I HAVE always been fascinated by springs where their natural outpourings of water emerge at the junction of permeable and impermeable rocks.
Where limestone, a permeable rock, overlies an impermeable rock layer, at that interface there is a large out-gushing of river water.
On a small scale near my house, I see my dog romp in the muddy waters exuded from a field spring. On a grander scale, I have witnessed such resurgent crystal clear water in other parts of the United Kingdom and in Slovenia.
This summer I visited one of the largest of such springs in the world at La Fontaine de Vaucluse in Provence, France. These springs are known internationally as Vauclusian springs with the very name taken from the place I visited.
The word vaucluse comes originally from the Latin wording vallis clausa or closed valley with high rock walls and towering cliffs above the emergent spring below.
With the nigh vertical limestone cliffs above me, I looked downwards onto the azure blue turning to sage green water as the spring emerged to feed the River Sorgue at its source.
The gradual resurgence of the water rather disappointed me, but it was summer time. In autumn and spring, particularly in the latter season after the winter snows on the heights above melt, the water surges out at an average rate of 190 cubic metres each second, thus creating massive turbulence downstream.
At La Fontaine de Vaucluse speleologists have dived into the cave waters to a depth of 308 metres at the point where it is thought that this spring’s waters may possibly start to emerge.
There are many such resurgent springs at the base of limestone formations in Malaysia. The springs at Gunung Mulu, and those alongside the plank walk leading to the Niah Caves come readily to mind.
Not witnessing the spring in France in its profusion, my eyes drifted up to the towering cliff faces overlooking the outlet cave.
I was staggered by the vegetative growth in the nooks and crannies in these cliffs – all secured in their niches, in fragile fashion, on bare limestone rock faces – not unlike the trees clinging to the outer rock faces of Niah Caves.
As limestone is principally composed of calcium carbonate with added impurities, plants growing on such soils are known as calcicoles, tolerant of and adapted to alkaline conditions.
Later I visited the ancient Roman arena in Arles to find plants growing high up on its carved limestone columns with their roots attached to precarious bits of almost 2,000-year-old hand-crafted limestone.
Frequently I have torn out ivy and small ferns rooted in my own slate garden walls to prevent their roots from expanding and slowly demolishing the walls. In doing so, I have often thought about other niche varieties of vegetation growing out of small cracks in the bare granite rock, above 3,050 metres in height, on Mount Kinabalu.
There, in severe conditions of exposure, with reduced oxygen levels, slow decomposition of the granitic rock, torrential rain, high wind speeds, burning ultraviolet rays by day, and freezing or near freezing temperatures at night, plants still survive.
Such plants are classified as calcifuges (from the Latin fleeing from calcium) and are tolerant of acidic rocks such as granite.
The seeds of these plants have lodged in relatively sheltered positions in small areas of decomposed granitic soils.
These species are regarded as Alpine vegetation and are similar to plants growing at altitude in the Himalayas.
Between 3,810 and nearly 4,000 metres, just below the highest point of Mount Kinabalu, there are grasses growing in wetter rock cracks and, in other niches, minute ferns.
Buttercups (Ranunculus lowii) adorn sunnier spots together with Leptospernum recurvum (a low growing, creeping shrub).
My greatest memory of Mount Kinabalu was seeing a miniature species of rhododendron (Rhododendron ericodes) growing out of the joints of the bare granite. Truly a minute species of the rhododendron family.
My boyhood memories, in climbing up much larger species of rhododendron trees in the granite rocks of West Cornwall (UK), but at a very much lower altitude, flooded back to me, albeit just below Low’s Peak.
Niche vegetation does not only exist in mountainous or hilly areas. The tree branches along the main roads and byways in Kuching support epiphytic ferns growing in the niches where the boughs meet the trunks.
There, accumulated and rotted vegetation has made a soil in which spores may prosper. Look at the rain gutters on our houses and see clumps of grass and other types of vegetation.
Yes, they need clearing. Look at our brick-laid backyards and see the weeds emerging between the cracks. Niche vegetation is all around us but so often our eyes never look at such beauty, for if it affects our urban environment and we naturally get our scrapers out.
For further information read ‘Royal Society Expedition to North Borneo’ by EJH Corner (1962) and ‘Kinabalu Summit of Borneo’ by KM Wong and A Phillipps (1978)
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