In January and February 2017, Richmond RAAF base recorded 11 days above 40°C, the 11th of February was the hottest day coming in at a whopping 47°C. Prof. David Ellsworth (my supervisor) and I were interested in how our local trees were handling such high temperatures. What a coincidence that I, a new employee at the Hawkesbury Institute for the Environment at Western Sydney University, would be given so many ‘chances’ for testing in extreme conditions. I had the opportunity to get out into the field for the first time, record some interesting data using fun ‘techy-gear’ and gain experience too.
During the earlier part of the very hot days in January and February, I would visit and experiment on various tree species found on campus and at OZBreed, Richmond. First, I would smother the underside of a leaf of a tree with grease, then, tag the branch so I could find it again later in the day.
As air temperature ramped up (usually around 1:30-3PM) I would revisit the tree and using an infrared thermometer, measure and record temperatures of the greased leaves; nearby ungreased leaves; surrounding ground surfaces; and ambient air temperature. I also used an infrared camera to take infrared images of the whole tree and the tested leaves.
The responses varied between species. What I found most interesting was the greased leaves from the Ficus hybrid, it’s leaves turned brown and shrivelled after only a few hours. Other trees with the same treatment took more than a day to show similar damage.
After getting some interesting results, we’re really excited and looking forward to further heat hardiness testing of our horticultural trees.
Elise Dando is a qualified Horticulturist with 7 years experience in retail nursery, a 2nd year student Bachelor of Science majoring in Conservation Biology at Western Sydney University's Hawkesbury campus and lab assistant at the Hawkesbury Institute for the Environment.