The area under plantations in northern Australia has increased
rapidly since the mid-1990s, much of it on soils and into climates
that are outside historical plantation management experience. The
estate now covers a wide range of latitudes and many challenging
geographic conditions: extreme weather conditions of cyclonic
winds, heavy rainfall and flooding in the north; and risks of
droughts and heavy frosts in the south. Predicting rotation-length
outcomes under these circumstances is difficult, and extrapolating
from experience in one region with a particular set of geographic
conditions to another region with different geographic conditions
is unwise. In many cases, the physiological and disturbance events
that determine the outcomes are very different from those in
southern and Mediterranean climates where experience is
rich.
To this challenge is added the prospect of climate
change—predicted to manifest itself in creating drier, hotter
environments where plantations are grown and, perhaps more
importantly, in creating greater annual climatic variability and
more extreme events or seasons.
This project focused on developing sufficient understanding of
the physiological and environmental determinants of growth and
profitable plantation development in our northern climate. The aim
was to use this knowledge to develop not only expected plantation
performance, but also to try to analyse the probable impact on
plantation success of low-frequency climatic events such as frost,
drought or cyclone damage.
The project worked to achieve these goals by focusing on a few
key and typical plantation species: Eucalyptus pellita
(grown in plantations in the humid tropics of the Northern
Territory and north Queensland and the South Pacific), and E.
dunnii and Corymbia citriodora subsp.
variegata (both planted extensively in the subtropics of
New South Wales, Queensland and internationally).
The aim was to use this understanding to parameterise and, if
necessary, structurally modify, an existing physiology-based model,
CABALA (Carbon Balance). CABALA
links carbon, water and nitrogen fluxes and pools to predict growth
under changed environmental conditions and is particularly well
suited to scenario modelling to estimate variability and risk once
site and species parameterisation has been undertaken. The
knowledge gained from applying this approach to CABALA can be
translated rapidly to other process-based models.
The leader of Project 1.4 was Dr Mila
Bristow (DEEDI, Qld).
