Alpine garden society lectures

These are some notes I made on the second lecture by Mark Hanger at the Alpine garden society AGM.  It was called “Artistry Above the Treeline – Insights into endemic Australasian alpine flora”.  This struck a chord so I thought i would share it with you.  Again, thank you to the AGS for allowing me to attend.

The lecture paid particular attention to the spear grasses (aciphylla).  These plants have cultural significance to New Zealand, as do phormiums and cordylines.  Most species of aciphylla occur in temperate climates, with a few being more tropical.

New Zealand’s flora was first documented in the western world following Captain James cook’s 3 voyages to Australasia and New Zealand.  Cook was commissioned with advice from the Royal Society to circumnavigate the globe as far south as possible. He commanded the first circumnavigation of New Zealand.

On the second voyage naturalist Joseph Banks refused to travel and was replaced at the last minute by Johann Reinhold Forster, who was accompanied by his son Georg Forster. On his return, Forster published Observations Made during a Voyage round the World in 1778.  He could not publish works prior to Cook by contract; however his son was not bound by the same terms as he was a minor.  Thus, Forster pipped Cook to the publishing post.  However, Forster did not make enough money from the sale of the book to cover his investments and was actually declared bankrupt.

Aciphylla has become dominant is because of its ability to regenerate after man induced fires in the north, and natural fire in the south.  This is due to their tap rooted structure which allows regeneration following the scorching of the crown.

The genus is made up of 42 species, subdivided into 4 groups.  One way species can be distinguished is by size.  Aciphylla scott-thomsonii is the largest, with aciphylla glaucescens being a smaller, but statureful architectural plant.  Smaller cauliflower types form cushion fields, for example aciphylla hectorii.  Moist streamsides have been colonized by aciphylla pinnatifida.  Smaller laxer habits are characteristic of moist herb fields.  True alpines are mainly cushion flora, for example aciphylla monroi.  Aciphylla dobsonnii inhabits the scree slopes of the central island.  Some plants are fairly longevous, being over 25 years old.

They have some interesting common names, such as wild Spaniards, wild Irishmen (discaria), and the bush lawyer.  The latter so called because their spines are hidden, and once they get hold of you they do not let go.

Aciphylla plants can form nutrient rich tussocks, for example aciphylla similes.  Their crowns, being sheltered also, are therefore desirable to insects and their larvae.  Pest pressure comes from introduced species of grasshoppers and weevils.  Grasshoppers can be as numerous as 20000 per hectare, and weevils are disease vectors as well  through their nature of being sap sucking insects.

Pollination is undertaken by general insect pollinators.  Aciphyllas are dioecious, having separate male and female inflorescences.  They flower en masse, and mast cyclically.  Masting is a synchronous production of seed at long intervals by a population of plants The frequency of the flowering cycles has been seen to vary over time, possibly as a result of climate change.  This may be seen in an increase in masting in recent years.

This leads to aciphyllas requiring plant associations, to allow pollinators to be fed in the years when the aciphyllas are not flowering.  Nothofagus, some celmisia and chinocloa may have 3-4 year flowering cycles.  The understanding of plant vitality and its link to reproductive cycles is vital in cultivation and conservation.

Aciphylla squarrosa is an interesting plant.  It has developed spiny adaptation.  However, with no real grazing mammals the severity of protection is intriguing and may be only partially explained by xerophytic adaptation.  Another unanswered question is the predominance flora from the umbelliferae group, which totals 428 species.  These are co dominant with tussock grasses in true alpine environments.  The alpine daisies and buttercups are dominant plants, as are hebes in the sub alpine habitats.

Anisotome is another important genus.  The genus is comprised of 16 species, with the majority in New Zealand and a small number in Australia.  Aninostome flexuosa is a diminutive species found 1400m above sea level in the high alpine region.  The highest observed plants exist at 2286m above sea level.  Other species include Anisotome imbricate, and Anisotome elanugosa.  Lignocarpa are important scree dwellers, with 2 species on the central and south island.

Basal rots are a common problem in garden cultivation.  The climate in which they reside has different drying rates to other temperate regions.  Thus, using a well drained substrate is vital to their success.

Overall New Zealand is said to be understudied, which makes its breathtaking landscapes mysterious as well.  One thing that was apparent that some of the man made introductions have had a high impact on flora.  An example of this would be the introduction of grazing mammals.  More recently climate change, perhaps particularly damage in the ozone layer, and its impacts on flora can be observed.

It seems that society is impacting significantly on nature.  Society has grown to such an extent that it’s influence seems to be most impactuous in the rate of change with which we alter nature. The difficulty of mediating effects so interlinked at a faster rate is the problem.  We are in a position to understand our impacts on nature.  This assumes responsibility to choose the best for all.  This is a complex position, but involves choice.  The environment should be a much larger part of decision making.  How we view our relationship with nature and its equilibriums seems to be encapsulated in the beauty of New Zealand.

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