326
M.J. Brown and J. Read
reflect soil fertility. On the most fertile and well-drained soils, derived
from dolerite and basalt, the rainforests have tall well-formed trees of
Nothofagus cunninghamii +/- Atherosperma with a park-like open or
ferny understory and abundant epiphytic bryophytes and lichens. These
forests have been termed "callidendrous" (= beautiful tree) by Jarman et
al. (1984). On poorer sites, the trees retain their form, but there is an
increasing complement of other tree and shrub species separated into
well-defined structural layers. These forests are termed thamnic (=
shrubby) forests. On the poorest siliceous quartzites and conglomerates
or in areas of very poor drainage , the forest trees are short and of very
poor form. There is no clear separation of layers and vascular plant
species richness is high, while the numbers of ferns is generally low.
These forests are called implicate forests by Jarman et al. (1984).
Biodiversity and Biogeography of Rainforests
There is a very low diversity of vascular plant species in Tasmania lowland
rainforests , but they are comparatively rich in nonvascular plants. There
are 70 angiosperm species from 25 families of dicotyledons and 5 families
of monocotyledons (Jarman et al., 1991). This represents about 5% of the
Tasmanian flora. Another 28 species of uncertain status also occur. There
are six species of gymnosperms in four families (58% of the flora) and 49
pteridophytes (50% of the flora) (Jarman et al. , 1986). In the lower plant
groups, 217 lichens and 168 bryophytes have been recorded, each representing about one third of the Tasmanian native complement (Jarman et
al., 1991). The differences in richness are greater at anyone site, where
for example there may be as few as 3 to 6 angiosperms , but 60 to 100
lichens and 30 to 70 bryophytes . The rainforests support a speciesdepauperate vertebrate fauna which is mostly adventive from surrounding
vegetation especially after disturbances such as fire. However they are
rich in invertebrates, such as Coleoptera (Coy, 1990).
The vascular plant species show pronounced regional distributions within
Tasmania (Brown, Kirkpatrick, & Moscal, 1983; Kirkpatrick & Brown,
1984). For example, the gallery rainforests of the western rivers have a
particularly distinctive flora, which includes Lagarostrobos [ranklinii,
Acradenia frankliniae, Epacris mucronulata, Leptospermum riparium ,
and the lily Milligania longifolia. Evidence is accumulating also that there
are strong regional differences in the nonvascular flora and invertebrate
species compositions of disjunct rainforest patches of the same floristic
community occurring on geologically and physiographically matched sites
(G. Kantvilas, R. Mesibov, personal communication).
The modern affinities of the flora generally reflect the proximity of
Tasmania to other land masses, but reflect also the strong Gondwanan
relationships . Thus only 6 of the 32 woody plant genera found in
Tasmanian rainforests are endemic. Of these, 13 are found in New
Zealand, seven are also found in South America, and 23 (72%) are
shared with the Australian mainland (Table 1; Read , in press). Similarly,
M.J. Brown and J. Read
reflect soil fertility. On the most fertile and well-drained soils, derived
from dolerite and basalt, the rainforests have tall well-formed trees of
Nothofagus cunninghamii +/- Atherosperma with a park-like open or
ferny understory and abundant epiphytic bryophytes and lichens. These
forests have been termed "callidendrous" (= beautiful tree) by Jarman et
al. (1984). On poorer sites, the trees retain their form, but there is an
increasing complement of other tree and shrub species separated into
well-defined structural layers. These forests are termed thamnic (=
shrubby) forests. On the poorest siliceous quartzites and conglomerates
or in areas of very poor drainage , the forest trees are short and of very
poor form. There is no clear separation of layers and vascular plant
species richness is high, while the numbers of ferns is generally low.
These forests are called implicate forests by Jarman et al. (1984).
Biodiversity and Biogeography of Rainforests
There is a very low diversity of vascular plant species in Tasmania lowland
rainforests , but they are comparatively rich in nonvascular plants. There
are 70 angiosperm species from 25 families of dicotyledons and 5 families
of monocotyledons (Jarman et al., 1991). This represents about 5% of the
Tasmanian flora. Another 28 species of uncertain status also occur. There
are six species of gymnosperms in four families (58% of the flora) and 49
pteridophytes (50% of the flora) (Jarman et al. , 1986). In the lower plant
groups, 217 lichens and 168 bryophytes have been recorded, each representing about one third of the Tasmanian native complement (Jarman et
al., 1991). The differences in richness are greater at anyone site, where
for example there may be as few as 3 to 6 angiosperms , but 60 to 100
lichens and 30 to 70 bryophytes . The rainforests support a speciesdepauperate vertebrate fauna which is mostly adventive from surrounding
vegetation especially after disturbances such as fire. However they are
rich in invertebrates, such as Coleoptera (Coy, 1990).
The vascular plant species show pronounced regional distributions within
Tasmania (Brown, Kirkpatrick, & Moscal, 1983; Kirkpatrick & Brown,
1984). For example, the gallery rainforests of the western rivers have a
particularly distinctive flora, which includes Lagarostrobos [ranklinii,
Acradenia frankliniae, Epacris mucronulata, Leptospermum riparium ,
and the lily Milligania longifolia. Evidence is accumulating also that there
are strong regional differences in the nonvascular flora and invertebrate
species compositions of disjunct rainforest patches of the same floristic
community occurring on geologically and physiographically matched sites
(G. Kantvilas, R. Mesibov, personal communication).
The modern affinities of the flora generally reflect the proximity of
Tasmania to other land masses, but reflect also the strong Gondwanan
relationships . Thus only 6 of the 32 woody plant genera found in
Tasmanian rainforests are endemic. Of these, 13 are found in New
Zealand, seven are also found in South America, and 23 (72%) are
shared with the Australian mainland (Table 1; Read , in press). Similarly,