A little known ‘southern alpine’ habitat: Altimontane fynbos

The Earth’s mountains form some of the most important areas for biodiversity and host about half of its biodiversity hotspots. Varying elevation gradients, aspects, geology and soils allow a huge diversity of habitats to exist in close proximity of one another.

Often, the species found in the mountains are endemic to their own individual micro-habitat.

Climate change, with its associated rising air temperatures and subsequent changes in precipitation, is having effects at both an international and local level and is increasingly seen as a real threat to mountain biodiversity. Individual species are having to either adapt to these changes or move to escape them. Plants cannot move as quickly as animals and, thus, are slower in being able to migrate. Many plants exhibit a narrow climatic tolerance, which when linked to their needs of specific soil conditions, leave them unable to move. Those at the very tops of mountains may find themselves with nowhere higher to move to or being out competed by those migrating upwards to higher altitudes.

The Cape Fold Mountains from the summit of Wemmershoek Peak

The Cape Fold Mountains from the summit of Wemmershoek Peak

The Cape Floristic region, the smallest of the six floral kingdoms, is the most floristically diverse region on earth. It holds an estimated 9,000 vascular plant species of which 69% are endemic. This diversity has been driven by the huge topographical, geological and climatological ranges created by the Cape Fold mountains – a series of parallel mountain ranges created though geological fold and thrust (when the Falkland plateau collided with southern Africa compressing the cape supergroup sediments in the Agulas sea) and uplifted about 180 million years ago. The Cape fold mountains range in height with a maximum altitude of 2325m at Seweweekspoortpiek located in the Klein Swartberg mountain range.

On the very tops of these peaks at elevations above 1800m a unique vegetation type can be found; Altimontane Fynbos. This high-altitude ‘Southern Alpine’ fynbos is found in two unique forms, Western Altimontane sandstone fynbos and Swartberg Altimontane sandstone fynbos, each with an individual assemblage of plant species.

The silent impacts of climate change coupled with their small distributions and limited altitudinal ranges mean that, whilst these unique Altimontane habitats and the species they hold are in no, immediate and obvious, danger, they are certainly threatened should humanity be unable to mitigate global warming (if current models for mountain environments are used). In addition, the impacts of non-native, invasive species and disease are also having their toll. There is no abrupt interface between altimontane and other sandstone fynbos types, the change is gradual and other factors dictate the change in vegetation from one to the next. Due to the occurrence at the very tops of the highest peaks in the Western Cape Province (WCP) the Altimontane fynbos forms islands with each being slightly different from the next. These small islands of Altimontane fynbos find themselves nested within other forms of sandstone fynbos; North Hex Sandstone Fynbos, South Hex Sandstone Fynbos, Hawequas Sandstone Fynbos, North Langeberg Sandstone Fynbos, South Langeberg Sandstone Fynbos, North Swartberg Sandstone Fynbos, South Swartberg Sandstone Fynbos, North Kammanassie Sandstone Fynbos, South Kammanassie Sandstone Fynbos and  Swartruggens Quartzite Fynbos.

Altimontane fynbos not far from the summit of Mannetjiesberg

Altimontane fynbos not far from the summit of Mannetjiesberg

Altimontane fynbos is one of the least studied vegetation types found in the WCP, due to the inaccessibility of the mountains in which it is found. It is also home to an assemblage of species of which many are endemic or near endemic and do not qualify for one of the 5 IUCN red list categories but do fall into one of two additional South African red list categories.

Rare A species is Rare when it meets at least one of four South African criteria for rarity but is not exposed to any direct or plausible potential threat and does not qualify for a category of threat according to one of the five IUCN criteria. The four criteria are as follows:

Restricted range: Extent of Occurrence (EOO) <500 km2, OR

Habitat specialist: Species is restricted to a specialized microhabitat so that it has a very small Area of Occupancy (AOO), typically smaller than 20 km2, OR

Low densities of individuals: Species always occurs as single individuals or very small subpopulations (typically fewer than 50 mature individuals) scattered over a wide area, OR

Small global population: Less than 10 000 mature individuals.

 

Critically Rare A species is Critically Rare when it is known to occur at a single site but is not exposed to any direct or plausible potential threat and does not otherwise qualify for a category of threat according to one of the five IUCN criteria.

 

Endemic Species found in Altimontane fynbos

Western Altimontane fynbos

Agathosma foleyana RARE

Agathosma tulbaghensis RARE

Amphithalea esterhuyseniae VU

Amphithalea. purpurea LC

Cliffortia esterhuyseniae RARE

Cyclopia glabra RARE

Erica brevicaulis RARE

Erica cameronii LC

Phylica intrusa RARE

Esterhuysenia alpina RARE

Helichrysum solitarium VU

 Swartberg Altimontane fynbos

Erica toringbergensis DDT

Calotesta alba CRITICALLY RARE

Cyclopia aurescens RARE

Cyclopia bolusii VU

Erica gossypioides EN

Erica hebdomadalis RARE

Erica jugicola RARE

Erica lignosa RARE

Erica oreotragus LC

Erica roseoloba RARE

Protea pruinosa EN

Selago esterhuyseniae CRITICALLY RARE

Pentameris glacialis RARE

Pentameris swartbergensis RARE

Restio papyraceus VU

Thamnochortus papyraceus VU

Staberoha stokoei RARE

There are also number of Proteaceae species associated with these habitats and it is these that interest us. One, Protea pruinosa, is endemic to Altimontane fynbos and is Endangered. The others are all montane species and whilst not endemic to the Altimontane fynbos the majority only occur within or just below the altitudinal range of Altimontane fynbos.

  • Protea punctata LC
  • Protea venusta EN
  • Protea effusa NT
  • Protea scabriuscula LC
  • Protea scolopendriifolia LC
  • Protea cryophila NT
  • Protea montana VU
  • Protea rupicola EN
  • Spatalla confusa LC
  • Spatalla incurva LC
  • Leucadendron dregei E
  • Leucadendron singulare VU
  • Leucospermum wittebergense LC

What is more, most of these species have either proven unsuccessful or, at best tricky, in cultivation. With this in mind we, on our two collecting trips to the Western Cape, set out to visit areas of Altimontane Fynbos and the ecotonal vegetation between it and other fynbos types.

Protea scolopendriifolia on the slopes of Mast Peak

Protea scolopendriifolia on the slopes of Mast Peak in an area that wasnt quite Altimontain yet.

Swartberg Altimontane Sandstone Fynbos on Waboomsberg and Bothashoek Peak

Of all the mountain ranges visited in South Africa in 2015, the Swartberg is the most extreme; the highest, the driest, the coldest and the hottest. It is bounded on both the north and the south by the arid lands of the Great Karoo and Little Karoo respectively. During the summer, temperatures can soar to between 30 and 40 degrees Celsius; however, during the winter frequent snow storms close the mountain passes to vehicular traffic. Sunlight levels are high, and humidity is low. Consequently, the vegetation is distinctly different from the other more coastal mountain ranges we have visited. Our first impression, having stepped out of the car at the summit of the Swartberg Pass, was that we were in a very different climate to both South Africa’s coastal mountains which we had previously visited and also to our home in the mild west coast of the UK. This place was not mild, but it did get cold, and it was for this reason that we wanted to collect seed here. Was it possible that the plants from here would tolerate cold better and just deal with our cool summers? Or would they need that summer heat to thrive? We reached our highest point on our 2015 collecting trip here, on the summit of Waboomsberg, at just shy of 2000m in altitude. Would we find those high-altitude specialists we were after here?

On approaching the mountain, we were confronted with the aftermath of fire. Burnt remains of Protea montana were found as well as the skeletons of a few Leucadendron dregei. It seemed that the previous summer had affected many different mountain areas in the Western Cape, but we did not lose hope of finding some survivors. We headed for the rocky outcrops that often make good refuges for plants during a fire and low and behold, survivors we found. At the top of a cliff and surrounded on all sides by large boulders was a creeping beauty. The prostrate mass of Protea venusta was unscathed and growing well. We saw another couple of plants of this species at the top of the same cliff that were not so well protected by rocks and which had been partly burned away from the cliff edge. Because they are only found at the tops of high mountains, populations of this endangered species are predicted to reduce significantly over the coming decades due to more frequent fires as a result of climate change (SANBI Red List justification). This species is actually in cultivation already, but it forms hybrids with other white-water sugar bushes and provenance is often difficult to determine. Plants labelled as this species in cultivation are sometimes obviously hybrids due to their upright nature.

Protea venusta sprawling over the top of Waboomsberg

Protea venusta sprawling over the top of Waboomsberg

Another endangered species we found growing further away from the cliff edge but still among rocks was Leucadendron dregei. These cone bush plants actually had many cones on them from previous years and in areas where they had been burned, seedlings were already growing. This species is another high-altitude specialist suffering from similar population reductions as Protea venusta. One vulnerable species which we did collect seed of near the summit was Protea montana. This mat forming plant had not been burned and looked like a green carpet dotted with goblets for flower-heads at ground level. This rodent pollinated species is one that we have high hopes for being hardy in the UK and it was growing in depressions and seeps that water from surrounding areas would be channelled into; though given the low rainfall in this area it certainly was not wet.

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Leucadendron dregei

Continuing to boulder-hop around the slopes surrounding the summit, we stopped to catch our breath and gaze down the length of this mighty chain of folded mountains. We were now in a dip between the main peak and a shoulder just to the north of it, which dropped away to the west via a smooth triangular slab of rock, broken up by narrow cracks.

Wanting to look more closely at what appeared to be the silhouette of a bonsaied shrublet growing out of one of these cracks, we climbed up this slab for a short way, being careful to keep to the rock and avoid the vegetation. “its Protea rupicola!” we both exclaimed, containing our excitement in order to keep clinging on. We had not expected to find this plant so easily, although come to think of it, it was exactly where it is always described as being – growing out of the side of a cliff. The plants we saw had large seed-heads and flower-head buds coming on. This is another endangered high-altitude species which is suffering population losses due to climate change (SANBI Red List) and we were very pleased to eventually find plants from seedling to mature on this rocky slab. Needless to say, the fire had not touched them here. Historically, plants of this species have been grown in cultivation in South Africa but very few times and never to maturity. Pleased as punch, we trotted back down to the pass and continued to our overnight stay at the Ou Tol Hut, which compared to the Helderfontein Hut in Boosmansbos, was luxury. Similarly, to that hut, we used it as a base for exploring the surrounding area.

The following day we started early, heading back up to the summit of the Swartberg Pass, this time turning east, along the trail which rides the crest formed by the highest peaks, towards the Bothashoek Hut. The fire which had engulfed much of Waboomsberg had also affected the south side of the pass itself and slightly east of it as well. The path went through alternating patches of burnt and unburnt vegetation, including Protea punctata. This species of white water sugarbush formed many small trees but did not occur much higher than the level of the pass and seemed to grow quite happily in some shady and damp areas. Also, in the area, just east of the pass, was a handsome stand of Leucadendron album in a flat, open, sunny spot near the ridge itself. It was a joy to see so many plants in this population compared to that which we found in Boosmansbos earlier in the trip. Full of pink, strawberry-like cones at various stages of ripening and with glaucous leaves, it was a wonderful sight to behold, even though the leaves were distinctly shorter than in Boosmansbos. We also passed several burnt shrubs of Protea lorifolia. This species was growing almost exclusively on the sunny side of the ridge and was a rather untidy plant when we did find an unburnt individual. At the first and second summits we reached, were plants of Leucadendron dregei. Never in high numbers and well placed in fire safe areas, we were pleasantly surprised to see the number of individuals that we did. At the top of the second summit (we think this is called Bothashoek Peak) we decided to head down the south facing ridge that descended below us. After a short while, we found a couple of small plants of Protea rupicola. How nice to see this species again, even though these were relatively young plants. But where were the parents? Further down, we saw what looked like a large mass of protea like leaves and large dark pink flowers on a rock pinnacle a little distance down the ridge. Scrambling towards the pinnacle, we came across another couple of plants of Protea rupicola, this time with a few old flower-heads. But what was the plant in flower up there? Climbing up to get a better look, we were rewarded with a sight neither of us shall forget. In the airy and lofty heights, a very large Protea rupicola, in full flower, basked in the midday sun. We stopped and admired this wonderful veteran for quite some time along with a rather splendid blue lizard below it. Feeling that we had gone down the ridge far enough and knowing we had to retrace our steps back to the hut, but still wanting to explore this superb habitat further, we traversed to the west facing side of the ridge to start heading back. On our return we found several other groups of Protea rupicola; this must be one of its strongholds.

Protea rupicola with the Ou Tol Hut far below in the valley

Protea rupicola with the Ou Tol Hut far below in the valley

Swartberg Altimontane fynbos in the Kammanassie mountains

At the eastern end of the Swartberg and a little to the south of it, a separate area of altimontane fynbos can be found on the highest peaks of the Kammanassie mountains. Whilst these peaks are dry, they certainly see a lot of cold and can be covered in heavy snow for extended periods on an annual basis. It was this fact and that the species we had collected in the Swartberg were doing so well in North Wales that lead us to explore this region in 2017, along with Di Turner and Peter Thompson from the Outramps CREW (Custodians of Rare and Endangered Wildflowers) group. Travelling with Di meant that apart from our own observations and collections, we would also be assisting with data collection for the Outramps.

Leucadendron rourkei with the Kammanassie as a backdrop.

Leucadendron rourkei with the Kammanassie as a backdrop.

The Drifter (Di’s bakkie) made little work of the 4×4 track leading up towards the high saddle below Mast Peak where we would make camp. A brief encounter with the Reserve Manager, Philip Esau, on route saw Di step out of the Drifter to exclaim, “Oh my! That is the biggest puffy I have EVER seen!”. The puff adder was not on the road when we drove off, so it was assumed to have hitched a lift with us by coiling itself into the under carriage. When we reached camp, we were all highly aware of our potential unwelcome guest. Camp involved our little tent, an awning attached to the side of the Drifter, proper camp chairs, chilled wine and a large lasagne. Certainly, higher standards than we are used to. Peter had not brought his tent and thus would be sleeping under the awning with camp tables as a wind break. The rest of the day was spent split up. Peter ascended Mast Peak, Di explored the track beyond our camp, while we walked back along the track we had come up. We were instructed by Di to take lots of photos of everything and collect a small sprig of every Erica we came across for identification. Along the road, we came across Leucadendron rourkei. John Rourke, its namesake, described this species as “the ugliest, most scruffy species in the genus”. This it might be, however with a small distribution and a fairly high altitudinal range, it was a target species for us. We also saw Leucadendron album nearby, which in contrast is a stunningly beautiful, silver leaved conebush. Protea scolopendriifolia, a snow sugarbush that had evaded us in 2015, taunted us on the side of the road with its stiff leaves but lack of seeds. Back at camp Peter, on hearing we had encountered this species, informed us of a large population on the slope just above camp, where we were able to make a good collection. Peter also brought back a sprig of a pincushion he found high up on the ridge west of Mast Peak. This was Leucospermum wittebergense and a very high observation of it too. Unfortunately, the plants were just coming into flower and a seed collection would not be possible.

Camp in the Kammanassie

Camp in the Kammanassie

The next morning, we woke early to ascend Mast Peak through the cool swirling mists of dawn. On the way up, we found more plants of Protea scolopendriifolia, this time in flower, as well as one plant of Protea venusta. At the summit we encountered a host of altimontane Proteaceae species. Spatalla confusa, a matt forming plant was in full flower and Leucadendron singulare bore both flowers and seed-heads. The most dominant member of the Proteaceae at just shy of 2000m was the endangered Protea rupicola. There were aged plants, dead plants and young plants here on the rocky fire refuges that it likes to inhabit. There was a large population of it here and we would carry on seeing this plant all along the high ridge between this peak and Mannetjiesberg.

Protea rupicola

Protea rupicola

Between the two peaks, we also found very high plants of Protea punctata and Protea repens. We only saw one other plant of Protea venusta during the whole day, even though we passed many suitable habitats for it. On reaching the summit of Mannetjiesberg, the highest peak in the Kammanassie, we found pristine altimontane fynbos, with sprawling matts of Protea montana alongside the now familiar Spatalla confusa and Leucadendron singulare. The sea of red flowers of Erica inordinata against the grey foliage and rocks really was spectacular, but we were warned by Di that this was by far the stickiest Erica and that should we choose to collect a spring that we should put it in a separate bag or risk everything else sticking to it. The day ended with an exciting show and tell of all the species seen by each member, including Agathosma zwartbergense and Liparia genistoides by Di, innumerable Ericas and a beautiful gladiolus discovered by Peter.

Western Altimontane fynbos on Wemmershoek Peak

On a separate day during our 2017 expedition, we climbed past a high valley in Mont Rochel Nature Reserve, near Franschoek, where we had previously looked for Disa x brendae (a naturally occuring orchid hybrid that hadn’t been seen since 1985) and headed towards Wemmershoek Peak, via a high peak called Perdekop. This trail winds through fynbos dominated by graminoids, mainly in the form of restios. These ‘snow fields’ were interspersed with small areas of taller vegetation, mainly along seeps. It was in one of these that we found the first altimontane species, Spatalla incurva, in both flower and seed. We had not expected to see this species here as it is more populous further north. This was not the last Spatalla of the day though.

Spatalla confusa on Wemmershoek Peak

Spatalla confusa on Wemmershoek Peak

 

Past Perdekop, along a south facing peaty ridge we found a small population of young plants of Spatalla setacea that had not yet reached maturity. The trail then became indistinct and we had to simply follow the ridge, picking our way through rocky terrain adorned with the pink flowering spires of Watsonia borbonica. On making the final ascent to Wemmershoek Peak, we came across an area of short south facing cliffs with restio covered ledges between them. It was in these cliffs that we found the western form of Protea rupicola. These hard to reach plants had a few flowers but were mainly half burnt.

Protea rupicola again but this time the western forma and very hard to reach!

Protea rupicola again but this time the western forma and very hard to reach!

 

At the 1700m summit, the habitat changed to one of huge, wind sculpted boulders on top of a fairly flat plateau. It was on the flatter areas that we found Spatalla confusa, a plant we had also seen growing near Protea rupicola in the Kammanassie. These were small plants and few and far between. The leaves here were broader and longer that those of the population we had seen further east and sat outside the parameters given by their taxonomic description, however we have subsequently had their identification confirmed. Between the minibus-sized boulders we found the enchanting Cape Edelweiss (Lachnaea macrantha) a member of the Thymelaeaceae, whose complex white flowers and pointy, succulent, glaucous leaves dumbfounded us. The plant was so unlike other members of its family that it was not until we showed the photo to Anthony Hitchcock at Kirstenbosch that we got an identification for it. It was particularly ornamental, growing next to an orange, long, tube-flowered Erica that Anthony thinks may be E. abietina subsp. aurantiaca. On the way back we took a longer, but less steep route, passing a small population of Protea magnifica. As we descended, we went through an area that had burnt three years ago. The fresh, young growth of Leucadendron spissifolium was bright green and tinged with pink, while the multitude of post-fire flowers was reminiscent of an alpine meadow. A truly beautiful sight! It was here that we found plants of Aulax pallasia, the only resprouting member of this genus.

Cape Edelweiss (Lachnaea macrantha)

Cape Edelweiss (Lachnaea macrantha)

The Altimontane fynbos is certainly a habitat type we have a need to explore further, however, the pockets of this habitat are difficult to access and to navigate once there. There are many areas that should hold Altimontane fynbos that so far have been little explored and thus little recorded. Who knows what they may hold? We have a need to explore the mountains of both the Klein Swartberg and the Hex River mountains, the second highest mountain range in the Western Cape. The Hex in particular is a draw for us with its highest peak being Matroosberg at 2,249 metres. The high areas of North and South Hex Sandstone Fynbos have the largest area of Western Altimontane Sandstone Fynbos embedded in them. And with altitudinal zonation known to be clearly evident here they demand further investigation. However, the habitats they hold remain very little documented – A future trip (or a full on alpine expedition) maybe?

Thanks to Di and Peter from the Outramps CREW GroupCapeNatureStellenbosch University Botanic GardenThe Royal Horticultural Society, the staff at SANBI and BAM clothing for all of your assistance with our trip.

You can read more about some of the subjects I have covered in this blog by downloading the Western Cape State of Biodiversity Report 2017