Download Chapter 50 notes: Ecology and the Biosphere Ecology: the study of

Chapter 50 notes:
Ecology and the Biosphere
Ecology: the study of the interactions between organisms and
their environments
Interactions determine both the distribution an organism and
their abundance.
3 main questions that Ecologists most; where do they live?
Why do they live where they do? How many are there?
Ecologists also study how the interactions between organisms
and the environment affect number of species living in an area,
the cycling of nutrients, and growth of populations. Ecology
reveals the richness of the biosphere and provides a basic
understanding that will help us sustain and conserve.
Ecologist use observations and experiments to test
explanations for the distribution and abundance of species and
other ecological phenomena.
Ecology and Evolutionary Biology are closely related sciences.
Events that occur in the framework of ecological time (minutes,
months, years) translate into effects over evolutionary time
(decades, centuries, millennia) Ex. Predator-prey interaction
where the selection for mice with fur coloration that enhances
its camouflage
The environment of any organism includes abiotic and biotic
components.
Abiotic factors: non-living, temperature, water, sunlight, wind,
rocks, soil
Biotic factors: living, interactions with other organisms, such as
predation, parasitism, provide its food, competition or change
its physical and chemical environment
These factors lead to 2 questions: What environmental factors
limit geographic range? (distribution) What factors determine
its abundance?
Sub-fields in Ecology:
Organismal Ecology: How an organism’s structure, physiology,
and behavior meet the challenges posed by the environment.
Population Ecology: focuses on the factors that affect how
many individuals of a particular species live in an area.
Community ecology: deals with an array of interacting species
in a community.
Landscape Ecology: deals with arrays of ecosystems and how
they are arranged in a geographic region. Research is focused
on the factors controlling the exchange of energy, materials,
and organisms among “ecosystem patches” making up the
landscape or seascape.
Ecosystem: consists of all biotic and abiotic factors and the
entire community of species that exist in a certain area.
Biosphere: is the global ecosystem – the sum of all the planet’s
ecosystems.
Ecology and Environmental issues:
Environmentalism: advocating for the protection or
preservation of the natural environment
Ecological information is always incomplete> given what we do
know about the interconnectedness of the biosphere, it would
be prudent to follow “precautionary principle” “an ounce of
prevention is worth a pound of cure”
Dispersal: the movement of individuals away from centers of
high population density from their area or origin. This
contributes to the global distribution.
Biogeography helps us understand the limiting factors for
dispersal and distribution.
Natural Range expansion: when organisms expand their range
by moving into an area where they did not exist previously
Species Transplants: for the transplant (accidental or
intentional) to be successful, the species has to survive and
reproduce. Often disrupt the communities and ecosystems
where they have been introduced. Ex. Zebra Mussules
Behavior and Habitat selection:
Least understood process. Some organisms do not occupy all of
their potential range even though they are physically able to
disperse and the new habitat is suitable. When we can not
determine if behavior is a limiting factor, we look at biotic and
abiotic factors.
Biotic and Abiotic influence on Aquatic Biomes:
Aquatic Biomes account for the largest part of the biosphere in
terms of area.
Physical and chemical differences separate Marine biomes and
fresh water biomes. Marine biomes generally have an average
salinity level of 3%. Fresh water biomes generally have a
salinity concentration of <1%.
Marine Biomes:
Intertidal zones:
Oceanic Pelagic Zone:
Coral Reefs:
Marine Benthic Zone:
The oceans (cover 75% of planet) evaporation provides most of
the rainfall. Ocean temperature major effect on the world’s
climate and wind patterns. Marine algae and photosynthetic
bacteria provide most of the oxygen and consume huge
amount of carbon dioxide.
Freshwater Biomes:
Lakes:
Wetlands:
Streams and Rivers:
Estuaries:
Freshwater biomes are closely linked to the soils and biotic
components they pass through. Particular characteristics are
influenced by speed of water flow and the climate
Many aquatic biomes are chemically and physically stratified.
Light is absorbed by both the water and photosynthetic
organisms. Photic Zone: where there is sufficient light for
photosynthesis. Aphotic Zone: where little light penetrates.
Benthic Zone: bottom of all aquatic biomes, made up of sand
and organic and inorganic sediments. Communities of
organisms that occupy this zone are known as benthos. The
major food source for benthos is detritus or dead/decaying
organic matter which fall from the photic zone.
Thermocline: found in oceans and most lakes, a narrow
stratum of rapid temperature change which separates the
warm upper layer from the cold lower layer of water.
In both marine and fresh water environments, communities are
distributed according to depth of water, degree of light
penetration, distance from shore, and open water versus
bottom.
Climate has a great effect on organism distribution in terrestrial
biomes.
Climographs are used to look at temperature, and precipitation
in a particular region. Annual averages for temp and rain fall are
reasonable well correlated with biomes that exist in different
regions. Other factors play a role as well: patterns of moisture,
and temp, bed rock for mineral nutrient availability and soil
structure which can determine what kind of vegetation will
grow.
General Features of terrestrial biomes:
Most terrestrial biomes are named for major physical or
climatic features and for their predominant vegetation.
Vertical stratification is an important feature as well as the
shapes and sizes of plants which define the layering.
Forests: upper canopy – lower tree stratum – shrub understory
– ground layer herbaceous plants – forest floor (litter layer) –
root layer.
Stratification of vegetation provides many different habitats for
animals – well defined feeding groups from bats and birds that
feed above the canopy to worms and arthropods that forage in
the litter.
Ecotone: area where different biomes feed into each other
without sharp boundaries. May be wide or narrow
Biomes are dynamic, disturbance rather than stability is the
rule. As a result, biomes exhibit patchiness with several
different communities represented in any particular area.
Human activity has altered the natural patterns of periodic
disturbance. Ex. Fire control and population encroachment
along the east coast (broad leaf forest)
Major terrestrial biomes:
Tropical forests:
Desert:
Savanna:
Chaparral
Temperate grasslands:
Coniferous forest:
Temperate Broadleaf forest
Tundra: