What are native grasslands, and why do they matter?



The Southern Tablelands contain rare native grasslands.
Tim J Keegan/Flickr, CC BY-SA

Mike Letnic, UNSW

Coalition minister Angus Taylor is under scrutiny for possibly intervening in the clearing of grasslands in the southern highlands of New South Wales. Leaving aside the political dimensions, it’s worth asking: why do these grasslands matter?




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The grasslands in much of eastern Australia are the result of forests and woodlands cleared to “improve” the landscape (from a grazier’s point of view) to make it suitable for grazing livestock.

The “improvment” typically entails cutting trees, burning the felled timber and uprooting tree stumps, followed by ploughing, fertilising and sowing introduced grasses that are more palatable to livestock than many native grasses.

However, largely treeless native grasslands once occurred at high elevations across much of the Monaro tableland, in the area stretching between Canberra and Bombala.

The Monaro grasslands (or in scientific speak, the natural temperate grassland of the Southern Tablelands) are in relatively dry and cold areas, particularly in upland valleys or frost hollows where cold air descends at night.

The combination of dry climate and cold restricts tree growth and instead has encouraged grasses and herbs. Native grasses such as kangaroo grass and poa tussock dominate the grasslands, but there are many other unique plants. A typical undisturbed grassland area will support 10-20 species of native grasses and 40 or more non-grass species.




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The grassy plains are also home to unique cold-adapted reptiles such as the grass-land earless dragon, little whip snake, pink-tailed worm lizard and striped legless lizards. This combination of plants and animals create a unique ecological community.

Striped legless lizards may resemble a snake, but most of its body is actually tail. It has vestigial limbs and a non-forked tongue.
Benjamint444/Wikipedia, CC BY-NC-SA

A fraction remain

It is estimated only 0.5% of the area that would once have been natural temperate grasslands in the Southern Tablelands remains. The rest has been gradually “improved” since the mid-nineteenth century to make them more productive for livestock grazing.

Livestock dramatically change the composition of grasslands, as animals remove palatable plants and compact the soil under their weight. Disturbed soil and the livestock also help to spread non-native weeds.

However, most native grasslands have not just been modified by grazing but completely replaced by man-made pastures. That is, the land has been ploughed, fertilised and the seeds of introduced grasses have been planted.




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These changes to the landscape mean much of the landscape is dominated by introduced plants and is now unsuitable for many of the native plants and animals that once lived and grew there.

Because the Natural Temperate Grassland of the Southern Tablelands is now so rare it is classified as critically endangered and federally protected. Furthermore, many of the distinct plants and animals that still live in these grasslands are classified as vulnerable or endangered.

The pink-tailed worm lizard is one of the rare species living in the native grasslands of the Southern Tablelands.
Matt Clancy/Wikimedia Commons, CC BY-SA

Some of the best remaining examples of the Monaro grasslands can be found in old cemeteries and in areas set aside as public livestock grazing areas. These areas of public land have often been spared from pasture improvement or only lightly grazed, and thus now support relatively intact native grassland ecosystems.




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While, to the untrained eye the Monaro grasslands may seem unremarkable and difficult to distinguish from grazing pastures, they are deeply important. They show us what Australia once looked like, and act as a haven for native biodiversity.

Indeed, what remains of the natural grasslands is now so disturbed by agriculture there is a real threat this distinctive ecological community and many of the species it contains may disappear altogether, if they are not protected from excessive grazing, fertilisers and the plough.The Conversation

Mike Letnic, Professor, Centre for Ecosystem Science, UNSW

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

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Logged native forests mostly end up in landfill, not in buildings and furniture



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Almost all native forest logging in Victoria is for woodchips, pulp and pallets, which have short lifespans before going to landfill.
Janelle Lugge/Shutterstock

Chris Taylor, Australian National University and David Lindenmayer, Australian National University

Victoria has some of the most carbon-dense native forests in the world. Advocates for logging these forests often argue that wood products in buildings and furniture become long-term storage for carbon.

However, these claims are misleading. Most native trees cut down in Victoria become woodchips, pulp and pallets, which have short lifespans before going to landfill. In landfill, the wood breaks down and releases carbon back into the atmosphere.

On the other hand, our evolving carbon market means Australia’s native forests are extremely valuable as long-term carbon stores. It’s time to recognise logging for short-lived wood products is a poor use of native forests.




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The problem with logging native forests

Victoria has about 7.6 million hectares of native forests. The most carbon-dense areas are in ash forests, consisting of mountain ash, alpine ash and shining gum trees.

These forests can store up to 1,140 tonnes of carbon per hectare for centuries.

Only 14% of logs cut from Victorian native forests end up as timber products used in buildings and furniture.
Shutterstock

But around 1.82 million hectares of Victorian native forests are allocated to the government’s logging business, VicForests.

VicForests claims logging is the only market for the large area of native forest allocated to it. In other words, its forests are exclusively valued as timber asset, in the same way a wheat crop would be exclusively valued for wheat grain production.

In Victorian native forests, industrial scale clearfell logging removes around 40% of the forest biomass for logs fit for sale.

The remaining 60% is debris, which is either burned off or decomposes – becoming a major source of greenhouse gas emission.




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Myth one: storing carbon in wood products

The first myth we want to address is logging native forests is beneficial because the carbon is stored in wood products. This argument depends on the proportion of forest biomass ending up in wood products, and how long they last before ending up in landfill.

On average, logs suitable to be sawn into timber make up only an average 35% of total logs cut from Victorian native forests.

Of this 35%, sawmills convert less than 40% into sawn timber for building and furniture. Offcuts are woodchipped and pulped for paper manufacturing, along with sawdust sold to chicken broiler sheds for bedding.

Sawn timber equates to 14% of log volume cut from the forest. The remaining 84% of logs cut are used in short-lived and often disposable products like copy paper and pallets.




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Forest soil needs decades or centuries to recover from fires and logging


The lifespan of paper products is assumed to be three years. Although around 75% of paper and cardboard is recovered, recycling is growing more uncertain with recovered paper being sent to landfill.

The maximum lifespan of a timber pallet is seven years. At the end of their service, timber pallets are sent to landfill, chipped for particleboard, reused for landscape mulch or burnt for energy generation.

Longer-lived wood products, such as the small proportion of native timber used in building and furniture, have a lifespan of around 90 years. These wood products are used to justify logging native forests.

But at the end of their service life, the majority of these wood products also end up in landfill.

In fact, for the 500,000 tonnes of wood waste generated annually from building, demolition and other related commercial processes in Victoria, over two thirds end up in landfill, according to a Sustainability Victoria report.

Myth two: the need to log South East Asian rainforests

A second myth is using logs from Victorian native forests will prevent logging and degradation of rainforests across South East Asia, particularly for paper production.

This is patently absurd. The wood from the Victorian plantation sector – essentially timber farms, rather than trees growing “wild” in native forests – could replace native forest logs used for paper manufacturing in Victoria several times over.

In fact, in 2016-17 89% of logs used to make wood pulp (pulplogs) for paper production in Victoria came from plantation trees, with the majority of hardwood logs exported.

And Australia is a net exporter by volume of lower-value unprocessed logs and woodchips.




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Processing pulplogs from well managed plantations in Victoria instead of exporting them would give a much needed jobs boost for local economies.

With most of these plantations established on previously cleared farmland, they offer one of the most robust ways for the land use sector to off-set greenhouse gas emissions.

Next steps

The time is right for Australian governments to develop a long-term carbon storage plan that includes intact native forests.

Logging results in at least 94% of a forest’s stored carbon ending up in the atmosphere. A maximum of 6% of its carbon remains in sawn timber, for up to 90 years (but typically much shorter). This is patently counterproductive from a carbon-storage point of view.




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State-owned forest management companies, such as VicForests, can transition away from the timber business and begin managing forests for carbon storage. Such a concept is not new – the federal government has already approved a way to value the carbon storage of plantations.

The same must now be developed to better protect native forests and the large amounts of carbon they can store.The Conversation

Chris Taylor, Research Fellow, Fenner School of Environment and Society, Australian National University and David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University

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

The dingo is a true-blue, native Australian species


Bradley Smith, CQUniversity Australia; Corey J. A. Bradshaw, Flinders University; Euan Ritchie, Deakin University; Justin W. Adams, Monash University; Kylie M Cairns, UNSW, and Mathew Crowther, University of Sydney

Of all Australia’s wildlife, one stands out as having an identity crisis: the dingo. But our recent article in the journal Zootaxa argues that dingoes should be regarded as a bona fide species on multiple fronts.

This isn’t just an issue of semantics. How someone refers to dingoes may reflect their values and interests, as much as the science.

How scientists refer to dingoes in print reflects their background and place of employment, and the Western Australian government recently made a controversial attempt to classify the dingo as “non-native fauna”.




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How we define species – called taxonomy – affects our attitudes, and long-term goals for their conservation.

What is a dog?

Over many years, dingoes have been called many scientific names: Canis lupus dingo (a subspecies of the wolf), Canis familiaris (a domestic dog), and Canis dingo (its own species within the genus Canis). But these names have been applied inconsistently in both academic literature and government policy.

This inconsistency partially reflects the global arguments regarding the naming of canids. For those who adhere to the traditional “biological” species concept (in which a “species” is a group of organisms that can interbreed), one might consider the dingo (and all other canids that can interbreed, like wolves, coyotes, and black-backed jackals) to be part of a single, highly variable and widely distributed species.

Members of the Canis genus: wolf (Canis lupus), coyote (Canis latrans), Ethiopian wolf (Canis simensis), black-backed jackal (Canis mesomelas), dingo (Canis dingo), and a representative of the domestic dog (Canis familiaris).

But the “biological” species concept used to name species came about long before modern genetic tools, or even before many hybrid species were identified by their DNA (such as the “red wolf,” an ancient hybrid of grey wolves and coyotes found in the southeastern United States).

Few people would really argue that a chihuahua, a wolf, and a coyote are the same species. In reality there are many more comprehensive and logical ways to classify a species. In our latest paper we argue that a holistic approach to defining species is essential in the case of the dingo and other canids.

Our work shows conclusively that dingoes are distinct from wild canids and domestic dogs based on many different criteria.

Truly wild

The first criterion is that dingoes are wild animals, and live completely independent from humans. This is fundamentally different to domestic, feral, or wild dogs, which must live near human settlements and rely on humans for food and water in some way to survive.

Yes, the dingo might have arrived in Australia with humans, and we know that Aboriginal Australians have had a close relationship with dingoes following the latter’s arrival. But neither of these observations excludes dingoes from being wild.




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For example, a relationship with humans does not constitute the rigorous definitions of domestication. Consider the red fox (Vulpes vulpes), which was also introduced to Australia by people and are now free-ranging: they are also not considered to be domesticated. Neither are wild animals such as birds that we feed in our backyards domesticated simply because they are sometimes fed by us.

Ecological role

In fact, dingoes have been living wild and independently of humans for a very long time — they have a distinct and unique evolutionary past that diverged some 5 to 10 thousand years ago from other canids. This is more than enough time for the dingo to have evolved into a naturalised predator now integral to maintaining the health of many Australian ecosystems.




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Dogs do not have the brain power or body adaptations to survive in the wild, and they cannot play the same ecological role as dingoes. From this ecological perspective alone, the two species are not interchangeable. Dingoes are Australia’s only large (between 15-20 kg), land-based predator, and as such play a vital role in Australia’s environment.

Shape and size

Viewed alone, the overall shape of the body and skull does not easily distinguish wild canids from dogs, mainly because of the sheer diversity among different breeds of domestic dogs.

But there are some important body differences between free-ranging dogs and dingoes, mainly in the skull region (as shown here and here).

Cranial 3-D reconstructions of a dingo (bottom) and a free-ranging dog (top), highlighting the differences in cranial morphology mentioned in the text.

Behaviour

Dingoes (and other truly wild canids) have some fundamentally unique behaviours that set them apart from dogs (although like shape, there are often exceptions among the artificial dog breeds). For example, dingoes have significantly different reproductive biology and care-giving strategies.

There are also differences in brain function, such as in the way the two species solve problems, and dingoes and dogs communicate differently with humans.




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Genetics

While dingoes and dogs obviously share an ancestral relationship, there is a lot of genetic data to support the distinction between dingoes and dogs.

While dingoes share ancestry with ancient Asian dogs from 10,000 years ago, the dingo has been geographically isolated from all other canids for many thousands of years, and genetic mixing has only been occurring recently, most probably driven by human intervention.

Since the 1990s, genetic markers have been in widespread use by land managers, conservation groups, and researchers to differentiate dingoes from domestic dogs.

A summary of the evolutionary relationships among wolves, dingoes and modern domestic dogs. Dingoes and other ancient lineages of dog such as New Guinea singing dogs form a distinct lineage separate from modern domestic dogs that have undergone successive generations of artificial selection.

What’s at stake?

Even acknowledging the dingo’s uncertain and distant past, lumping dingoes and dogs together is unjustified.

Labelling dingoes as “feral domestic dogs” or some other misnomer ignores their unique, long, and quintessentially wild history in Australia.




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Inappropriate naming also has serious implications for their treatment. Any label less than “dingo” can be used to justify their legal persecution.

Further loss of dingoes could have serious, negative ecological consequences, including potentially placing other Australian native animals at increased risk of extinction.The Conversation

Bradley Smith, Senior Lecturer in Psychology, CQUniversity Australia; Corey J. A. Bradshaw, Matthew Flinders Fellow in Global Ecology, Flinders University; Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University; Justin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash University; Kylie M Cairns, Adjunct associate lecturer, UNSW, and Mathew Crowther, Associate professor, University of Sydney

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

Australia’s native rhododendrons hide in the high mountain forests



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Rhododendron lochiae, photographed on Bell Peak.
Image by Dan McLeod

Stuart Worboys, James Cook University

Sign up to the Beating Around the Bush newsletter here, and suggest a plant we should cover at batb@theconversation.edu.au.


The 1800s was a time of colonial expansion across the globe. During this time the great and the good of Britain filled their grand gardens with exotic novelties from all corners of the world.

Amongst these were many species of Asian rhododendron, a diverse and colourful genus of shrubs and small trees, whose high altitude origins made them well suited to the cool temperate climate of England and Scotland.




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Throughout the 19th century, commercial collectors and field naturalists discovered rhododendron species in southern China, the Himalayas, on the high peaks of Borneo, Java and especially New Guinea.

These finds lead Victoria’s government botanist of the time, Ferdinand von Mueller, to speculate about finding rhododendrons on the high tropical mountains on the northeast coast of Queensland. He wrote:

When in 1855 [I] saw… the bold outlines of Mount Bellenden-Ker, the highest mount of tropical Australia, towering to 5,000 feet, [I] was led to think, that the upper region might prove to be the home of species of Rhododendron… forms of plants characteristic of cool Malayan sylvan regions.

But the lofty heights of Mt Bellenden Ker were unknown to European Australians. It would be another 32 years before an expedition led by naturalist W.A. Sayer reached its central peak.



The Conversation, CC BY-ND

Sayer’s expedition, accompanied by two indigenous assistants, reached the mountain’s high ridge after several mishap-filled attempts. It was here they confirmed Mueller’s suspicions. Sayer’s account of its discovery is interesting:

The top of the range is razor-backed, and on travelling along the range beyond the spur by which we ascended, I could not see the sides, they being, if anything, hanging over. We tumbled rocks over, but could not hear them fall.

It was here that I observed the Rhodendron Lochae growing, and asked the Kanaka to get it; but he remarked, ‘S’pose I fall, I no see daylight any more; I go bung altogether;’ so I had to get it myself.

Mueller received the hard-won specimens and named the species Rhododendron lochae (later corrected to R. lochiae) after Lady Loch, the wife of the Victorian Governor.

Since then, rhododendron plants have been found on nine peaks and tablelands in the Wet Tropics region of north Queensland. Populations on peaks south of Cairns are called Rhododendron lochiae, whilst plants growing on mountains to the north of Cairns are considered by some to be a distinct species: Rhododendron viriosum.

Australian rhododendron at Smith College Botanical Garden.
Ren Glover/Flickr, CC BY-NC

Both northern and southern plants are straggly shrubs that grow in thin soils or rock cracks, sometimes in open cloud-swept boulder fields, sometimes in deep shade along creeks, or rarely as epiphytes on moss-covered trees. They produce bunches of gloriously red, bell-shaped flowers, followed by dry brown capsules filled with small winged seeds that are apparently spread by wind.

They grow slowly but with relative ease from cuttings, and are often cultivated in gardens and nurseries in temperate Australia. However, over time knowledge of the precise origin of these cultivated plants has been lost, which means they are unsuitable for detailed scientific investigations.

All of Australia’s rhododendron populations are located at altitudes above 950m in National Parks within the Wet Tropics World Heritage Area. Most are difficult to access, requiring arduous climbs on rough foot tracks through leech-infested rainforest. And yet, although isolated in protected areas, they are threatened by human activities: loss of habitat due to climate change.

Recent climate modelling research published by scientists from James Cook University and the CSIRO predicts significant reductions in suitable habitat for a suite of mountaintop flora species in Australia’s tropics (our rhododendrons were not included in the analysis, but occupy the habitats assessed).

The habitat of many of these species is predicted to disappear altogether well before the end of the century.

Conservationists are racing to preserve samples of native rhododendrons.
Author provided

Using rhododendron as a model, the Australian Tropical Herbarium at James Cook University is working to save these threatened species through “ex situ” conservation – cultivation in temperate zone public gardens, well outside their natural range. Because the threatening process – climate change – is not readily mitigated, establishing precautionary ex situ collections is the only viable conservation intervention for these plants.

With funding from the Australian Rhododendron Society Victoria Branch and the Ian Potter Foundation, and the support of traditional owners, Queensland National Parks and the Wet Tropics Management Authority, we have mounted expeditions to collect samples from most of the known populations.

These expeditions have put expert naturalists into rarely visited and challenging environments. Beyond gathering rhododendron samples, new moss species have been discovered and are being named, a fern previously thought extinct was rediscovered, and beautiful little epiphytic orchids have been found on a mountain where they’d not previously been recorded. Golden bower-bird bowers have been mapped in remote mountain rainforests, and a likely new species of snail has been discovered.




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Australia now has a well-documented and genetically diverse collection of native rhododendron plants thriving in the Dandenong Ranges Botanic Garden.

We plan to expand this work, ensuring the preservation and public display of rhododendron and many other mountain species threatened by climate change.

Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.The Conversation

Stuart Worboys, Laboratory and Technical Support Officer, Australian Tropical Herbarium, James Cook University

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

Figs, ferns and featherwoods: learn all about Australia’s native trees and plants


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You love Australian plants, I love Australian plants, we all love Australian plants!
Percita/Flickr

Madeleine De Gabriele, The Conversation and Molly Glassey, The Conversation

Sign up to the special Beating Around the Bush newsletter here.


Australia is classified as “megadiverse” meaning it’s a global hotspot for plant and animal diversity, and has vast numbers of unique species found nowhere else on Earth. With this newsletter we want you to be able to wander down the garden path, off the beaten track, and smell the gum leaves. Specifically, what kind of gum leaf? What is it from? Where does it grow?




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We’ll let you know every time a new edition in our Beating Around the Bush series comes out, putting the spotlight on a different native plant every time. We’re on a roughly fortnightly schedule, but like any garden there might be a few surprises along the way. I’ll also be rounding up some of the greatest hits from our archives, and talking about what’s new in the plant world.

This one is for all you floraphiles out there.
Felicity Burke/The Conversation

The ConversationIf someone else in your life might enjoy this mix in their inbox, please let them know about it. And if you have any feedback, feel free to let us know in the comments.

Madeleine De Gabriele, Deputy Editor: Energy + Environment, The Conversation and Molly Glassey, Audience Development Manager, The Conversation

This article was originally published on The Conversation. Read the original article.

Native forest protections are deeply flawed, yet may be in place for another 20 years



File 20180322 165550 14cxr7f.jpg?ixlib=rb 1.1
Current protections for native forests are hopelessly out of date.
Graeme/Flickr, CC BY-NC

David Lindenmayer, Australian National University

State governments are poised to renew some of the 20-year-old Regional Forest Agreements (RFAs) without reviewing any evidence gathered in the last two decades.

The agreements were first signed between the federal government and the states in the late 1990s in an attempt to balance the needs of the native forest logging industry with conservation and forest biodiversity.

It’s time to renew the agreements for another 20 years. Some, such as Tasmania’s, have just been renewed and others are about to be rolled over without substantial reassessment. Yet much of the data on which the RFAs are based are hopelessly out of date.




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Concerns about the validity of the science behind the agreements is shared by some state politicians, with The Guardian reporting the NSW Labor opposition environment spokeswoman as saying “the science underpinning the RFAs is out of date and incomplete”.

New, thorough assessments are needed

What is clearly needed are new, thorough and independent regional assessments that quantify the full range of values of native forests.

Much of the information underpinning these agreements comes largely from the mid-1990s. This was before key issues with climate change began to emerge and the value of carbon storage in native forests was identified; before massive wildfires damaged hundreds of thousands of hectares of forest in eastern Australia; and before the recognition that in some forest types logging operations elevate the risks of crown-scorching wildfires.

The agreements predate the massive droughts and changing climate that have affected the rainfall patterns and water supply systems of southwestern and southeastern Australia, including the forested catchments of Melbourne.

It’s also arguable whether the current Regional Forest Agreements accommodate some of the critical values of native forests. This is because their primary objective is pulp and timber production.




Read more:
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Yet it is increasingly apparent that other economic and social values of native forests are greater than pulp and wood.

To take Victoria as an example, a hectare of intact mountain ash forests produces 12 million litres more water per year than the same amount of logged forest.

The economic value of that water far outstrips the value of the timber: almost all of Melbourne’s water come from these forests. Recent analysis indicates that already more than 60% of the forest in some of Melbourne’s most important catchments has been logged.

The current water supply problems in Cape Town in South Africa are a stark illustration of what can happen when natural assets and environmental infrastructure are not managed appropriately. In the case of the Victorian ash forests, some pundits would argue that the state’s desalination plant can offset the loss of catchment water. But desalination is hugely expensive to taxpayers and generates large amounts of greenhouse emissions.

A declining resource

Another critical issue with the existing agreements is the availability of loggable forest. Past over-harvesting means that much of the loggable forest has already been cut. Remaining sawlog resources are rapidly declining. It would be absurd to sign a 20-year RFA when the amount of sawlog resource remaining is less than 10 years.

This is partially because estimates of sustained yield in the original agreements did not take into account inevitable wood losses in wildfires – akin to a long-distance trucking company operating without accident insurance.

Some are arguing that the solution now is to cut even more timber in water catchments, but this would further compromise water yields at a major cost to the economy and to human populations.




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Profits from forests? Leave the trees standing


Comprehensive regional assessments must re-examine wood supplies and make significant reductions in pulp and timber yields accordingly.

The inevitable conclusion is that the Regional Forest Agreements and their underlying Comprehensive Regional Assessments are badly out of date. We should not renew them without taking into consideration decades of new information on the value of native forests and on threats to their preservation.

The ConversationAustralia’s native forests are among the nation’s most important natural assets. The Australian public has a right to expect that the most up-to-date information will be used to manage these irreplaceable assets.

David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University

This article was originally published on The Conversation. Read the original article.

For whom the bell tolls: cats kill more than a million Australian birds every day



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On the prowl in the outback.
Hugh McGregor/Arid Recovery, Author provided

John Woinarski, Charles Darwin University; Brett Murphy, Charles Darwin University; Leigh-Ann Woolley, Charles Darwin University; Sarah Legge, Australian National University; Stephen Garnett, Charles Darwin University, and Tim Doherty, Deakin University

Cats kill more than a million birds every day across Australia, according to our new estimate – the first robust attempt to quantify the problem on a nationwide scale.

By combining data on the cat population, hunting rates and spatial distribution, we calculate that they kill 377 million birds a year. Rates are highest in Australia’s dry interior, suggesting that feral cats pose a serious and largely unseen threat to native bird species.


Read more: Ferals, strays, pets: how to control the cats that are eating our wildlife


This has been a contentious issue for more than 100 years, since the spread of feral cats encompassed the entire Australian mainland. In 1906 the ornithologist A.J. Campbell noted that the arrival of feral cats in a location often immediately preceded the decline of many native bird species, and he campaigned vigorously for action:

Undoubtedly, if many of our highly interesting and beautiful birds, especially ground-loving species, are to be preserved from total extinction, we must as a bird-lovers’ union, at no distant date face squarely a wildcat destruction scheme.

His call produced little response, and there has been no successful and enduring reduction in cat numbers since. Nor, until now, has there been a concerted effort to find out exactly how many birds are being killed by cats.

Counting the cost

To provide a first national assessment of the toll taken by cats on Australian birds, we have compiled almost 100 studies detailing the diets of Australia’s feral cats. The results show that the average feral cat eats about two birds every five days.

We then combined these statistics with information about the population density of feral cats, to create a map of the estimated rates of birds killed by cats throughout Australia.

Number of birds eaten per square kilometre.
Brett Murphy, Author provided

We conclude that, on average, feral cats in Australia’s largely natural landscapes kill 272 million birds per year. Bird-kill rates are highest in arid Australia (up to 330 birds per square km per year) and on islands, where rates can vary greatly depending on size.

We also estimate (albeit with fewer data) that feral cats in human-modified landscapes, such as the areas surrounding cities, kill a further 44 million birds each year. Pet cats, meanwhile, kill about 61 million birds per year.

Overall, this amounts to more than 377 million birds killed by cats per year in Australia – more than a million every day.

Which species are suffering?

In a related study, we also compiled records of the bird species being killed by cats in Australia. We found records of cats killing more than 330 native bird species – about half of all Australia’s resident bird species. In natural and remote landscapes, 99% of the cat-killed birds are native species. Our results also show that cats are known to kill 71 of Australia’s 117 threatened bird species.

Birds that feed or nest on the ground, live on islands, and are medium-sized (60-300g) are most likely to be killed by cats.

Galahs are among the many native species being killed by feral cats.
Mark Marathon, Author provided

It is difficult to put a million-plus daily bird deaths in context without a reliable estimate of the total number of birds in Australia. But our coarse assessment from many published estimates of local bird density suggests that there are about 11 billion land birds in Australia,
suggesting that cats kill about 3-4% of Australia’s birds each year.

However, particular species are hit much harder than others, and the population viability of some species (such as quail-thrushes, button-quails and ground-feeding pigeons and doves) is likely to be especially threatened.

Our tally of bird deaths is comparable to similar estimates for other countries. Our figure is lower than a recent estimate for the United States, and slightly higher than in Canada. Overall, bird killings by cats seem to greatly outnumber those caused by humans.

In Australia, cats are likely to significantly increase the extinction risk faced by some bird species. In many locations, birds face a range of interacting threats, with cat abundance and hunting success shown to increase in fragmented bushland, in areas with high stocking rates, and in places with poorly managed fire regimes, so cat impacts compound these other threats.

Belling the cat

What can be done to reduce the impact? The federal government’s Threatened Species Strategy recognises the threat posed by feral cats, albeit mainly on the basis of their role in mammal extinctions.

The threatened species strategy also prioritised efforts to control feral cats more intensively, eradicate them from islands with important biodiversity values, and to expand a national network of fenced areas that excludes feral cats and foxes.

But while fences can create important havens for many threatened mammals, they are much less effective for protecting birds. To save birds, cats will need to be controlled on a much broader scale.


Read more: The war on feral cats will need many different weapons


We should also remember that this is not just a remote bush problem. Roughly half of Australia’s cats are pets, and they also take a considerable toll on wildlife.

While recognising the many benefits of pet ownership, we should also work to reduce the detrimental impacts. Fortunately, there is increasing public awareness of the benefits of not letting pet cats roam freely. With such measures, cat owners can help to look after the birds in their own backyards, and hence contribute to conserving Australia’s unique wildlife.


The ConversationWe acknowledge the contribution of Russell Palmer (WA Department of Biodiversity Conservation and Attractions), Chris Dickman (University of Sydney), David Paton (University of Adelaide), Alex Nankivell (Nature Foundation SA Inc.), Mike Lawes (University of KwaZulu-Natal), and Glenn Edwards (Department of Environment and Natural Resources) to this article.

John Woinarski, Professor (conservation biology), Charles Darwin University; Brett Murphy, Senior Research Fellow, Charles Darwin University; Leigh-Ann Woolley, Research Associate, Charles Darwin University; Sarah Legge, Associate Professor, Australian National University; Stephen Garnett, Professor of Conservation and Sustainable Livelihoods, Charles Darwin University, and Tim Doherty, Research Fellow, Deakin University

This article was originally published on The Conversation. Read the original article.