Mountain Journal

Many people know the story of the Pine beetle which has been devastating huge areas of forest across North America because of climate change.

In brief, the mountain pine beetle’s ability to survive and multiply rapidly is highly sensitive to temperature and precipitation. Warmer average temperatures allow pine beetles to complete their life cycle in just one year instead of two. Rising minimum temperatures in the Colorado Rockies have allowed more beetles to survive the winter and from 2009 to 2010, mountain pine beetle activity increased more than 10-fold, infesting 200,000 acres (80,000 hectares) on the Front Range, and killing off millions of hectares of trees in North America.

There is a similar scenario emerging in Australia’s mountain forests, although it is much less known.

Snow gums are experiencing dieback in Kosciuszko National Park, largely because of the impacts of the native longicorn (or ‘longhorn’) beetle. These beetles prefer to lay their eggs on moisture-stressed trees and, in warmer weather, the longicorn beetle can hatch and grow up to 75% faster.

According to work published in the Resort Roundup winter 2019 edition (produced by the NSW government), ‘reduced snowfall, high summer temperatures such as January 2019 where temperatures at Thredbo top station were 4.4oC above average, and a reduction in autumn rainfall mean that snow gums are under much greater moisture stress than in the past.’ This means that larger beetle populations are causing more frequent dieback of some snow gum trees.

So far, impacts seem to be limited to areas in the Snowy Mountains among two distinct subspecies of snow gum – in the Guthega and Perisher areas and parts of Thredbo. The main species affected is Eucalyptus niphophila. Additionally, the population of Weeping snow gum Eucalyptus lacrimans in the Long Plain area appears to be significantly impacted by longicorn beetle. At this point it does not seem that the infestation is affecting the widespread E. pauciflora subsp. pauciflora.

Apart from the visual and ecological impacts of losing these important trees, increased dieback will lead to an increase in fire risk in alpine resorts and other areas within Kosciuszko National Park. With increasing climate change, it is expected that the longhorn beetle will continue to increase in numbers and therefore its associated impacts on snow gums will also become more extensive.

This is yet another compelling reason for us to be taking serious action to respond to climate change!

Continue reading “Snow gum die back linked to climate change” →