Ecosystem Changes and Conservation Strategies

• Ecosystem


  A community and its environment (the biotic and abiotic factors in a given area), and the interactions between them
• Stable ecosystems


  • Can be sustained over long periods of time
  • One sign of a healthy ecosystem is that it can sustain stress in the form of extreme conditions, such as floods, droughts, invasive species, disease and overexploitation; it shows resilience
• Human impact on the environment


  Human activities that alter trophic structures, energy flow, cycling of matter and biodiversity
• Human population increase


  Human impact on biodiversity and ecosystems increase
• The southwest of Australia is one of 36 internationally recognised biodiversity hotspots
• Biodiversity hotspot


  • Has a minimum of 1500 vascular plants that are not found in any other region on Earth
  • Has suffered at least a 70% reduction in its original natural vegetation
• The Southwest Australia Ecoregion and the Forests of East Australia are Australia's only two biodiversity hotspots
• Human activities that impact biodiversity and ecosystems

  • Harmful fire regimes
  • Habitat destruction
  • Cat and fox introduction and predation
  • Spread of disease (such as phytophthora)
• Conservation strategies


  • Bush Heritage buy and manage land in partnership with Indigenous peoples, actively protecting native species by controlling competitor pests such as rabbits, and revegetating the area with native plants
• Wetlands


  Neither aquatic nor terrestrial, but exist as a merger of these two, changing seasonally to become more or less of each type of ecosystem
• Only 10% of Perth's wetlands remain
• Perth's population will increase to approximately 3.8 million by 2050
• Planning for the conservation of the last 10% of wetlands is needed to ensure their survival into the future
• Many important wetlands on the Swan coastal plain are being degraded by human impact because they lack protection
• Species diversity is declining, as well as population numbers
• Habitat


  The environment in which a species normally lives
• Habitat destruction and fragmentation is a human activity that greatly impacts ecosystems
• Habitat loss has reduced species richness and is the greatest threat to biodiversity
• When its habitat is lost, a species is vulnerable to extinction
• Urbanisation


  The extreme modification of an ecosystem by humans to support a human population of gradually increasing density; often, this happens as more people migrate to towns and cities from rural areas
• Urban ecosystems have reduced biodiversity and are dominated by people
• There is little recycling of matter between the community (the living things present) and the non-living surroundings in urban ecosystems
• Additional inputs of energy and matter are needed from other ecosystems to maintain modern standards of living in urban ecosystems
• Agriculture


  The practice of farming; cultivating soil, growing crops, raising animals, preparation of plant and animal products for market
• Many animals and plants have lost their habitat due to land clearing for agriculture
• Habitat fragmentation


  Parts of the habitat of an ecosystem are separated into isolated sections
• Traditional land managers, organisations, farmers and conservation scientists have worked together to strategically revegetate gaps of cleared land to restore the fragmented habitat
• Land and soil degradation

  Overgrazing and the hard hooves of farm animals are factors that lead to land and soil degradation
• Shallow rooted plants have more of an opportunity to grow on degraded land
• With significantly reduced tree cover and an increase in shallow-rooted grasses, the topsoil becomes more exposed to the effects of abiotic factors such as wind and rain
• Past land clearance practices, the move to shallow-rooted pastoral grasses and the overuse of fertilisers that have affected soil organisms have placed enormous pressures on the structure of the soil and the ability of the land to hold its topsoil
• Erosion


  The removal of soil by wind, where some soil particles can be carried up to thousands of kilometers away
• Farming land in WA can be subjected to high winds
• A dry climate also contributes to the soil's susceptibility to erosion
• Measures to reduce the impact of wind and water erosion

  • Groundcovers
  • Wind-breaker trees
  • Spreading of clay
• Dryland salinity


  The concentration of salt in the soil becomes too high, plants such as crops will no longer grow and the soil is infertile
• Over a million hectares of agricultural land in WA's south west is affected by dryland salinity
• The underlying reason behind the rising water table is the removal of deep-rooted, perennial (long lived), usually native, vegetation
• Salinity is a significant problem that can happen when natural vegetation is replaced with crops that require irrigation
• Steps leading to dryland salinity

  1. Removal of deep-rooted vegetation

  2. Rising water table

  3. Concentration of salt in soil