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Posted May 2009

The plants and animals that make their home in the world’s alpine ecosystems are some of the most threatened by climate change.

Unlike other regions, where species can migrate to escape warmer temperatures, plants and animals living at higher altitudes are often at the top of their range, and have nowhere to go if they are to survive climate change.

In New Zealand there are more than 600 alpine vascular plant species, 93 per cent of which are found nowhere elese on earth.

Monitoring (reported in 2001) found no evidence of changes in the tree-line that could be attributed to climate change, because large-scale occasional disturbances were over-riding any signals changes due to climate.

But modelling reported in a 2003 paper by Stephan Halloy and Alan Mark found that a 3°C rise in temperature combined with a large pool of exotic plant species could lead to the loss of up to half the native alpine plant species.

Thankfully, northern hemisphere plants are not well adapted to New Zealand’s alpine climate, which has longer, cooler summers and milder winters than on the other side of the equator. Few of the many exotic alpine plants in gardens have invaded the Alpine regions.

But while few weeds can be found in New Zealand’s alpine regions now, modelling predicts that many more will invade in the future. With a 3°C rise, the modelling shows that weeds could make up about one-third to one-half of the alpine flora.

Alpine animals could also suffer from changed weather patterns. The rock wren, for example, is a poor flier and would be vulnerable to rats and cats that may be able to move higher with warming.

References
Halloy SRP, Mark AF. 2003. Climate-change effects on alpine plant biodiversity: A New Zealand perspective. Arctic, Antarctic, and Alpine Research 35: 248-254.
Dorfman E. 2008. Melting point: New Zeland and the climate change crisis. Auckland: Penguin.

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