Week 3: Threatening processes Flashcards
australia’s level of threats
Australia’s species are often more threatened by different factors than species are at a global level
indirect drivers of threats
Economic
Demographic
Sociopolitical
Cultural and religious
Science and technology
These things feed into: consumption per capita, population and resource intensity which feed into demand for food and demand for energy
direct drivers: fed by demand for food and demand for energy
Over-exploitation
Habitat change
Nutrient loading and pollution
Invasive species
Climate change
These lead to: loss of biodiversity
Pressure-State-Response model
A cycle
Pressure: human activities change the environment
Can provide information and lead to a response
Can provide pressures on the state
State: the environment and natural resources; prompts institutional response
Can provide resources for human activities
Can provide information for a response
Response: policies and action; affects human activities
Can lead to decisions and actions that change the state
Can have social responses that worsen pressure
Indicators:
Monitor pressures: pesticide use….
Monitor state: levels of active residues in dung, dead dung beetles, reduced nutrient cycling…
Monitor response: research, improved techniques, better control of overuse
DPSIR - invasive species
Pressure: Dynamics of pathways and instability factors; propagule and individual pressure
State: abundance and distribution; effects on ecosystem services
Response: adaption, mitigation, do nothing
extinct and threatened in Australia
> 10% endemics extinct
Further 21% threatened
ultimate threat factors
Transformation of indigenous land management to pastoralism
Non-native species
intermediary mechanisms
Change in fire regime
Livestock and feral stock
Exotic pasture grasses and weeds
Native predators interact with non-native predators
Cane toads
Black rats
proximate factors threats
Habitat change
Increased predation
Poisoning
Novel disease
pastoralism causes
Over grazing
Tree removal
Water points
Dingoes targeted
Introduced pasture plants
exotic meso-predators
Cat and fox introduction and spread correlates with declines across the continent
Mammals in decline are between 35g and 5.5kg
changed fire regime
Aboriginal regime - regular, fine-scale, patchwork burning
Current regime - fire suppression, exotic plants changed regime, infrequent severe fires, reduced habitat mosaics, loss of fire-tolerant plants
major threats in Australia
Other exotics
Land cleaning
Altered water regimes
Climate change
consequences of change in Australia
Soil compaction
Reduced resources
Competition with introduced species
Reduced cover and exotic plant spread
Reduced recruitment of many native trees and shrubs
Meso-predator release
PSR model in australia
Pressure: pastoralism, exotic predators, changed fire regimes
State: mammal declines and extinctions
Response: fox baiting, sensing, translocation, cat culling, research
what are the interactions with predators?
Habitat-mediated pathways
Community-mediated pathways
how do we increase resilience?
Strategic burning can increase habitat complexity
Dingoes reduce predation pressure
prioritising threat management description
What threats and where to manage?
Maximise the overall benefit
Efficient as possible
Avoid catastrophic outcomes
Maximise opportunities
assumptions of prioritising threat management description
Management of threats is successful
All sites are independent
Distributions are known
Costs are known
cost-benefit approach for threats
Benefit depends on:
Number of species affected by threat
Proportion of available habitat treated
Number of threats
Cost:
Grazing - loss of profits
Fox baiting - cost of implementation
functional groups, types of guilds
A group of species that exploit the same class of environment resources in a similar way
methods of defining functional groups
Similarity in structure or function: growth form, feeding guild, traits
Response to disturbance: fire, grazing, gap loving/shade tolerant, successional role
Data-driven: use broader range of characteristics
why use functional groups?
Species problem -too many to study or manage
Generalise findings - to different species or conditions
Management activities - monitoring change and predicting change, both require transferring results and simplicity, shift from species to ecosystem focus
grazier functional group
Time horizon: 1-10 years
Concerns: condition suitable for grazing and profit
Cool/warm season growth
C3 and C4
Palatable/unpalatable
Grasses/forbs/woody
Annual/perennial
Grazing response
Noxious weeds
functional group regional natural resources planner
5-20 years
Concerns: fire hazard, remnant vegetation, biodiversity, salinity, ecosystem services
Woody/non-woody
Fuel accumulation
Root depth
Invasive species
Rare or threatened species
Fire and grazing response
Habitat quality
climate policy maker/modeller
50+ years
Concerns: climate change, biomass, land use, disturbances
Carbon metabolism (for CO2 increase)
Woody/non-woody
Evergreen/deciduous
Grazing response
Fire response
Nutrient cycling/uptake
Litter decomposition rate
functional response types
Groups that respond in similar ways to the abiotic and biotic environment
Gap vs understory, fire tolerant vs intolerant, drought or frost resistant
functional effect types
Groups that have similar effects on ecosystem processes such as productivity, nutrient cycling and trophic transfer
Nitrogen fixers, ecosystem engineers, fire promoting species
are traits functional?
Global trait distributions are constrained
Plants face consistent trade-offs
This reflects traits having function
how hard do we need to look when a species is absent?
Detectability:
The probability that you will detect an individual if it is present at a site per unit search effort
Critical to appropriate survey design
Specific to the species in question
Time to detection:
Observed experience
Weather
Time of day
Grass cover interaction
Search for a long time!
