Veld & Flora Feature
THIS FEATURE IS FROM VELD & FLORA SEPTEMBER ISSUE 108(2), PAGES 24-29
Beating the boom
The fight to save a tiny succulent reveals that even our current conservation approach might not be enough to save SA’s threatened species
Nov 11, 2022 | WRITTEN BY STEFAN SIEBERT & FRANCES SIEBERT. PHOTOGRAPHS by S.J. SIEBERT
Above: Blasting began for a new coalmine just moments after the last threatened plants were removed. Photo by S.J. Siebert
WHEN OUR RESCUE TEAM removed the last sods of threatened plants from a new mining site just moments before their sandstone habitat was blasted to access coal seams beneath, we thought we were chalking up a victory for conservation.
Little did we know then, back in 2009, that this was the good news. Our journey of hope would become one of despair and then sad realisation.
The bad news was slowly revealed over the next decade, making us question one of SA’s conservation commandments – that moving threatened plant species to new sites in equivalent habitat would protect them.
RACE AGAINST TIME
There had been excitement when a sharp-eyed environmental consultant surveying the planned new mining site, north of Emalahleni in Mpumalanga, had spotted a large population of more than 4 000 Frithia humilis. This plant is commonly known as fairy elephant feet because its leaf tips look like the soles of tiny elephants.
At the time, this tiny succulent species was listed as endangered. Various national and provincial government organisations swung into joint action to rescue as much of the population as possible.
Fairy elephant feet is a rare endemic. It is found only in gravel-filled crannies on rocksheets in an area of about 600 square kilometres, straddling the Gauteng-Mpumalanga border between Bronkhorstspruit, Ogies and Middelburg. Sadly, some of its most successful adaptations are currently proving its downfall.
You will encounter it only rarely because – unlike other spectacular and well-known highveld succulents, such as the Magalies aloe (Aloe peglerae) or khadiwortel (Khadia acutipetala) – it is so challenging to see. As well as its tiny size, this so-called window plant also survives during winter and dry spells by pulling its leaves back into the soil.
It is also adapted to establish itself and thrive only in quite specialised soil conditions. It requires very dry (xeric), shallow soil – only two centimetres deep. The soil should be made up of a mix of quartzite sand and humus, covered with half a centimetre of quartzite gravel.
Above: Known as fairy elephant feet, these dainty little succulents have leaves arranged in spirals. Photo by S.J. Siebert
Surprisingly, perhaps, fairy elephant feet is not alone in requiring this exacting habitat. A few other toughies such as the Crassulaceae succulents, krans brosplakkie (Adromischus umbraticola) and moriri-oa-letlapa (Crassula lanceolata) and a resurrection plant (Selaginella dregei), a fern that likes growing on rocks (lithophytic), also thrive in these conditions.
All of these plants find the soil (edaphic) conditions that they need on formations of Dwyka and Ecca sandstone. Unfortunately, these unique habitats overlay rich coal deposits that feed SA’s notorious power stations.
Fairy elephant feet, for example, has lost more than half its habitat to mining and agricultural expansion. This era of human domination of our planet (Anthropocene) has been very unforgiving to all the species that live alongside us. The highveld grasslands, in particular, are one of SA’s hardest-hit ecosystems with habitats degraded, fragmented and lost as urbanisation, crop cultivation and mining have completely transformed large areas.
Grieving for Highveld grasslands
Highveld grasslands have been decimated and degraded by urbanisation, agriculture and mining. Worst of all, they cannot be restored to their previous state after we humans have disturbed them – because the plant species that are the backbone of this ecosystem do not have the characteristics needed to enable them to recolonise even restored habitats.
Despite being called grasslands, only a third of the plant species here are grasses. Two thirds of the plant species making up this habitat are, in fact, forbs – including many beautiful bulbs, herbs, dwarf shrubs and succulents.
Sadly, these forbs are much more threatened by human activities than grasses would be. Most of all, it is the inconspicuous forbs – such as fairy elephant feet (Frithia humilis) – that are most in peril because of habitat loss.
Above: Less than 10 populations of Frithia humilis are known and plant numbers are so few that they occupy less than 2 hectares of our planet. Photo by S.J. Siebert
All of this emphasised the importance of our rescue operation – but we were working against the clock. The plants on the planned mining site had been added to the To Save list at the last minute but would still have to be moved (translocated) within a time schedule set well before we even knew they must also be rescued.
Aerial surveys helped pinpoint a shortlist of sites with suitable habitat to which we could move the rescued (translocated) plants. These sites were rapidly assessed for underlying rock (substrate), ecological integrity, genetic impact and long-term protection. We decided to move most of the fairy elephant feet population to sites with the underlying Ecca group sandstone that these plants prefer.
However, we also wanted to test whether Frithia humilis could survive on different rock types without underlying coal deposits. Five square metres of sods were translocated to two such sites. One was on Waterberg group sandstone and the other on Rooiberg group felsites.
At the time, we were all satisfied that this major rescue operation had saved a population of this rare endemic and given the plants a second chance to survive.
Since the dramatic rescue operation, we have funded ourselves to monitor the translocated populations regularly. Unfortunately, the mining company responsible for this translocation withdrew its support after two years when the mining of the original site was completed. What had been held up as a major success story for their purposes proved ultimately to result in a disappointing outcome for the species.
The most recent surveys took place in 2021. Time has shown us that we presumed too much about the outcome of our rescue operation. Initially, the plants’ survival and reproduction looked promising.
Admittedly, rodents did remove large volumes of plants – somewhere between 500 and 1 000 plants – from the loose sods in the new sites. It was not until after 2017 that plant numbers started dropping severely, however.
We believed that the reason was straightforward. Frithias cannot self-pollinate to prevent inbreeding (are self-incompatible) and we suspected that too few pollinators in the new sites had led to fewer and poorer quality fruit.
Above: Fairy elephant feet can hide their leaves underground, where the bulk of the plant is also better protected. Photo by S.J. Siebert
Now you see it . . .
Now you don’t
Fairy elephant feet (Frithia humilis) is called a window plant because its leaves grow upward from a succulent rootstock for one or two centimetres. At its most revealing, only the translucent tips of the leaves protrude above ground to capture sunlight. In dry times or winter, it pulls its leaves back into the soil.
It is mostly spotted only when it is flowering – typically, hundreds of white blossoms cover its sandstone habitat. It is closely related to the larger, dark pink-flowered bobbejaanvingers (Frithia pulchra), which occurs on exposed sandstone rocksheets further west in the Magaliesberg.
This theory was trumped by a follow-up study which compared our site with a very large population of F. humilis in nearby Ezemvelo Nature Reserve, Bronkhorstspruit.
All indicators – pollinator numbers, the frequency of their visits, plants’ flowering, fruit set and seedling development – at our new sites were mostly on par with the natural Ezemvelo population. We even discovered a few new pollinators not recorded for the species before.
The problem was not plant reproduction or seedlings numbers. Something else was preventing significant numbers of seedlings from establishing themselves long term and
surviving to maturity.
Above: Monitoring the translocated plants became a disappointment for researchers. Photo by S.J. Siebert
We expected – and saw – that transplanting the sods containing rescue plants to the new sites prompted the seedbank within these sods to flush with new growth.
We had expected this to continue until about 2012 or 2013. In fact, only from 2014 did the number of seedlings gradually decline as the seedbank became depleted. Then there was a second flush in 2017 after the drought.
As the habitat settled after the rescue plants had been introduced, we expected population numbers to grow slightly and stabilise – which is just what had happened. Unfortunately, over the past three years, plant numbers have decreased drastically.
Top: Bottom: Rodent feast. Photo by S.J. Siebert
This has included the fairy elephant’s feet moved to their preferred Ecca sandstone sites. Most especially, however, it affected those translocated to the experimental Waterberg and Rooiberg sites where they were tried on non-typical rock types.
Since 2020, no more rescued F. humilis plants have been recorded at some of the rock sheets. Close observation and photographic comparisons suggested the habitat had been degraded by severe erosion.
When we restored habitat at some of the sites in 2020, we saw the remaining plants recover within just one season. We are now waiting to see whether the plants will flower and set seed better, with more successful seedlings produced.
Top: A decade of decline – whether researchers counted individual plants and their flowers (top), adult plants (centre) or seedlings (below), the trend at all sites was downwards, even after the short flush of new growth when the rescue plants had established themselves. Image by Clarissa Minnaar
This has taught us something very important. We must remember that rare succulents with specialised soil needs, such as F. humilis, have adapted over millions of years to habitats which were formed over billions of years.
We cannot simply translocate these and then expect them to thrive in their new habitat. We as humans cannot come up with instant solutions for habitat creation and then stand back and expect nature to do the rest. Once we have interfered, we need to keep on monitoring and invest in maintaining the habitat.
Eventually we realised that translocating natural species is not a perfect answer to man’s consumption of our environment. Quite simply, some species just need to be left untouched where they occur naturally.
Carl Sagan, renowned planetary scientist, once remarked, “Extinction is the rule. Survival is the exception.” How true that is for all life on earth.
Often we forget this, or prefer to do so, and every so often we are subtly reminded of it when our perceived good intentions to contribute towards the wellbeing of a species come undone.
The Botanical Education Trust helped fund this research.
Note: Frithia humilis was assessed as endangered in the 2009 Red Data List when the rescue was attempted. Since then, better population counts across the habitat have allowed the plant’s threat level to be relaxed to vulnerable.
Stefan Siebert (email@example.com) and Frances Siebert are both botany professors at North-West University. Stefan has a strong interest in geoecology (plant-soil associations) and Frances is a forb ecologist of grassy biomes.
This article was featured in Veld & Flora in the September 2022 edition.
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