We modelled the future of Leadbeater’s possum habitat and found bushfires, not logging, pose the greatest threat



Rohan Clarke, Author provided

Craig Nitschke, University of Melbourne; Andrew Robinson, University of Melbourne; Melissa Fedrigo, University of Melbourne; Patrick Baker, University of Melbourne, and Raphael Trouve, University of Melbourne

The Federal Court recently ruled that a timber harvesting company couldn’t log potential habitat of the critically endangered Leadbeater’s possum.

This decision led to the immediate protection of more Leadbeater’s possum habitat and will lead to further habitat set aside over the next ten years as native timber harvesting is phased out in Victoria.

But these short-term, site-based measures will not guarantee the long-term conservation of this iconic Victorian species.




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Our new study modelled changes in forests over the next 250 years, focusing on 280,000 hectares of Victoria’s Central Highlands, home to the majority of remaining Leadbeater’s possums.

We looked at different scenarios of how both climate change and timber harvesting might play out. And we identified three important findings.

First, Leadbeater’s possum habitat is dynamic. It’s transient across the landscape over time as disturbances, such as bushfires, continually change the spatial distribution of hollow-bearing trees and young forests.

Second, while timber harvesting poses a local-scale threat, at a larger scale – across hundreds of thousands of hectares – bushfire poses the greatest threat to the species’ habitat.

Last, we found less than half of the area within current parks, reserves, and timber harvest exclusion zones provided stable long-term habitat for Leadbeater’s possum over the next century.

The Black Saturday bushfires razed almost half of the Leadbeater’s possum habitat in 2009.
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Future habitat scenarios

Leadbeater’s possums live in ash and snow gum forests. They depend on two key habitat features: hollow-bearing trees for nesting and dense understorey for moving around the forest.

We used a set of four scenarios to explore how climate change and timber harvesting impact long-term habitat availability by focusing on the where and when hollow-bearing trees and dense understorey are found in the landscape.




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The scenarios included projecting current climate conditions, and projecting a 2℃ rise in average annual temperature with a 20% reduction in yearly rainfall.

For each of these climate scenarios, timber harvesting at current harvesting rates was either excluded or allowed in areas zoned for timber production.

Bushfires drive long-term habitat loss

Our simulations showed bushfire, not logging, is the biggest threat to habitat availability for Leadbeater’s possum in the Central Highlands. As the cumulative area burnt by fire increased, the quantity and quality of Leadbeater’s possum habitat decreased.

Tthe 2009 Black Saturday fires burned almost half of its habitat, causing its conservation status to jump from endangered to critically endangered.




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Bushfires have always been part of Australian landscapes and many species, including Leadbeater’s possum, have evolved alongside them. Eleven years later, Leadbeater’s possum are now recolonising areas burned in the 2009 bushfires.

But as climate change increases the frequency and scale of bushfires, our models suggest the Central Highlands landscape may support less suitable habitat.

Timber harvesting is less of a threat

While timber harvesting compounds the impacts of bushfires on Leadbeater’s possum habitat, across the landscape the effect is small in comparison. Timber harvesting reduced suitable habitat by only 1.4% to 2.3% over 250 years compared to scenarios without harvesting.

Within a coupe (the area of forest harvested in one operation), timber harvesting immediately reduces nesting and foraging habitat. But foraging habitat returns within 10 to 15 years and can be recolonised by Leadbeater’s possum – as long as nesting sites are nearby.




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Protecting vegetation around waterways, in particular, was critical for the development and survival of hollow-bearing trees in an increasingly fire-prone landscape.

But while timber harvesting had much smaller impacts than bushfires, the two did interact. Over time, the cumulative impacts of timber harvesting and bushfire homogenised forest structure across the landscape, leading to smaller patches of habitat that were less connected.

This increases the risk of local extinction for populations of Leadbeater’s possum living in these patches.

We need dynamic conservation areas

A core question for the conservation of any threatened species is: how well does the network of protected areas protect the species?

Our modelling framework meant we could test whether current areas set aside for Leadbeater’s possum conservation actually provide long-term protection.

Over the next 100 years, less than 50% of existing parks, reserves and timber-harvest exclusion zones will provide continuous habitat for Leadbeater’s possum due to climate change.

Distribution of Leadbeater’s possum habitat in the Central Highlands landscape modelled in our paper. Stable zones provided suitable habitat throughout the scenarios. Loss and gain were areas that lost or became habitat over the scenario.
Author provided

However, we also identified approximately 30,000 hectares of forest outside the current network of protected areas that can provide stable habitat for Leadbeater’s possum over the next century.

It’s vital we put protection zones into the areas possums are likely to migrate to as the climate changes. These areas should be a priority for conservation efforts.

A new conservation strategy

Historically, conservation planning has taken a static, site-based approach to protecting species.

This approach is doomed to fail in dynamic landscapes – particularly in fire-prone landscapes in a warming climate. For conservation planning to be successful, we need coordinated forest, fire, and conservation management that accounts for these dynamics across the whole landscape, not just in individual locations.




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We need a vision for how to make our landscapes more resilient to the growing threat of climate change and provide better protection for the unique flora and fauna that inhabit them.

This will require government agencies responsible for land management and conservation to coordinate current management activities across tenures, while simultaneously implementing future-focused conservation planning. Our landscape-modelling approach provides a first step in that direction.The Conversation

Craig Nitschke, Associate Professor – Forest and Landscape Dynamics, University of Melbourne; Andrew Robinson, Managing Director for Biosecurity Risk Research, University of Melbourne; Melissa Fedrigo, Remote Sensing Scientist and Ecological Modeller, University of Melbourne; Patrick Baker, ARC Future Fellow and Professor of Silviculture and Forest Ecology, University of Melbourne, and Raphael Trouve, Post-Doctoral Research Fellow Ecosystem And Forest Sciences, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Leadbeater’s possum finally had its day in court. It may change the future of logging in Australia



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Julia Dehm, La Trobe University

The Federal Court last week ruled that VicForests – a timber company owned by the Victorian government – breached environmental laws when they razed the habitat of the critically endangered Leadbeater’s possum and the vulnerable greater glider.

Environmentalists welcomed the judge’s decision, which sets an important legal precedent.

Under so-called “regional forest agreements”, a number of logging operations around Australia are exempt from federal environment laws. This effectively puts logging interests above those of threatened species. The court ruling narrows these exemptions and provides an opportunity to create stronger forestry laws.

A legal loophole

Since 1971, the Leadbeater’s possum has been the faunal emblem of Victoria. But only about 1,200 adults are left in the wild, almost exclusively in the Central Highlands region.




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Official conservation advice identifies the greatest threat to the species as habitat loss and fragmentation caused by the collapse of hollow-bearing trees, wildfire, logging and climate change.

Australia’s federal environmental laws require environmental impact assessment of any action likely to significantly impact a matter of national environmental significance, such as a listed threatened species.

But thanks to exemptions under regional forest agreements, logging has continued in the Central Highlands – even in the aftermath of this summer’s devastating bushfires.

So what are regional forest agreements?

Regional forest agreements were designed as a response to the so-called “forest wars” of the 1980s and 1990s.

In 1995, after logging trucks blockaded parliament, then Prime Minister Paul Keating offered a deal to the states: the federal government would accredit state forest management systems, and in return federal law would no longer apply to logging operations. Drawing up regional forest agreements between state and federal governments achieved this.




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Between 1997 and 2001, ten different agreements were signed, covering logging regions in Victoria, New South Wales, Tasmania and Western Australia. These agreements were for 20 years, which means many have now either expired and been renewed or extended, or are about to expire.

The agreements are supposed to satisfy a number of conditions. This includes that they’re based on an assessment of environmental and social values of forest areas. They should also provide for the ecologically sustainable management and use of forested areas, and the long-term stability of forest and forest industries.

But conservation experts argue the agreements have failed both to deliver certainty to forestry operations or to protect environmental values and ensure the conservation of biodiversity.

History of the court case

The legal proceedings against VicForests were initiated in 2017 by Friends of the Leadbeater’s Possum, a small community group which relied on crowd funding to cover legal costs.

Initially, the group argued Victoria’s failure to undertake a required review of the Central Highlands regional forest agreements every five years meant the usual exemption to federal environment laws should not apply.




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But in early 2018, Justice Mortimer ruled against this. But she also rejected VicForests’ arguments that any operation in an area covered by a regional forest agreement is automatically exempt from federal law.

She ruled that the logging operations will only be exempt from federal law if they comply with Victoria’s accredited system of forest management. This includes the requirements for threatened species, as specified in official action and management plans.

In response to this ruling, Friends of the Leadbeater’s Possum reformulated their claim.

They argued logging operations in 66 coupes (small areas of forest harvested in one operation) didn’t meet these requirements for threatened species, and so the exemption from federal laws didn’t apply.

The court ruling

In her ruling last week, the judge found VicForests unlawfully logged 26 coupes home to the Leadbeater’s possum and greater glider, and that logging a scheduled 41 other sections would put them at risk.

The court found the company breached a number of aspects of the Code of Practice for Timber Production 2014. This code is part of the Victorian regulatory system accredited by the regional forest agreement.

In particular, VicForests had not, as required, applied the “precautionary principle” in planning and conducting logging operations in coupes containing the greater glider.




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Nor had VicForests developed a comprehensive forest survey system, or engaged in a careful evaluation of management options to avoid dangers to these threatened species.

These failures meant the logging operations were not covered by the exemption from federal laws. As such, the court found VicForests had breached federal environmental law, as the logging operation had, or were likely to have, a significant impact on the two threatened species.

What now?

This case will have clear implications for logging operations governed by regional forest agreements.

In fact, the timber industry has called for state and federal governments to urgently respond to the case, and clarify the future of regional forest agreements.




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Arguably, logging operations conducted under a regional forest agreement can no longer rely on the exemption from federal environmental laws if those operations don’t comply with the state regulatory frameworks accredited under the regional forest agreements, especially provisions that protect threatened species.

And while making logging operations subject to federal environmental laws is a good thing, it’s not enough. Federal environmental laws are weak and don’t prevent species extinctions.

In any case, the result is the perfect opportunity for state and federal governments to rethink forest management. That means properly taking into account the ongoing threats to threatened species from climate change, wildfires and habitat loss.The Conversation

Julia Dehm, Lecturer, La Trobe University

This article is republished from The Conversation under a Creative Commons license. Read the original article.