Ecological Biogeography

examines the factors (principally physical) that

control the range and abundance of organisms

ENVIRONMENT BIOTA(climate, soil, . . .)

Species-environment relations

Individual performance (e.g. growth or reproductive

success)

Biogeographic consequences

Extreme conditions may control a species distribution

Low temperatures (polar

areas) High temperatures (deserts) Dessication (deserts) Saturated soils (bogs) High salinity (ephemeral

lakes) Low nitrogen (dune-fields)

today

next week

The rotation of the Earth

produces a 24h day-

night cycle

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Image: earthobservatory.nasa.gov

Diurnal temperature variation in a non-vegetated (desert) environment

Effects of vegetatio

n on diurnal

rhythms: thermal

regimes in a tropical rain forest

Seasonal variations in day and

night length are a product of axial tilt

Day and night length varies with latitude

Graphic: M. Pidwirny

Biogeographic implications of variations in daylength:

photoperiodism

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Long-day plants: flower after exposure to long days/short nights (spring); predominant in cool temperate and polar latitudesShort-day plants: flower after exposure to short days/long nights (fall); predominant in warm temperate and subtropical latitudes

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red clover “Japanese” anemone

night day

night day

vegetative

vegetative

Seasonal solar radiation receipt varies with latitude

(as a result of variations in daylength and solar angle)

Graphic: M. Pidwirny

Variable radiation receipt produces

seasonal variations in

surface temperature

above: Manaus, Brazil (3°S)below: Fairbanks, Alaska (65°N)

Graphics: M. Pidwirny

Extremophiles

• Archaeans (bacteria) can survive and grow over an extreme temperature range, from >113°C in oceanic thermal vents to -18°C* in bubbles of brine in Arctic sea ice.

*the bacterium Colwellia, which grows in microbial mats in Arctic sea ice, can metabolize in liquid nitrogen (at -196°C)!

Source (and graphic): New Scientist, August 12, 2006

Temperature ranges of some common “cold-blooded” organisms (poikilotherms)

Thermally limited growth/activity season (e.g.

Fairbanks, Alaska)

Surviving extreme

temperatures[migration, hibernation, dormancy

(eggs, seeds, pupae, etc.)]

Temperature and habitat occupation

Water temperatures and fish distribution

0 10 20 30 40 Water temperature (°C)

bald rock cod (Antarctica)

coho (adults)

goldfishdormant

?dormant desert pupfish

A eurythermal/haline animal:

the desert pupfish (Cyprinodon spp.)

© Joan Barnett

pupfish in Salt Creek, Death Valley

pupfish in a hot spring

stream, Death Valley

Photosynthesis-temperature relations for major plant groups

Cardinal temperature

Thermal limits for trees from tropical, temperate and boreal

biomes

compare tropical, temperate and boreal species

Extreme temperature resistance in plants

Cold resistance Heat resistance

chilling frost resistance resistance

frost avoidance frost tolerance heat tolerance heat avoidance by bysupercooling shielding & reflection thermal insulation cooling by transpiration

Cold-resistance strategies

• Evolved responses growth of fur & feathers, shorter/smaller extremities, larger body size

• Seasonal responsesfat storage, metabolic changes (e.g. glycoproteins supress ice formation in plants), deciduousness (loss of sensitive parts), migration, hibernation

• Daily behavioural responseshabitat choice, refuging (nest, roost, burrow, den….), body position and orientation (especially for poikilotherms)

Tropical species e.g. effects of frost on Saguaro cacti in central

Arizona

1961 1962 1979(after frost) (frosts: 1971, 1978)

many deador dying

injured dead

Thermal control on polar limit of saguaro (Carnegiea gigantea)

Saguaro (Carnegiea gigantea) range in

relation to frost

frequency

Polar limits of other tropical desert species

Temperate forest trees:common polar limits =

similar limiting temperatures?

American beech red oak red maple

(plus white oak, black oak, 2 hickories . . . . )

Is polar limit controlled by the length and warmth of the growing season?

mean dailytemperatures

>10°C for morethan 4 months

mean Julytemperature18°C

Is polar limit controlled by dormant season temperatures?

mean Januarytemperature-12°C

Ice formation in beech (and red oak, red maple, etc.) tree trunks

-10 -20 -30 -40(°C)

extracellular Intracellular; Cells ruptured

Exothermic reactions

(ice-formation events) in temperate and boreal

tree species

Extra-cellular

Intra-cellular

Tree anatomy and thermal limits

chestnut American elm birch red maple

Ring porous Diffuse porous

Probability of temperatures falling below -40°C

A = common

B = rare

C = never

American beech

Hardiness zones: annual temperature minima

zone 1(-50°C)

to zone 11

(0°C)

http://www.glfc.cfs.nrcan.gc.ca/frontline/bulletins/bulletin_no.13_e.html

Can

ad

ian

pla

nt

hard

iness

zones

0b Shining willow Saule brillant Salix lucida ssp. lucida         1 White spruce Épinette blanche Picea glauca 1 Lodgepole pine Pin tordu latifolié Pinus contorta var. latifolia 1b Laurel willow Saule laurier Salix pentandra         2 White elm Orme d'Amérique Ulmus americana 2a Cranberry viburnum Viorne trilobie Viburnum trilobum 2b Ponderosa pine Pin ponderosa Pinus ponderosa         3 Rocky Mountain juniper Genévrier des Rocheuses Juniperus scopulorum 3 Red maple Érable rouge Acer rubrum 3b White ash Frêne blanc Fraxinus americana         4 Black locust Robinier faux-acacia Robinia pseudoacacia 4a Rocky Mountain Douglas-fir Douglas bleu Pseudotsuga menziesii var. glauca 4b Scotch elm Orme de montagne Ulmus glabra         5 Norway maple Érable de Norvége Acer platanoides 5 English oak Chêne pédonculé Quercus robur 5a Douglas maple Érable nain Acer glabrum var. douglasii 5b Horsechestnut Marronnier d'Inde Aesculus hippocastanum                 6 Western redcedar Thuya giant Thuja plicata 6b Eastern flowering dogwood Bois bouton Cornus florida         7 Sweetgum Copalme d'Amérique Liquidambar styraciflua 7b Coastal Douglas-fir Douglas vert Pseudotsuga menziesii var. menziesii         8 Arbutus Arbousier d'Amérique Arbutus menziesii 8 Western flowering dogwood Cornouiller du Pacifique Cornus nuttallii

ZONE HARDINESS OF SOME INDICATOR TREES

http://sis.agr.gc.ca/cansis/nsdb/climate/hardiness/trees2000.html

When is cold good for a plant?

• Short days signal plants of impending cold period

• Many deciduous plants require chilling to grow well in subsequent growing season

• Vernalization required for buds to break out of dormancy and to develop into flowers. These plants (e.g. apple, lilac) cannot be grown “successfully” at lower latitudes because the winters never get cold enough (a few days at 0–10°C).

• Hardening

Accclimation to winter

cold initiated by falling

temperaturesand reduced photoperiod in autumn

Temperature effectscold hardiness vs. dormancy

• Cold hardiness is ability to withstand cold

• Dormancy is inability to achieve normal growth– Biological adaptation to region with

decreasing temperatures and shortened daylength

– Apples: require about 1000-1600 hours of chilling (45F) to break dormancy.

http://www.uga.edu/fruit/apple.htm

Freezing resistance acclimation in two willow (Salix) species in northern

Japan

leaves open

leavesyellowing

buds form

Freezing resistance in red-osier dogwood (Cornus

stolonifera) ecotypes

growing in Minnesota

Ecotypic variation in cold

resistance in Douglas-fir

(Pseudotsuga menziesii)

Seeds planted May, 1954; Seedling response to severe

frost (-16°C at ground level),

mid-November, 1955.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 2 3 4 5 6 7 8 9 10 1112 13 14 15 16

% undamaged

% damaged

% killed

P. menziesii var. menziesiiN S

var. glaucaN S

Seedling response to severe frost (-16°C at ground level), mid-November, 1955.

Freezing damage in tree species ecotypes

What controls equatorward limits of temperate and boreal

species?• Similar heat injury ranges• Stratification: chilling requirements for

seed germination• Vernalization: chilling requirements for

blossoming

In tropical areas the stratification and vernalization requirements of temperate and boreal plant species are not met; they are unable to produce seed.