At a glance
The main pressures negatively affecting biodiversity have not changed greatly over the past three national State of the Environment reports, except that climate change has received greater recognition as a current and future driver of environmental change, and local climate has become a more prominent pressure as the nation has faced a decade of drought. The most significant past and present pressures are clearing and fragmentation of native ecosystems, invasive species and pathogens, inappropriate fire regimes, grazing pressure and changed hydrology. Steps have been taken to limit clearing of native vegetation, but it remains a significant pressure in some areas, and the legacy effects of past clearing mean that the impacts are not yet reducing. Inadequacy of systematic information limits our ability to assess trends in other pressures with confidence, but available evidence and expert consensus suggests that pressures from grazing, invasive species, altered fire regimes and changed hydrology are still major and have been growing worse over the past decade.
For some or all of these pressures, improvements are possible once remedial actions start to take effect, but there is as yet no strong evidence of that improvement. Three major interacting drivers affecting all these pressures have been (and will be) climate, human population growth and the demands placed on the environment to support human lifestyles. It will be important to address all three of these drivers if pressures on biodiversity are to be reduced to desirable levels.
The Assessment of Australia’s terrestrial biodiversity 200815 has been drawn on extensively in this section as it is a recent and comprehensive review of pressures on Australia’s terrestrial biodiversity. That study drew on syntheses of jurisdictional analyses, listings of threatened species under the EPBC Act, and a series of case studies on representative species to conclude that the key threats to biodiversity in Australia are:
- fragmentation of habitat
- climate change
- land-use change
- invasive species and pathogens
- grazing pressure
- altered fire regimes
- changed hydrology.
The most frequently cited threats in listings under the EPBC Act and resulting recovery plans are habitat fragmentation and the spread of invasive species.15
Additional pressures identified for marine species include the extraction of resources through fishing; introduction of marine invasive species; disturbance to habitats through shipping, and oil and gas exploration and production; habitat alteration through urban expansion or aquaculture facilities; and pollution including catchment run-off (see Chapter 6: Marine environment).