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Mountain Journal

Environment, news, culture from the Australian Alps

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Mountain Ash

Chasing Giant Trees in lutruwita/ Tasmania

Carl Hansen and Jan Corigliano report on a recent mission to catalogue newly discovered forest giants.

This story first appeared in the Mountain Journal print magazine for 2021 (available here).

The tallest and biggest living things in the world are trees. While the biggest and tallest are the well-known Coast Redwoods of California, the towering Mountain Ash (Eucalpytus Regnans) of Victoria and Tasmania have largely escaped the limelight, despite being the tallest trees in the southern hemisphere.

In the Tasmanian Wilderness World Heritage Area, to the west of the Florentine River in the vicinity of McLeod’s Creek, grows a patch of extremely tall forest unmatched in extent and integrity in Australia. Remote, rugged and barely visited by Europeans, it contains 29 LiDAR-identified “‘hits’ over 85 meters tall. In recent years, the advent of LiDAR (a 3D scan of tree heights from a small plane) has uncovered many previously undiscovered giant trees. But what’s shown on LiDAR doesn’t always stack up with what’s on the ground, so ground surveys must be done in order to see how big the trees really are.

Continue reading “Chasing Giant Trees in lutruwita/ Tasmania”

National Threatened Species Day 2021

Every year on September 7, National Threatened Species Day is commemorated across Australia to raise awareness of plants and animals at risk of extinction.

There are currently 457 species of fauna and 1348 species of flora listed as vulnerable, endangered or critically endangered under Australia’s Environment and Biodiversity Conservation Act 1999 (EPBC Act). Many of these are found nowhere else in the world.

This is a summary of some of the threats facing mountain species.

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Old forests slow fire

We know that climate change is driving longer and more intense fire seasons. We know that fuel reduction can greatly reduce the spread and intensity of wildfire. However, in extreme fire conditions, the value of fuel reduction burning is reduced, and fires will burn through almost anything, regardless of recent fuel reduction treatment an area may have had. We also know that logging will make forests more flammable because of the loss of more humid micro climates and thick growth of the seedlings that will occur after logging. But we also know that older forests are less fire prone, burn less intensely than regrowth forests, and have the ability to slow down fires as they move through the landscape.

This has been highlighted again in research called Propensities of Old Growth, Mature and Regrowth Wet Eucalypt Forest, and Eucalyptus nitens Plantation, to Burn During Wildfire and Suffer Fire-Induced Crown Death by Suyanti Winoto-Lewin, Jennifer C Sanger and James B Kirkpatrick at the University of Tasmania. It highlights the value of older forests in slowing fire. (Available here).

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The O’Shannassy Catchment: ‘2/3 of the rainforest is gone’

Eleven years on from the 2009 Black Saturday fires, many landscapes are still recovering. The Central Highlands were an epicentre of old mountain ash and rainforest, but this has been steadily destroyed by decades of logging and the wild fire of 2009 burnt large sections of remaining old growth.

Prior to the 2009 fires, the O’Shannassy Catchment was a standout example of the remaining old growth of the Central Highlands. As a Designated Water Supply Catchment Area, legislated under the National Parks Act to protect water catchment and resource values, much of it is closed to the general public. Yet you could see the upper catchment from a number of vantage points, such as the road between the Lake Mountain turnoff and Camberville.

Much of it was burnt in 2009. A decade and a bit on, how is it faring?

The short answer is that while the forest is recovering, in the severely burnt portion of the catchment, 96% of the original rainforest ‘could no longer be classified as such’. And, overall, the severe fire in 2009 has led to the loss of around two thirds of the Cool Temperate Rainforest previously mapped in the O’Shannassy Catchment.

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Reseeding the Alpine Ash and Mountain Ash forests

There is no doubt that our fire seasons are getting longer and more intense and this is starting to have potentially landscape changing impacts. There is concern that Alpine Ash forests could be wiped out in some areas where fire comes in multiple waves before the recovering trees can set seed. Parts of north eastern Victoria have been burnt three times in a decade. Mountain Ash forests face similar threats.

It is tragic that fires are so frequent and intense that we face the prospect of seeing these vegetation communities collapse. There are many ways we must respond: acting decisively on climate change, and protecting these forests from wildfire and over logging. Aerial seeding programs also aim to help these forests survive.

Continue reading “Reseeding the Alpine Ash and Mountain Ash forests”

Mountain Ash forests facing ‘collapse’

There is ever growing evidence of the impacts of climate change on natural ecosystems. We know that, without meaningful action now, the future of alpine vegetation in Australia doesn’t look good. This is true around the world. For instance, research shows that, in many instances, forests in the western part of the USA are not growing back after wildfire, and warmer temperatures are being blamed.

Here in Australia, longer and hotter summers are increasing the risk of longer fire seasons. Some parts of the Alps have been burnt three times in the space of a decade or so, with resulting impacts on what species grow back.

Continue reading “Mountain Ash forests facing ‘collapse’”

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