http://oncampus.richmond.edu/academics/as/education/projects/webunits/biomes/map2.gif

Weather vs. Climate 

•WeatherCondition of the atmosphere at any place and time http://weatheroffice.ec.gc.ca/forecast/city_e.html?yql

•ClimateCharacteristic behaviour of weather over time Includes averages and extremeshttp://www.theweathernetwork.ca/weather/stats/pages/C02080.htm?CAAB0194 

Climatology is the study of climate

Climatic regions: zones with characteristic weather patternsEmpirical (statistics) or genetic (causative) classificationEg. Köppen-Geiger Climate Classification System (1928) 

Climographs

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LETHBRIDGE, AB VANCOUVER, BC

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Determinants of climate:

•Distribution and seasonal variation of solar insolation intensity (zenith angles and daylength)

•Atmospheric and oceanic global circulation patterns

•Controls of temperature: altitude and latitude, land-water heating differences, cloud cover, polar front

•Controls on precipitation: distribution of pressure systems, lift mechanisms (convergence, convection, orographic, frontal), location of ITCZ, subtropical high pressure, jet streams

Source: Solomon, 2000

Effect of Altitude

Effect of Latitude and Cloud Cover

Global CirculationPatterns

Climate Distribution

Classification systems: Köppen-Geiger, Thornthwaite (not shown) A Tropical - equatorial regionsC Mesothermal – eg. Mediterranean, marine W. coastD Microthermal – eg. humid continental, subarcticE Polar H Highland – cooler than surroundingsB Dry – deserts and steppes

See Figure 6-4

A Tropical Climates

Straddle equator: 20N to 20S

Coldest month is above 18C

Consistent daylength, small zenith angles

Includes tropical rainforest, tropical monsoon and tropical savanna

1. Tropical Rain Forest Climate

•Warm and moist•Thunderstorms – local convection in convergent ITCZ•All months receive more than 60mm

•Precipitation pattern follows migration of ITCZ•Two wetter seasons near equator, one wetter season near tropics

•High rainfall and solar insolation sustain lush, evergreen, broadleaf tree growth

•High leaf area index (LAI) •Dark canopy floor with sparse vegetation•Rapid decomposition – more nutrient mass in vegetation than soil

Rainforest ClimographManokwari, New Guinea

Little variability in average monthly temperature

Driest month receives more than 100 mm of rainfall

Source: http://www.geocities.com/Athens/Parthenon/1020/biome.html

Source: http://www.world-builders.org/lessons/less/biomes/rainforest/tropi_rain/tropgifs

Tropical Rain Forest Vegetation

Layers in the Tropical Rain Forest Canopy 

The Tropical Rain Forest

The world’s most biologically-diverse biome

Layers in the Tropical Rain Forest Canopy 

Emergents

•Trees “emerge” from the forest canopy

•Exposed to high light, fluctuating temperatures, higher winds

•Huge trees (up to 70m) with massive, buttressed trunks

•Seed dispersal often by wind

•Home to many birds and animals looking for safety from predators (eg. eagles, bats, monkeys, snakes, butterflies)

ButtressedTrunks

Helps supportlarge tree biomass, weight of water andepiphytes

Canopy Layer

•Continuous layer (about 45 m)

•Most have buttressed trunks

•Especially high diversity of plants and animals

•Same tree found once or twice per square kilometre

•Lianas (vines) connect trees

•Epiphytic vegetation common -28,000 species (eg. mosses, bromeliads, ferns, orchids)

•Abundant fauna (eg. monkeys, sloths, bats, treefrogs, ants, beetles, parrots, hummingbirds and snakes)

Understorey Layer

•Receives 2-5% of incident light (blocked by canopy)

•Understorey plants photosynthesize most efficiently under low light (low respiration rates)

•Layer consists of small trees (eg. dwarf palms) and seedlings of taller trees

•Low wind: insect pollination, strong smelling and conspicuous flowers often on trunks

•Abundant fauna (eg. insects, snakes, frogs, parakeets, leopards, jaguars etc.) 

Forest Floor•Approximately 1% of light incident upon the canopy

•100% relative humidity, less temperature variation

•Rapidly-decomposing organic matter

•Few flowering plants

•Fungi thrive on decomposing organic matter

•Large mammals forage for roots and tubers (eg. tapirs)•Many insects (eg. termites, cockroaches, beetles, centipedes, millipedes, scorpions and earthworms)

Global Distribution of Tropical Rain Forests

Deforestation•>50% already gone (pasture, timber, fuelwood, farming)

• Approximately 169,000 km2 lost each year • Fire clears land for agriculture (food production, rubber, coffee etc.)

• Slash and burn – soil nutrient reserves quickly exhausted • Destruction generally along transportation networks

• Tropical Forestry Action Plan (FAO, UNDP, WB, WRI) • Remote sensing and GIS play key role in monitoring

2. Tropical Monsoon and Savanna Climates 

Tropical Monsoon Climates

•Rainfall from ITCZ affects regions for 6-12 months of the year (eg. text example Yangon, Myanmar)

•Seasonal variation in winds and precipitation

•1 or more months have less than 60mm of precipitation

•Evergreen broadleaf trees grade toward thorn forests along drier margins with savanna 

Tropical Monsoon Climograph

Dry season during theNorthern Hemispherewinter

Wet season during thesummer

Tropical Savanna Climates

•ITCZ effect for <6 months of the year

•Winters are dry (subtropical high pressure)

•Summers are wet (influence of ITCZ)

•Tropical cyclones possible near east coasts

•Grasslands dominate: scattered, drought-resistant trees

•Text example: Mérida, Mexico (relatively wet) and Kenya

Tropical Savanna Distribution

http://www.cotf.edu/ete/modules/msese/earthsysflr/savannah.html

Savanna Climograph

Long dry season duringthe Southern Hemispherewinter

Wet season during the summer

Vegetation in the Tropical Monsoon and Savanna Climate Zones:

Tropical Seasonal Forest and Scrub •Poleward transition from tropical rain forest to grasslands

Monsoonal forestsopen woodlandsscrub woodlandthorn forestsdrought-resistant scrubgrassland

•Leaf loss and dry season flowering during seasonal moisture deficits 

Monsoonal forests:

•Discontinuous, 15 m high canopy

•Denser undergrowth

•Orchardlike parkland with grassy openings in drier sectors

•Flat-topped acacia trees become common in drier zones

•Examples: Caatinga (Brazil), Chaco (Paraguay), Brigalow (Australia), Dornveld (S. Africa)

•Wildlife: elephants, large cats, rodents, ground-dwelling birds•Koalas and cockatoos in Australia

Monsoon Forest of India

Increasedlight penetrationcompared to lowland rain forest

DiscontinuousCanopy and Lower LAI

Source: I. de Borhegyi FAO

Vegetation of the tropical savanna

•Large expanses of grassland, interrupted in areas by trees and shrubs

•Trees and shrubs are xerophytic (small, waxy, thick leaves)

•Most expansive in Africa (Serengeti plains, Sahel)also Los Llanos (Venezuela), Campo Cerrado, Pantanal (Brazil)

•Fires common during the dry seasons (beneficial if early)

•Affected by desertification

•Soils richer in humus than tropical rain forests: sorghum, wheat, peanuts can be grown

•Home to large land mammals in Africa: lion, cheetah, zebra, giraffe, buffalo, gazelle, wildebeest, antelope, rhinoceros and elephant

The Serengeti Plain (Savanna)

C Mesothermal Climates 1.  Humid Subtropical Hot Summer Climate

•Influenced by maritime tropical air masses in summer

•Continental polar and maritime tropical air masses mix in fall/winter/spring: frontal precipitation

•Convectional precipitation in moist, unstable summer airmass

•Tropical cyclones near coasts in summer and fall

•1000 – 2000 mm/yr total

•Examples: southeast U.S., southeast China, southern Japan, northern Argentina

•Broadleaf and mixed forest

Source: M.K. House, near Tallahassee, Fl.

2. Humid Subtropical Winter Dry Climate

• Similar to above, but dry in winter

• Heavy precipitation in summer

• Circulation in winter prevents moist, tropical air mass interaction with pressure systems

eg. much of southern China, eastern South Africa

• Broadleaf and mixed forest, but largely deforested

(see Figure 6-11)

3. Marine West Coast Climates

•Mild winter and relatively cool summer

•Winter maximum of precipitation, especially in southern zones

•Heavy precipitation in mountains (may exceed 4000 mm/yr)

•Precipitation varies at low altitude: much more precipitation in northern portions of the Marine West Coast Climate than in the south

•Dominated by maritime polar air masses but unusually mild for their latitudes

•Coastal fog is common

Temperate Rain Forest•Narrow margin of Pacific NW North America

•Less species diversity than TRF

•Needle/broadleaf trees, ferns and undergrowth

•Tallest tree in world (Sequoia sempervirens – Redwood) may exceed 100m

•Also Douglas Fir, Spruce, Cedar, Hemlock

•Moist, lush vegetation

•Fauna: Bear, badger, deer, wild pig, wolf, bobcat, fox and numerous bird species

Source: www.inforain.org

4. Mediterranean Dry Summer Climates

•Poleward of subtropical high pressure on west coasts•Subtropical high prevents precipitation and influx of tropical moist air in summer•At least 70% of precipitation occurs in the winter•Summer water resource problems•Agriculture requires irrigation•Hot summer and cool summer varieties•Cool offshore currents enhance stability of marine air mass along west coasts

Examples: Mediterranean, southwest California, northwest coastal Mexico, central Chile, southern tip of South Africa

Mediterranean Shrubland: “Chaparral”

•Sclerophyllic shrubsShort-statured, deep roots, leathery leaves, low branchesGrass between shrubs

•Fire adaptation Resprouting capability

Cork Oak, Pine and Olive trees in Mediterranean

Commercial agriculture: fruits, vegetables and nuts

Fauna: deer, coyote, wolf, bobcat, rodents and birds

                                                                    

Source: S. Johnson, U. California, Berkeley

                                                  

                  

Source: F. Tanaka

D Microthermal Climates

Temperature variation is high due to season and air masses 

1. Humid Continental Hot Summer Climate

•Frequent passage of pressure systems•Maritime tropical air masses and convection influence climate in summer •Occasional intrusion of cold, polar air in winter•Some areas have a dry winter, but others have similar year-round precipitation totals. Why ?Influence of coastal storms or lake effect snows in winter•Corn, soybean, hog and cattle farming without irrigation•Midlatitude broadleaf and mixed forest

See New York City Climograph (Figure 6-15)

2. Humid Continental Mild Summer Climate

•Precipitation is generally lower than in the hot summer climate•Temperature is cooler than in the hot summer climate•Snowmelt in winter important for soil moisture recharge

•Winter is relatively dry except near lakes and oceans

Agriculture: includes dairy cattle, poultry, flax, sunflowers, sugar beets, wheat and potatoes (usually without irrigation)

•Midlatitude broadleaf and mixed forest tending to needleleaf forest to north on shallower soils

Examples: Great Lakes, much of northeast Europe (See Moscow climograph – Fig 6-16)

Midlatitude Broadleaf and Mixed Forest

•Very productive in summer, senescence in fall•High LAI, limited undergrowth in old growth forest

Trees: Maple, Oak, Beech, Elm, Chestnut in Great Lakes, New England and Maritimes, mixed with White Pine, Red Pine and Eastern Hemlock

Fauna: Red fox, white-tailed deer, southern flying squirrel, opossum, bear and a great variety of birds (eg. cardinal, blue jay)

3. Subarctic Climates

•Very long, cold winters – dominated by high pressure•Discontinous or continuous permafrost at high latitude

•Boreal forests or Taiga where growing season sufficientFir, Spruce, Larch and Birch

•Open northern woodlands and tundra in far north •Winters are generally drier than summerHowever, the Dry Winter form of subarctic climates occurs only in Russia

Bitter cold occurs in these areas in winterVerkoyansk has an average 63C temperature range

Climograph: Subarctic climate

Low precipitation and cold temperatures in Winter

Huge temperaturerange

Needleleaf forest and Montane Forest

•Boreal forest from Alaska, across northern portions of AB, SK, MB, ON, QC to east coast of Newfoundland and Labrador•Taiga from European plain across much of Russia through Siberia•Only extensive in N. hemisphere, but occur at montane sites in S. Hemisphere

Trees: Pine, Spruce and Fir

Fauna: wolf, moose, bear, lynx, beaver, wolverine, small rodents, hawks, eagles, grouse, owls and migratory birds

South Knife Lake, Manitoba, CanadaPhotograph by Lynda Dredge (GSC, Natural Resources Canada)

4. Tundra Climate

•8-10 months of snow

•Generally underlain by permafrost

Vegetation: Stunted sedges, mosses flowering plants and lichen in brief summer

Most rapid climate warming is in this zone

Only in northern hemisphere, except in highlands 

Light and heat may not be the only limiting factors for plant growth•Days are long and temperatures may reach the teens in summer

Wind and moisture deficit are also important•Thin, active layer holds limited moisture. Small, leathery leaves, closely spaced to protect stomata•Hairs limit air circulation•Flowers are small•Plants often occur in tufts for protection•Prostrate growth - stems spread out over ground with little vertical growth - especially willow

Arctic tundra

Climograph: Tundra Climate

Low Arctic Tundra

•Extends north from treeline along a line from Northern Alaska to northern Quebec and southern Baffin Island (10 degree C isotherm)•Cold, with low precipitation•Nearly the entire area is underlain with permafrost

•Almost complete vegetation coverage (except unfavourable areas)•Dominated by dwarf shrubs (birch and willow)

•Vegetation traps snow and provides shading from summer heating

•Peat accumulation at poorly-drained sites•Any black spruce is very stunted and abraded by snow

•Major summer range and calving grounds of some of Canada's largest caribou herds

Mid Arctic Tundra

•Transitional band between high and low arctic•Plant cover more than 50% in most areas but bare ground still exists locally•Vascular plants more common than in high arctic - willow common

Cumberland Sound, Baffin Island, Nunavut, CanadaPhotograph by Govt. of the Northwest Territories

Photo: JoAnn ElliottDenali National Park

Arctic Willow

Arctic willow

http://www.sasked.gov.sk.ca/~gregory/arctic/plants/awillow.jpg

Vendom Fiord, Ellesmere Island, Nunavut, CanadaPhotograph by Douglas Hodgson (GSC, Natural Resources Canada)

High Arctic

Wetland Environments

•Cover 14 to 18% of Canada

•Mainly just to the south of treeline in discontinuous and sporadic permafrost

•Pockets further north

•Major carbon sink

•Potential future source of greenhouse gases

•Hydrophyllic vegetation present due to water table at or above mineral soil

Source: Natural Resources Canadahttp://atlas.gc.ca/english/facts/wetlands/wetlands_ewetdist2_e.html

Bog• Sphagnum moss dominated• Receives nutrients only from precipitation

Fen• A peatland receiving nutrients from mineral soil below• Flora is more abundant and diverse, including sedges, grasses,

shrubs and even trees (tamarack)

Swamp• A wooded wetland• May develop into a peatland• Coniferous and deciduous trees, shrubs, herbs and mosses

Marsh• Periodically inundated wetland (fresh or salt water)• Little peat accumulation

Why does peat accumulate ?

•Production by plants exceeds decomposition

•Abundant growth due to available moisture during growing season

•Preservation of plants (cool conditions)

•Saturated conditions - slow, anaerobic decomposition by methanogenic bacteria

•Release of methane rather than CO2

5. Ice Cap Climate

•Dominated by dry, frigid air masses

•Average temperature below freezing most or all year

•World’s coldest surface air is found in Antarctica in S. hemisphere winter

•Glaciers accumulate snow and ice despite low precipitation (<80mm/yr in Antarctica)

•Precipitation exceeds small evapotranspiration demand

Examples: Antarctica, North Pole, Greenland

Climograph: Ice Cap Climate

B Desert and Semiarid Climates Vegetation is xerophyticPhreatophytes along stream channels Subtropical dry climates•Subtropical high pressure cells dominate•Stable air, low relative humidity•Extend to western continental margins from 15 to 30N•Cool stabilizing ocean currents  The Rain Shadow effect•Orographic lift over western mountains and subsequent descent of air•Extends along eastern edge of Andean and Rocky mountains north of 30N

1. Hot Low Latitude Desert Climate•0 to 350 mm precipitation•Western side of continents in subtropical high zone•Also Egypt, Somalia and Saudi Arabia 

2. Cold Midlatitude Desert Climate•Approx. 150 mm precipitation•Gobi Desert, southern countries of former USSR, US southwest, Patagonia•Any precipitation due to summer convection

Distribution of Earth’s Deserts

Desert Biomes•>1/3 of Earth’s land area

•Ephemerals (wait a year or more for precipitation)Seeds quickly germinate, plants develop, flower, and produce seeds

•Long, deep tap roots (eg. mesquite), succulence (thick, fleshy, water holding tissue), waxy coatings and fine hairs on leaves to retard water loss, leafless conditions during dry periods

Fauna: Desert bighorn sheep, camel, kangaroo rat, lizards, scorpions, snakes are active at night, when temperatures are lower.

Birds include roadrunner, thrashers, ravens, wrens, hawks and grouse

3. Hot Low Latitude Steppe Climate•Around periphery of hot low latitude desert

Eg. northern Sahel, parts of Iran and Afghanistan, Turkistan and Kazakhstan

4. Cold Midlatitude Steppe Climate•Occur poleward of 30 latitude, mainly in northern hemisphere,in areas distant from major moisture source or rainshadowed

•Widely variable, undependable precipitation (200 – 500 mm/yr)

•Cyclonic storms occur, but precipitation tends to be light

•Summer convection produces much of year’s precipitation

Midlatitude Grasslands

•The world’s breadbasket – grain and livestock production•Heavily modified by human activity (few natural sites)•Good soil quality•Only trees are deciduous broadleafs along streams•Shrubs in protected areas •Tall-grass prairie once rose to 2m, with short grass steppe further west

Fauna: deer, antelope, pronghorn, bison, gophers, prairie dogs, coyote, badger, hawks, eagles, owls, grasshoppers

Look out the window !