Transcript ECOLOGY CH. 9 NOTES

Ecology
Chapter 9 Notes
“Forest”
I. Coniferous Forest
Location
• Primarily in the subarctic regions of North
America, Europe and Asia
• In the Southern Hemisphere generally on
high mountains, where conditions are
similar to high northern latitudes
• Many are harvested due to the increasing
need for wood
Climate:
• Summers are warm, lasting 2 to 5 months
• Winters are long, cold and dry with little
sunlight
• Receives 40 to 200 cm of precipitation a
year
Organisms
• Coniferous means “cone-bearing”
• Coniferous trees or Conifers are trees that produce
seed cones
– They are not diverse and contain only a few species of trees
• Most common tree species: pine, hemlock, fir, spruce, & cedar
– Most are Evergreens
• Means they do not lose all their leaves at a given time each year
• They lose and replace leaves slowly throughout the year
– They share unusual leaves called Needles
• long and thin covered in thick waxy substance
• Help trees conserve water
• Help the trees shed snow during the winters
• Ferns, Lichens, and Sphagnum moss are plants that can
grow in the dim light of the forest floor
• Limiting factors = Harsh winters and nutrient
poor soil
– Soil is poor and acidic due to conifer needles which
are acidic and decompose slowly
• Snow acts as insulating blanket, trapping heat
and preventing the ground from forming
permafrost…which protects the roots of the trees
• Small Herbivores:
– Most are seed eaters
– Mice, squirrels, jays, other rodents and birds
– Insects are common in summer…due to the poor soil
and drainage
• Large Herbivores:
– Moose, elk, beaver, snowshoe hare feed on plants
and bark
• Predators:
– grizzly bears, wolves and lynx
II. Deciduous Forest
Location
• Grow at lower latitudes than coniferous
forest
– Temperate zones- areas with lower latitudes,
they have four well defined seasons
• Spring, summer, fall, & winter
Climate
• Temperatures vary greatly
• Summer temperatures can be as high as
30 degrees Celsius (86 degrees F)
• Winter temperatures can fall as low as –30
degrees Celsius (-22 degrees F)
• Precipitation usually falls as rain or snow
depending on the season
– Receive 50 to 300 cm annually
– Falls fairly regularly throughout the year
Organisms
• Deciduous trees shed their leaves during a particular
season of the year
• Growing season last about 6 months
– The tree grows quickly
– Produces and stores large amounts of food
• Autumn has shortening daylight and cooling
temperatures which triggers the tree to change and shed
its leaves becoming dormant
– This loss of leaves allows for the tree to conserve water during
cold winter months
– Photosynthesis stops and tree no longer produces food
• Winter is survived by consuming food stored in its trunks,
branches, and roots
• Spring is when the trees grow new leaves and
photosynthesis begins again in preparation for the next
winter
• Deciduous forest are more diverse than coniferous forest
• Six most common types of tree species :
– Maple, oak, beech, ash, hickory, and birch
• The forest has three distinctive layers:
– Canopy: the highest layer, made up of branches and
leaves of tall trees, captures most sunlight
– Understory: beneath the canopy, made up of
younger, smaller trees and shrubs
– Forest floor: mosses, ferns and other low light plants
• Soil is enriched from leaves that fall from the
trees which decay quickly in the warm humid
summer months forming a humus layer
– Humus- home to many insects and other
invertebrates that feed on abundant organic matter
• Most common organisms in deciduous
forest due to abundant food and many
different habitats are:
– Decomposers such as: fungi
– Insects and other invertebrates
– Birds, mice and other small mammals
– White-tailed deer
– Reptiles and amphibians (in the warmer forest)
– Predators such as: wolves, mountain lions,
birds of prey, foxes & migratory birds in the
summer months
Human Impact
• Deciduous forest have been changed drastically due to
human activities such as farming, orchards, and urban
developing
• Two factors that have driven human consumption:
– Rich soil…its deep and fertile due to humus making it excellent
farmland
– Trees…generally they are hardwoods making them better
material than conifers for making furniture and flooring
• Because of this impact the forest regenerates slowly
because many of the species dependant on the trees
have disappeared
• Planted forest are known as monoculture forest
– Often very productive but have low biodiversity and are highly
susceptible to diseases, parasites and pollution
III. Rain Forest
Location
• Located at latitudes near the equator
• Tropical zone
Climate
– Temperatures here average around 25 degrees
Celsius year around (77 degrees F)
– This areas receives direct rays from the sun during
most of the year
– Precipitation falls as rain except for atop high
mountains
– Receives between 200 and 400 cm of rain annually
– Growing season can last 12 months
– No real difference in the seasons…has almost an
unchanging climate
– Because of unchanging seasons, water and
temperature are NOT limiting factors
– Soil Nutrients is the most common limiting factor
General Information
• Most diverse terrestrial ecosystem on Earth
• Biome with a dense canopy of evergreen
broadleaf trees supported by at least 200 cm of
rain annually
• May contain as much as 70% of all terrestrial
species on Earth
• They only cover 6% of Earth’s land surface, but
may contain 50% of Earth’s land biomass
Structure of Rain Forest
• Trees are the basis
• Thousands of extremely diverse species of
trees
– Most common species: cypress, balsa, teak
& mahogany
– Peter Ashton (British ecologist) found 700
species of trees in only 10 hectares (2.74
acres) of tropical rain forest in Borneo
• Layers of the Rain forest:
– Emergent trees- extremely tall trees which grow past
the canopy
– Upper Canopy- highest structure formed by the leafy
tops of trees which reach as high as 25 to 30 feet
• Captures almost 99% of sunlight
– Lower Canopy- just below upper, made up of younger
trees that have not reached their potential heights
– Understory & Forest Floor- made up of plants that are
able to live in low light and nutrient poor soil
• Forest floor is sparse because it only receives about 1% of
filtered sunlight
• Soil is poor in nutrients because the dead organic matter is
recycled in days or weeks instead of years like in other biomes
Organisms
• Warm temperature and constant moisture
are ideal conditions for decomposers such
as: insects, fungi, and bacteria
• Because of the diversity in the rain forest
most organic matter is held in its
organisms causing the topsoil to be thin
and poor in nutrients
– Most of the soil nutrients is found in the top 5
cm of soil
• Because of poor, thin topsoil layer most
trees widen their trunks at the bases
– Buttresses: ridges of wood that support the
trees at their base
• Roots are shallow to take advantage of
nutrients in the thin topsoil
• Other plants use the trees for support
– Lianas: woody vines that grow up the sides
of trees to reach sunlight in the canopy
– Epiphytes: plants that live entirely on the
trunks or limbs of trees absorbing airborne
nutrients and moisture
• Bromeliads and Orchids
• Most organisms of the rain forest live in
the canopy
– Arboreal: tree-dwelling organisms live their
whole lives without ever touching the ground
• Animals diversity is caused by two main
factors:
– Diversity in rain forest plants
– Wide variety of habitats that exist in the
different levels of the forest
• Habitats vary from tree to tree and from
one part of a tree to another part
• E.O. Wilson (American biologist) found 43
species of ants on a single tree
• Terry Erwin (British ecologist) estimates
that there may be over 30 million species
of insects on Earth, mostly in the rain
forest
Deforestation
• In 1950, over 10 percent of Earth’s land
surface was covered by rain forest.
• Now they only cover about 6 percent of
Earth’s surface and the area is decreasing
• This is due to the destruction of forest as a
result of human activity
– Main cause of destruction of rain forest is the
human population’s need for space and wood