Chapter 46, pages 1073-1081
Biomes 1
Biomes 2
I.
Ecology
- The study of living organisms, their relationships to one another and to
the
environment
II. Organization of the living world
A. Biosphere
1. Portion of the earth that supports life
2. Floor of the ocean to the top of the highest mountain
a. 36,000 feet below the ocean surface is the deepest part of the ocean
b. 30,000 feet above the ocean surface is the highest mountain
3. Life is scarce at the extremes of the biosphere
a. Most of life is in a narrow band around the earth
b. 100-300 feet in water to where light penetrates
c. Timberline on terrestrial habitats (about 15,000 feet)
d.
99% of life exists in about a 3 mile band (approximately 5,000 feet per mile)
around the earth
e. The earth is about 8,000 miles in diameter
f. Thus life exists in about 3/8000ths of the earth's diameter
4. Three distinct parts to the biosphere:
a. Atmosphere - gaseous envelope
b. Hydrosphere - water
c. Lithosphere - rocks and earth
5. The energy necessary for life comes from the sun
6. The chemicals necessary for life come from the air, water, soil
7. The earth is a
closed
system: all things necessary for life except the sun comes
from
within the earth, nothing comes from outside the earth
III. Subdivisions of the biosphere
A. Aquatic Habitats - water habitats of the earth
B. Biomes - terrestrial habitats of the earth
1. Very large terrestrial regions of the earth characterized by:
a. Climate - precipitation and temperature
b. Vegetation
c. Animal life
d. General soil type
2. There are about a dozen biomes of which we will study about nine
C. Biome groupings
1. The Boreal Biomes
a. General characteristics
(1) Generally circumpolar
(2) Generally in the far north
(3) Extends southward along the high mountain tops
b. Tundra Biome
d. Temperate Coniferous Forest Biome
2. The Temperate Biomes
a. General Characteristics
(1) Exists below the boreal forests
(2) Are not
circumpolar
nor evenly distributed because they are influenced by
precipitation
(3) Rainfall varies greatly with longitude (as one moves from west to east)
(4) Various physical features of the environment modify the
amount of rainfall a
given region receives
e. Desert Biome
3. Tropical Biomes
a. General Characteristics
(1) Determined mainly by the amount of precipitation
(2) Includes grasslands and deserts as well as forests
(3) Seasonal distribution of rainfall is also as important as the amount
(4) Mineral-poor soil
leached
by heavy
precipitation
with little or no
organic
material in it
(5) Still very productive - most of the nutrients in this
ecosystem
are tied up in
the
vegetation
D. Discussion of each biome
1. Tundra Biome (tundra)
a. Location
(1) Far north where ever the snow melts seasonally
(2) Circumpolar
(3) Does not exist in the
Southern
Hemisphere because there is no land in the
proper
latitudes
(4) Extends south along the highest mountain tops and exists
as the regions
above
timberline
b. Physical characteristics
(1) Swampy landscape of broad shallow lakes, sluggish streams, and bogs
(2)
Permafrost
- the
permanently
frozen ground below the upper part that
thaws seasonally
(a) Interferes with drainage
(b) If too near the surface, plants can't get any roots down in the soil
(3) Some have very little rainfall and thus are arctic deserts
(1) Growing season very short
(2) Low species diversity
(a) Large numbers of individuals
(b) Low numbers of different species
(c) Dominated by
reindeer
moss (a
lichen),
other
perennial
grasses,
sedges,
and
annuals
(d) No shrubs or trees
(e) Animals such as:
lemmings,
weasels,
arctic
foxes,
snowshoe
hares,
ptarmigan,
snowy
owls,
hawks,
musk-oxen,
caribou,
and
reindeer
d. Regenerates very slowly because of the low rates of photosynthesis
(1) Military use and oil exploration have caused great damage to tundra
(2) May take hundreds of years to heal
2. Boreal Forest Biome (boreal forest)
a. Location
(1) Circumpolar
(2) Dominated by coniferous forests in the far north just below the tundra biome
(3) Extends south into the highest mountain tops and comprises
the
timberline
tree species
b. Physical characteristics
(1) Permafrost usually absent
(2) Deeper and better soil than tundra biome
(3) Soil is
acid
and mineral-poor because of the acid produced by
decomposing
needles
(1) Growing season longer than the tundra biome but still short
(2) Conifers clearly dominate
(3) Can have aspen or birch as successional trees in logged or burned areas
(4) These plants have a hard time getting water from the soil
because of the cold
or frozen conditions of the soil particularly
in the winter when the soil is
frozen
(5) Animals: caribou, wolves, bear, moose, rabbits, lynx, sable, and fisher
(6) Most birds
migrate
into the area in the summer and out of the area in the
winter
d. Line between Tundra Biome and Boreal Forest Biome
(1) Hard line to draw
(2) Southern most
tundra
biome is interspersed with patches of
evergreen
forest
where the
permafrost
is locally absent or deeply buried
(3)
Muskeg
- waterlogged soil that is many times a
peat
bog where
black
spruce will grow
e. Timberline
(1) At timberline the trees are
stunted
and distorted because of the harsh
environment
(2)
Krummholz
- the stunted miniature forest at this elevation where the trees
are
flagged
3. Temperate Coniferous Forest Biome (temperate coniferous forest biome)
a. Location
(1)
Temperate
regions of North America, mainly in the west. The best
examples are in Washington, Oregon, and
Northern California
(2) Gets large amounts of winter rainfall and drought during the summer
(3) Exists as the upper middle elevations of coniferous forests in California
(4) Essentially the coniferous forest just below timberline in California
b. Physical Characteristics
(1) Mainly tall (100-200 foot) coniferous trees
(2)
Temperate Rain Forest exists along the Olympic Peninsula
in Washington
State and up the coastal regions of British
Columbia and Alaska
(a) Has very high rainfall
(b) Similar in structure to a
tropical rain forest biome with equivalent types
of species
(c) Nutrient-poor soils
(3) Generally plenty of minerals in the soils but the soils aren't well developed
c.
Species
diversity amounts to about a dozen
conifers
and a number of different
species of animals
4. Deciduous Forest Biome (deciduous forest biome)
a. Location - Europe, Asia, and Eastern U.S.
b. Physical characteristics
(1) Precipitation is from 70 to 150 cm annually
(2) Dominated by broadleaved hardwood trees
(3) Loose leaves in fall
(4)
Broadleaved evergreens increase and
broadleaved deciduous trees
decrease as one moves south
(5) Good deep soils that are good for agriculture
(a) Among the first biomes to be converted to agriculture by the pioneers
(b) No substantial loss in fertility
of the soil over the years of agricultural use
even in Europe
(1) Good species diversity
(2) Animals - puma, wolves, deer, bison, bears, plus other animals and birds
(3) Plants - mostly broadleaved deciduous hardwoods
5. Temperate Grassland Biome (temperate grassland biome)
a. Location
(1) Typical of the North American midwest
(2) Other parts of the world such as the Ukraine
b. Physical characteristics
(1) Few trees except those that are riparian
(2) Burned frequently by indians which discourages
forests
and encourages
grasslands
(3) Thus areas of grasslands
(4) Soils very good rich and deep, held together by the mat
of roots from the
grassland
(5) Less rainfall here than the deciduous forests
(6) The mass of roots made it hard for the wooden plow to turn
over the soil
but the tractor and steel plow has changed
all that
(7) Little now exists because of its usefulness for agriculture
(8) Of all the biomes, this biome has the best soils
(1) Originally tall grasses grew here
(3) Other animals -
wolves,
coyotes,
prairie
dogs,
foxes,
black-footed ferrets,
various
hawks,
grouse,
snakes,
lizards,
and
insects
d. Subdivisions
(1) Tall Grass Prairie - the prairies described above
(2) Steppes
(a) Short grass prairies
(b) Greater
precipitation
than the deserts and less precipitation than
the tall grass prairies
(c) Shallower soil than the tall grass prairie
(d) Mostly bunch grasses with bare soil between
(e)
Drought
and
overgrazing
have destroyed these in the U.S. and other
places in the world
6. Chaparral Biome (chaparral)
a. Physical characteristics
(1) Brushy areas composed of shrubs
(2) Mild winters and very dry summers
(3) Typical Mediterranean climate
(4) During the rainy season the habitat will be lush and green
but will soon turn
dry and brown when summer comes
(a) Hard, small, and leathery leaves
(b) These type of leaves resist water loss and wilting
(6) Frequent fires occur in chaparral so species are fire-adapted
b. Location - California, Mediterranean region, and Australia
(1) Medium amount of different species
(2) Dominated by shrubs
(3) May contain drought-resistant pines or oak trees
7. Desert Biome (desert biome)
a. Physical characteristics
(1) Arid areas
(2) Sparse to no vegetation
(3) Low water content of the environment leads to temperature
extremes of hot
and cold in one day, up to 100o
F in one day
(4) Vegetation varies greatly depending upon the amount of rainfall
(a) 5 inches per year produces
deserts
like exist in southern California with
cactus,
yucca,
and
Joshua
trees
(b) 0 to less than 5 inches per year
with no rainfall in some years produces
deserts like the Sahara
where there is little or no vegetation at all
(1) Small
rodents
like the
kangaroo
rat,
lizards,
snakes,
jackrabbits,
and
desert
bighorn sheep
(2) Plant life very well adapted for a dry environment
(a) Reduced or no leaves at all
(b) Stomata open at night
(c)
Allelopathy
is best exhibited in desert plants (growth inhibiting
chemicals produced
by plants to keep other plants from growing
too close)
(d)
Thorns
and
spines
are present on plants to keep animals from eating
them
(e) Water storage tissue is typical in desert plants
c. Some deserts are so dry that virtually no plant life occurs in them
(1) African Namib Desert
(2) Atacama-Sechura Desert of Chile and Peru
(a) Coastal desert
(b) Fog from the ocean provides moisture
(c) Animals emerge at night or in
early morning and lick moisture produced
by fog from coats
(d) Plants absorb moisture from leaves
8. Tropical Rainforest Biome (tropical rainforest biome)
(1) Greatest amount of species diversity of all the terrestrial habitats
(2) No one species dominates
(3) In a quarter of a mile it is possible to see all different
tree species with no
two of the same species
(4) Mostly evergreen broadleaved trees in these forests
(a) These trees have shallow roots so to get minerals from decaying leaves
(b) Thus poor anchorage of these trees
(c) These trees have swollen bases (buttresses) to help hold them up
(5) Ants are prominent in the tropical rain forest biome
(a) Need no sunlight to keep them warm in the tropics
(b) Thus they nest and rove everywhere
(c) Some have developed a
symbiotic
relationship with
Acacia
trees and
shrubs
(6) Animal species - insect, reptile, amphibian fauna, birds, and mammals
b. Physical characteristics
(1) Vegetation is not dense at ground level in a mature forest
(2) Vegetation is very dense in areas recovering from logging,
fire, agricultural
use, or near streams
(3) Continuous
canopy
produces a dark habitat with an extremely
humid
microclimate
(4) Much of the
precipitation
is locally recycled water coming from
transpiration
of the forest's own trees. Thus, if the forest is removed it
may be hard to reestablish the forest.
(5) Three distinct stories
(a) Canopy story - crowns of the tallest trees
(b)
Middle story - continuous canopy of leaves that produces
the humid
environment
below
(c)
Understory
- plants specialized for life in constant shade as well as
seedlings of canopy
and middle story trees
(6) All stories support extensive
epiphytic
communities. These epiphytic
communities can be so extensive as to
interfere with
photosynthesis
and
can break limbs
(7) Most mineral cycling occurs among the
epiphytes
and the growing leaves of
the forest
canopy
(8) Vines as thick as a man's thigh abound
(a) Strangler tree is an example
(b) Overgrows the trunk of the host, eventually killing it
c. Epiphytes
(1) Rain tends to run off the host tree branches immediately
leaving
xerophytic
condiditons for many epiphytes
(2) Cacti make good epiphytes under these conditions
(3)
Staghorn ferns possess specialized leaves that retain pockets
of spongy soil
that absorb water
(4)
Orchids
have specialized spongy tissues surrounding their roots that store
water and harbor
cyanobacteria
for
nitrogen
fixing
(5) Bromeliads store as much as a gallon of rainwater in their leaf cups
(a) Mosquito larvae and other insects live in these aerial swamps
(b) Quite a diversity of life!
d.
High temperature decomposes organic material in the
detritus food chain very
rapidly
9. Savannah Biome (savannah biome)
a. Savannah (veld) is a tropical grassland or very open woodland
b. Widely spaced trees like Acacia (with thorns) grow amid tall grasses
c.
Greatest
herbivore
biomass occurs in the African savannah -
antelope,
giraffe,
zebra,
lions,
hyenas,
etc.
d.
The Savannah Biome is maintained by either low annual rainfall or seasonal
rainfall
e. Thus the herds of animals may migrate during these times
f.
This biome is rapidly being converted to range land for cattle and
other animals
which produces severe
over-grazing
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