The Peak

Just back from a four day trip to a remote part of the island.  We camped on the Base at 1000 m above sea level, on the boundary between Island Tree (Phylica arborea) scrub woodland and short sward Blechnum penna-marina (a fern) and heathy Empetrum rubrum (similar to our Crowberry, Empetrum nigrum). We pitched the tents in a small clearing amongst Island Tree for shelter, pegged well down and guys tied tightly.  Necessary because of near galeforce winds for much of the time. But weirdly warm, sunny and very humid. Quite nice in sheltered ravines (gulches) and in scrubby woodland. And it was great waking up and finding you’re above the clouds!

Sooty Albatross chick line-up...

It is not easy to describe just how difficult the terrain is.  One kilometre on the Base can take anything between one and three hours. Every step and handhold requires a calculation on how much weight it can take. Nothing is certain. Even the rock is unreliable (but rarely exposed). The uneven spongy peat surface is covered by dense leaf litter and prostrate branches. All of which are hidden by ferns.  Amongst the scrubby tangle there is much deadwood which despite looking solid enough snaps instantly.  Green wood is more reliable but surprisingly brittle.  At times all-fours is the best way to squeeze through the tangle of branches.  It is just as well my work partner, Lourens, is adept with the machete!  Unwooded slopes are climbed by grabbing handfuls of vegetation. I’ve just about figured out how much you can trust different species, but there is a lot of trial and error (and cuts and scrapes).     

The bottom of a small gulch

The main question is ridges or ravines. Exposure sometimes makes ridge vegetation more open. There are also short peaty paths made by Mollys (Yellow-nosed Albatrosses) to commute between their sheltered nest sites and exposed launch-pads.  But otherwise they can be almost impenetrable.  Ravines (gulches) are often better for covering the ground as there is less rank vegetation and the rivers are usually dry unless it is actually raining.  (Few streams flow constantly on Tristan as the terrain is porous.)  But gulches are invariably steep-sided, deep and have periodic dry waterfalls - some hundreds of feet high - that are only bypassed with difficulty. 

The gulches are certainly much more interesting botanically.  For example last week we recorded 65 species in each 1km square on the days spent in gulches. But only 35 on a 1km square in which we ridge walked.  We have only ever found the rare endemic fern Asplenium insulare once so far on Tristan – and then a single population with just a few plants. So it was good to find a second much more extensive population.  It likes humid and sheltered conditions – so gulches are perfect. Especially narrow, sheltered ones with overhanging edges.  Its constant associate is Trichomanes angustatum – itself a rare endemic.  The secret appears to be to find the right habitat then look under other bigger ferns.  

Dryopteris wallachiana

These gulches are home to other rare endemics such the buttercup Ranunculus carolii, the starwort, Callitriche christensenii, and the Floating Sweet-grass, Glyceria insularis.  Amongst the bigger ferns we occasionally encounter Athyrium medium and Hypolepis rugulosa but the real surprise was to find the biggest population of Dryopteris wallachiana seen to date. This is a lot like our Scaly Male-fern (Dryopteris affinis agg.) and produces splendid yellow-green frond shuttlecocks. That is not to say that wooded ridges are without interest. We saw more of the rare endemic and well-named Bootlace Fern (Radiovittaria ruiziana) than ever previously. But generally they are less diverse, and you don’t cover as much ground.

However the highlight of the trip was an ascent to the 2,060 metre peak. This carrying our camping gear and surveying as we went. (Another day that would make SAS training seem easy!)  The peak has concentric vegetation bands that change with altitude.  The Blechnum/Empetrum sward quickly gives way to a heath dominated by Empetrum and the moss Rhacomitrium lanuginosum;  vegetation very similar to that found on the Scottish mountains, but rarely in such fine condition with so little sheep trampling and grazing damage.  Around 1200 metres, my eagle-eyed work partner Lourens spotted another population of the rare endemic rush, Rostkovia tristanensis.  (If you remember this had not been recorded since the 1938 Norwegian Survey Expedition.)  

The summit plateau

The spongy Empetrum-Rhacomitrium sward becomes increasingly patchy with altitude. Eventually the ground becomes too unstable, loose and dry for any but the hardiest of mosses. This is the Alpine desert cinder scree zone.  All plants at this altitude form dense mats or tight cushions – adaptations which create a (relatively) warm and humid microclimate that helps to minimise water loss.  We find the highest flowering plant at 1970 metres, just above Crater Lake – Empetrum rubrum again!  The view from the top is spectacular. Its like looking out an aircraft window on a brilliantly sunny day - down on distant clouds and blue sea. Closer in the Base looks surprisingly extensive and several other water-filled crater lakes are evident. But no where is the coast visible due to the steep escarpment. We have a quick dip in crater lake - a beautiful and sheltered spot - before continuing our survey on the descent to the settlement.

Crater Lake

After a few day's specimen pressing, data entry, battery charging - literally and personally, cooking, shopping, clothes washing and with a good weather forecast we are getting ready to go on another camping trip early tomorrow morning..

News Snippets:

• The island went back to work on Monday – after the three week summer holiday.  This meant the Island Store re-opened for the first time since Christmas. I’d only run out of cereal and coffee but was also running dangerously low on beer supplies.
• The MV Edinburgh is due to arrive from Cape Town tomorrow – hopefully with my Christmas presents that didn’t make the last ship.  And with some emergency supplies that my cousins, Sandy and Ali in Cape Town have kindly bought and despatched.  How exciting!
• Simon is in Edinburgh this week catching up with friends and family. Unfortunately the Alfa Romeo is playing up - I think through lack of use!

• Mum is making a great recovery, after breaking her leg in October.  She is able to drive again and can now get to the shops and to her normal full program of events and meetings.     
• My sister, Catherine, and her family are coming over from America to see mum and help my brother, Peter, on the farm with the lambing this spring.