DECLINE OF CALLITRIS-INTRATROPICA BAKER,R.T. AND SMITH,H.G. IN THE NORTHERN-TERRITORY - IMPLICATIONS FOR PRE-EUROPEAN AND POST-EUROPEAN COLONIZATION FIRE REGIMES
Dmjs. Bowman et Wj. Panton, DECLINE OF CALLITRIS-INTRATROPICA BAKER,R.T. AND SMITH,H.G. IN THE NORTHERN-TERRITORY - IMPLICATIONS FOR PRE-EUROPEAN AND POST-EUROPEAN COLONIZATION FIRE REGIMES, Journal of biogeography, 20(4), 1993, pp. 373-381
Callitris intratropica R. T. Baker & H. G. Smith occurs in a range of
environments throughout the lower latitudes of the Northern Territory.
A geographic survey of the demographic structure of stands revealed a
continuum ranging from populations which have a majority of dead indi
viduals, a lack of regeneration and fire-scarred living adults, to sta
nds with few dead or damaged individuals and a heavy stocking of juven
iles. A TWINSPAN classification divided this continuum into four group
s. There were no significant differences between the cover of rocks, g
rass or shrubs between the four groups of stands, nor was there a sign
ificant association with substrate type. Damaged stands were most comm
on and occurred throughout the species' range, while the healthier sta
nds were more typical on coastal sites with > 30% tree canopy cover. S
tands with dense regeneration were significantly associated with an ar
ea actively protected from fire by a forestry operation. A helicopter
survey on parts of the remote and currently uninhabited Arnhem Land Pl
ateau revealed a significantly greater count of dead stems than counts
of living C intratropica trees. Detailed studies at one site on the A
rnhem Land Plateau showed that there is currently a high mortality of
tagged stems, and that the abundant C intratropica stags died since th
e 1940s. It is argued that the widespread crash of C intratropica popu
lations is a response to a change in fire regime associated with the c
oming of Europeans.