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 non-native 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-pulpitEctotherm orEndotherm?

Colorado Potato Beetle

Colorado Potato Beetle as weapon?• 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 forestrefuges 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