High Living; above the treeline: #1

This is another in an irregular (and hitherto informal) series on habitats. Earlier ones were on intercontinental habitats mangroves and sandstone, and a uniquely Australian one, the mallee. I have ideas for future ones on rainforests (probably with separate offerings on tropical and temperate rainforests and cloud forests), deserts, woodlands, grasslands and wetlands, but any other suggestions welcomed!

Today however I'm starting at the top, as it were. 'Alpine' is a term used often just to refer to mountains (originally specifically referring to European mountain ranges, though the etymology, from Latin, is unclear), but ecologically it has a more precise definition. It is that area above the treeline, where conditions are too harsh - specifically with insufficient solar energy - to support trees. It is defined around the world as the elevation at which the mean temperature of the warmest month is below 10 degrees centigrade. Below that there is simply not enough available solar energy to build and maintain the massive trunks and supporting root systems that define a tree. The line is often quite abrupt, though locally the altitude will vary locally depending on the landscape; trees might grow higher in sheltered situations on sunny slopes. And of course it is lower towards the poles and higher in the tropics, so some of what follows on the treeless zones in the far south of South America does not necessarily relate to high mountains. 

Treeline at 1800 metres above sea level (masl from here on) in the Australian alps
in Kosciuszko NP, far southern NSW, at 36.5 degrees south.

Across the Pacific and much further south at 52 degrees of latitude, the treeline at
Puerto Natales in Chilean Patagonia is at only 1200masl. 

However nearby in Torres del Paine National Park, the influence of constant winds from the huge Southern Ice Cap, the second largest ice field in the world* outside the polar regions, brings the tree line down to 500masl. (*The only larger one is in south-eastern Alaska.) The vast grassy and heathy plains there are part of the Patagonian Steppe, most of which is found in Argentina.

The spectacular Torres del Paine skyline from the south.

These lakes at Torres del Paine are less than 100masl; the forest doesn't extend far above
them on the Horns. 

This spectacular range however is not in the Andes chain. It is instructive (and equally, I hope, attractive!) to look at some Andean mountains up the chain from Tierra Del Fuego to northern Ecuador, almost on the equator, noting how the treeline rises as we go north.

Here near Ushaia in Argentinian Tierra del Fuego at 55 degrees south, the world's longest 
(and second highest) mountain range ends - or rather rather disappears under the ocean 
to reappear briefly as Cape Horn. The treeline here is at 500-600masl.

Volcano Calbuco, in the Lake District of northern Chilean Patagonia at 41 degrees south
 (a little further north than Hobart). Here the trees end at approximately 1300masl.

Nearby, above Lago Llanquihue ('yahn-KEE-way') is the perfect volcanic dome of Orsono.

This is not a particularly high mountain by Andean standards at 2600masl, and 
as we'd expect from the situation on Calbuco, the trees only go about halfway up.

Then we go much further north, deep into the tropics in Ecuador (I'll show some landscapes in between soon, but they mostly don't involve specific mountains). 

Volcano Chimborazo, in the centre of the Ecuadorian Andes, a truly mighty mountain and
the highest in Ecuador. It's snowy peaks are 6300masl, and the clearly delineated treeline is
 here at 3500masl (much higher than the highest point in Australia, on top of Mt Kosciuszko),
as it is for the next two Ecuadorian volcanoes, not much further north.

Volcano Cotopaxi, a 5900m active volcano clearly visible from Quito; this however was
taken from Papallacta Pass about 80km away, while heading east over the Andes to the Amazon basin.

Sunrise on Volcano Antisana, 5800masl, from the deck of the lovely Wild Sumaco Lodge
on the eastern slope of the Andes, 70km away. It is only 50km from the equator.

And before we take a much closer look at the ground on some very high mountain ranges, here are three more tropical mountains that I feel privileged to have seen as well, on a couple of other continents. 

The spectacular mass of Mount Kinabalu in Sabah, Malaysian Borneo, 6.5 degrees 
north of the equator. It's peak is at 4100masl and the clear treeline is 3400masl.

Mount Kenya (for which the country was named, incidentally) is less than 20k south
of the equator, which actually runs across its lower slopes. A fraction of the original
glaciers can just be seen in this somewhat murky photo; the Kenyan Wildlife Service
predicts that they will disappear by about 2050. The treeline is at 3500m and 
with a high point of 5200masl, only one African mountain is taller...

Young Cheetahs playing in front of magnificent Mount Kilimanjaro, in fading light
in northern Tanzania (taken from Amboseli NP, to the north across the border in Kenya). 
It is 3 degrees south of the equator, rises to 5900masl (4900 metres above the plains)
and the treeline is at 3800 metres - two vertical kilometres above Kosciuszko's
highest Snow Gums!

Treelines themselves are interesting, as a transition zone from forest or subalpine woodland to treeless heathland or grassland (or a mix of the two). Generally up here the trees are sparser and more stunted as they struggle at their ecological limits. The understorey here includes species that are shared with the true alpine zone above it, though up there are also plants which specialise in the harsh treeless zone. 

Elfin forest at Acjanaco Pass at about 3800masl on the Manu Road from Cusco to
the Amazon basin in the southern Peruvian Andes.

At the upper edge of the elfin forest we can just see the start of the high altitude 
treeless grasslands of the Puna in the mist.

Within the elfin forest though is a wealth of flowering plants, especially orchids, and birdlife. 

Epidendrum ardens, endemic to the Peruvian cloud forests.

Odontoglosssum (or Cyrtochilum) mystacinum, another cloud forest specialist,
also found in Ecuador and Bolivia. 

In some places bamboos form part of the highest forests.

Bamboo Chusquea sp. just below the treeline at 3400masl in the Talamanca Range
in central Costa Rica.

In El Cajas National Park near Cuenca in southern Ecuador there is an interesting situation. The treeline in general is around 3300masl as we'd expect in the tropics, but there is an exception. The remarkable Queñoa trees Polylepis spp. (family Rosaceae) can form thickets far above the treeline, to over 4000masl, at the highest elevation of any tree in the world. 

Polylepis thicket high in El Cajas NP.

Polylepis growing above the otherwise treeless boggy páramo in El Cajas NP.

In Australia the trees that form the treeline are Snow Gums - Eucalyptus pauciflora on the mainland and E. coccifera in Tasmania. Beneath them are plants which continue upwards to grow on the harsh treeless alpine heaths.

Old gnarled Snow Gums at 1770masl at Charlottes Pass, Kosciuszko NP, 
only just below the treeline.

Daisies growing among the Snow Gums at about 1700masl on Mount Ginini
in the Brindabella Ranges above Canberra. This is below the Kosciuszko treeline,
but in addition this is a bit north of Kosciuszko so we'd expect the treeline to be a bit higher.
There is very little true alpine habitat in the ACT.

Pineapple Grass Astelia alpina (actually a lily, family Asteliaceae) growing
under Tasmanian Snow Gums at Mount Field NP, Tasmania. It is a common
plant in alpine bogs in Tasmania. The treeline here is at 1200masl, which
matches that of mountains at the same latitude in Patagonia.

So what does it look like above the snowline where the trees can't survive? I can only offer photos from South and Central America and Australia - I've not been that high in either Borneo or Africa. (I was planning to include Ireland but have realised that the landscape has been so cleared of trees over the last couple of millennia that the original treeline does not exist.) 

Mat plants and 'cushions' - opposites to a tree - reduce wind resistance and enable shoots to be protected inside the foliage. 

Hard cushions of Azorella sp., Family Apiaceae, are prominent in the landscape around
Chivay and the Colca Canyon, at over 3600masl in the southern Peruvian Andes.

In the Australian Alps (and elsewhere in the world) many unrelated species form dense mats across
the ground and rocks. This is Snow Beard-heath Leucopogon montanus. 
Most other Leucopogons I know grow as shrubs.

In the central-southern Andes of southern Peru, Bolivia and Patagonia (ie Chile and Argentina) the puna comprises vast areas of dry grasslands.

Puna as far as we can see, at 4000masl in the Andes above Cusco, southern Peru.

Puna below the Horns, Torres del Paine NP, Chilean Patagonia.

Further north (from northern Peru), the páramo is boggier and with a more heathy/shrubby vegetation.

The view from 4200masl of El Cajas NP, páramo and ponds.

Páramo at 3400masl in the central highlands of Costa Rica, dominated by low shrubs.

Eventually there are altitudes where very little grows at all. I'm no mountaineer; the highest I've been on the ground is 4900masl (by vehicle!) at Patapampa Pass in southern Peru, where the landscape is as barren as anything I've seen, beyond which is a magnificent vista of volcanoes on the horizon. I am fortunate in not being particularly susceptible to altitude sickness, but the short walk from the vehicle to the little lookout was a bit of a struggle! Needless to say, the local women selling crafts by the roadside were entirely unfazed by it.  

This is far from the upper limits of plant growth, which is over 6000masl in 
the Himalayas, and I think that this is literally a scorched landscape 
from past eruptions by the nearby volcanoes.

Volcanoes Ampato, Sabancaya and Hualca Hualca, between 10 and 20km away from
Patapampa Pass. Sabancaya is very much an active volcano and erupts constantly
(part of the cloud just above it is actually smoke), but I don't know when lava last flowed this far.

And finally some Australian alpine landscapes, which provide less than 0.1% of the continent's landmass; it is a very old and eroded continent and the mean altitude is only 300masl. 

Looking east from near the summit of Mount Kosciuszko, the highest point of Australia (not
including the sub-Antarctic territories) at a mere 2228masl.

Looking across the granite landscape to Lake Cootapatamba, the highest lake in Australia.
It is a cirque lake, gouged out by glaciers in the most recent glaciation, 
some 15,000 to 20,000 years ago.

The brief summer flowering is spectacular; here is a field of snow daisies Celmisia sp. on the
Main Range of Kosciuszko NP.

Along with the adjoining Victorian Alps, the only other Australian alpine areas of significance are in Tasmania to the south, where its higher latitude compensates for the lower altitudes.

Granites and heath on kunanyi / Mount Wellington above Hobart.

Cloud, granite and heath on Ben Lomond NP, a spectacular mountain plateau
in north-eastern Tasmania.

Wombat Moor on Mount Field, west of Hobart.

And that might be enough of mountains for one sitting. Next time I'll conclude this blog with a post on some high altitude plants; I'd been planning to do a joint post on plants and animals, but it would have been a long one, perhaps testing your patience unreasonably. So two posts still to come on this topic. Thanks for staying with me, despite the cold and the thin air.

NEXT POSTING THURSDAY 23 JULY

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