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Lecture 22

GGR100H1 Lecture Notes - Lecture 22: Andropogon Gerardi, Temperate Broadleaf And Mixed Forest, Andropogon

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Nina Hewitt

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GGR100 Week 12: Forest and Grassland Biomes
Large areas of earths surface having similar climate and vegetation
oSeasonal tropical forest
oWet tropical forest
Defined by form and function of dominant vegetation:
oLianas (vines)
oBryophytes (e.g. Moss)
oEpiphytes (air-plants)
Vegetation isn’t specific to species, animals differ between biomes, but vegetation
type and form, and climate type constitute different biomes
Earth’s major terrestrial biomes
Equatorial and tropical rain forest
Midlatitude broadleaf and mixed forest
Needleleaf forest and Montane forest
Temperate Rain forest (ex. west coast Vancouver, Washington)
Tropical Savanna
Arctic tundra
Alpine tundra
Tropical Rain Forest
oLush, dense forests with horizontal complexity
oVariety of species and life forms: tree shrubs, epiphytes, lianas
oLower level canopy consists of shrubs, thorns, palms
oMid-level canopy houses lianas (vines) and air plants
oHigh level tree provides continuous cover, receives 90% of insolation,
creating darkened, shaded lover levels
oRoot buttresses, seiba tree is exclusively tropical
oCool, highly evolved biotic interactions
oFlowers attract pollinators ant-plant mutualism, ex. acacia plant
oPlants provide food and shelter for ant in exchange for protections against
predators and competition for growth with other plants.
oFound commonly in tropics, also protect from plant competitors, bite off
overhead vines so home plant can receive energy
oStrangler figs: hemi-epiphytes: establish in the canopy of host like
epiphytes (“air plants”); later send roots down stem. Eventually kill host
while dead trunk continues to supports it
oAmazon rainforest losses
Deforestation by multinationals (beef farms, mining, forestry),
slow to reforest due to weathered condition of mineral soils
– require long periods to regain organic matter, capture
nutrient inputs in dust, rainfall
Threatens a large proportion of earths biodiversity
Midlatitude Broadleaf and Mixed Forest
oTemperate forest in NA
Maple/beech forests
Oak/hickory/chestnut forests
Needleleaf Forest
oIn Europe, Siberia called Taiga
oIn NA, called Boreal Forest
oExtends north to 10-12 degree Celsius July isotherms
oDominated by black and white spruce
oCan withstand prolonged freezing, has short growing season
Boreal forest –tundra ecotone
oEcotone: transition area between two biomes
oMay be gradual or abrupt
oTimberline appears abrupt when viewed from a distance, but up close,
gradual changes evident
Fragmentation Nation
oTemperate (mid-latitude) forests have been particularly affected by human
settlement and timber extraction
oThey exist as small isolated patches in a sea of human land use.
oaffects species populations and survival
oIslands in a sea of inhospitable lands
Cleared Needleleaf Forest
oFragmentation of Ontarios boreal forest has had a severe impact on
sensitive wildlife such as caribou and wolverine
oMillions of songbird nests have been cut down in the race to feed pulp and
saw mills
oOil sands projects also cause large disturbances in boreal forests
Midlatitude Grasslands
oRich, deep coils
oGrazing animals
oConverted for agriculture throughout breadbaskets of NA
oProne to dust storms with rainfall deficits, if cleared, bare soil becomes
susceptible to wind erosion
oRelatively modern ecosystems, evolved recently in last 40 million years,
grasslands and environments
oDeveloped in past dinosaur age, due to plate tectonic effects on moisture
oPrairie, NA
Andropogon gerardii (big bluestem): dominant species of tall-grass
Deep roots tap ground water; heights of >1m
Build large population via effective resource uptake