BIOS1301 Lecture Notes - Lecture 8: Geomorphology, Habitat Fragmentation, Soil Salinity
29 May 2018
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BIOS1301 – Ecology and Sustainability – Part 5
LEC 8: *Continued
Weather disturbance
• Cyclones are influential in tropical Australia
• Allow successional growth
• Wind may affect individual trees, patches of forests
Forest disturbance (pink pigeon - Mauritius)
• Forest destruction and rats caused population decrease to 60 birds
• Recovery through captive breeding
Fire disturbance
• Critical for structure and composition of many plant communities in Australia
• Many species depend on fire during their life cycles
o Banksia - fire allows their seeds to be spread
• Fire regimes have changed with fire suppression and burning
Drought disturbance
• Many animals and plants require a dry phase
• Allows for build up of nutrients and organic matter
• Colonisation by dryland plants and animals
Human disturbance
• Habitat loss
• Forestry
• River regulation
• Altered fire regimes (changing natural frequency of fires)
• Overharvesting
• Climate change
Intermediate disturbance:
• Causes for higher diversity:
o Few species can cope with high disturbance
o Overlap of early and late successional species
LEC 9:
• Wildfires as a global phenomenon
o Climate - key driver for fires
• Australian plants adaptation to a highly volatile landscape
o E.g. seedlings that only sprout when exposed to smoke
• Fire regimes
o Frequency, location (net productivity/fuel loads), season, intensity of past fires,
pattern
• Positive and negative impacts of fire on biodiversity
• Back-burning: removes understory (typically removes species that are not fire prone),
therefore the area becomes a fire hotspot (with species with high oil content,
eucalyptus)
find more resources at oneclass.com
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Document Summary
Bios1301 ecology and sustainability part 5. Weather disturbance: cyclones are influential in tropical australia, allow successional growth, wind may affect individual trees, patches of forests. Forest destruction and rats caused population decrease to 60 birds: recovery through captive breeding. Fire disturbance: critical for structure and composition of many plant communities in australia, many species depend on fire during their life cycles, banksia - fire allows their seeds to be spread. Fire regimes have changed with fire suppression and burning. Drought disturbance: many animals and plants require a dry phase, allows for build up of nutrients and organic matter, colonisation by dryland plants and animals. Forestry: habitat loss, river regulation, altered fire regimes (changing natural frequency of fires, overharvesting, climate change. Intermediate disturbance: causes for higher diversity, few species can cope with high disturbance, overlap of early and late successional species.
