Introducing the Planet:
The Earth Before Humans
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Climate and Weather
Ecosystems and Eco-regions
Biodiversity
Climate and Weather
• Lands near the equator are, on average, warmer. Closer to either pole
and the earth is colder.
• High elevation locations are much colder than lower elevations. These
areas also receive more precipitation.
• Locations at high latitudes have extreme seasonality. Near the equator
there are no seasons.
• Middle latitude areas (30-60 degrees N or S) are characterized by
moderate temperatures, but they experience seasons and storms
associated with conflicts between cold and warm air masses.
• 20% of the earth is covered with snow.
• 30% of the earth is arid or desert.
• Water is constantly changing states, storing and releasing huge
amounts of energy, via evaporation, condensation, and freezing.
Earth From Space
Earth From Space (click for latest image)
World Precipitation
Climate Regions
World Climates
Selected World
Climographs
A
Tropical Wet, hot equatorial regions, that cover about a third
of Earth’s surface. Rains nearly every day. No or little
seasonality. Precipitation around 80-100” annually. Frequent
thunderstorms. Hurricanes.
B
Dry Arid and semi-arid deserts and steppes; evaporation
exceeds precipitation. U.S. example: Albuquerque, New Mexico
(annual precipitation, 22 cm [9 inches]). Rain falls as infrequent,
but powerful, summer thunderstorms.
C
Mesothermal Humid subtropical, may have dry summers.
Warmest month above 10oC (50oF); coldest month above 0oC
(32oF) but below 18oC (64oF). U.S. example, New Orleans,
Louisiana. Mid-latitude storms and thunderstorms common.
D
Microthermal Humid climate with long winters, mild
summers. Warmest month above 10oC (50oF); coldest month
below 0oC (32oF). U.S. example, Flint, Michigan. Most rain falls
in mid-latitude frontal storms.
E Polar No true summer, warmest month average temperatures
below 10oC (50oF); always cold. U.S. example, Barrow, northern
Alaska. Very short growing season. No thunderstorms.
H Highland Lower temperatures and more precipitation. U.S.
example, Blue Canyon, Sierra Nevada, California (annual
precipitation, 170 cm [68 inches]). Very short growing season.
Vegetation Regions
Biomes (Ecosystems)
http://www.untamedscience.com/biology/world-biomes
A biome is a major class of ecologically similar communities of
plants, animals, and soil organisms, often referred to as
ecosystems. Biomes are defined based on factors such as plant
structures (such as trees, shrubs, and grasses), leaf types (such as
broadleaf and needleleaf), plant spacing (forest, woodland,
savanna), and other factors like climate. Biomes are often
identified with particular patterns of ecological succession and
climax vegetation.
Boreal Forest (Taiga)
Tropical Savanna
World Biomes
(Click title for photographs and descriptions)
Tropical Rainforest (Af)
• High rainfall all year (>2” /
month)
• Warm every month
• Precipitation exceeds
evaporation.
• Straddles Equator by 5o - 10o
Tropical Climates (A)
Tropical Climates (A)
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•
•
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1/3 of Earth’s total surface (about 20 ºN to 20 ºS)
Consistently warm (all months > 18ºC/64.4 ºF)
Daily temp range exceeds annual temp range
Subcategories based on rainfall (ITCZ influence)
Subcategories based on
rainfall distribution:
• Tropical rainforest (Af)
• Tropical savanna (Aw)
Tropical Rainforest (Af)
• High rainfall all year (>2” /
month)
• Warm every month
• Precipitation exceeds
evaporation.
• Straddles Equator by 5o - 10o
Tropical Rainforest (Af)
– Vegetation : Highest average biomass on earth.
Highest biodiversity on earth! Thousands of species, tall
trees, many canopy layers, evergreen, broadleaf trees, epiphytes,
lianas (vines), climbers, stranglers, ferns
– Fauna: More species than all other biomes combined!, colorful
insects, amphibians, reptiles, and birds, few large animals, high
density of biomass and incredible species diversity
• Other: Among most threatened biomes
Lianas
Epiphytes
Buttresses
Deforestation, Malaysia
Strangler Fig
3-Toed Sloth, Panama
Savanna (Aw) – Tropical Grassland Climates
• The tropical wet and dry or savanna (Aw)
has an extended dry season during winter.
• Region/Distribution: Subequatorial Africa,
and South America, Southern India (25° N
and S Latitude)
• Vegetation: Continuous cover of grasses,
scattered trees or shrubs
Masai Reserve, Kenya
• Other: Susceptible to desertification
Acacia and Wildebeest
Serengeti Plain, Tanzania
Dry / Semiarid Climates (B)
• Occupy about 1/3 of Earth’s land area
(Most extensive climate over land surface)
• Evaporation exceeds precipitation
(water deficit)
• Subcategories
– Desert (BW)
– Steppe (BS)
Deserts (BW): dry
Deserts (BW):
Temperature:
• Widest range: up to 100oF/day!
• Hot at low latitudes, wide
variation at higher latitudes
Precipitation:
• Scarce: <10 inches/year
• Unreliable: wide variation
from average
• Intense: convective downpours
Desert Causation:
• High Pressure Cells and
resultant stability
• Rainshadows
True Deserts (BW)
• Vegetation: Widely scattered thorny bushes,
cacti, small flowers, extensive shallow roots
or long tap roots, shrubs, succulents
• Fauna: Many rodents, lizards, toads, snakes
and other reptiles, many birds, owls,
vultures, many insects (adaptive strategies)
• Other: Deserts cover roughly 1/3 of earth.
May be growing due to desertification.
• Steppe: semi-arid high elevation or high
latitude
Desert Plant Survival Strategies
 schlerophyllous adaptations
- small, waxy leaves or thorns
replace leaves
 succulents - stems modified
to spongy water storage
structures
 ephemerals (obligate seeders)
- fast reproductive cycle
 wide spacing with shallow
roots - collect sparse rainfall
Organ Pipe Cactus
Organ Pipe National Monument, Arizona
Steppe (BS): temperate grasslands
• more precipitation than BW
• narrower temperature ranges
• grasslands
Temperate Grassland/Steppe (BS)
• Region/Distribution: Central North America, parts
of Africa, Australia, SE South America (Pampas)
• Soil: very fertile soils, best on earth
• Vegetation: Grass tall to short prairie, pampas,
steppe. Sod forming grasses, Sparse bushes,
occasional trees in some areas
• Fauna: large grazing animals, bison, antelope, wild
horses, kangaroos, giraffes, burrowing animals:
rabbits, prairies dogs…; predators: coyotes, lions,
leopards…...
• Other: Most N. American grasslands have been
converted to agricultural fields. Wild grazers replaced
by cattle, sheep, goats. Less than 1% of original grasses
left.
Mesothermal Climates/Temperate (C)
• True seasonality
(air mass conflict)
• Subdivisions based on
precipitation variation
– Humid Subtropical
(Cfa)
– Mediterranean (Cs)
Humid Subtropical
Broad-leaf Deciduous Forest
Allegheny Mtns., Pennsylvania
Mediterranean Coastal Sage Scrubland
Channel Islands N.P., California
Mesothermal Climates (C)
Humid Subtropical (Cfa)
Mediterranean (Cs)
Subtropical Forest
Sarasota, Florida
• Hot summer, substantial
Humid Subtropical year-round precipitation
• Low latitude east coasts
Midlatitude Forests
(warm currents).
• Summer max precipitation.
• Cold spells; seasonality.
Cfa - New Orleans, LA
Temperate Broad-leafed Forest (Deciduous)
• Region/Distribution: Western Europe, East Asia,
Eastern U.S.. Between 30-50° north or south
• Soil: brown soils, good for agriculture
• Vegetation: Broad-leafed deciduous trees, (120150’ tall), oaks, hickories, maples, …
• Fauna: mammals such as white tail deer,
porcupines, raccoons, rabbits, squirrels, most
carnivores eliminated by hunting i.e. wolf,
mountain lion, bobcat; many birds; frogs and
salamanders, snakes
• Other: Plants and animals well adapted to
seasonality including hibernation, migration
Mediterranean
• Dry summers (shifting
subtropical highs)
• Surrounds Mediterranean
• Also on west coasts near 30o N
and S (Australia, S. Africa,
Chile)
Mediterranean
• Region/Distribution: West coast and Central
California, SW. Australia, tip of S. Africa, West
Peru. Chile, Mediterranean (good wine places!)
• Vegetation: Scrubland, scattered trees (oaks,
eucalyptus), grasses. Fire tolerant, sclerophyllous
(hard-leafed) evergreens, chaparral (scrubby
evergreen)
• Fauna: Burrowers like ground squirrels, gophers;
deer, mountain lions, coyotes, many birds
• Other: Susceptible to fire during dry season, some
species need fire to regenerate; susceptible to
erosion and desertification, development;
threatened biome
Chaparral
Manzanita
Microthermal Climates (D)
Only found in Northern
Hemisphere
• 50o-70o N latitude
• long, bitterly cold winters
• highest annual temp range: up to
100O F
•Great annual temperature ranges
(continentality, air mass conflicts)
Dw – Calgary, Canada
Coniferous (Boreal) Forest – Koppen D
• Region/Distribution: Northern parts of
North America, Europe and Asia, South So.
America, much of Russia
• Vegetation: Coniferous (mostly evergreen)
forest, ex. Spruce, Fir, Pine, Larch, needleleaved
• Fauna: Large herbivores: moose, elk; small
herbivores: squirrels snowshoe hare, beaver;
Predators: wolves, foxes, bears, lynx, weasel
family; Mosquitoes in summer
• Other: Acid rain, logging , oil drilling,
hunting of predators
Fir Trees, Alaska
Spruce Needles
British Columbia
Polar Climates (E)
- all months < 50OF
Polar Climates (E)
- all months < 50OF
• Tundra (ET)
– warmest month 32-50F
• Ice caps (EF)
– warmest month below 32F
• Both have very low precipitation
Koppen Classification: ET
Vertical Zonation of Vegetation
Vegetation Succession
Pioneer Stage
Climax Stage
Occurs after disturbances: fires, storms,
landslides, etc.
Vegetation Succession
Riparian Vegetation
Vegetation that
grows along
water courses.
Often supports
much richer
diversity of plant
and animal life,
including more
trees in a dry
environment.
Sespe Wilderness near Ojai, CA
Ecosystems:
Food Chains
Energy flows up
the chain as
more and more
heat is lost at
each trophic
level.
Ecosystems: Food Web
“Now when you cut a
forest, an ancient forest in
particular, you are not just
removing a lot of big trees
and a few birds fluttering
around in the canopy. You
are drastically imperiling a
vast array of species within
a few square miles of you.
The number of these
species may go to tens of
thousands. ... Many of
them are still unknown to
science, and science has
not yet discovered the key
role undoubtedly played in
the maintenance of that
ecosystem, as in the case
of fungi, microorganisms,
and many of the insects.”
(E. O. Wilson, 2000)
Biodiversity
Biodiversity refers to diveristy of
1.
Species
2.
Habitats
3.
Genetic Diversity (within a species)
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Scientists estimate that upwards of 10 million—
and some suggest more than 100 million—different
species inhabit the Earth. Each is uniquely adapted
to a particular habitat.
Scientists have discovered and named only 1.75
million species—less than 20 percent of those
estimated to exist.
Taxonomic Categories
% of Genera Extinct in Period
Mass Extinctions
Millions of Years Before Present
Source: Rohde, R.A. & Muller, R.A. (2005). "Cycles in fossil
diversity". Nature 434: 209-210.
Mass Extinctions
- The Sixth Extinction
Biodiversity loss and species
extinction
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Extinction = last member of a species dies and the
species vanishes forever from Earth
Extirpation = disappearance of a particular population,
but not the entire species globally. This is still a loss of
biodiversity and ecosystem stability.
These are natural processes.
On average approximately one species per million
goes extinct naturally in a year. This is called the
background rate of extinction. Today it’s estimated
that somewhere between 100 and 1000 per million
become extinct each year.
99% of all species that ever lived are now extinct, but in
general more species evolve over time than go extinct.
There were more species on Earth at the beginning of
civilization than the Earth had ever had before.
Today’s mass extinction
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Currently Earth is about to experience its sixth mass
extinction – this time because of humanity.
Humans have increased the extinction rate by a
factor of somewhere between 100 and 1,000!
1,100 species are known to have gone extinct in the
past 400 years.
The Red List, from the IUCN, lists species that today
are facing high risks of extinction. The total number
of known threatened species is currently above
10,500. Over 3,300 of these are vertebrates!
Today’s Population Reductions and
Mass Threats = Tomorrow’s Mass
Extinction Event
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Numbers of of
large mammals
and birds
plummeted with
the arrival of
humans,
independently, on
each of three
continents—
suggesting that
human hunting
was the cause.
Figure 15.9
Causes of species extinction
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Primary causes spell “HIPPO”:
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Habitat alteration
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Invasive species
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Pollution
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Population growth
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Overexploitation
“HIPPO”: Habitat alteration
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The greatest cause of extinction today
Accounts for 85% of population declines of birds
and mammals
Habitat change hurts most organisms because
they are adapted to an existing habitat.
Alteration due to:
Forest clearing
Urban development
Agriculture
etc….
Global climate change
“HIPPO”: Invasive species
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Accidental or intentional introduction of
exotic species to new areas
Most do not establish or expand, but
some do—likely because they are
“released” from limitations imposed by
their native predators, parasites, and
competitors.
In today’s globalizing world,
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invasive species have become perhaps the
secondworst threat to native biota.
“HIPPO”: Invasive species (USDA Invasive Info Center)
• Mosquito fish
(Australia from SE
U.S.)
• Zebra mussel
(U.S. from Asia)
• Kudzu (U.S. from
Asia)
• Asian long-horned
beetle (U.S. from
China)
• Rosy wolfsnail
(Hawaii from U.S.
Mainland)
• Cane toad
(Australia)
• Bullfrog (United
States from U.S.)
•Gypsy moth
(United States
from Europe))
• European starling
(U.S. from
Shakespeare!)
• Indian mongoose
(Hawaii)
• Caulerpa algae
(CA from
aquariums)
• Cheatgrass
(United States
from Europe)
• Brown tree snake
(Guam from
Australia)
“HIPPO”: Pollution
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Air and water pollution; agricultural
runoff, industrial chemicals, etc.
Pollution does serious and
widespread harm, but is not as
threatening as the other elements
of HIPPO.
“HIPPO”: Population growth
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Human population growth exacerbates every
other environmental problem.
Magnifies effects of the other elements of
HIPPO:
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More people means more habitat change, more
invasive species, more pollution, more
overexploitation.
Along with increased resource consumption, it is
the ultimate reason behind proximate threats to
biodiversity.
“HIPPO”: Overexploitation
Two meanings:
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Overharvesting of species from the wild
(too much hunting, fishing…)
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Overconsumption of resources
(too much timber cutting, fossil fuel use…)
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Usually overexploitation is not the sole cause of
extinction, but it often contributes in tandem with
other causes. Was more important in some cases
in the past.
Causes of species extinction

In most cases, extinctions occur because
of a combination of factors.
(486 critically endangered; 43% of species in decline)
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e.g., current global amphibian declines
are thought due to a complex
combination of:
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Monteverde Golden Toad,
Last seen 1989
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Chemical contamination
Disease transmission (fungus)
Habitat loss
Ozone depletion and UV penetrance
Climate change
Synergistic interaction of these factors
The Value of Biodiversity?
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Food
Fuel
Construction
Medicine
Aesthetics (Beauty)
Spiritual
Educational
Ethics
The Encyclopedia of Life – http://eol.org
E.O. Wilson on the Value of Biodiversity (PBS Bill Moyers Journal)