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Impacts on Terrestrial and Freshwater Biodiversity: Habitats and Ecosystems


What is Happening What might happen

Australia wide

  • Woody thickening - an increase in the density of trees and shrubs at the expense of grassland species - is occurring across all major Australian ecosystems
  • For some terrestrial species, increased woody vegetation may provide more habitat, but other species that rely on open habitats could be threatened or outcompeted by encroaching shrubs and trees108


  • Thickening is predicted to be a major issue as climatic changes progress 109
  • Some species will be directly threatened by woody thickening - the endangered golden shouldered parrot, endemic to Cape York Peninsula, is threatened by increased predation risk and impacts of thickening on seasonal food availability110
  • Prescribed burning can stall thickening but timing of the burn is vitally important - in the north, burning in the late dry season and storm-season favours the maintenance of grassland, while burning at other times favours the woody species 111

Mediterranean woodland and shrublands


  • Lower annual rainfall and increased abstraction have lowered groundwater levels and negatively affected native vegetation 112
  • Tree mortality and progressive floristic change towards drought tolerant species in Banksia woodlands113,114, 115,116
  • Lower rainfall and seasonal shifts in intensity have resulted in declines in streamflow, soil water storage and groundwater levels, affecting flora117,118



  •  Projected  declines in rainfall,119 streamflow120 and groundwater levels 121 resulting in ecosystem stress and changes in community composition122,115, 123
  • Projected  temperature increases and rainfall declines may negatively affect South West Australian Floristic Region’s endemic plant diversity124,125,126
  • Suitable habitat will decline for many endemic Banksia species 125,126
  • Community composition changes as susceptible species decline in Western Australia125


Temperate forests, woodlands and grasslands (including montane and rainforest)


  • Increase of mire wetland  associated with contraction of eucalypt woodland in south-east Australia127



  • Production could increase where rain is not limiting, due to increased CO2128,129
  • Reduced forest cover associated with soil drying128
  • Generally earlier grass130and tree flowering131
  • Conversion of grassland to woodland or shrubland
  • Loss of carbon stocks through changed fire regimes and drying132,133,134,135


Tropical savanna and grasslands

top savannah

  • Plant mortality following drought136,137
  • Expansion of rainforest at expense of eucalypt savanna and grassland in Northern Territory and Queensland associated with increased rainfall and CO2138,139
  • Increasing canopy cover in tropical savannas140
  • Shift in composition could occur from perennial Mitchell grasses to annual grasses or forbs141
  • Shift from C3 to C4 plants142

Tropical and sub-tropical rainforest


  • No reported impacts at time of press.
  • Increasing floristic turnover for species at the altitude of the cloud base143
  • Changes to structure of rainforest canopy144
  • Damage to shallow-rooted species from high-intensity cyclones145 - and subsequent potential for weed invasion146
  • Increased growth of vines with increased CO2, leading to tree mortality147
  • Drying of tropical montane cloud forest, reducing productivity148
  • Rainforest contraction with increased fire frequency, favouring fire-tolerant species149
  • Short term heat events and drought likely to affect cool rainforest species more than dry rainforest species150


Arid and semi-arid   regions


  • Vegetation thickening in semi-arid mulga woodlands in southwest Queensland151  


  • Altered competition between C3 and C4 grasses, favouring C4 species142
  • Relatively flat landscape may mean community change will be widespread and more extensive than in other regions, as there is little opportunity for altitudinal shifts152  
  • Reduction in patches of fire-sensitive mulga in spinifex grassland could lead to increase in spinifex153


Alpine regions


  • Decline in depth and duration of snow cover154
  • Tree line shifts of 30-40 m in altitude in 25 years in Victoria155
  • Increase in shrub cover and decrease in grass cover particularly in response to drought 156
  • Decline in specialist alpine ecosystems e.g. snow patch herb fields, cushion plants 157
  • Contraction of fens and bogs158
  • Native and feral mammals projected to move to higher elevations159
  • Encroachment of snow gums into subalpine grassland and higher elevations155
  • Frost damage in snow gums due to interaction between warming and increased CO2 160
  • Generally earlier time of flowering, seed set and budding with associated fitness effects161,162


Inland wetlands and waterways (including peatlands)


  • General reductions in flow and changed seasonality of flow, causing drying163,164
  • Contraction of Melaleuca swamp forests in Kakadu due to intrusion of salt water165
  • Drought-related mortality in floodplain forests166


  • Degradation and drying of peatlands127; drying of wetlands; loss of seasonal ponds127
  • Drought conditions likely to become more common in Murray-Darling Basin, south-east and south-west Western Australia163
  • More frequent burning of peaty sediments in wetlands167
  • Loss of taxa intolerant of temperature rises168
  • Shifts to species-poor, salt-tolerant biota in southern wetlands with drying    climate 164


Islands (including Heard, McDonald, Macquarie, Frasier, Christmas, Torres Straits; Lowe Howe and Norfolk Island groups)


Faster seed maturation with increase warming169
  • Change in mossy cloud layer may lead to reduced occult precipitation which affects the ability of vegetation to harvest moisture109
  • Changes in vegetation cover and loss of endemic flora and fauna
  • Erosion of dunes, coastal cliffs and rocky shore platforms
  • Changed fire regimes
  • Deglaciation; establishment of introduced species in ice-free ground 170
  • Fundamental changes in the condition of subantarctic lakes and ponds109


Coastal (estuarine, sandy, rocky)


  • Increase in mangrove extent (1974-2004) in Northern Territory, likely due to rising sea levels and increased CO2171
  • Landward mangrove  expansion linked to increased rainfall in the south east172
  • Change to structure and composition in Tasmanian saltmarsh community173
  • Marine inundation of terrestrial systems with sea level rise174
  • Rocky shore and saltmarsh species vulnerable to total loss of habitat175
  • Saltmarsh and wetlands affected by landward movement of mangroves138
  • Coastal squeeze - coastal habitats trapped between landward boundaries and rising sea level176

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