AKA Fagus cliffortioides, Fuscospora cliffortioides and in Māori tawhai rauriki.

A species of Southern Beech endemic to New Zealand, widespread in mountainous areas at high elevations, but near the treeline it forms 'goblin forests' barely 2m tall. Lower on the slopes it easily reachs 20m.

Not the only Nothofagus species I saw on the trip - they're the dominant trees in most higher altitude forests.

The sunlit mountain range of Cerro Torre in southern Patagonia, in the foreground a lenga beech (Nothofagus pumilio), that is native to the southern Andes of Chile and Argentina. found by @amazinglybeautifulphotography via @ihopedtherewouldbestars

One of the features of the Antarctic Beech forests of New Zealand, particularly on the South Island, is the thick layer of what looks like black moss covering many of the trees. And the ground. And most of the plants in the understory.

The black moss is actually sooty mold, a complex combination of fungi from a variety of different Orders, thriving on the ludicrous amounts of honeydew pumped out by the Sooty Beech Scale Ultracoelostoma assimile. The white filaments sticking out of the mold in the first photo is the anal tube of the scale insects, the longest such tube of any insect. The insect is most abundant on Black Beech Nothofagus solandri (the black in the name is from the mold) and middle-aged trees may lose 80% of the sugars they make to them. Younger trees have smooth bark that doesn't offer safe nooks and crannies for the crawlers, and in mature trees the bark is too thick for the scale insects to drill through.

The honeydew is a keystone feature of the Nothofagus forests - birds, bats, reptiles and insects all feed on the honeydew. Some rely on it. There's at least two species of caterpillar that prey on the scale insects. And a beetle - the only one in its family - that feeds only on the sooty mold.

And then the wasps arrived.

Two species are the problem - Vespula vulgaris (see photo) and Vespula germanica. Both are now more common in the Nothofagus forests then they are anywhere else in the world, and by a horrifying degree. Not only are they getting a diet of pure rocket fuel for much of the year, they then denude the forest of invertebrate life to feed their larvae. By monopolising the honeydew supply they're starving the birds and other animals that need that food supply, especially since introduced mice, rats, and stoats are eating the fruit and seeds of the forest, or turning on the birds when they run out of mice.

After getting across Cook Strait without being shipwrecked (the weather was actually quite pleasant compared to some of the unholy gales that come through the gap, with the wind merely howling), we started our explorations of Te Waipounamu, the Island of Greenstone Waters. Pounamu is such a beautiful and useful stone that the Māori named the entire island after it.

Europeans called it South Island, or archaically New Munster. It covers 150,437 square kilometres, making it the world's 12th-largest island. We stopped at the Omaka Aviation Museum, which was worth it, but our first night was spent at St. Arnaud, formerly Rotoiti, a tiny alpine village.

It's certainly surrounded by mountains, and shows some really nice alpine geomorphology - hanging valleys left where subsiduary glaciers got cut off by the larger glaciers in the main valley, scree slopes where the greywacke of the mountains is disintigrating, and alpine lakes like Lake Rotoiti itself, formed when the glaciers retreated at the end of the last Ice Age and left behind huge piles of pebbles, gravel, and boulders to dam the meltwater.

On the other hand St. Arnaud has also been built right on top of a considerably larger geological feature - the Alpine Fault. This tectonic boundary between the Australian and Pacific Plates runs for over 600km, and is one of the fastest moving faultlines in the world, moving, on average, almost 40mm a year. Geological formations that originally straddled the fault are now 480km apart. Unfortunately most of that movement happens during huge earthquakes every few hundred years - the last big one on the Alpine Fault happens around 1717, rupturing 400km of the fault at once.

Over the last 12 million years a significant upwards element to the fault movement has been added, creating the Southern Alps. Most of what is now the South Island got pushed 20 kilometers up, whereupon New Zealand's weather promptly ground it 16 kilometers back down again. The assorted rubble forms the plains on the east and southern coast, or got swept north by prevailing currents on the west coast. Exposed basement rock on the South Island is mostly greywacke, or heavily metamorphised rocks such as schist from even deeper. That's where the greenstone originally formed.

Anyway, the next big quake will probably trash St. Arnaud completely, and cut every road across the mountains for months. Happily that didn't happen on this trip - @purrdence had enough problems with a cyclone cutting roads and trainlines last time.

The original forest around St. Arnaud is mostly Antarctic Beech (Nothofagus sp.) and forms the basis of a unique and seriously threatened ecosystem. I'll tell you all about that over the upcoming posts.

Here's some species I've covered before.

AKA Nothofagus solandri var. solandri or Fuscospora solandri.

An endemic evergreen tree growing to 27 m tall. Found on both the North and the South Island at low elevations up to the mountains. Widespread on ridges in inland Taranaki.

Black beech gets that name because of a sooty mold which covers the trunk and branches. I'll discuss that more when I get to the St. Arnaud section of the trip, where it's a vital part of the ecosystem.

Black beech is known to hybridise freely with mountain beech (Nothofagus cliffortioides) where the two species co-exist, although Mountain beech generally grows at higher elevations. It also hybridises with hard beech (Nothofagus truncata) to form the hybrid species Nothofagus × apiculata, and with red beech (Nothofagus fusca) to form the hybrid species Nothofagus × dubia.

AKA Fuscospora fusca, and tawhai raunui.

A medium-sized evergreen tree growing to 35 m tall, usually on lower hills and inland valley floors where soil is fertile and well drained, on North and South Island.

Fossil pollen has been found in Antarctic Eocene strata.

Red beech hybridises with mountain beech (Nothofagus cliffortioides) to form the hybrid species Nothofagus ×blairii, with black beech (Nothofagus solandri) to form the hybrid species Nothofagus ×dubia, and the ruil tree (Nothofagus alessandrii) from Chile to form the hybrid species Nothofagus ×eugenananus.

Grown as an ornamental tree in regions with a mild oceanic climate. The timber is excellent if carefully dried, It was often used in flooring in many parts of New Zealand.