Cypress pine (Callitris intratropica
) is a long-lived tree that occurs across northern Australia in a range of
habitats with free-draining soils. High-intensity fires will kill or scar
mature cypress trees but the termite-resistant stems remain standing for
many years. Low-intensity fires may kill juvenile trees but will not
generally affect mature trees.
condition of cypress stands are therefore a guide to the severity of the
fire regime - dead cypress stems indicate there have been high-intensity
In recent years, ground-based cypress
surveys over many parts of northern Australia have counted living and dead
pine trees to determine their current condition and former range. Both
living and dead cypress are highly visible in the savanna landscape, and
aerial surveys can also be used.
An aerial survey in October 2000 showed
that the condition of cypress pine stands in western Arnhem Land varied
considerably. There were more living trees than dead stems in areas
protected from frequent fire - in the rocky areas in the dissected sandstone
and the escarpment country.
On the open sand sheets and savanna lowland
woodlands, the dead stems far outnumbered the living, indicating that fire
severity has increased in recent times. The diameters of dead trees are
measured, sections cut and the growth rings counted to determine a
relationship between tree diameter and age.