Mistletoe are one the groups adversely affected by modern long-term fire regimes in the Pilbara. Image: Shutterstock
Mistletoe in the Pilbara could be facing regional extinction.
Fires ignited by arson, lightning or prescribed burns can burn thousands of hectares in the Pilbara region. This is a problem for mistletoe species, as their foliage and fresh seeds are killed when scorched.
A new study conducted by the Department of Environment and Conservation suggests Western Australian mistletoes are one of the groups adversely affected by modern long-term fire regimes, which have been in place since the 1980s. Mistletoe do not have a long-term seed storage mechanism and a limited capacity for long-distance seed dispersal.
Study author A. N. Start said that pastoralists imposed radical changes on the landscape when they settled in the region just over a century ago. “Former fire regimes were abandoned and fire was used for novel purposes, including the manipulation of pastures.
“Anthropogenic fire is still common across northern and central Australia where the trend has been to hotter and more extensive burns.”
The researchers noted that mistletoe have adapted to fire in various, imperfect ways; twelve species have attempted to reduce the risk of fire by favouring host species that grow in sites sheltered from fires. But when the host stems are killed, the length of time the hosts required to re-establish prohibits mistletoe regeneration.
Two species have low host specificity, which allows them to regenerate faster after fire events. However, both of these species are located in hummock grasslands, so they are affected by the issue of fire frequency.
While there is no extinction threat at a national or bioregional level, there is evidence of subregional contraction, particularly in the hummock grasslands. “The outlook is bleak for mistletoes growing in areas dominated by hummock grasslands,” Start said.
“Subregional extinction is likely and there are broader implications for biodiversity.”
Many insect species, including butterfly genera Ogyris and Delias, are dependent on mistletoe for larval food. They also support the mistletoebird, as well as spiny-cheeked and grey honeyeaters, which are important pollinators in the region.
Source: Science Network WA
