Prescribed burn brings engangered orchid back from the brink of extinction
The Naked Sun-orchid (Thelymitra circumsepta) is an endangered species in South Australia known to occur in only a single location – a swamp near Mount Lofty. In 2017, the situation for the orchid was so dire that only 12 individual plants were found.
Some orchids are known to respond positively to fire and it is thought that much of the habitat that Naked Sun-orchids had occupied in the past has been taken over by the native Coral Fern (Gleichenia microphylla) in the absence of fire. DEW ecologists and fire management officers had the idea to try to use a prescribed burn to reduce the cover of Coral Fern and stimulate orchid recruitment. But ecological responses to fire are often complex and with only 12 surviving plants there was no room for error.
Crews were very careful to burn only half of the existing population to ensure some plants survived as a precaution. Since 2017 when the burn was completed, staff and volunteers from the Native Orchid Society of SA have monitored the burned and unburned areas to see how the species is responding.
Happily, the results have been very positive! In the area that was burned, there were originally only 6 orchids counted before the fire but that number has now increased to more than 80 plants post-fire! Compare that to no increase in orchid numbers in the unburned area and it seems clear that, so far, the burning was beneficial.
Monitoring of the area will continue to see how many orchids flower and set seed and to see if any more emerge in the burned area previously covered by ferns outside of the known occupied zone. This prescribed burn has been successful in achieving dual benefits both reducing fuel loads to protect lives and property and contributing to threatened species conservation.
You can find a video about this story here https://youtu.be/qoMICoHroSU