SIEF And The Quest For Productive Eucalypts

 

Using advanced genetic technologies to find productive plantation forest eucalypts for a new future 

Plantation Forests

Australian forestry plantations cover approximately 2 million hectares and produce nearly $6 billion worth of product every year for domestic and export markets. The plantation hardwood industry relies on Eucalyptus as its primary hardwood type, with the  main production species being Eucalyptus regnans, E. saligna, E. globulus and E. camaldulensis.

Current measures to test tree species for suitability to different climatic and growing conditions are expensive and limiting, relying on labour-intensive methods that have little commercial benefit. Through this five-year research project, the intention is to develop new methods and tools to rapidly identify tree lines that show a positive response to elevated CO2.

Predictions are that atmospheric CO2 will reach between 500 and 600ppm this century, and given the decades needed for plantation timber to grow, managers need a much more rapid method for identifying the genetic types that will respond to rising CO2 and its associated effects (higher temperatures, physiological responses and changes in water and carbon use).

Phase One at Hawkesbury

In this project, researchers at the Hawkesbury Institute led by Professor David Tissue are collaborating with CSIRO and the ANU. The first phase has involved exposing cutting-grown eucalypts to 400ppm and 640ppm CO2 and then harvesting the plants to assess the trees' growth in terms of biomass gain above and below ground, leaf area, and measures of RNA and other genetic measures.

The trees are greenhouse-grown and the gallery below shows the process of them being harvested for assessment.

Tube grown eucalypts
In this experiment, we have grown 26 different genotypes (genetic types) of Eucalyptus camaldulensis (River Red Gum) under ambient and elevated CO2. The plants are cutting-grown from a selected source and we are looking for those that show a positive response to elevated CO2 up to 640ppm. Having grown to around 80cm tall, they are now ready to be harvested to measure their biomass gain and growth under each condition.

Taking measures of the height of each stem
The first step is to take size measurements of each specimen. Here, Kaushal measures the height of each trees' stem and makes a count of the leaves present on each plant.

Measuring the trees' girth.
Next, we take measurements of the trees' girth using digital calipers to assess the growth of the stem.

Renee and Sebastian separate the leaves from the stems.
Pictured here are Ms Renee Smith (background) and Dr Sebastian Pfautsch. In this step, the leaves are removed from the trees and collected in containers according to the size of the leaves. The trees are then left in their tubes as bare stems.

Containers of leaves.
You can see the containers with leaves sorted according to size.

Bare stems ready to cutting at ground level.
The bare trees are placed together. The next step from here involves cutting the stems at ground level and slicing up the stems to weigh and record their mass, giving us an indication of the relative ability of each treatment to influence biomass gain.

Scanning leaves in a light machine
Next, we use scanning technology to process each of the leaves in a batch. This scanner allows us to measure the leaf area, an important measure of the trees' ability to thrive under each treatment. Additionally, we can also gain imaging of the trees' stomata, those tiny pores in the leaves that capture carbon dioxide from the air.

Cylinder of roots removed from the tube
Next we are interested in how the roots of each specimen have performed. Elevated CO2 has significant effects on the below-ground response of both plants and the organisms that inhabit the root zone. We need to separate the soil from the root matter which is done by careful washing of the roots and collection of any roots that fall off.

David Tissue and Michael wash roots
Here, Prof David Tissue and Dr Michael Loik (University of California, Santa Cruz) begin the root washing process. It's a careful process of washing the soil from the roots.

Washing the root ball.
The root washing process can be messy! We carefully wash the root ball to remove the soil, using hessian to collect the soil and loose roots.

Two researchers washing roots.
Using sieves and containers, we collect the root matter and the end result is a set of roots that can be measured and weighed to assess biomass gain.

Bare roots in the root ball being washed.
Here, you can see the long roots that traverse the inside of the tube and the particles of wood material that become bound to the roots. These particles need to be removed without tearing off too many roots.

Paper bag containing finished samples.
Finally, we end up with marked samples from each treatment that will be used to conduct RNA and genetic analysis.

Project ID P00021081 - Forests for the future: making the most of a high CO2 world - is funded by Western Sydney University and the Science & Industry Endowment Fund.