| Despite some initial gatherings of lichens made from the islands by Henry Travers in 1864, followed over the last 100 or so years by a few other botanists, much of our present knowledge of the
Chatham Islands lichens has come from the pioneering work of former Conservation Board Chair Dr Peter Johnson. Peter has made a concerted effort to collect lichens from the islands, most especially the outer islands and also from lichen groups others tend to ignore. Indeed it was
Peter's efforts that resulted in the discovery of Caloplaca
maculata. However, despite his hard work it is clear that our knowledge of
the Chatham Island lichen flora is still very rudimentary
and that more collection effort is needed to obtain a better idea of what is
out on the islands.
To that end, and despite their reputation for
being difficult to identify Department of Conservation staff have been working
closely with Landcare Research to try and better sample the islands ecosystems
to see what lichens are present on the island. This has meant the painstaking
sampling of a range of ecosystems and habitats, and the careful curation of the
gatherings back in New
Zealand. One particular lichen, Sticta fuliginosa even had the
authorities back in New
Zealand very excited. This species reeks of
fish as it dries, so the innocuous little plant caused some consternation for
botanists at both Christchurch
and Auckland
airports when its presence attracted the attention of a paua dog last May! Its
smell lead to some involved explanations as to why a series of boxes labelled
"Lichens" smelt like paua, and that "No we were not paua smugglers".
Results
based on the September 2007 and May 2008 major lichen collecting efforts are
still coming in. Indeed some gatherings have had to be sent to the United States and
Europe to be identified, while others will
probably remain in their collection bags awaiting the day when some future
researcher will take an interest in a particular genus or group of lichens.
Nevertheless,
and despite these inevitable delays in identification, we now have better collections
spanning the main islands of the Chathams
group, and the key ecosystems on offer. Currently, 239 types of lichen are
known from the islands, that's a 398% increase on what we knew in 2007!
Again, as
has been demonstrated by other studies of Chatham Island
liverworts and mosses, the Chatham Lichen flora shows the same
intriguing mix of
tropical and northern New Zealand species with southern New Zealand and
subantarctic species. Indeed some associations you are very unlikely to
see
anywhere else in the New Zealand subcontinent, for example on Pitt
Island one
can see the tropical lichen Ramalina
luciae growing with the subantarctic R.
inflata, both reaching their
respective world southern and northern limits on the island. While a drive to the Awatotara will reveal
masses of the normally alpine Usnea
acromelana festooning the roadside banks at a mere 100 m above sea level.
On Pitt parts of the summit crest of Hakepa (Walkemup) are covered in the
worm-like Thamnolia vermicularis - a
species that is more commonly seen high up in the Southern
Alps of the South Island! While
coastal and swamp forest trees on both Chatham and Pitt are often festooned in Usnea angulata and Pseudocyphellaria aurata, two lichens more commonly seen on
mangroves in northern New Zealand. Also there are some genera that have an
unusually high representation on the islands. For example 13 of the New Zealand's 28
species of old man's beard (Usnea),
and 35 of New Zealand's
38 species of Pseudocyphellaria are
known from the islands. The island also supports thriving populations of
species that are becoming scarce in New Zealand or even globally. For
example, the brilliant orange air pollution sensitive Teloschistes flavicans and the peat bog dwelling Icmadophila splachnirima are locally common on the Chatham
Islands.
As with
liverworts and mosses the dearth of endemics on the islands flies in the face
of the flowering plant and fern flora which contributes an estimated 50 to the Chatham flora. There are
still no endemic liverworts known from the islands and only one moss, the
doubtfully distinct Macromitirum ramsayae is considered endemic. The sole Chatham
endemic lichen, Caloplaca maculata also remains on the uncertain list. Although it is a distinctive species until
better collecting of this genus is undertaken elsewhere in the New Zealand
subcontinent we just can't be sure if it is truly endemic. Irrespective of
that, it possibly also qualifies as one of the Chatham
Islands most threatened lichens. Currently it is known from just
one coastal rock platform, where it grows on a hard exposure of basaltic tuff
just above the spray zone. The little plants cover an area of c.2 × 3 m, and
while several hundred individuals exist at this site, that population's
eventual loss from coastal erosion is inevitable.
|
Pseudocyphellaria rubella
Teloschistes flavicans and Ramalina peruviana |
