Slime Moulds at Black Sugarloaf, Birralee
by Sarah Lloyd
Trichia decipiens (height 3 mm) appears frequently on bark and decaying wood
The recent attention grabbing headline - Slime mold uses an externalized spatial “memory” to navigate in complex environments - about research at the University of Sydney, was carried out in the comfort of a laboratory where the plasmodium of Physarum polycephalum moves about on an algal film in a Petri dish.
My study of plasmodial slime moulds involves the next phase in the life of these extraordinary organisms - searching for their reproductive structures. Physarum polycephalum is the ‘lab rat’ of slime moulds that would rarely, if ever, be seen in the field. But other species of Physarum along with an extraordinary array of other minute forms (most around 2 millimetres high) are frequently encountered in the tall wet eucalypt forests of northern Tasmania.
Plasmodial slime moulds (also known as myxomycetes) are common and
widespread in terrestrial ecosystems where suitable habitat
(i.e. decaying plant material) exists. Despite the fact that they
are known to be abundant in temperate regions of the world, and that
several type specimens were collected in Tasmania, there has been
very little research on slime moulds here.
I started a study of slime moulds in the tall eucalypt forest at Black
Sugarloaf, Birralee, in May 2010. I am fortunate enough to live
permanently in my study area and so can make daily visits to monitor
the progress of species in the field. After the first year of
observation I thought I had begun to get a sense of the frequency of
appearance of some species, but observations over the following two
years have confused the picture. My limited experience tells me that
even with daily visits to a number of sites it is too early to make
assumptions about whether species are rare or common as there seems
to be great variation in the abundance of particular species from
year to year.
Black Sugarloaf (41° 23’ 42” S 146° 48’ 23” E) is located in central north Tasmania. It has well-drained, rocky, dolerite-derived soils and its forests are dominated by Eucalyptus species. Over the past one hundred or so years these have been cut for sawlogs, railway sleepers, telegraph poles and, more recently, for woodchips. 130 acres of forest at approximately 450m asl is privately owned land protected by a conservation covenant. Current land management practices do not include removal or burning of coarse woody debris or the understorey vegetation. The areas most often surveyed for slime moulds (Big Tree Track, Thismia Gully and Swamp) are all within about 100-200 metres from Home. Big Tree Track is visited at least once each day; the other areas are usually visited once a week.
Tall wet Eucalypt forest
Home
'Home' is open eucalypt forest dominated by gumtopped stringybark
(Eucalyptus delegatensis), black peppermint
(E. amygdalina), stringybark (E. obliqua), white gum
(E. viminalis) and swamp gum (E. ovata). The diverse
understorey has silver banksia (Banksia marginata), forest
daisybush (Olearia lirata), native cherry (Exocarpos
cupressiformis), guitarplant (Lomatia tinctoria),
prickly moses (Acacia verticillata), dollybush (Cassinia
aculeata) and mountain correa (Correa
lawrenciana). Ground layer vegetation includes sagg (Lomandra
longifolia), forest flaxlily (Dianella tasmanica),
cutting grass (Gahnia grandis), swordsedge (Lepidosperma
sp.), bracken fern (Peridium esculentum) and other
ferns. Some clearing of understorey vegetation for fire protection
occurs around the house but old logs are left in situ.
Melaleuca Swamp Forest
Swamp
'The Swamp' is approximately 100 metres north of 'Home'. It is a damp
shady area with a permanent small creek that overflows onto a level
flood plain after extended rainy periods. The closed canopy forest is
dominated by blackwood (Acacia melanoxylon) and swamp gum
(E. ovata) with a mid layer of tall swamp paperbark
(Melaleuca ericifolia) and scented paperbark
(M. squarrosa). The ground is mostly devoid of vegetation
except for cutting grass, hard waterfern (Blechnum watsii)
soft waterfern (B. nudum), treefern (Dicksonia
antarctica) and mother shieldfern (Polystichum
proliferum). There is a small patch of rainforest species
including sassafras (Atherosperma moschatum) and the endemic
heartberry (Aristotelia peduncularis). There are numerous
logs and lots of leaf litter.
Old growth Eucalypt sp.
Big Tree Track
The Big Tree Track (BTT) is so called because when we first moved to
Black Sugarloaf a large old-growth tree, the only remaining such tree
on Black Sugarloaf, was still standing. The tree fell in about 1990
and the stump and large log now provide substrate for numerous
bryophytes, fungi and slime moulds. The 1 km track meanders through
closed wet forest dominated by stringybark (Eucalyptus
obliqua) and blackwood (Acacia melanoxylon). The
midstorey species include silver banksia (Banksia marginata),
dogwood (Pomaderris apetala), blanketleaf (Bedfordia
salicina), treefern (Dicksonia antarctica), forest
daisybush (Olearia lirata), and musk
(O. argophylla). The ground layer is mostly devoid of
vegetation except for patches of hard waterfern (Blechnum
nudum). There is a deep layer of leaf litter and numerous rotting
logs covered in mosses, leafy liverworts and lichens.
Shaded wet forest
Thismia Gully
Thismia Gully (TG) is a southeast facing slope approximately 100
metres downslope from ‘home’. It has a watercourse with an ephemeral
creek that flows only after extended rainy periods. It has a closed
wet forest dominated by blackwood and swamp gum. The mid layer
vegetation is mostly dogwood (Pomaderris apetala), musk (Olearia
argophylla) and native currant (Coprosma quadrifida). The ground is
devoid of vegetation except for occasional ferns including hard
waterfern, treefern and tender brake (Pteris tremula). There is a
litter layer of leaves, many fallen small trees, particularly dogwood,
and numerous very large old bryophyte-covered eucalypt logs.
The area is referred to as Thismia Gully because of the occurrence of Thismia rodwayi a small saprotrophic plant whose common name is fairy lanterns.
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