The Western Australian Government has committed $6.5m to extend the existing 1170 km State Barrier Fence. The fence is designed to reduce stock losses by dingoes and prevent emu and kangaroo damage to wheat crops. Once completed, the fence will form a largely continuous barrier that runs through five bioregions from North of Geraldton to Cape Arid. The extension will cut through the largest intact temperate woodland on earth, the Great Western Woodlands. The 490 km extension would separate 300,000ha of contiguous bush from the main block. The fence will impact biodiversity in three main ways: by restricting emu dispersal, limiting dingo populations and subdividing populations of many native species whose dispersal is limited by barriers.
- The existing State Barrier Fence restricts the flow of tens of thousands of emus during migration years. Emus disperse seeds of many plant species over long distances. In the absence of this dispersal, plant species may decline across large areas as isolated populations die out. Further, without long-distance dispersal, some plant species will not be able to respond to climate change by shifting their distribution.
- The fence is designed to prevent dingo re-establishment in the west and south. In areas where dingos are poisoned, foxes, cats and large herbivores increase in abundance, while small and medium sized mammals, and some plant species decline. There is a body of evidence suggesting that dingos can exclude foxes and cats, to the benefit of smaller mammals, and dingos reduce kangaroo numbers, reducing herbivore impacts on plants.
- The fence may fragment the distribution of native species including small mammals and some reptiles. There are no studies examining the barrier effect of the fence on non-target species so it is uncertain how many non-target species will suffer fragmentation in addition to the plants that emus disperse.