WILDLIFE OF LANCEWOOD (ACACIA-SHIRLEYI) THICKETS AND WOODLANDS IN NORTHERN AUSTRALIA .2. COMPARISONS WITH OTHER ENVIRONMENTS OF THE REGION (ACACIA WOODLANDS, EUCALYPTUS SAVANNA WOODLANDS AND MONSOON RAIN-FORESTS)
Jcz. Woinarski et A. Fisher, WILDLIFE OF LANCEWOOD (ACACIA-SHIRLEYI) THICKETS AND WOODLANDS IN NORTHERN AUSTRALIA .2. COMPARISONS WITH OTHER ENVIRONMENTS OF THE REGION (ACACIA WOODLANDS, EUCALYPTUS SAVANNA WOODLANDS AND MONSOON RAIN-FORESTS), Wildlife research, 22(4), 1995, pp. 413-443
Embedded in the extensive Eucalyptus open forests and savanna woodland
s that dominate the northern Australian landscape are patches of monso
on rainforest and Acacia thickets and woodlands. In this paper, the ve
rtebrate species composition of patches of lancewood (Acacia shirleyi)
thickets and woodlands of the Northern Territory is compared with tha
t of other environments of this region: two other Acacia woodlands (pi
ndan and gidgee), patches of monsoon rainforests and the extensive Euc
alyptus open forests and woodlands. The vertebrate fauna of lancewood
thickets is distinct from that of Eucalyptus open forests, and has few
er species. Differences in species composition and richness are associ
ated with substantial differences in resource availability, with lance
wood thickets having far less grass cover (and hence relatively few gr
anivorous birds and rodents, but more ground-feeding insectivorous and
omnivorous birds), fewer nectar-bearing flowers (and hence fewer nect
arivorous birds) and lower structural and floristic diversity than Euc
alyptus open forests. There is little difference in species richness o
r total abundance between the three types of Acacia woodlands sampled.
Lancewood thickets have fewer species than monsoon rainforests. Speci
es composition Varies almost continuously from coastal wet monsoon rai
nforests to coastal dry monsoon rainforests to inland dry monsoon rain
forests to lancewood thickets to pindan woodlands to gidgee woodlands,
in accord with the pronounced rainfall gradient of this region and wi
th canopy cover and height. Within this broad continuum the three Acac
ia woodlands are most closely grouped. Species turnover along this gra
dient consists of substantial decrease or loss of some foraging groups
(e.g. frugivorous birds) or replacement of species within broad forag
ing groups. The faunal relationship of the monsoon rainforests and Aca
cia communities provides some support for considering these fire-sensi
tive environments as fragments of a formerly extensive continuum. Thre
e species (Pomatostomus temporalis, Struthidea cinerea and Melanodryas
cucullata), all ground-foraging insectivorous or omnivorous birds, we
re significantly associated with lancewood in this region, but all thr
ee have extensive ranges beyond this area.