Transcript Document 7286643

Biomes
Limits to Biome Distribution
Temperate grasslands
Temperate grasslands
• Occur where annual precipitation is 25 to 75 cm
(10 to 30 inches)
• Summers hot, winters cold, rainfall is often
sporadic
• soil is rich in organic matter, minerals build up in
top layer of soil, dead organic matter from annual
die-back of grasses builds up soil organics, grass
roots may form turf or sod
• shortgrass prairies may be called steppes, more
rainfall than deserts but not much - 10 to 15 inches
• Plants – grasses dominate – tallgrasses where
wetter, shortgrasses where drier – trees only along
rivers
• Animals – bison, antelope, wolves, coyotes,
prairie dogs, ferrets, birds of prey, grouse, reptiles,
many insects
Mediterranean ecosystems
Mediterranean ecosystems
• Mediterranean - thickets of evergreen shrubs and small
trees
• some temperate areas have climates with mild winters with
abundant rainfall and very dry summers - called
Mediterranean climates - occur around Mediterranean,
California, western Australia, Chile, South Africa
• In California we call this ecosystem chaparral - soil is very
thin and nutrient poor
• Fires are common, frequent in late summer, early autumn
• plants usually dense growth of evergreen shrubs, but may
have short scrubby pines and oaks - often have
sclerophyllous leaves - hard, small, leathery leaves that
resist water loss
• Animals – mule deer, wood rats, chipmunks, lizards, many
songbirds, other birds
Deserts
Deserts
• Deserts are very dry habitats of both temperate
and tropical zones - low water content of the
desert atmosphere leads to wide daily temperature
range
• deserts vary greatly depending upon amount of
precipitation - usually less than 25 cm (10 inches)
per year
• desert soil poor in organics, rich in minerals
• some deserts so dry have virtually no plant life Namib and Atacama desert
• Plant cover sparse, much soil exposed – perennial
and annual or ephemeral plants – in North
America – cacti, yucca, Joshua trees, bunchgrass
• Animals – small – rodents, lizards, tortoises,
snakes, birds, insects
Tropical savanna
Tropical savanna
• Savannas are a tropical grassland which typically
have widely scattered trees
• either low rainfall or seasonal rainfall with
prolonged dry periods - often 85 to 150 cm (34 to
60 inches)
• Temperature doesn't change much - often in 80's
or 90's
• Savanna soil is low in mineral nutrients
• Tropical savanna found in Africa, South America
and northern Australia
• Plants – grasses, acacia trees – adapted to survive
or recover quickly from fire
• Animals – huge herds of hoofed mammals in
Africa – many predators – lion, leopard, hyena,
wild dog
Tropical rainforest
Tropical rainforest
• Tropical rain forest occurs where temperatures are
high throughout the year and precipitation occurs
almost daily - annual precipitation may be 200 to
450 cm (80 to 180 inches) - much of the rainfall is
locally recycled as water that enters atmosphere
from transpiration quickly falls out again
• Soil is usually very old and nutrient poor, low in
minerals and organics - decomposition and
recycling is very quick due to high temperature
and high availability of water
• extremely diverse forests - trees, lianas –
evergreen flowering trees
• Animals – very diverse insects, reptiles,
amphibians, birds, monkeys, sloths
Model predictions of global
temperature increase
Distribution of Biomes in Current Climate
Possible Distribution of Biomes in Climate with CO2 Doubled
Global Climate Change
Potential climate migration for Illinois
Will our prairie ecosystem change from
this to this?
Illinois tallgrass prairie
East Texas Piney Woods
Or something entirely different?
Dan Janzen has predicted that with increasingly
human dominated ecosystems, global climate
change and the spread of cosmopolitan nonnative species, the entire world will become
ecologically uniform.
Ecological Conditions
Conditions
• An abiotic factor that influences the
immediate survival of an organism –
temperature, humidity, pH, salinity, wind
velocity, current flow, soil, pollutants, etc.
Law of the Minimum
• The distribution of a species will be
controlled by that environmental factor for
which the organism has the narrowest range
of adaptability or control.
- Carl Sprengel 1828
Temperature as a Condition
Bullfrog – Ectotherm – an organism which relies on external
sources of heat to regulate its body temperature
Hippopotamus – Endotherm – an organism which is able to generate heat
within its body in order to elevate its body temperature.
Bullfrog – Ecto- or Endotherm?
Jack-in-the-pulpit
Ectotherm or
Endotherm?
Colorado Potato Beetle
Colorado Potato Beetle as weapon?
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Germany is known to have pursued entomological warfare programs during
World War II.[9] The nation pursued the mass-production, and dispersion, of
the Colorado Potato Beetle (Lepinotarsa decemlineata), aimed at the enemy's
food sources.[9] The beetle was first found in Germany in 1914, as an invasive
species from North America.[11] There are no records that indicate the beetle
was ever employed as a weapon by Germany, or any other nation during the
war.[11] Regardless, the Germans had developed plans to drop the beetles on
English crops.[12]
Germany carried out testing of its Colorado potato beetle weaponization
program south of Frankfort, where they released 54,000 of the beetles.[11] In
1944, an infestation of Colorado potato beetles was reported in Germany.[11]
The source of the infestation is unknown, speculation has offered three
alternative theories as to the origin of the infestation. One option is Allied
action, an entomological attack, another is that it was the result of the German
testing, and still another more likely explanation is that it was merely a natural
occurrence.[11]
http://en.wikipedia.org/wiki/Entomological_warfare
Day-Degrees in Ectotherm
Development
Austroicetes cruciata –
Australian plague grasshopper
Pieris rapae –
Cabbage white moth
Atlantic Puffin in Iceland
Acclimatization
• The habituation of an organism's
physiological response to environmental
conditions - usually occurs gradually over a
certain length of time.
Plant Cooling by Transpiration
Antarctic toothfish
Red-Osier Dogwood
Amazonian rain forest distribution today and rain forest
refuges during last glacial period
Margaret B. Davis,
Mother of Paleoecology
Changes in Oak and Spruce distributions
Summary of the effects of conditions on
species distributions
• Lethal conditions may limit distributions
but they only need to occur occasionally in
order to do so.
Saguaro cactus in snow
Summary of the effects of conditions on
species distributions
• Distributions are more often limited by
conditions that are regularly suboptimal
(rather than lethal) leading to a reduction in
growth or reproduction or increased chance
of mortality.
Click beetle on snow
Summary of the effects of conditions on
species distributions
• Suboptimal conditions often act by altering
the outcome of a biological interaction
between the species of interest and other
species.
St. John’sWort
– aka
Klamath weed
Chrysolina Beetles on St. John’s Wort
Summary of the effects of conditions on
species distributions
• Suboptimal conditions often interact with
other conditions so that it is often
impossible to locate a single condition as
the most important factor.
Mediterranean fruit fly
Summary of the effects of conditions on
species distributions
• Suboptimal conditions are often moderated
by the evolutionary, physiological and
behavioral responses of the organisms.
Kangaroo Rat
Summary of the effects of conditions on
species distributions
• Towards the edge of a species range, it
occupies patches in which conditions are
closest to those found in the center of its
range.
Rufous grasshopper