This research project focuses on the effects of climate variability, climate change and water use in two different types of eucalypt trees, Corymbia maculata (spotted gum) and Eucalyptus tricarpa (red ironbark).
These two different species were chosen because they cope with low rainfall and drought in different ways; spotted gum is a drought ‘avoider’ and uses an extensive root system to maintain its water intake, whereas red ironbark is a drought ‘tolerator’ and alters its metabolism to stop growing during drought.
Irrigation to these trees is being manipulated to simulate drought in forests 98, 99 and 101 in this long term, detailed study on the adaptability, genetics, physiology and ecology of the Eucalyptus genus.
Cris Brack, Fenner School, Australian National University (ANU)
Michael Roderick, Tim Brown and Justin Borovitz, RSB, Australian National University
Albert van Dijk, Fenner School, Australian National University
- Compare the growth and yield of two eucalypt species to various watering regimes.
- Determine the below ground moisture and temperature environments under the different forests and watering regimes.
- Allow the modelling of the response of eucalypts to varying climate scenarios, including more extreme rainfall patterns.
- Technical advances in the development and use of variable scale sensor arrays in the field.
- Improve the parameterisation of native tree growth and yield models.
- Randomised block design with: two eucalypt species with different physiological approaches to water stress; three watering treatments; replication.
- Establishment of sensor network including, in the first stage:
- Two below ground sensors (moisture and temperature)
- Two above ground sensors (temperature, PAR)
- Two dendrometer sensors per treatment/species block.
- Establish giga-pixel, multi-focus time lapse camera capture.
- Integrate data and network.
- Forests 98 and 99 established although numerous individual Corymbia maculata trees will need to be replanted in 2015 after losses in 2013/2014.
- Sensors to be fully installed by 12/2014.
- Tower (for camera) to be installed by end of 2015.
- Recording to be continuous (as fine as 15 minute intervals during some time spans) until trees are at least mature (30 years).
- Sensor data will be 'live' and available over internet in 2015.
- Publications in relevant professional and technical journals, including but not limited to, Australian Forestry, Ecology, Tree Physiology, Remote Sensing in the Environment.
Results as of September 2013
Many of the seedlings survived establishment, however, a late and severe frost in October 2012, followed by extreme heat, caused many of the Corymbia maculata (spotted gum) to die or die-back, whereas most of the Eucalyptus tricarpa (red ironbark) survived the extreme temperatures. Water availability was deliberately restricted to both species.
Eucalyptus tricarpa (red ironbark) Sept 2013
Corymbia maculata (spotted gum) Sept 2013.
Key research questions
- How will these two different types of eucalypts respond to climate change with a drier climate and longer droughts, as projected to occur in many parts of Australia?
- How much carbon do eucalypt forests sequester from the atmosphere?
- Will eucalypt trees change their shape or the properties of their wood under different climate extremes?
- How do eucalypts respond to moisture stress (tree physiology)?
- Can we enhance the survival of eucalypts in a more variable climate (genetics)?
All data collected will be available online for research, outreach and educational use.
Two eucalypt species were selected for their different responses to low rainfall:
- Corymbia maculata, also known as Eucalyptus maculata (spotted gum), is a “drought avoider” that uses extensive and efficient roots to fully exploit any soil moisture available.
- Eucalyptus tricarpa (red ironbark) is a “drought tolerator” that significantly alters its metabolism to stop growing when in severe moisture stress.
The trees were planted in blocks of single species, with the blocks arranged to allow three watering treatments and replication. Such an arrangement allows researchers to measure the effects of different watering regimes on the growth and survival of the trees, and consequently estimate the effects on many other eucalypt species. The blocks are large enough to allow them to be split to examine other important environmental effects such as competition.