herbivores
Tundra
Tropical forests
Distribution: equatorial
Precipitation: very wet
Temperature: always warm
Characteristics: many plants and animals, canopy; thin, poor soil
Tropical forests
Savanna
Distribution: equatorial
Precipitation: seasonal, dry season/wet season
Temperature: always warm
Characteristics: fire-adapted, drought tolerant plants;
herbivores; fertile soil
Savanna
Deserts
Distribution: 30o N and S latitude band
Precipitation: very little
Temperature: variable daily and seasonal; hot and cold
Characteristics: sparse vegetation and animals, cacti,
succulents, drought-tolerant; reptiles, insects, rodents, birds
Deserts
Chaparral
Distribution: coastal mid-latitude
Precipitation: seasonal, dry summer/rainy winter
Temperature: hot summer/cool winter
Characteristics: scrubby vegetation, drought-adapted, fire-adapted;
herbivores, amphibians, birds, insects
Chaparral
Threats to Ecosystem Stability
Introduced Alien and Invasive Species