00 WILD AUTUMN 2010

BOTANY

www.wildcard.co.za

Science

Botanists working in South Africa’s parks are astounded by the high levels of diversity and endemism. On one side of the country, in the arid Richtersveld National Park, Elsabé Swart is helping save the giant quiver tree from extinction. On the other side, in the lush Kruger National Park, Michelle van der Bank is using DNA to discover new species of flora.

CLOSE-UPElsabé Swart takes a picture of a ‘young’ giant quiver tree, about 50 years old.

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Elsabé has a passion for all plants in the arid Richters­veld. Here she carefully greets the halfmens (Pachy-podium Namaquanum) – the spines on the stem are poisonous. Another suc­culent found in the area is soutslaai (Mesembryanthe-mum guerichianum), which stores water in its leaves.

BY SCOTT RAMSAY

treesrescues rare It was stIll early mornIng,

but the desert sun was al-ready hIgh In the sky. The hikers were setting a steady pace up

the rocky slope, in a jagged mountain range which the local baster people aptly call tandeberge. leading the way was botanist elsabé swart, seemingly oblivious to the harsh terrain and climate.

“I’ve walked all over the richtersveld for 10 years,” she said, stopping to adjust her backpack. “It’s the ninth time I’ve hiked up this mountain.”

elsabé was on her way, along with col-league Conrad geldenhuys, to the top of the rosyntjieberg, to download data from a small weather station which she’d installed a few years previously. The information on climate patterns will help her understand one of the mysteries of this desert: is one of south africa’s iconic trees on the road to extinction?

with temperatures reaching into the mid 50s, the richtersveld doesn’t seem like an obvious place to go hiking nor looking for plants. most years there’s less than 70 millimetres of rain, sometimes none at all. desiccating berg winds regularly scour the land and a few of the springs in the area contain water with toxic levels of sulphur.

yet elsabé has scrambled up, down and around these mountains for the past decade, enjoying every minute of it. you could say she’s crazy, or that she’s in love. It’s probably the latter. and it’s the rare, critically threat-ened giant quiver tree (Aloe pillansii) which has captured her heart.

In a region where most plants struggle to grow taller than your ankle because of the near-absence of rain, the basterkokerboom can reach a dizzy height of 12 metres, with a trunk almost two metres wide. while some flora emerge, wither and die within the same season, this denizen of the desert can live more than 400 years and store hundreds of litres of water in its fibrous structure. Importantly, they are found no-

where else except in the richtersveld and in southern namibia.

unsurprisingly, the giant quiver trees captivate visitors with their graphic, defi-ant shapes. ecologically, they are crucial to a multitude of animals that rely on their moisture during prolonged droughts and, for many people, the richtersveld without Aloe pillansii is like africa without baobabs. unimaginable. This is why in the 1990s, when scientists and park visitors noticed an increasing number of dead or dying speci-mens, the alarm was raised.

It became clear wild specimens were being stolen from the veld, to be sold to private buyers who wanted exotic-looking gardens. but some trees, of all ages and sizes, seemed to be dying where they stood. bizarrely, some healthy specimens seemed

to be committing suicide by ‘self-amputating’ their branches. Climate change was mooted as the most probable cause, although no conclusive evidence existed.

Then in 1999 elsabé, a botanist from the northern Cape direc-torate of Conservation, visited the richters-veld for the first time and was immediately gripped by the landscape, especially the giant quiver tree. “when I’m around them, I feel something very positive,” elsabé explained. “They lift my spirit.”

her combination of rigorous science and emotional attachment to the trees proved a formidable formula. when she first arrived other experts told her there were about 900 specimens in total. she then spent the first of several months hiking the area, docu-menting each and every giant quiver tree she found.

“I soon realised I was going to be busier than I thought!” laughed elsabé. “There were way more than anyone had originally anticipated.” she eventually counted exactly 3 141 specimens in the richtersveld.

later she installed 11 small weather sta-tions near large sub-populations of Aloe pillansii. some were accessible, others were on top of steep mountains such

Elsabé Swart and the mystery of the Richtersveld giant

A combination of rigorous science and emotional attachment to the trees proved a formidable formula.

|Ai-|Ais/RichtersveldTransfrontier Park

Kruger National Park

SOUTH AFRICA

NAMIBIA

36 WILD SPRING 2010

BOTANY

WINTER 2010 WILD XX

FIELD OF RESEARCH The top of the Rosyn-tjieberg is where Elsabé installed one of several weather stations.

kikoi AfdAk download­ing data from one of the mini­weather stations. A kikoi provides shade so Elsabé can see the laptop’s screen.

as rosyntjieberg. she’d head into the wilderness alone, sleeping under the branches of a quiver tree silhouetted against a sparkling southern night sky. The seclusion suited her.

“I actually don’t like being around people too much,” elsabé confided. “I prefer not talking. some people who don’t know me find that difficult to deal with.” In 2002, elsabé gave herself a birthday present: a week’s holiday in the richters-veld, alone.

after 10 years of collecting data and making meticulous measurements, elsabé has managed to solve some of the riddles. surprisingly, despite global warming, the giant quiver tree doesn’t mind the heat. This is contrary to studies done on a simi-lar aloe species, the common quiver tree (Aloe dichotoma) which prefers relatively cooler conditions.

“unlike the common quiver trees, the giant quiver trees don’t mind the hotter locations,” explained elsabé, adding that these areas may receive more coastal fog. Could the giant quiver tree get most of its moisture from fog? Is climate change as big a threat to Aloe pillansii as initially thought? It could be. elsabé emphasises that even if the giant quiver tree is happy in hotter climates, it could still be in trouble if global warming causes less rain to fall; seedlings rely on regular above-average rainfall to establish themselves. however, she believes other factors are as important, such as the presence of nurse plants, which provide cover for the

WhERE tO SEE thE gIANt quIvER tREECornell’s kop on the road to Sen­delingsdrift is what botanists call the ‘type locality’. it’s where, in 1926, the species was first collected by botanist Neville S Pillans. it’s also where scientists first noted an increasing number of dying, or removed, specimens. However, there are still several prominent specimens and it’s probably the most acces­sible location in the Richtersveld to see the trees. Remember to treat them with due respect: on average they grow only two centimetres every year, so even the smaller ones around a metre high can be older than 50 years. They are a protected species and it is illegal to remove them from the wild or trade cultivated speci­mens, unless you have a licence.

Could the giant quiver tree get most of its moisture from fog? Is climate change as big a threat as initially thought?

seedlings during their first few critical years of growth.

It appeared the initial concerns about their long-term survival stemmed from a declining population at only two or three of the 16 sites which elsabé studied in south africa. her work has proven that the other sub-populations are holding steady, or in some cases, even increasing in number.

nevertheless, the total number of about 6 000 specimens in south africa and na-mibia is still critically threatened. because each tree recruits new specimens only every 50 to 70 years, it will take more than one human lifetime to detect negative im-pacts and understand the situation fully.

This isn’t something that bothers elsabé. “I think by knowing too much, or knowing everything, part of the mystery is lost,” she said as we finally made it to the top of rosyntjieberg and admired the never-ending panoramic view, north over the orange river to namibia and south over the mountains of the richtersveld. “I’ve accepted I’ll never know everything about the giant quiver tree.”

RESPECT! Giant quiver trees can grow up to four metres high and live for more than 400 years.

thE RIchESt DESERt IN thE WORLD?The Richtersveld forms part of the Succulent karoo, one of only two internationally recognised arid biodiversity hotspots in the world (the other is the Horn of Africa). While the climate is extremely arid, this hotspot has 4 849 succulent species, which is nearly half of all succulent species in the world. of these, 1 940 species are endemic. Yet only 0,5 per cent of the Succu­lent karoo is formally protected. The rest is vulnerable to grazing, mining and farming. The Rich­tersveld National Park thus has a crucial role in preserving the region’s flora.

The giant quiver tree (Aloe pillansii) is the most conspicu­ous succulent species, along with its close cousins Aloe dichotoma (common quiver tree, which is shorter, with more branches) and Aloe ramosissima (maiden quiver tree, the short­est of the three, with the most branches). Their name derives from the Bushmen using the tree’s branches as quivers for

their arrows.

FOOTHOLD This giant quiver tree has found a crack in which to anchor itself against the strong desert winds.

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In the remote northeast of kruger natIonal Park, near the mozambICan border, the shrubveld Is

notorIously tall and thICk. It’s easy to get lost and getting trampled by a surprised elephant is a real possibility. two rangers armed with rifles provided protec-tion for botanists michelle van der bank and olivier maurin. together, the rangers and botanists were going hunting – for a new species.

It didn’t take long to locate the target. “There it is!” said michelle excitedly. “That’s what we’ve been looking for!” In the middle of a dense thicket was a tree that looked to the untrained eye like all the others. “It may not look special, but this is a new species of Combretum!”

It’s a common thorn in the side of bota-nists. with 20 000 plant species in south africa and 2 000 in kruger alone, different plants can often appear the same. some-times even experts can’t distinguish be-tween them. now, dna testing is proving to be invaluable.

for five years, michelle has led a team of botanists on a project, named self-evi-dently as ‘dna barcoding the flora of the kruger national Park’. The goal is to iden-tify accurately all plant species in south africa’s largest park, using dna sequenc-ing technology.

It was initially in the university lab that michelle and her team had stumbled across this ‘new’ Combretum or bush-willow. she and olivier had run some genetic tests, thinking it was another Combretum species called mkuzense, but then they noticed a difference in the dna structure. There could only be one expla-nation: it was a new species that had never been accurately described.

Though their laboratory work had ‘dis-covered’ a new species, they still wanted to see the Combretum for themselves during flowering season. every species of plant has a flower which looks unique. even if the differences are almost imperceptible, the flower is visual proof it belongs to a separate species. a trip back to this remote section of kruger was critical.

to her relief, the new Combretum was flowering. It’s not always possible to predict exactly when a plant, especially an unknown one, will flower. but there it was, seemingly unspectacular and nondescript. yet its flower was different, albeit only slightly, to other Combretum species and it confirmed what science had already proved.

later that evening, around a braai un-der a new moon at shingwedzi, a toast was drunk and a new species celebrated: Combretum nwambiyana, after the nwambia sandveld eco-zone in which it had been found. The new tree is number 400 on the list of kruger’s plant species which michelle and her team have bar-coded so far.

The project initially focused on trees only, but now extends to all plants, includ-ing herbs, grasses and bulbs. The team have several hundred more species to barcode, but they’ve come a long way since michelle started in 2005.

It didn’t begin on a good note. while planning the project, she spent some time hiking the wolhuter wilderness trail near berg-en-dal. she was charged by a rhino, which was shot by the ranger as it rumbled towards the group of botanists. “That was really traumatic, obviously,” said the quiet-ly spoken, ever-smiling scientist.

as a university student, michelle aban-doned her zoology studies because she became too upset when she was required to dissect frogs. her pharmacist father sug-gested she change to botany, because “you didn’t have to kill plants to study them.”

“my father inspired me,” michelle re-marked, adding that he would sometimes spend the whole day collecting creatures and plants from the veld. “but my mother wasn’t too happy when he knocked down the dining room wall to build an observa-tion tank for his collection!”

The change to botany would prove momentous in michelle’s life. she is now the Professor of botany and Plant biotechnology at the university of Jo-hannesburg, has won numerous awards, worked at the illustrious kew gardens in london and is one of south africa’s top 20 woman scientists. although she is now sometimes confined to the lecture rooms, it’s the surprise and unpredict-ability of fieldwork she still lives for. “ex-cept charging rhinos,” michelle added.

“when I started, I never in my wild-est dreams thought I’d discover so much diversity in kruger, which has more than 400 tree species. Compare this to the whole of europe, where there are only about 340 species.”

The kruger project has proven such a success, michelle has been selected by the international organisation treebol as one of two representatives from africa. Their goal is to create a database of dna infor-mation of all tree species on the continent. already michelle’s team has collected and sequenced 80 per cent of the roughly 1 700 tree species in southern africa. ultimately, the information will play an important role in conservation.

This is crucial, michelle emphasised, because vast amounts of protected hard-wood species are being chopped down illegally in southern africa and exported, mostly to the east. “dna information is the only foolproof way for police to en-force the law.”

with dna identification, plant species can be identified more easily and their ongoing protection ensured, whether it’s a highly localised endemic or one of the 50 protected tree species under the national forest act. Currently, when a shipment of wood is exported from the continent, customs officials are unable to accurately identify the timber, which is usually cut and stripped. In time, michelle says, a hand-held dna ‘barcode device’ will allow identification of any plant species in a mat-ter of minutes. all that will be required is a tiny piece of leaf or wood.

It will also make life easier for botanists who come across rare species in the field,

Michelle van der Bank and the quest to barcode Africa’s flora

Kruger has more than 400 tree species. In the whole of Europe there are only about 340 species.

38 WILD SPRING 2010 www.wildcard.co.za

BOTANY

GREEN TEAM Ranger Jacob Mlangeni, botanist Michelle van der Bank, section ranger Stephen Midzi and botanist Olivier Maurin after successfully identifying the new species of Combretum.

REMARKABLE Botanist Michelle van der Bank ad-mires a sycamore fig (Ficus syco-morus) in Kruger.

FIguRINg Out WhAt IS WhAtOkay, so not everyone can distinguish between Combretum nwambiyana and Combretum mkuzense, but Piet van Wyk’s excel-lent book Field Guide to the Trees of Kruger National Park (R153, www.kalahari.net) will certainly help you. It features more than 200 species, with close-up photographs of leaves and flowers to aid identification.

NEW FIND The leaves of Combretum nwambiyana, the new tree species identified by DNA testing.

such as Combretum nwambiyana. “you’d think that because kruger is africa’s oldest park, everything would already have been discovered and docu-mented,” michelle said. “It amazes me how we’re still discovering new plants here.”

FIND OUT MORE Michelle’s DNA barcoding project in Kruger: www.florakrugerpark.org TreeBOL Africa: www.uj.ac.za/botany

thREE WAYS tO ENJOY thE FLORA IN KRugERKruger National Park hosts more than 400 species of trees, 250 grasses, 1 000 herbs and hundreds of different types of bulbs. Most of these are preserved at the Skukuza herbarium, which can be visited by appoint-ment. call guin Zambatis on 013-735-4140, guinz@sanparks.org

Michelle recommends a guided bush walk if you’re interested in flora. “it’s difficult to appreciate the trees and plants from your car,” she says. Several of kruger’s camps offer daily walks with a trained field guide, costing R310 a person for a morning walk and R240 a person for an afternoon walk. Walks usually last between two and three hours.

Visitors can also do the guided wilderness trails, which last four days. Nights are spent at a central base camp and each day you explore the area with a guide. R3 120 a person.

North: Pafuri and Punda MariaThis area has the highest rainfall in the park, as well as a diversity of different soil types, making it a fascinat­ing region for plant enthusiasts. The Nyalaland Wilder­ness Trail is near Pafuri gate, the base camp being the northern­most accommodation in the park. Look out for rare endemics such as the sesame tree, as well as impressive fever tree forests.

South: Pretoriuskop and Berg-en-DalThe granite koppies and hills host several highly local­ised endemic species. The Wolhuter Wilderness Trail (near Berg­en­dal) and Napi Wilderness Trail (near Pretoriuskop) reward walkers with floral displays in spring. Look out for Combretum woodii (large­leaved forest bushwillow) which occurs only on Skip Mountain and Faurea rochetiana (broad­leaved beechwood) on Shabeni Hill near Pretoriuskop.

East: Lebombo MountainsThe Metsi­Metsi Wilderness Trail, between Lower Sabie and Satara, takes in the rocky bushveld ecozones of the Lebombo Mountains. Special trees to look out for are the wonderfully named drooping resin­tree, forest iron plum, northern soap berry, Nwanetsi spike thorn, river jujube, sandveld newtonia, small leaved guarri and yellow firebush.

BOTANY

40 WILD SPRING 2010

WEIRD AND WONDERFuL

Kruger National Park has some remarkable flora. 1. Euphorbia monteiri sub-species ramosa belongs to the euphorbia family. 2. This lily is aptly named Gloriosa superba, also known as the flame lily. 3. The bright orange-red fruits of the small honeysuckle tree (Turraea obtusifolia) look like miniature pump-kins. 4. The paintbrush lily (Scadoxus puniceus) grows slowly and takes four to five years to start flowering.

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Want to know more about botany research in our parks? Go to www.wildcard.co.za

Olivi

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