Conifers of the South; #1 the cypresses

Another in my sporadic series of favourite trees - which covers quite a number when I start thinking about the concept. The most recent one was here, and you can work back from there if you're so minded.

Some 300 million years ago, in a world without flowers or birds or mammals, the fossil record reports the appearance of the first conifers, woody plants (mostly trees) with seeds born in cones, and no flowers but abundant pollen that was cast to the winds and relied on chance to deposit a few grains on a receptive female cone of the same species. One big advantage of pollen is that the plant is freed from the shackles of having to live near water, as did their predecessors relying on swimming sperm; a pollen grain is a sperm contained in a water-proof coat, though I'm sure you'll appreciate that this is somewhat of a simplification!

Black Cypress Pine Callitris endlicheri, Cooma, southern New South Wales.
This species is monoecious, with female (left) and pollen-bearing male (right) cones;
some species however are dioecious, with separate male and female plants.

The big break for conifers came 245 million years ago, when the Permian-Triassic extinction event knocked out several competing groups, including the 'seed ferns', and opened the landscape for them. Dinosaurs would have munched on them, doubtless triggering the production of harsh and even toxic resins. They dominated the world, which for a while then comprised just one vast continent, Pangaea, for at least 100 million years. However the eventual rise of the flowering plants presented them with strong competition and now their descendants only dominate the landscape in latitudes or altitudes too high for the pollinators on which the flowerers depend. Mind you, this still represents vast areas of the sub-Arctic, right across the northern hemisphere, where the forests of the taiga and their North American equivalents provide a greater carbon sink than all the tropical rainforests.

Pencil Pines Athrotaxis cupressioides, Cradle Mountain NP, Tasmania.

There are now six living families of conifers, only three of which are found in the southern hemisphere, my area of interest. This excludes Pinaceae, the biggest and probably best-known family, comprising pines, cedars, spruces, larches and firs, found only in the north. Of the rest, the largest family and the most widespread is that of the cypresses Cupressaceae, found on every continent. The other two southern families, Araucariacaeae and Podocarpaceae, are solely southern so it would be a reasonable conclusion that they are Gondwanan in origin. 

Reasonable, but wrong. In much earlier times the conifer families were far more widespread; for instance sequoias were found across the Northern Hemisphere and Australia, but now live naturally only in North America (two species) and east Asia (one). The sub-family that comprises King Billy and Pencil Pines grew throughout the Americas but now comprises just two species in western Tasmania. Fitzroya fossils - now represented by just one species, Alerce, in the southern Andes - have been recently found in Tasmania. Not a conifer, but a group of seed plants from the same general era as the conifers, the Gingko G. biloba is now the sole survivor of its entire Order, but fossil relatives are known from across the Northern Hemisphere and, most recently, from Tasmania. I could go on, but you get the picture. We are now seeing just remnants of a formerly much richer and more extensive dynasty - like a few eroded peaks above the water to remind us of a once mighty and continuous mountain range.

Callitris endlicheri almost co-dominating with eucalypts, Goulburn River NP, New South Wales.

The cypress family is strongly represented in Australia by the genus Callitris ('beautiful trio', for the leaf arrangement); there are 13 Australian species and three in New Caledonia. Originally a rainforest genus, it began to diversify around 30 million years ago as the land dried. The family itself however goes far further back than that, into the Triassic, some 240 million years ago in the upheaval following the Permian-Triassic extinction mentioned earlier.

Australian cypresses are highly adapted to life in the arid and semi-arid zones, notably the White Cypress Pine Callitris columellaris. (There is disagreement about this species; a strong body of opinion would split it, limiting C. columellaris to a small coastal strip straddling the NSW-Queensland borders, leaving C. glaucophylla to cover much of the rest of  sub-tropical Australia.) Here are some White Cypresses in the harsh central deserts, where they are generally associated with ranges.

Rim, King's Canyon, central Australia.

Barrarrana Gorge, Arkaroola Ranges, South Australia.

Ormiston Gorge, Western MacDonnell Ranges, central Australia.

Many Callitris species are associated with colourful, especially orange, lichens.

Lichens on Black Cypress Pine, Goulburn River NP.

There are also endemic members of the family in Tasmania (though they were not always restricted to there, as mentioned previously). In particular there are two members of the genus Athrotaxis, with a putative third, A. laxifolia, generally believed to be a hybrid, though conclusive genetic proof was still lacking the last time I read of it. They are slow-growing cool mountain rainforest trees, very susceptible to the increasing burning regimes that are the lot of most Tasmanian forests these days. They are however protected from logging, in and out of reserves. In protected situations such as at Cradle Mountain National Park, there are some magnificently ancient specimens, mostly battered by old lightning strikes.

Pencil Pines A. cupressoides looks, as its species name suggests, very cypress-like. The next three photos were all taken around Dove Lake in Cradle Mountain National Park.

The origin of the cupressoides name ('cypress-like') is very clear here - totally unsurprisingly,
given that it's in the same family.

An old Pencil Pine on the shores of Dove Lake.

Foliage detail, with scale-like leaflets.

King Billy Pine A. selaginoides is sometimes asserted to be named for a nineteenth century indigenous man (needless to say this wasn't his real name) but I've never read a suggestion as to why this should have been so!

King Billy Pine foliage and cones, both of which are larger than those of Pencil Pine.

The species name refers to the this foliage, and its similarity to that of Selaginella, a genus of club mosses (an even more ancient group, not mosses at all).

Selaginella uliginosa, north-eastern Tasmania.

And just for the record, here's a photo of Athrotaxis laxifolia in the Australian National Botanic Gardens, Canberra.

Beyond that there are only four members of the family native to Australia, in two small genera, found only in Tasmania and the far south-west of the continent.

In South America there are just three others, all comprising single-species families. Alerce Fitzroya cupressoides is a magnificent tree of the cool wet montane Valdivian rainforests of the southern Andes. It was named for Captain Robert FitzRoy who captained the famous Beagle expedition of the 1830s, on which Charles Darwin sailed as his companion. (FitzRoy feared suicide, driven by the lonely pressures of command, and the fate of other captains that he knew. Thirty years later, burdened by financial woes and his ever-looming depression, he did indeed take this own life.)

The tree can be huge - Darwin recorded one with a diameter of over 12.5 metres - but intensive logging has rendered big old ones hard to find; it yields superb building timber. Since 1976 it has been completely protected in Chile.

Alerce, Puerto Montt, Chile, above and below.
Big trees in this small reserve are reputed to be 2800 years old.

 

This superb old Alerce is reputedly 3500 years old;
Alerce Andino NP, southern Chile.

A fascinating remnant of the last glaciation on a beach near Puerto Montt is a dramatic testament to the durability of Alerce. Here are the stumps of Alerce, originally growing well above sea level, drowned when the sea rose with the melting of the ice caps at end of the last glaciation around 15,000 years ago (that was the figure I was given, though I might have expected it to be closer to 10,000 - but still!).

Ancient Alerce stumps at low tide, Puerto Montt.

Another South American cypress has a similar unfortunate story to that of the Alerce. This is Pilgerodendron uviferum, also the sole member of its genus, but found much further south than Alerce, though they overlap at the southern end of Alerce's range. On Tierra del Fuego, at the southern tip of South America, this cypress becomes the world's southern-most conifer. It is known in Chile as Ciprés de las Guaitecas, 'cypress of the Guaitecas Archipelago'. This windswept archipelago runs south from the island of Chiloé near Puerto Montt; together they represent the emergent peaks of the Coastal Range of Chile, which runs into the sea just south of Puerto Montt.

Pilgerodendron uviferum, Puerto Aiguierre, Guaitecas Archipelago. It can grow into a 20 metre high tree,
with a 1.5 metre diameter trunk and produces superb building timber, for which the forests were ruthlessly
plundered. It is now protected by being listed on Appendix 1 of CITES, which deals with species
threatened with extinction at least partly due to trade; the timber may not be exported.

Next time I'll conclude this two part series by talking about the other two southern conifer families, both of which are now found only in the Southern Hemisphere. For now though, I'll leave you with another image of Pencil Pines at Dove Lake in Tasmania; in many ways pure Old Gondwana, though the pines themselves are of a lineage much older even than that.

Pencil Pines in front of Dove Lake and Cradle Mountain, Tasmania.
(And it's worth knowing that Cradle Mountain is the souvenir of one of the most significant events in Australia's story. Around 55 million years ago Antarctica began to 'unzip' from the southern margins of what is now Australia, starting from the west. As the rift opened, vast quantities of subterranean molten material flowed into it, including an estimated 5,000 cubic kilometres beneath Tasmania! The dolerites of Cradle Mountain derived from the final disintegration of Gondwana and the isolation of Australia.)

NEXT POSTING THURSDAY.

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