Download Xanthoparmelia willisii – a rare Tasmanian lichen 1 Introduction

For. Snow Landsc. Res. 75, 3: 401–405 (2000)
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Xanthoparmelia willisii – a rare Tasmanian lichen
Gintaras Kantvilas and S. Jean Jarman
Tasmanian Herbarium, G.P.O. Box 252-04, Hobart, Tasmania 7001, Australia
[email protected]
Abstract
A study of the distribution and conservation status of Xanthoparmelia willisii in Tasmania has
confirmed that this lichen is very uncommon, known only from three viable populations, all on
private land. The habitat of the species, native grassland and herbfield grazed by sheep, has been
severely modified and fragmented elsewhere in Tasmania. Sufficient data now exist for nominating
this species for listing under the Tasmanian Threatened Species Protection Act 1995. Remnant
dry grasslands appear to be an important habitat for terricolous lichens and several additional
species are also likely to be at risk.
Keywords: lichens, Tasmania, Parmeliaceae, Xanthoparmelia, conservation, non-vascular plants
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Introduction
With approximately 40% of its land area in formal reserves, Tasmania has taken significant
steps towards the conservation of its largely unspoilt natural landscape, complex mosaic of
plant communities and rich diversity of species. The Reserves are based on scenic, aesthetic,
wilderness and biological values. In addition to the Reserve system, there is also the
Threatened Species Protection Act 1995, which provides for the protection and management
of threatened native flora and fauna. As of 1999, more than 460 vascular plant species have
been listed under the Act, based on guidelines derived from IUCN criteria (1994), local
geographic and biological knowledge and expert assessment of threatening impacts.
It is generally accepted (HALLINGBÄCK et al. 1995) that many of the criteria, especially the
more quantitative ones, can be difficult to meet for non-vascular plants, mainly due to the lack
of sufficient data on such matters as population sizes and decline in numbers of individuals.
In Tasmania, in response to this problem, criteria for listing these plants have been based
extensively on expert knowledge of inferred habitat, known distribution and risk. Thus at
present, four lichen species are listed on the Schedules of the Act: Xanthoparmelia vicaria Elix
& J. Johnst., Punctelia subflava (Taylor) Elix & J. Johnst., Hypotrachyna laevigata (Sm.) Hale
and Parmotrema crinitum (Ach.) M. Choisy. However, many others appear to be uncommon
and may also be at risk. In order to ascertain whether such species are indeed rare, endangered or vulnerable, and therefore worthy of listing, or whether their apparent rarity is
due solely to their inconspicuous nature and lack of data, considerable research effort is
required, involving field surveys, evaluation of the species’ habitat and assessment of risks and
threatening impacts. In the meantime, such species can be regarded as “data deficient” and
await further study.
A significant number of the “data deficient” lichens in Tasmania belong to the genus
Xanthoparmelia. Fifty-five species of this genus occur in Tasmania (G. Kantvilas & J.A. Elix,
unpublished data), mostly in dry sclerophyll forests and dry coastal heathlands in the eastern
parts of the island, where they are often one of the major contributors to plant cover,
colonising extensive patches of otherwise bare rock or soil. Many species are also found in
disturbed areas such as roadsides, or on man-made surfaces such as roofing tiles, bricks and
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Gintaras Kantvilas, S. Jean Jarman
bitumen. A feature of the genus is the unusually high number of species with an apparently
very restricted geographical distribution in the State, especially in areas not included within
formal Reserves (see also G. KANTVILAS, this volume). The present paper describes a small,
circumscribed project to determine the current distribution in Tasmania of Xanthoparmelia
willisii (Kurok. & Filson) Elix & J. Johnst., a lichen which is very poorly known and apparently uncommon.
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The Species
Xanthoparmelia willisii is a small foliose lichen, known from Tasmania and southern Australia.
It is characterised by linear-elongate lobes with a pale yellowish undersurface virtually devoid
of rhizines, and forms rosettes or pulvinate clumps loosely attached to the substrate (Fig. 1).
It contains usnic acid,fumarprotocetraric acid,succinprotocetraric acid and protocetraric acid.
A full taxonomic description is provided by ELIX (1994). The species is very conspicuous and
readily recognised in the field, features which are highly advantageous in such a study that
requires extensive areas to be searched rapidly without removal of large quantities
of specimens for identification in the laboratory. In Tasmania, there are only two other
potentially confusing species. These are X. amphixantha (Müll. Arg.) Hale, which grows in
similar habitats, but differs from X. willisii in containing stictic acid and in having a weakly
maculate upper surface and sparsely rhizinate undersurface; and X. molliuscula (Ach.) Hale,
which may occur as scattered more or less terete laciniae that superficially resemble X. willisii
but also differ by containing stictic acid.
Before the present study, Xanthoparmelia willisii was known in Tasmania only from a few
collections, held in the Tasmanian Herbarium. All were more than 25 years old and rather
imprecisely located geographically. The collections were from dry, rough grazing country, a
habitat that is likely to have been significantly modified to the detriment of the species. The
most likely causes of degradation of this habitat are pasture improvement and over-grazing.
Fig. 1. Thalli of Xanthoparmelia willisii, growing with grasses, forbs, bryophytes and other lichens.
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Material and methods
The basic strategy adopted was to visit earlier collecting areas to locate the species and then
extend the search to other sites once a better understanding of the habitat had been gained.
The area searched is in the southern Midlands as indicated in Figure 2.
Selected specimens examined: Tasmania: Lake Tooms Road, 8 km from Ross, 5. xii. 1969,
G.C. Bratt & J.A. Cashin 69/861 (HO, AD, MEL); Tor Hill Road at gate to Clairveaux, 20. iv.
1999, G. Kantvilas 168/99 (HO); Meadsfield Road, 30. iii.1999, G. Kantvilas 134/99 (HO); near
Hartfield homestead, 30. iii. 1999, G. Kantvilas 131/99 (HO).
TASMANIA
41°
42°
Ross
Bothwell
43°
145°
148°
147°
148°
Fig. 2. The known distribution of Xanthoparmelia willisii. The dotted line represents the boundaries of
the search area.
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Gintaras Kantvilas, S. Jean Jarman
Results
The initial search was successful, in that two of the previously recorded populations were
located, one near Ross and the other near Bothwell, further to the south-west. A third locality
derived from herbarium data appears to be erroneous and based on a misinterpretation of
the original label information.
Of the two viable populations relocated, the first was in an area of rough sheep pasture
with scattered Eucalyptus pauciflora, native herbaceous plants such as Leucochrysum
albicans, and outcropping basalt (Fig. 3). The second was on rough ground at the margin of a
ploughed paddock on sandstone.
On the basis of the ecology of these sites, additional areas in the southern Midlands were
searched. They included open eucalypt woodland or rough pasture on basalt, dolerite or
sedimentary rocks. Only two further populations were located. One was in an “improved”
pasture and comprised three depauperate thalli; the species is considered on the verge of
extinction at this site. The second is a small population on rough grazing land beneath
eucalypts, and is also very small and fragmented. All the populations are on private land.
The habitat of Xanthoparmelia willisii can now be characterised as unimproved native
grassland-herbfield where the cover of vascular plants is kept low by grazing. All sites are
within the 600 mm per annum isohyet, at an altitude range of 200–400 m.
Fig. 3. The typical habitat of Xanthoparmelia willisii, comprising rough pasture and sparse eucalypts.
For. Snow Landsc. Res. 75, 3 (2000)
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Conclusions
Although Xanthoparmelia willisii is still present in the Tasmanian landscape, with at least two
viable populations and one rather small fragmented one, its long-term future could well be
tenuous. Field observations suggest that it cannot survive in improved pasture but that it is
also unlikely to survive without heavy grazing that will maintain open ground with stunted
grasses, small herbs and bare soil. Sufficient data are now available to nominate this species
for listing on the schedules of the Threatened Species Protection Act 1995 and it is anticipated
that it will be included under the schedules of the Act in the near future.
This lichen is an indicator species for a very lichen-rich habitat, and several of the species
with which it occurs, even though poorly known at present, are likely to be equally uncommon
and vulnerable. Associated species include X. molliuscula, which appears to be even more
uncommon and known from a single tiny population extending over just a few square metres.
This species was discovered in Tasmania in the course of the study; it also occurs on the
Australian mainland, New Zealand and in southern Africa. Other uncommon terricolous
grassland species, observed in the course of the project, although not necessarily in association
with X. willisii, include as yet undetermined species of Caloplaca and Verrucaria, Rinodina
conradii Körber, Endocarpon species, Collema coccophorum Tuck., Psora species, Xanthoparmelia amphixantha, Neofuscelia torulosa Elix and N. luteonotata (J. Steiner) Essl.
Acknowledgements
We thank Dalia Howe for technical assistance, and Christoph Scheidegger and the Swiss Academy
for their support, which enabled an abridged version of this paper to be presented as a poster at
the Licons Conference in Birmensdorf in August 1999. The work was funded in part by the
Threatened Species Unit at the Tasmanian Department of Primary Industries, Water and
Environment in Hobart.
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References
ELIX, J.A., 1994: Xanthoparmelia. Flora of Australia 55: 201–308.
HALLINGBÄCK, T.; HODGETTS, N.; URMI, E., 1995: How to apply the new IUCN Red List
categories to bryophytes. Species 24: 37–41.