Download 2011 Ecology training notes

20ll ECOLOGY
(B
& C) - Training Handout
Ecology Event:
Ecology Content
General Principles of Ecology (about 50%)
o Ecological Principles applied to North American Prairies and Taiga (about 50%)
Process skills - in data, graph and diagram analysis
Event parameters - be sure to check the event pararneterc in the rules for resources allowed.
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Part I: General Principles of Ecology
General Principles of Ecologlt:
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Ecology and the abiotic environment
. ecology - introduction and terms
o ecology : how organisms interact with one another and with their environment
o environment = biotic (other organisms) and abiotic ( physical factors)
. natural selection - adaptation
. soils and nutrients
. climate
Ecology of individual organisms
. physiologicalecology
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temperature and water balance
light and biological cycles
physiological ecology and conservation
Ecology of populations - group of individuals of the same species occupying a common
geographical area
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patterns of distribution and density
intraspecific competition
population dynamics
population growth and regulation
altering population growth
human impact
Ecological interactions among species
. interactions
' competitive interactions - interspecific competition, competitive exclusion, resource
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properties of populations
partitioning
predation
exploitation
symbiosis - mutualism, parasitism, conlmensalism, amensalism
Ecology of communities - two or more populations of different species occupying the same
geographical area
. closed vs. open communities
. species abundance and diversity
I concept ofthe ecosystem
r trophic structure of communities
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food webs and food chains
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Ecology of ecosystems,-. a community plus its abiotic factors, e.g. soil, rain, temperatures, etc
r energy flow within ecosystems - energy-flow and bio-mass pyramids
r community succession and stability
. nutrient recycling - biogeochemical cycles
Biomes - weather and climate
'. terrestrial biomes - fundra, taiga, temperate forest, grassland, desert, tropical forest
aquatic biomes - marine, freshwater
Biomes for 09 - North American
r Grasslands(Prairies)
. Deserts
Biosphere - the portion of the earth that contains living species. It includes the atmosphere,
oceans, soils and the physical and biological cycles that affect them
Review of Ecology Principles:
Ecology : the systematic study of how organisms interact with one another and with their
environment
Environment consists of both a living component, the biotic environment (other
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organisms)
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soil,
and a non-living component, the abiotic environment, e.g. physical factors such
rainfall, sunlight, temperafures
Ecology is an extremely complex and very diverse subject and it includes a variety of
disciplines in addition to biology, e.g. geology, chemistry, physics, meteorology, and
mathematics
Four levels of ecological organization:
o Population - group of individuals of the same species occupying a common geographical area
o Community - trvo or more populations of different species occupying the same geographical
area Populations and communities include only biotic factors
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Ecosystem - a community plus its abiotic factors, e.g. soil, rain, temperatures, etc.
Biosphere - the portion of the earth that contains living species. It includes the atmosphere,
oceans, soils and the physical and biological cycles that affect them
Ecologt of Populations
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Population Ecology
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the study of how populations interact with their environment
Population: group of individuals of the same species occupying
a common geographical area
Habitat - where a species normally lives
Characteristics of populations - Each population has certain characteristics:
o Population size: number of individuals making up its gene pool
o Population density : number of individuals per unit of area or volume, e.g.
o persons/square mile
o Population distribution : the general pattern in which the population members are dispersed
through its habitat, may be: clumped (most common), undormly dispersed (rare.;, or
Randomly dispersed
o Age structure defines the relative proportions of individuals of each age: pre-reproductive,
Reprod uctive, and Po st-reproductive
o Population size and growth
o Population size is dependent on births, immigration, deaths, and emigration
t zero population growth designates a near balance of births and deaths
o Exponential growth: If birth and death rates of a population remain constant they can be
combined into one variable r: netreproduction per individual per unit time (rate of increase)
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Population growth may be represented mathematically as: G = rN Where G: population
growth per unit time, r : rate of increase and N: the number of individuals. When plotted
against time a graph in the shape of a J will be obtained denoting exponential growth, i.e. one
variable increases much faster than the other
As long as per capitabirth rates remain even slightly above per capita death rates, a population
will grow exponentially - with ever-increasing rates and shorted "doubling times"
It took 2 million years for the world's human population to reach 1 billion, yet it took only 12
years to reach the fifth billion
If a population lives under ideal conditions it may display its biotic potential - the maximum
rate of increase under ideal conditions. Few populations live under ideal conditions because a
number of factors limit their growth
Limiting factor - any resource that is in short supply, e.g. food, minerals, light, living space,
refuge from predators, etc.
Carrying capacity : maximum number of individuals of a species or population a given
environment can sustain. Each habitat or area can only support so many individuals
Because of limiting factors populations rarely exhibit J shaped growth curyes
Logistic growth
Early on populations will exhibit very rapid growth but as they near the carrying capacity they
will level off is called logistic growth and it produces an s shaped curve
Logistic growth is density dependent, i.e. the growth is affected by the density of individuals.
For example - 26 rerndeer were introduced onto an island off the coast of Alaska in 1910.
Within 30 years the herd increased to 2,000. However, overgrazing reduced the food supply
and the population crashed to 8 animals by 1950
High density and overcrowding put individuals at greater risk of being killed, e.g. predators,
parasites and pathogens have greater numbers of prey and hosts in a smaller area to interact
Bubonic plague swept through Europe in the 14th century, killing at least 25 million. The
disease spread rapidly in overcrowded cities where sanitary conditions were poor and rats were
abundant
Population size and growth may also be controlled by density-independent factors, e.g.
adverse weather, floods, droughts, cold temperatures
Life history patterns
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Not all individuals in a population are the same age.
Different populations may have very different age structures and these will determine their
growth patterns
Age structure refers to the proportions of pre-reproductive, reproductive and post- reproductive
age individuals in a population. The age structure of a population will determine its future
Each species has a characteristic life span and the probability of dying increases with age
Population ecologists, as well as insurance companies track cohorts and construct life tables
for populations
Cohort = a group of individuals born at the same time, e.g. baby boomers are a large group of
individuals born just after World War II
A life table is an age-specific death schedule. Such a schedule is often converted to a more
palatable survivorship schedule. For each age interval there is an predicted life expectancy or
survivorship
Ecologists divide populations into age classes and assign birth rates and mortality risks to each
class. Absolute population numbers mean very little unless their age structure is known
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For example, population A might have many more members than population However, all the
members of A might be post-reproductive, whereas population B might consist of mostly prereproductive and reproductive age individuals. Population A might be in danger of extinction.
Life historv stratesies
o r-selected organisms - put most of their energy into rapid growth and reproduction. This is
common of organisms that occupy unpredictable environments, e.g. weeds are usually annuals
with rapid growth and early reproduction. They produce large number of seeds containing few
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stored nutrients
K-selected organisms - put most of their energy into growth. They are common in stable
environments near carrying capacity, e .g. long lived trees such as redwoods take many years
growth to reach reproductive age
E cology
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of Communities :
Communitv: two or more
populations of different species occupying the same
geographical
area
o Community Ecology = the study of how different species interact within communities
o Habitat: the physical place where an organism lives, e.g. a pine forest or fresh water lake
o Some organisms, particularly migratory birds require more than one habitat
o Niche : the functional role of an organism in a community, its job or position
o Each species has a potential niche - what they could do with no competitors or resource
limitations but due to competition and/or resource limitations, most organisms occupy a
realized niche, the part of the fundamental niche that a species actually occupies in nature
Snecies interactions
o Neutral - two species that don't interact at all
o Commensalism - beneficial to one species but neutral to another, e.g. birds that nest in trees,
epiphytes (plants that grow on other plants) such as tropical orchids
o Mutualism - an interaction that is beneficial to both species, e.g. plants and their pollinators,
plants and animals that disperse their seeds, certain fungi and plant roots
o Parasitism - an interaction that benefits one species and is detrimental to another. Note that the
host is generally not killed.
o Predation - an interaction beneficial to one species and detrimental to another. In this case the
prey is killed. Predators are those that kill and eat other animals. Although many organisms eat
plants they usually don't kill them because they are a constant supply of food. Prey are killed
and eaten.
Competitive interactions
o Competition has negative effect on both organisms competing for a resource
o Because resources are limited in nature there will always be competition for them
o Competition is the driving force of evolution, those that win leave more offspring
o Types of competition:
I Intraspecific - competition among individuals of the same species, e.g. humans compete
against other humans
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Interspecific - competition between different species, e.g. humans compete against a wide
variety ofspecies seeking to utilize our food resources
The theory of competitive exclusion maintains that species who utilize the same resources
cannot coexist indefinitely - the "one niche, one species" concept
resource partitioning - the resources are divided, permitting species with similar
requrrements to use the same resources in different areas, ways and/or times
Communitv stabilitv
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Communities are assemblages of many different species occupying the same geographical area
Communities are not static, they gradually change over time because the environment changes
and species themselves tend to also change their habitats
Ecologt of Ecosystems :
Ecosvstem: a community of organisms interacting within apartrcularphysical environment
or an ecosystem is a community plus its abiotic factors, e.g. soil, rain, temperatures, etc. Virtually
all energy on earth comes from the sun, via photoautotrophs (primarily piants), and it is
ultimately distributed throughout ecosystems.
o Primary producers are the autotrophs
o All other organisms are consumers Consumers which eat plants are called herbivores
r Consumers which eat animals are called carnivores Organisms such as humans, which eat
both plants and animals, are called omnivores
o DecomPosers, which includes fungi and bacteria, obtain their energy by breaking down the
relnalns or products of organisms
o Detritivores are decomposers which eat detritus - organic wastes and dead organisms
Structure of ecggyglq
EnergY flows through ecosystems via food webs, intricate pathways of energy flow and
material cycling
o Ecosystems are arranged by trophic (feeding) levels between various producers, the
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autotrophs, and consumers, the heterotrophs:
First trophic level - contains the autotrophs which build energy containing molecules
They also absorb nitrogen, phosphorous, sulfur and other molecules necessary for life
They provide both an energy-fixation base as well as the nutrient-concentration base for
ecosystems
Two types of autotrophs: Photoautotrophs - plants and some protista
Chemoautotrophs - bacteria
Second trophic level - contains the primary consumers which eat the primary producers
includittg herbivores, decomposers and detritivores, e.g. insects, grasshoppers, deer and
wildebeest
Third trophic level - contains the second ary consumers, primary carnivores which eat the
herbivores, e.g. mice, spiders and many birds
tr'ourth trophic level - contains the tertiary consumers, secondary carnivores who eat the
primary carnivores, e.g. weasel, owl, sharks and wolves.
Linear food chains as described above are probably rare in nature because the same food
source may be part of several interwoven food chains and many organisms have several food
sources
Energv flow though ecosvstems
o Gross primary productivity: the rate at which the primary producers capture and store
energy per unit time since the primary producers expend energy during respiration the net
primary productivity is considerably lower than the gross productivity
o Productivity is usually measured as biomass (dry weight of organic matter) per unit arcaper a
specified time interval, e.g kg/m2/yr
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The trophic structure of an ecosystem is often represented by an ecological pyramid, with the
primary producers at the base and the other levels above
Most of the food eaten by organisms is converted to biomass, or used to maintain metabolic
functions, or lost as heat, only about 107o of the energy makes it to the next level This massive
energy loss between trophic levels explains why food chains can't contain more than a few
levels It takes billions of primary producers (plants) to support millions of primary consumers,
which support a few secondary consumers. This is why there are so few large carnivores on
earth
An energy pyramid is a more useful way to depict an ecosystem's trophic structure
Each block of the pyramid is proportional to the amount of energy it contains
Pyramids may also represent biomass or numbers of individuals
The energy pyramid concept helps explain the phenomenon of biological magnification - the
tendency for toxic substances to increase in concentration at progressively higher levels ofthe
food chain
Ecological succession
through time
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a directional, cumulative change in the species that occupy a given area,
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Primary succession - starts from barren ground, e.g. new islands or de-glaciated
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Succession starts with a pioneer community, the first organisms to occupy an af,ea
Several transitional communities may come and go
A climax community, a stable, self-perpetuating anay of species in equilibrium with one
another and their habitat, will form
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Secondary succession - starts from disturbed areas, e.g. abandoned farm land or storm ravaged
land
Biodiversitv - Biodiversity, the number of different species within arr area, is greatest in tropical
areas near the equator and it decreases towards the poles
o Tropical areas have more sunlight and of greater intensity, more rainfall and longer growing
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seasons for plants
This environment is quite stable and contains many vertical "layers" which provide more
microhabitats
These areas can support more species, e.g. the number of bird species is directly correlated with
latitude
Weather and climate
r Biome : alarge region of land characterized by the climax vegetation of the ecosystems within
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its boundaries
The distribution and key features of biomes are the outcome of temperatures, soils and moisture
levels (which vary with latitude and altitude), and evolutionary history
Weather : the condition of the atmosphere at any given time
Climate : the accumulation of weather events over a long period of time (temperatures,
humidity, wind, cloud cover, rainfall)
o Climate is dependent upon several factors:
. Solar radiation
. The earth's daily rotation
. The earth's rotation around the sun
. The distributions of continents and oceans
Elevation Heat energy from the sun drives the earth's weather systems, which ultimately
determine the composition of ecosystems
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Part Ir: North American Biomes
- Tundra and raiga
Ecological Principles applied to North American Biomes
Abiotic Fators of Biomes
Biotic Features of Biomes
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C haracte ris tic s
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Organisms
Not intended to be a taxonomic event
Emphasis on adaptations of common plants and animals of each biome
Common members of food chains and food webs of each biome
Limiting factors of each biome
T un dras
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Extremely cold climate
Low biotic diversity
Simple vegetation structure
Limitation of drainage
Short season of growth and reproduction
Energy and nutrients in the form of dead organic material
Large population oscillations
The tundra is divided into two types:
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Arctic
Arctic tundra is located in the northern hemisphere, encircling the north pole and
extending south to the coniferous forests of the taiga. The arctic is known for its cold,
desert-like conditions. The growing season ranges from 50 to 60 days. The average
winter temperature is -34o C (-30" F), but the average summer temperature is 3-l2o C
(37-54'F) which enables this biome to sustain life. Rainfall may vary in different regions
of the arctic. Yearly precipitation, including melting snow, is 15 to 25 cm(6 to l0
inches). Soil is formed slowly. A layer of permanently frozen subsoil called permafrost
exists, consisting mostly of gravel and finer material. When water saturates the upper
surface, bogs and ponds may form, providing moisture for plants. There are no diip root
systems in the vegetation of the arctic tundra, however, there are still a wide variety of
plants that are able to resist the cold climate. There are about 1,700 kinds of plants in the
arctic and subarctic, and these include:
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low shrubs, sedges, reindeer mosses, liverworts, and grasses
400 varieties of flowers
crustose and foliose lichen
All of the plants
are adapted to sweeping winds and disturbances of the soil. plants are
short and group together to resist the cold temperatures and are protected by the snow
during the winter. They can carry out photosynthesis at low temperatures and low light
intensities. The growing seasons are short and most plants reproduce by budding and
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division rather than sexually by flowering. The fauna in the arctic is also diverse:
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Herbivorous mammals: lemmings, voles, caribou, arctic hares and squirrels
Carnivorous mammals: arctic foxes, wolves, and polar bears
Migratory birds: ravens, snow buntings, falcons, loons, ravens, sandpipers, terns,
snow birds, and various species of gulls
Insects: mosquitoes, flies, moths, grasshoppers, blackflies and arctic bumble bees
Fish: cod, flatfish, salmon, and trout
Animals are adapted to handle long, cold winters and to breed and raise young quickly in
the summer. Animals such as mammals and birds also have additional insulati,on from
fat. Many animals hibemate during the winter because food is not abundant. Another
alternative is to migrate south in the winter, like birds do. Reptiles and amphibians are
few or absent because of the extremely cold temperatures. Because of conitant
immigration and emigration, the population continually oscilates.
Alpine
Alpine tundra is located on mountains throughout the world at high altitude where trees
cannot grow. The growing season is approximately 180 days. The nighttime temperature
is usually below freezing. Unlike the arctic tundra, the soil in the alpine is well drained.
The plants are very similar to those of the arctic ones and include:
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tussock grasses, dwarf trees, small-leafed shrubs, and heaths
Animals living in the alpine tundra are also well adapted:
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Mammals: pikas, marrnots, mountain goats, sheep, elk
Birds: grouselike birds
Insects: springtails, beetles, grasshoppers, butterfl ies
Types of Plants and Their Adaptations
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Most tundra plants are perennials-they spend several years gathering and storing nutrients
between each episode of seed production. Many can reproduce by sending nrnners
through the soil, sprouting new plants at the nodes. This is less costly than blooming and
producing seeds and fruits.
Heat Efficient - To deal with cool summers, the flowers of Arctic dryad and Arctic poppy
revolve slowly throughout the long days, catching the sun's rays like tiny satellite dishesProtective Covering - Some plants, such as wooly lousewort, protect themselves from
wind, desiccation, and cold by growing thick "fur" that is made up of thousands of tiny,
curly hairs.
Nutrition - Some tundra plants, such as Labrador tea and Arctic dryad, retain old leaves
rather than dropping them. This conserves nutrients and helps protect the plant from cold,
windscour, and desiccation. Other plants, such as Kamchatka rhododendron. achieve
extra protection by growing in dense mats or cushions.
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Evolution for Survival - Some tundra plants, such as arctic birch, are considerably
tougher than their non-tundra relatives, and are able to survive in harsher conditions.
They have also evolved a prostrate growth form, enjoying the extra warmth trapped in the
boundary layerjust above the ground surface.
Types of Animals and Their Adaptations
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Some animals migrate.
Warm winter coats - Many mammals have specialized coats to ward off the winter cold.
Caribou have hollow hairs that trap warmth close to their bodies. Muskoxen are so well
insulated with underfur that they have little trouble with cold, even in the fiercest
blizzards.
Heat-efficient body shape - Since bodies with long legs, ears, and tails lose warmth faster
than those with shorter limbs, many arctic animals, such as arctic fox and arctic hare,
have evolved more compact bodies than their southerly counterparts to better conserve
heat.
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Growth and reproduction - Many tundra animals grow more slowly, and reproduce less
frequently, than do their non-tundra relatives. Tundra-dwelling lake trout may take ten
years to reach maturity, compared to six years for those in more southern regions.
Camouflage - Arctic fox and ptarmigan, along with arctic hare and ermine, are
camouflaged according to the season, changing from winter white to summer brown, and
back again, each year.
Hibernation - Two tundra animals-arctic ground squirrel and grizzly bear-hibernate
(spend the winter in a state of deep dormancy, where heartbeat and respiration slow) to
escape the hardships of winter.
Snow as insulation - Small mammals, such as tundra voles, lemmings, ermine, and
shrews can't hibernate. Instead, they rely on the snow layer to insulate their tunnels and
nests. In some places, snow insulation is so good that tundra-dwelling lemmings are able
to breed in the winter.
Consemation Concerns
for T undra
The Arctic tundra is the least exploited of Earth's biomes. It is a unique biological laboratory for
scientists to study unaltered ecosystems. The chief ecological concerns in the Arctic tundra are
cumulative impacts of oil and mineral exploitation, roads, tourism, and long-range transport of
air pollution from industrial centers to the south. Global warming is likely to have its greatest
effect on tundra. Major concems are the fate of permafrost and the carbon contained in Arctic
peat. Decomposition of this carbon could increase the concentration of carbon dioxide in the
atmosphere.
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Charucteristics of Tuigu (Coniferous or Boreul Forests)
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2"d largest forest in the world
Ring Artic between Artic and Deciduous Forest - 50 to 60
degrees North Latitude
Upper elevations of Mountains
Angle of incidence for incoming solar rudtatton is low and
twilight lasts many hours
Seasons are divided into short, moist and moderately waffn
summers and long, cold, dry winters.
Temperature - vary greatly from summer to winter (-65 to +70
degrees Fahrenheit)
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Variable precipitation: 6-40 in ( 15- 100 cm).
Soils - thin because they were scraped by glaciers and
very acid because of decomposition of pine needles
Absence of earth-churning invertebrates as earthwoffns so soil is hard and compact
Fire a major factor in maintaining biome
Environmental importance of the Taiga
Filters millions of liters of water
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Stores large amounts of carbon
Produces oxygen
Rebuilds soils and restores nutrients
Bogs and marshes provides habitats for large numbers of species from fish to birds
Types of Plants
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Conifers are major producer
Most common fypes - spruce, balsam fir and pine
Others - hemlock, cedar, redwood, junipers
Latitude and altitude influences specles
Berry-producing shrubs import ant to birds, marnmals and people
Some types of fungi, lichens, and mosses
Plant Adaptations
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Trees have upside down cone shape so snow slides offthe branches
Branches are flexible to hold great amounts of snow and not break
Trees grow thin and close together to protect them from cold and wind
Needles waxy for protection from freezing temperatures and prevent them from drying out
Needles are present year round and deep green to absorb the maximum warmth from the sun
Thick bark which does not easily burn and protects inner layers from heat and cones protect
the seeds
Types of Animals
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- millions of insects in the summer herp to feed the migration
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- to 3 billion insect-eating birds breed each year in Taiga-over 200 species
Seed eaters like finches and sparrows as well as omnivorous birds as crows stay all year
Crossbill has specializedbill for prying open cones and nuthatch can break the cones open
Herbivores as small mammals, snowshoe rabbits, red squirrels, voles and lemming
Insects
birds
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Predators feeding on small mammals as owls, wolves, lynx, bobcats, minks, wolverines,
weasels, mink, otters, martens, fishers
Deer. elk and moose
Largest predators as grizzlies, lynx, and mountain lions will also feed on weakened
or young deer, elk or moose
Animal Adaptations -for very long cold winters and short warm surnmers
. migrate south in winter (birds)
. go into hibernation during wrnter
. store extra fat layers on their bodies for winter
. change diets from season to season
o $row extra fur on the bottom of their feet to tread on snow easier (lynx and snowshoe rabbit)
. change fur color and coat thickness from season to season
. live under snow in winter in snow tunnels (lemmings, mice, shrews, voles)
Conservation Concerns for Taiga (Boreal forest)
Pollution - chemical waste, mining, hydroelectric development
Clear cutting - trees are cut in large sections leaving no protection for wildlife or soil
2.5 million acres are harvested per yeaf, with2l3 going for newspapers promotional mailings
and catalogs - which end up in landfills
r Illegal logging - logging in national parks and other protected areas without government
permission
r Poaching - hunting and frshing out of season, on protected land, or to endangered species
o Forest fires - unnatural fires caused by careless humans.
o Mining - can destroy wildlife habitat
o Drilling for oil and natural gas disrupt the forest
r Global warming
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Role of Taiga in regulating the Earth's climate
o It stores large quantities of carbon stored as plant material on forest floor (up to 10 feet in some
areas
. I cm of plant material can hold 2.5 tons of carbon per acre
. Taiga acts like alarge refrigerator preventing fallen trees, needles and other debris from
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decomposing (decomposition would put carbon dioxide into the atmosphere)
Heating up the taiga is causing the following problems
Litter begins to decompose putting carbon into the atrnosphere
Increases in forest fires
Infestation by bark beetles which is killing the trees and forming tinder to fuel the forest
fires and adding more carbon dioxide into the atmosphere
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