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17 Cards in this Set
- Front
- Back
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Characteristics of Wet Sclerophyll Forest
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= Tall open forest
-infrequent crown fires -typically tall eucalypt overstory -distinct layers -ground too dark for eucalypt seedlings to survive -charcoal in the soil -dense understory of soft-leaved shrubs -canopy cover 40-70% -grow in high rainfall areas |
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Ecotone
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with regards to wet sclerophyll forest, it is the cross over zone between dry sclerophyll forest and rainforest
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Why are there only very old Eucalyptus trees in the Rainforest?
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-the seeds of eucalypts cannot grow under the shade of rainforest
-Rainforest is very invasive - with out fire, wet sclerophyll eventually become rainforest -FIRE DESTROYS UNDERSTORY ALLOWING EUCALYPT SEEDLINGS TO GROW. IT MAY TAKE 200 YEARS FOR THIS TO OCCUR THEREFORE ONLY OLDER EUCALYPTUS TREES THAT GREW BEFORE ARE AROUND |
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What makes up the "Fire Regime"
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1) Fire frequency
2) Fire Intensity 3) Fire Season -its what makes up the pattern of fire |
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Fire Intensity!
(what is it made up of?) |
-Wind --> fans the fire
-Fuel Load --> amount of combustable material in the enviornment -Temperature --> determines moisture content |
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Why does sclerophyl vegetation burn well naturally?
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-dry evironment
-leaves are low in moisture --> woddy tissue -little docmposition --> fuel load high! -open canopy = dry understory + easy for wind to fan fire -oil in eucalyptus is flammable |
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How do Australian Plants survive Fire?
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1)Resprouting:--> all about insulation!
lost folliage is replaced by sprouting new leaves from specially protected buds (epicormic buds, lignotubers, protected meristems) 2) Reseeding: Fire damages plants but it stimulates the release of seeds for germination (serotiny, fire induced flowering, heat cracking of seed coats) |
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Eppicormic Buds
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-Merristems insulated under thick bark
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Lignotuber
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mass of dormant underground meristem tissue
*Eucalypts do it!! |
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Flash Fying
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-plants build up fuel to create extreme fires but only for a short period of time
-does not burn long enough to get through thick bark therefore the apical meristem is protected eg: xanthorroea |
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Serotiny
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= seeds protected in woody "cones" or "nuts" eg: Banksia and Eukalyptus
-fire burns foliage but seeds are protected in woody capsules -in response to heat / wood smoke, capsules open and release the seeds |
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Why germinate after fire?
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-competition reduced
-space created -nutrients available -fewer herbivores / granivors |
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Why are Eucalpyptus trees the supreme example of a "fire plant"
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-open crown drys out understory
-serotinous "gum nuts" -high fuel load on forest floor -resprouts from lignotubers -flamable woody foliage with flammable oils thick insulating bark resprouting epicormic buds -hanging strips of bark that can cause spot fires |
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Why do trees promote fires even though it could destroy itself?!?!
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-evolution is SELFISH! --> works for the individual and its offspring, not the species
-want to take out the competition -as long as its offspring survives the tree with be "happy" |
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Fire Stick Farming
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aboriginal purposefull burning of landscape to benefit themselves
eg: syncronize seed crops, clear competing vegetation, promote new growth which attracts kangaroos! |
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Issues in Managing Fire
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-since European settlement, fires are becoming much more frequent
-controlled burns are necessary but unpoular --> closes parks, smoke every where -does controled fire protect human intrests rather than biodiversity? |
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Fire Seasons
North Australia vs South Australia |
North Australia: summers are hot but wet. Winter is cool but dry (fire!)
Southern Australia: winter rains. summers are dry with strong dry winds creates a lot of FIRE!!! AHHHH!!!! |
