Forest Biome Notes
Voc. List: domains, hardwood trees, nurse logs, seedling, emergent layer, canopy, epiphytes, understory
layer, shade-tolerant, buttresses, lianas, arboreal, deciduous forest, humus, dormant state, softwood
trees, cones, evergreens, needles, litter layer, migrate, permafrost
There are five main climate groupings or domains:
1. Tropical: The mean monthly temperature is at least 64OF (18oC) year round
2. Subtropical: The mean monthly temperature is at least 50oF (10oC) eight to nine months of the
year
3. Temperate: The mean monthly temperature is at least 50oF (10oC) for four to eight months out
of the year
4. Boreal: The mean monthly temperature is at least 50oF (10oC) for one to 4 months of the year
5. Polar: The mean monthly temperature is usually less than 50oF (10oC) all year long
U.S. Forest Regions: (Information from Project Learning Tree Exploring Environmental Issues: Focus on Forest p. 69)
1. Northeast: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New
Jersey, New York, Pennsylvania, Rhode Island, Vermont, West Virginia
2. North Central: Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, Wisconsin
3. Southeast: Florida, Georgia, North Carolina, South Carolina, Virginia
4. South Central: Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Oklahoma, Tennessee,
Texas
5. Great Plains: Kansas, Nebraska, North Dakota, South Dakota
6. Intermountain: Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming
7. Alaska: Alaska
8. Pacific Northwest: Oregon, Washington
9. Pacific Southwest: California, Hawaii
I.
Rain Forests (Tropical and Temperate)
Rain forest consists of Hardwood trees and the Tropical Rain forest has the most biodiversity of all
terrestrial biomes.
 Hardwood trees are produced by Angiosperm trees and have broad leaves.
o The leaves fall off during droughts and sporadic climate changes during the year in the
Rain Forest.
A. Tropical Rain Forests are generally located in the Tropical zone near the equator.
 As a result average temperatures are 25oC year round.
 Growing season is year round
 Lots of rain: 200-450 cm per year
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Limiting Factor: Soil nutrients are low in a few areas of the Rain Forest
Only 6% of the Earth’s surface is covered in Rain Forest but contains 50% of the world’s
plant life (biomass) and up to 70% of all terrestrial species -Most diverse biome in the
world
 Trees are the basis of the Rain forest
o 1000s of species of trees
Tropical Rain Forest has four layers
1. Emergent Layer –Consists of the tallest trees (60 to 70 meters in height)
a. These tree trunks can measure 5 meters
b. They receive direct sunlight
c. Examples of animals: monkeys, eagles, bats, and snakes
i. Tree –dwellers also called arboreal are organisms that never
touch the ground
The canopy is the primary layer of the rain forest and is split into two layers:
2. a.)Upper Canopy-The trees form a dense leave layer to absorb 95% of the
sunlight
o Most of the action of a Rain forest occurs in the trees especially in the
canopy.
b.)Lower Canopy-Below the Upper canopy and absorb less sunlight
a. Epiphytes such as orchids, and bromeliads, live entirely on the trunks of
limbs of trees, absorbing airborne nutrients and moisture on the lower
canopy
3. Understory-Very little sunlight reaches this layer.
a. Lots of smaller trees and shrubs adapt under this covered area and rarely
get taller than 3.5 meters.
i. Trees that are found in the understory receive very little light
and are called shade-tolerant. Since these trees get very little
sunlight they will not get tall
ii. Example: Hemlock
b. Decomposition and recycling occur very fast so the nutrients are in the
top 5cm of soil.
c. Because of the quick decamping and recycling tree trunks widen at their
bases, with ridges of wood called buttresses that support the trees
d. Woody vines called lianas grow up the sides of tree trunks to reach the
sunlight at the canopy
4. Forest Floor
B. Temperate Rain Forest
 Locations: Northwestern part of North America (Pacific coast south of Alaska) and Northern
part of South American there are four main types of trees: Douglas-Fir, Sitka Spruce, Western
Red Cedar, and Western Hemlock
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There height at maturity is between 130 to 280 feet tall.
Usually when Sitka Spruce fall to the forest floor it forms nurse logs.
 Young trees (seedlings) take root and grow on the top mossy surface of the
fallen tree.
o In California the Giant Redwood Trees are dominate and a lot taller
Temperate Rain forest experience the Temperate Zone temperatures –cooler than Tropical Rain
Forest
They only have three layers: Canopy, Understory, and Forest Floor
Rainfall is 60 -200 inches a year
Problems for Rain Forest areas: Deforestation, Habitat destruction, Illegal trapped exotic animals, and
Global warming
Helpful: Scientists have found secretions and plants themselves that are now being used to discover
new medicines especially in Tropical Rain Forest areas.
II.
Deciduous Forests (Temperate Forests)
The Deciduous forests also consist on hardwood tree with broad-leaf leaves that fall off the tree during
autumn. They also have the same amount of layers as the Temperate Rain Forest.
 The climate zone is temperate
 There are four well-defined seasons
 Summer temperatures can reach 30oC
 Winter temperatures can get to -30oC
 The growing season is roughly six months (Spring and Summer)
 A tree grows quickly and produces and stores large amounts of food by
photosynthesis
 During autumn there are cooler temperatures and shortening amounts of
daylight.
 Both these changes trigger the leaves fall to the ground
o It helps trees conserve water and prepare for winter-dormant
state
 Precipitation falls as rain or snow depending on the temperature and the season
 Range: 50-300 cm per year
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The leaves that fall quickly decompose enriching the soil
 The decaying leaves form a deep, rich layer of soil called humus
 The humus is home to many insects and other invertebrates that feed on the
material
 These areas have very rich soil and are fertile-great for farming
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Deciduous forests locations stretch out in parts of Europe (virtually gone now though), China, parts of
South America, Middle American Highlands, and Eastern United States
 Typically undergo succession including a pine stage
 Deciduous Forest species include: Many varieties of maple, oak, beech, hickory, ash, and birch
 Organisms include fungi and other decomposers, insects, invertebrates, birds, mice, small
mammals, deer, reptiles, and amphibians
 Predators include foxes, birds, mountain lions, and wolves
I.
II.
Specific types of Eastern North America Deciduous Forests
Northeastern forest
 South to the Mid Atlantic: Beech maple dominate
Mid Atlantic
 Down to Southern Appalachians: Oaks and Hickories dominate
Problems: Farms, orchards, and urban development are replacing the native deciduous forest of North
America and Europe
 Hardwood trees are great for building furniture and flooring and a great heat source
Limiting Factor: Temperature is not warm enough for a 12 month a year growing season (usually 6
months)
III.
Taiga {(Northern Coniferous Forests)-Boreal Forest}
Location-Regions of North America, Europe, and Asia just below the Arctic Circle
 Precipitation ranges: 40-200 cm-Least of the three types of forests
 Temperatures: Lowest temps of the three types of forests (Average temperatures are
below freezing and often fall to -20oC.)-Polar Zone
The word coniferous means cone-bearing
 So, in a Coniferous forest the trees produce cones
 The cones hold seeds of the tree
Most coniferous or conifers are also evergreens
 Evergreens are trees that do not lose all their leaves at the same time
 Exception-Bald Cypress loses its leaves in the Autumn
 Species include different types of pine, hemlock, fir, spruce, and cedar
 Usually only a few species of trees present
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Conifers have unique leaves called needles
 Needles are long, thin, thick, waxy green leaves that help the tree conserve water and
shed snow off of in the winter. –Needles can turn brown and drop to the ground
 A litter layer of needles are often deep, poorly decomposed, acidic, and often
poor in nutrients
 Mites and fungi decomposers are common in these litter layers
Conifers are generally narrow-shaped triangulars to help allow the snow to fall off the tree to prevent
damage to the tree structure.
 A lot of the trees lean because their roots are shallow due to permafrost-permanent
layer of ice and snow.
There are a few species with broad-leaf such as aspen and birch present along with other plants such as
ferns, lichen, and sphagnum moss that can be found in a Coniferous Forest
The taiga has many lakes and swamps that attract birds that eat insects, fish, or other aquatic organisms
in the summertime.
 Many birds migrate south in the winter to avoid harsh conditions.
Animals
Small herbivores include: mice, squirrels, and birds
 They feed on seeds and/or the bark of plants
Larger herbivores include: moose, elk, beaver, shrew (burrow underground), and snowshoe hares
(shred their brown hair in the winter for white fur to avoid predators-camouflage)
Predators include: grizzly bears, wolves, lynxes, and foxes
Limiting factors: Harsh winters (6-10 months), nutrient-poor soil, and short growing season (about 50
days depending on the latitude)
 The soil is poor and acidic because of the conifer needles
 Decomposition of materials is slow so nutrients have trouble getting into the soil
Problem: Logging –Soft wood trees are great for building materials
Specific Coniferous Forest
Boreal (northern) forest or Taiga (Russian for Coniferous)
 Four bands of communities include
1.) Forest/Tundra ecotone (stunted spruce, lichen, and moss)
2.) Open boreal woodland (lichen and black spruce)
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3.) Main Boreal forest (continuous conifers except early successional
communities of poplar and birch)
4.) Boreal/mixed forest ecotone (conifers grade into mixed hardwoods of
southern Canada and Northern USA)
Southern Pine Forest
 Located on coastal plains
 Nutrient poor
 Well-drained coastal sands
 Fire adapted: Some seeds germinate after fire, others simply benefit from more sun
 Located as far North as the NJ Pine barrens: Dwarfed Pitch Pine and Blackjack Oak
 It takes 20 years for a forest to grow to maturity –A Loblolly Pine grows 18 meters
tall and 20 cm in diameter-heavily timbered
Fire Ecology (see separate handout)
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