Transitional Rainfall Zone

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The Transitional Rainfall Zone (TRZ) is one of three biogeographic zones into which south-west Western Australia is divided, the others being the High Rainfall Zone and the Low Rainfall Zone. The TRZ is recognised as having a much higher diversity of rare and endemic plant species than the other Zones.

The Zones were first defined by

IBRA regions.

The TRZ is widely recognised as having very high species diversity and endemism compared to the other zones. Some botanists have claimed that this is due to the species richness of the near-coastal

at the north-western and south-eastern extremes of the zone, suggesting that the intervening Wheatbelt region is relatively species poor. Other botanists have refuted this, however, claiming that the entire TRZ is species rich compared to the other zones.

See also

• Vegetation Survey of Western Australia

References

• doi:10.1146/annurev.es.10.110179.002151
  .

Further reading

• Hopper, Stephen D. (1992). "Patterns of plant diversity at the population and species levels in south-west Australian mediterranean ecosystems". In Hobbs, Richard J. (ed.). Biodiversity of Mediterranean Ecosystems in Australia. Chipping Norton: Surrey Beatty and Sons. pp. 27–46.
• Thackway, R and I D Cresswell (1995) An interim biogeographic regionalisation for Australia : a framework for setting priorities in the National Reserves System Cooperative Program Version 4.0 Canberra : Australian Nature Conservation Agency, Reserve Systems Unit, 1995.
  ISBN 0-642-21371-2