Paul Killey
PhD student
Topic: Physiological response
and growth of subtropical eucalypts following repeated pruning.
School of Botany
and Zoology, Fenner School of
Environment and Society, Australian National
University (ANU)
email: paul.killey@anu.edu.au
Pruning plantation trees is an important silvicultural tool for
enhancing commercial log value. For the tree, however, pruning
removes the photosynthetic machinery required to capture the energy
needed for survival and growth. Previous research has demonstrated
that a number of eucalypt species have an ability to compensate for
lost foliage through a short-term increase in the photosynthetic
capacity of the remaining crown. As a result, if less than 50% of
the green crown is removed after canopy closure, then growth (DBH
and height increments) remains equivalent to unpruned trees.
Research to date has investigated the response of two
subtropical eucalypts (Eucalyptus cloeziana and E.
pilularis) to a single pruning event. The effect of current
silvicultural regimes involving multiple pruning events and
different subtropical species is not known. Nor can we
anticipate how pruned trees will respond to concurrent other
stresses, such as drought or herbivory. Further investigation of
this group of eucalypts is required to inform pruning regimes for a
wider range of subtropical species.
My research will address these knowledge gaps by answering the
following questions:
- Is the ability to increase photosynthetic capacity consistent
across a range of commercially important species from different
subgenera?
- Can the physiological response to defoliation be predicted by a
species’ phylogeny and/or the ecological envelope defined by
its geographic distribution?
- Is the ability to increase photosynthetic capacity impaired by
repeated pruning events?
- If so, what is the physiological basis for a decline in
compensation, and how might this be managed for silviculturally
favourable results?
- Is the ability to increase photosynthetic capacity impaired by
concurrent events such as water stress or heat stress?
- Is the physiological response to pruning different to other
defoliation events such as herbivory, fire or drought?
The results of this research will inform the pruning regimes
applied to subtropical eucalypt plantations. Recommendations
will include the optimum timing of repeated pruning events and
modifications to pruning prescriptions for favourable and
unfavourable conditions. This research will also assist in refining
yield predictions for pruned trees.
I completed my undergraduate studies in 2008, graduating from
the Australian National University (ANU) with a Bachelor of Science
(Forestry) with Honours, for which I was awarded a University
Medal. My honours research investigated the production of coarse
woody debris in yellow box – red gum woodlands in the ACT. I
have also worked as a research assistant investigating carbon
stocks and sequestration in the vegetation biomass of the ACT.
My current research is financially supported by the Australian
Research Council, the Australian National University and the CRC
for Forestry.
My supervisors are Dr Adrienne
Nicotra (School of Botany and Zoology, ANU) and Dr Chris
McElhinny (Fenner School of Environment and Society, ANU).
Within the CRC for Forestry, my research contributes to Program Two
‘High value wood resources’.
