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Lecture 23

GGR100H1 Lecture Notes - Lecture 23: Homo Sapiens, Understory, Myrmecophyte


Department
Geography
Course Code
GGR100H1
Professor
Nina Hewitt
Lecture
23

Page:
of 2
GGR100 Week 13: Biomes Cont’d
TROPICAL SAVANNA:
Borders tropical deserts, has a prolonged dry season
Found in Botswana, Namibia, Kenya, Southern Brazil, India, Australia
Sparse tree cover (less than 30% of land area) amid herbaceous understory of grasses
and forbs
Fire-maintained: controls tree cover, this biome is adapted to frequent fires
Maintains ecosystem, removes dense tree cover, protects grasses and allows them grow
After fire roots quickly regrow , seeds germinate
African Savanna
oAmazing megafauna
oHerbivores: wildebeest, elephants, zebra, giraffe, rhino, gazelle
oAcacia: adaptations to avoid predation – ant –plant mutualism, toxins
oPredators: cheetah, lion, leopard
oOther: hyena, warthog, ostrich
oCradle of humanity: initial habitat of homo sapiens
Adapted to seasonal moisture shortages, ex. baobab tree
oEx. baobab tree
oLoses leaves for 9-month dry season
oStores 120,000L of water in thick corky trunks
oMay live thousands of years
ARCTIC TUNDRA:
Tolerate short growing seasons, wind whipped ice crystals, shallow or poorly developed
soils on permafrost
Small-stature, vascular plants, ex. Dryas (rose relative), arctic willow, grasses and
sedges
Lichens, mosses prominent
Not enough energy for larger plants, small plants that hug ground are provided with
insolation and heat
APLINE TUNDRA:
Some tundra species are losing habitat that is not being replaced upslope/ polewards
(run out of land surface) due to climate change
BIODIVERSITY:
Earth’s biodiversity: >10 million species: Plants, animals, fungi, algae, viruses (1.5
million known)
200,000 years ago biodiversity was at its peak but with modern decline, risks include
oHabitat Destruction: deforestation, fragmentation, land conversion
oOverharvesting: especially ocean fisheries
oInvasive species: introduced or promoted by humans
oClimate change
Climate change forces biomes to shift. Can species move fast enough?
oSpecies must ‘move it or lose it’ (geosystems now , p587)
oForcing species and climate belts upwards
oBiomes shifting rapidly
oSolution: Assisted migration?
o