THE BIG PICTURE
Cracking the lichen code
‘Nearly half of all SA lichens are still mysteries to science – we’ve been taking on the challenge and already found two new genera!’
REPORT: DANIELLE WARD, MADELEEN STRUWIG, SUTAPA ADHIKARI, ALAN FRYDAY, PAULA STRAUSS, DYLAN SMITH & NISHANTA RAJAKARUNA
Colours of sandstone-dwelling lichens at Tswalu Kalahari Reserve – the orange of Teloschistaceae species, the yellow of Acarospora, the powdery white of Xanthoparmelia and the white Lecanora species with their characteristic brown fruiting bodies. Photo by Danielle Ward
From the fynbos to the Kalahari, our exploration so far has led us to one inescapable conclusion about lichens – the closer you look, the more you find. In fact, in our recent research in the Western Cape and the Kalahari, we found two new genera and, we believe, several new species.
Many southern African conservation organisations are becoming increasingly fluent with their local flora, fauna and even fungi but lichens have remained a relative mystery – even though they are a vital thread in the fabric of any southern African ecosystem. In fact, so little is known about them that there is still plenty of foundational work to be done to begin putting this right.
“During our latest field research, we believe that we collected several new species,” says Dr Alan Fryday of Michigan State University. I am confident that there are at least two further undescribed species among them – and probably more.”
CALL FOR HELP
A couple of years ago, when Dr Alan Fryday and Dr Nishanta ‘Nishi’ Rajakaruna from California Polytechnic University worked with North-West University’s Prof Stefan Siebert, Veld & Flora featured their intriguing report, ‘Scoring a lichen hat trick’ (June 2021, pp.26-31). They estimated that there could be about 3 000 lichen species in South Africa – almost half of them still unknown to science.
About that time, Paula Strauss of the Grootbos Reserve in the Western Cape and Dylan Smith of the Tswalu Kalahari Reserve had both recognised the distinct diversity of lichens that occur on their reserves. They wanted to learn more and asked Alan and Nishi for help.
We put our team of seven together to help answer that call. We hoped that our findings might contribute to combatting the scanty baseline information on lichens that leads to the typical problems of lack of introductory resources for curious naturalists and the all-too-familiar difficulties in identifying lichens without reference material.
Danielle Ward and Alan Fryday sample lichen diversity along a transect at the Grootbos Reserve in the Western Cape. Photo by Paula Strauss
Over the course of the project, our team encountered virtually every colour – from white and blue-grey, to green and brown to bright yellow and red – and every growth form of lichen that exists, reflecting the richness of lichens reported from southern Africa.
We estimate that we interacted with upwards of 100 lichen species, although this is likely to be a fraction of all the lichens that occur in the two reserves. Among the several new species that we believe we have collected, and two have already been confirmed by molecular sequence data to represent new genera. These specimens are currently being investigated by the team and other taxonomists. Genetic analysis is underway.
A fertile Usnea species (stringy pale green) grows alongside a Crocodia aurata (leafy green with yellow edges) at the Grootbos Reserve. Photo by Danielle Ward
AT HOME ON A LEAF
The Grootbos Reserve covers an expansive breadth of fynbos and includes pockets of Afromontane and milkwood forests. In one patch of Afromontane forest, the team discovered leaf-dwelling lichens belonging to the Strigula genus.
The Afromontane forest is moist enough to support typically tropical and subtropical leaf-dwelling lichens that flourish when they are tucked away from the drier fynbos ecosystem surrounding them.
Right: A leaf-dwelling lichen from the Strigula genus was found at the Grootbos Reserve. Photo by Danielle Ward
A STUDY IN CONTRASTS
Not surprisingly, the drastically different environments of the fynbos of the Grootbos Reserve and the Kalahari desert at the Tswalu Reserve support distinct lichen biota. The lichens of the Grootbos Reserve are generally more conspicuous, shrubby and grow on trees. At the Tswalu Kalahari Reserve, the lichens frequently grow as vividly coloured crusts on south-facing rocks.
Arid environments, such as the Kalahari desert, tend to be too harsh for shrubby macrolichens and the landscape is dominated by crusty (crustose) microlichens. Meanwhile, the Grootbos Reserve is home to lichens that prefer wetter climates and includes those that drape down from the tops of the tree canopies.
Left: The diverse colours and forms of the bark-dwelling lichens at the Grootbos Reserve can be seen with this dark, leafy jelly lichen and the white Brigantiaea leucoxantha with its orange fruiting bodies. Right: Standing out among lichens on this tree branch at Grootbos Reserve are the white Haematomma species with orange fruiting bodies and the shrubby green Ramalina species. Photos by Danielle Ward
Overall, the characteristic lichens of the Grootbos Reserve are the green-blue, shrubby Ramalina lichens along with their stringy, beard-like cousins from the genus Usnea genus.
They are joined by copious jelly lichens (Collemataceae species) and the iconic powdery Crocodia aurata coating tree branches and trunks with a leafy layer.
UPON CLOSER INSPECTION
Enjoy these astonishing watercolour studies of tiny lichens by Grootbos artist in residence Chris Lochner:
“I have long been fascinated by the lichens and think they are just too beautiful,” says botanical artist Chris Lochner. His two lichen paintings measure 56cm by 76cm but the lichens they depict are just 6cm tall. These are two of the most commonly occurring and charismatic lichen genera in the Grootbos Reserve, Ramalina and Usnea. They hang abundantly from trees in the milkwood and the Afromontane forests. Chris is Grootbos Reserve artist in residence and spends his time closely observing and painstakingly painting locally occurring lichens, plants and animals.
By contrast, the Tswalu Kalahari Reserve lichens are dominated by neon yellow Acarospora species. These are commonly joined by the cheerful orange splashes of crusty sunburst lichens (Teloschistaceae species), and a highly diverse range of rock shield lichens (Xanthoparmelia species).
At both reserves, our team members were frequently rewarded after stopping to look closely at the microbiomes we encountered.
We found lichens of all different forms and colours inhabiting nooks and crannies within their environments. Soil, rocks, trees, rotting logs, leaves and roofs of buildings all serve as suitable lichen habitats.
Sandstone rocks at Tswalu Kalahari Reserve are home to lichens such as (left) this striking orange Teloschistaceae species and (right) this Xanthoparmelia species displaying its brown fruiting bodies. Photos by Danielle Ward
GUIDING THE FUTURE
A key message became clear as we engaged with staff and visitors at Grootbos and Tswalu during our project – people are aware of lichens but would like more information about these cryptic critters.
To equip those interested with photos and information about lichens that occur in the Western Cape and Kalahari, our team is creating a guide showcasing the diversity of lichens we found in the field.
DETECTIVE WORK CONTINUES
All the lichens that we collected will be permanently housed in either the Grootbos or the North-West University Mahikeng campus herbaria. We anticipate these collections will be useful reference sets for future researchers to document changes in lichen biota.
We hope to ensure our lichen-focused work is sustainable by encouraging further interest and supporting honours students at North-West University in pursuing lichen-related projects. Lichens can be used as model organisms for research that ranges from bioindication applications to medicinal uses to ecological functions and we hope to encourage students with a diversity of interests to become involved in this fascinating field.
What lichens mean to me
- Dr Sutapa Adhikari, environmental scientist and North-West University botany post-doctoral fellow: Lichens can be used as bioindicators of air quality, which I intend to study in urban environments specifically affected by mining operations.
- Dr Madeleen Struwig, North-West University senior botany lecturer, plant taxonomist and curator of the SD Phalatse Herbarium: The 1 751 species of lichens reported from mainland South Africa can certainly keep me busy – and it looks as if there are plenty of new ones to come.
- Dr Alan Fryday, research associate in plant biology, Michigan State University: As former curator of MSU herbarium’s cryptogamic collection, what fascinates and excites me are the presumed 1 500 species that we have yet to discover!
- Dr Nishanta Rajakaruna, professor of plant biology at California Polytechnic State University, extraordinary professor and Fulbright US scholar at North-West University: As a geoecologist, asking questions and pursuing answers about how lichens and plants flourish on seemingly inhospitable substrates has been a career-long pursuit for me.
- Paula Strauss, research coordinator and entomologist at the Grootbos Foundation: As someone who is trained to focus on the delicate details of biodiversity, I find the lichen biota of Grootbos full of surprises and complexity.
- Dylan Smith, head of Dedeben Research Centre and conservationist at the Tswalu Foundation and the Tswalu Kalahari Reserve: Engaging with researchers from all fields helps inform Tswalu’s management, so learning about the role and diversity of lichens that occur here is a step towards holistic conservation.
- Danielle Ward (email@example.com), PhD student in integrative biology at the University of California Berkeley and recipient of Exploration Fund Grant from Explorers Club: Learning about lichens enables me to fit an important piece into the ecological puzzles I seek to understand.
(From left) Madeleen Struwig, Alan Fryday, Nishi Rajakaruna and Danielle Ward get set to go lichen hunting at Tswalu Kalahari Reserve. Photo by Dylan Smith
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