- Ecology is the study of the
distribution and abundance of organisms.
- Biosphere: The area of the earth
inhabited by life. It contains all the earth's
- This is a thin layer of oceans, lakes, and
streams. The land to the depth of a few meters and the atmosphere
to an altitude of a few kilometers.
- Organisms in these areas are acted upon by
nonliving factors called abiotic
- Abiotic Factors:
- 1. Temperature:
affects the organism's metabolism, The normal range is between 0
degrees and 50 degrees centigrade.
- 2. Water:
adaptations for water homeostasis and conservation play a large
role in determining a species' habitat range.
- 3. Light: The
sun is the major energy source of nearly all ecosystems.
Availability of light can determine habitat. In aquatic
environments, water selectively reflects and absorbs certain
wavelengths of light. As a result of this most photosynthesis
occurs near the surface of the water. Animal and plant behavior is
often sensitive to photo periods.
- 4. Soil:
Physical structure, pH, and mineral composition of soil limit
distribution of plants and have an effect on the animals that feed
- 5. Wind:
Increases the effects on temperature by increasing heat loss by
evaporation and convection.
- 6. Natural
Disasters: Fire, hurricanes, typhoons,
volcanic eruptions can devastate biological
- Principle of Allocation: Each organism
uses a small amount of its total energy for growth, reproducing,
obtaining nutrients, escaping predators and coping with
- Species living in stable environments lead a
good life in a small area.
- Species living in unstable environments lead a
rough life over a wider range.
- Terrestrial Biomes: Most often named
for the predominant vegetation but each is also characterized by
animals adapted to that particular environment.
- a). biomes blend into each other without sharp
- b). May contain several communities
represented in one biome.
- c). Prevailing climate, particular temperature
and rainfall, is most important factor in determining what kind of
- A climatograph
plots temperature and rainfall and shows the impact of climate on
the distribution of biomes.
- A. Tropical
Forest (rain forest): found near the equator,
temp varies little from 25 degrees C. and day light varies from 12
hours by less than one hour. Lowlands receive very little rain
fall, and develop thorn forests. Nearer the equator regions have
distinct wet and dry seasons and tropical deciduous forests occur.
Trees relief following heavy rains.
- Near the equator, where rainfall is abundant ,
and the dry season lasts less than a few months is tropical rain
forest. Contain more plant and animal species than any other
community. Competition is strong for light, soil is poor due to
the rapid recycling of nutrients. Animals are mostly tree
- B. Savanna: is a
grassland with scattered individual trees. Found covering: Central
South America, central and South Africa, and parts of Australia.
Soil is generally porous with a thin humus layer. 3 distinct
seasons: cool and dry; hot and dry, and warm and wet in that
order. Frequent fires inhibit invasion of trees. Large herbivores
( giraffes, zebras) are commonly most active.
- C. Desert: is
characterized by low precipitation less than 30 cm / year, not by
temperature: both cold and hot deserts exist. Hot deserts occur in
S.W. USA, W. South America, North Africa, Middle East, Central
Australia. Cold deserts occur: E. Argentina, central Asia, and
west of the Rocky Mountains. Reptiles and seed eaters are common.
Cacti and succulents are also common.
- D. Chaparral:
scrub land are regions of dense, spiny shrubs, with tough
evergreen leaves found along coasts where cool ocean currents
circulate offshore making mild rainy winters and long hot dry
summers. Mediterranean , California coastline, Chile, S.W. Africa,
and S.W. Australia. Deer, snakes, fruit eating birds are
- E. Temperate
Grasslands: similar to savanna but occur in
cold regions. Veldts of S. Africa, the pusta of Hungary, pampas of
Uruguay and Argentina, steppes of Russia, and the plains of the
USA, are examples.
- F. Temperate
Forests: grow throughout the mid latitude
regions that contain enough moisture to support large
broad-leaved, deciduous trees. Occur in Eastern US, Middle Europe,
and E. Asia. There is a 5-6 month growing season, very cold
winters, and very hot summers. High precipitation and evenly
distributed through out the year. Soil rich in
- G. Taiga: (
coniferous or boreal forest) is characterized by harsh winters and
occasionally warm summers. N. America, Europe, Asia, and at high
elevations in more temperate latitudes. Soil thin and acidic. It
- H. Tundra: is
the northern most limits of plant growth and at high altitudes
plant forms are limits to shrubs and mat-like vegetation. Arctic
Tundra: encircles the North Pole. Brief warm summers are marked
with nearly 24 hours of sunlight.
Permafrost, saturated soil prevent
large plants from growing. Alpine Tundra: occurs at high
elevations at all latitudes.
- Aquatic Biomes:
- 78% of the earth's surface is covered with
water. This aquatic environment is divided into two distinct
areas: Marine and fresh
water biomes. Without this enormous volume of
water life on earth would be impossible. The ocean acts as a
machine that drives the earth's weather patterns, helps regulate
its many climates, servers as a reservoir for phytoplankton that
generates 50% of the earth's oxygen, and absorbs large amounts of
the earth's carbon dioxide. The structure of biomes are based upon
the temperature of the water and its over all depth.
- The depth of the water divides it into two
distinct zones: The photic zone
where abundant light is available for photosynthesis and the
aphotic zone where minimal light is
- The water temperature at different depths
causes a layering effect to occur. The warmer water (less dense)
will reside near the surface, while the more dense, colder, water
will sink and remain near the bottom. The line of demarcation
separating these different densities is called the thermocline.
Certain times during, the year when the temperatures equalize, a
mixing occurs bringing the nutrient rich lower water up to the
top, The lower area of these biomes is called the benthos and
contains a tremendous amount of dead organic material called
- Marine Biome:
- The marine biome is divided into distinct
areas both horizontally and vertically. The horizontal divisions
include (in order) the inter tidal zone, neritic zone, and oceanic
zone. The vertical divisions are: the photic zone ( 0- 200 M), The
aphotic zone (200-6,000 M). The benthic zone or sea floor, extends
from the neritic zone to the lower depths of the ocean or abyssal
zone. This zone contains a tremendous amount of nutrients from
aquatic life that died and filtered down. The pelagic zone (all
water) is a vertical designation ranging from the sea surface to
the abyssal zone. Let's examine these areas more
- Intertidal Zone: This area is the beach with
its sand and wave action though some are very rocky and void of
sand. It is a harsh environment to live in and is under constant
change. The tide plays an important role in how plants and animals
survive in this area. Few plants are found in this area due to
tidal action. Animals are mostly burrowers and filter feeders.
- Neritic Zone: In tropical areas coral reefs
are found in this area immediately after the intertidal zone.
Since coral and algae form a mutualistic relationship by having
the algae provide them with the by products of photosynthesis and
they in turn provide them shelter and support.
- Pelagic zone: This area is considered the open
ocean. It is vast and contains very little nutrients.
Phytoplankton are abundant here and produce most of the world's
oxygen. Zooplankton (small arthropods, copopods, jellyfish, etc.)
are also found here. In the deeper areas of the ocean animals
called nekton are found. These squid, sea mammals, fish, and
reptiles swim freely to find food.
- Fresh Water Biome:
- The freshwater biome is also divided
horizontally and vertically. The horizontal divisions include the
littoral zone which is closest to the shore of the lake. The
limnetic zone encompasses the open area of the lake. Vertically
you have the photic and aphotic zones and the benthic zone still
makes up the lake floor. The deep vertical zone is called the
profundal zone. Lakes are classified as Oligotrophic (deep and
nutrient poor) and Eutrophic (shallower and rich in nutrients).
Since there are no absolutes in ecology, a third lake type is
recognized the mesotrophic lake. This is a middle ground between
the two extremes.
- Marshes, bogs and swamps are examples of this
type of biome. These areas are either permanently flooded or
periodically flooded. They contain aquatic plants and animals and
are considered one of the nutrient rich biomes. Under federal and
state law many of these areas are protected from commercial or
- These are areas where the marine and
freshwater environments come in contact with each other. This
biome is a very nutrient rich and productive environment. Algae,
phytoplankton, and marsh grass are the major producers in this
environment. Many invertebrates (clams,worms,and crabs) along with
fish makes up its animal complement. This biome is under a
tremendous stress from development and pollution.