In late 2013, I joined a Te Papa science team on an expedition to the Snares Islands Nature Reserve, 105 km south-southwest of Stewart Island. Here we completed a range of seabird and plant research projects. One of our research goals on the Snares Islands was to collect non-vascular plants. Non-vascular plants include mosses, liverworts and hornworts (collectively known as bryophytes) and lichens.
Mosses have two main life stages – the gametophyte stage and sporophyte stage. Both stages are visible in images on this post. The gametophyte (gamete plant) leafy stage produces the male and female reproductive organs. The sporophyte (spore plant) develops from female reproductive organs on the gametophyte. The sporophyte structures seen in these moss images are wiry and longer lasting in contrast to more fleshy, transient liverwort sporophyte structures.
One reason why we focused our plant collecting efforts on these plant groups was that the Snares Islands have a well-documented and stable vascular plant flora. We felt it was more likely that previous collecting efforts may have missed species of bryophytes or that the small and very light spores could have more easily traversed the c.100km from Stewart Island since the last thorough survey in the 1960’s. So it was these groups that were most likely to increase the known plant diversity of the Islands.
The place to start collecting bryophytes and lichens is under your feet, so to speak. So I started at the concrete footstep to the hut where I collected two species of moss (Tayloria purpurascens & Rhynchostegium laxatum) and two species of lichen (Haematomma fenzlianum and Xanthoria parietina). Most lichen species were found on coastal rocks, but we also managed to collect lichens from decaying branches inland. We are hopeful that these ‘epiphytic’ species may be additional records for the islands.
In total we collected 15 species of lichen, 11 species of moss and 12 species of liverwort. We failed to locate 3 previously collected moss species, but extended the known number of Snares moss species by 1-3 (records still being checked). We failed to locate 7 previously collected liverwort species but extended the known number of Snares liverwort species by 7 . One of the ‘concrete footstep’ species is a new moss species record for the Snares Islands. This moss was not seen elsewhere on the island.
Among the more common species were the liverworts Frullania patula and Chiloscyphus cuspidatus and the mosses Calyptrochaeta apiculata, Rhapidorynchium amoenum and Wijkia extenuata. It was also interesting to find species that were common on the mainland, such as ‘pipe cleaner’ moss (Ptychomnion aciculare) and the liverwort Trichocolea mollissima, were very rare on the Snares. Both species were found once, the latter species being a new record for the island (with records of pipe cleaner moss being checked). These species have either become recently introduced or find environmental conditions on North-East Island challenging.
Three environmental factors limiting habitat and influencing bryophyte diversity on the Snares are: 1. disturbance by marine mammals and seabirds. 2. exposure to salt-laden winds and 3. availability of moisture. Unsurprisingly, the greatest bryophyte diversity was to be found on rotting branches and undisturbed banks in gullies which provided protection from exposure and animal activity as well as a more constant supply of moisture.
What superficially looks like a leafy liverwort, in the below image, was identified by David Glenny as a fern gametophyte. And indeed, in the image, you can see the fern gametophyte and young fern fronds emerging. Usually fern gametophytes are impossible to identify without DNA sequencing. However, we were able to identify these specimens as Asplenium, based on scale characteristics from scales at the frond base. The limited presence of other fern genera (three) also helped us reach this determination.
The collections are now stored as specimens at the Te Papa herbarium (WELT). The herbarium has almost 300 000 plant specimens and it provides a vouchered biodiversity record of what grows where. These specimens can be used by taxonomists to differentiate between species.
There is more work to do, before we have a more accurate picture of recorded bryophytes and lichens on the Snares. We intend to update and publish the bryophyte species list for the Snares Islands at a later date. I’ll be certain to update this post at that time.
Thank you to the botanists who provided the formal identifications for these collections. The lichen identifications were completed by Barbara Polly, Te Papa. The bryophyte specimens were identified by moss expert, Allan Fife, Landcare Research and liverwort experts, David Glenny, Landcare Research and Peter Beveridge, Te Papa. Duplicates of most WELT specimens have also been accessioned at the Landcare Resaerch Allan herbarium (CHR). Thank you to Jean-Claude Stahl, Alan Tennyson & Colin Miskelly for help with collecting the specimens.
Other blogs on the Te Papa Snares Islands Expedition: