Yr 12 Ecosystems and Biodiversity Flashcards
(107 cards)
What is biocapacity?
the capacity of an ecosystem to regenerate after human interference
How does energy flow from producer to consumer?
- Plants (producers) convert sunlight into chemical energy via photosynthesis
- Consumers gain energy by eating plants and other consumers
What are two ways that humans can disrupt the nutrient cycle?
Eutrophication and soil nutrients depletion
What is eutrophication?
- Artificial fertilisers adding excess nutrients
- Often carried into waterways by run-off
- Excess nutrients can encourage algae growth
- Algae consume oxygen - kills flora and fauna
Why soil nutrients depletion harmful?
- As plants consume nutrients from soil, it must be replaced
- Land & vegetation clearing remove humus (decomposed plant matter) - key source of returned nutrients
- Removing roots which keep soil in place leaves soil susceptible to erosion
- Leaf matter usually reduces percolation - without enough plants, water percolates into the ground, dissolving nutrient chemicals
- Nutrient leaching - rainfall “washes” nutrients out of the soil
What is the nutrient cycle?
A system where energy and matter are transferred between living organisms and non-living parts of the environment
What is dynamic equilibrium?
All ecosystems are in a constant state of change, however, nature will always attempt to restore a state of balance so the ecosystem can function. When an ecosystem’s vulnerability is equal to resilience, it is in a state of dynamic equilibrium.
What is vulnerability?
the ease with which an ecosystem can be changed
What is resilience?
an ecosystem’s ability to cope
What are the factors that affect vulnerability?
- Location - proximity to a hazard, e.g. an active volcano or human-induced hazard, and specialisation to a particular environment (polar or desert) = more vulnerable
- Extent - the size of an ecosystem, bigger = more resilient
- Biodiversity - diversity adds resilience, more complex food webs and many species and connections = more resilient
What is a feedback loop?
When one process gives rise to another, which in turn accelerates or diminishes the original process
* accelerates = positive
* diminished = negative
How can human activities impact feedback loops?
- Humans can create feedback loops
- e.g. altering ground cover through deforestation causes the soil to continue to lose nutrients through leaching
- ↳ soil is less able to support vegetation, which means even fewer nutrients are added
- ↳ the cycle continues until the soil loses all fertility
Why is genetic diversity important?
- Ecosystems with higher genetic diversity have greater resilience and can recover better from stress
- some organisms can survive during periods of stress as they have beneficial genetics
- natural selection prevents extinction
- decreases vulnerability
What are environmental services?
- Natural regulation processes which benefit humans and other organisms
- protecting catchments
- purifying water
- regulating temperature
- regenerating soil
- recycling nutrients and wastes
- maintaining air quality
What is the intrinsic value of ecosystems?
The recognition that ecosystems provide many inspirational, aesthetic, and spiritual needs of people without being used for their resources
What is natural heritage?
Natural features consisting of physical and biophysical formations or groups of such formations, which are of outstanding aesthetic, scientific, historical, cultural, or social value for future generations and the present community
What are the conditions necessary to protect areas from human interference?
- Be large enough to protect and conserve intact ecosystems effectively and to allow evolutionary processes to continue
- Have boundaries that reflect the environment (e.g. hills, mountains)
- Take into account the interests of local people
- Be well managed and effectively resourced
- Be surrounded by a ‘buffer zone’ where human activity is carefully managed, as disruptions may interrupt migration patterns, water and air quality, or breeding
What is an ecological stress?
- a natural disaster or naturally occurring environmental process
- typically slow, allowing time for the environment to adapt
What is a human stress?
- a human alteration to an environment that damages the ecosystem or its natural processes
- typically fast and cause drastic changes
- can result in a loss of habitat and the extinction of a species.
How are the effects of stresses measured?
- The magnitude of change - the extent to which an ecosystem has been stressed beyond its state of dynamic equilibrium. Requires a comparison between known data and whatever benchmark data is available
- The rate of Change - speed at which the change is occurring. Ecological change occurs over long periods of time (thousands to millions of years). Human change can be very quick (clear-felling forests can take a matter of days)
What is ecological integrity?
When an ecosystem is whole and unaltered by human activity
What are the impacts of humans on global insect populations?
- Declined by about 45% in the last 40 years due to the widespread use of pesticides in agriculture
- decreases the diversity of insect populations
- freshwater insect populations have increased by around 11% per decade, perhaps due to improved water quality in inland rivers and lakes.
What is the biodiversity intactness index?
- an estimated percentage of the original number of species that remain in the area and their abundance
- The closer the score is to 100%, the more intact its biodiversity is
What are some threats that climate change poses to biodiversity?
- Changing precipitation patterns
- Increase in frequency and intensity of severe weather events (e.g. droughts, storms)
- Ocean acidification
- More frequent and intense bushfires
- Melting ice caps
- Increase in temperature (air and water)
- This causes habitat loss and places pressure on species, usually killing them
- This decrease in species greatly reduces biodiversity