Ecosystem

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As the east coast bushfire crisis finally abates, it’s easy to see nothing but loss: more than 11 million hectares of charcoal and ash, and more than a billion dead animals.
But it is heartening to remember that bushfire can be a boon to some plants and animals. We’re already seeing fresh green shoots as plants and trees resprout. Beetles and other insects are making short work of animal carcasses; they will soon be followed by the birds which feed on them.
Australia’s worsening fire regimes are challenging even these tolerant species. But let’s take a look at exactly how life is returning to our forests now, and what to expect in coming months.
<img src="https://images.theconversation.com/files/315625/original/file-20200217-10985-gmpykj.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="">
Life is returning to fire-ravaged landscapes. Flickr, <a class="license" href="http://creativecommons.org/licenses/by/4.0/" target="_blank">CC BY</a>
<h2>The science of resprouting</h2>
Of course, bushfires kill innumerous trees – but many do survive. Most of us are familiar with the image of bright green sprouts shooting from the trunks and branches of trees such as eucalypts. But how do they revive so quickly?
The secret is a protected “bud bank” which lies behind thick bark, <a href="https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.12001" target="_blank">protected from the flames</a>. These “epicormic” buds produce leaves, which enables the tree to photosynthesise – create sugar from the sun so the tree can survive.
Under normal conditions, hormones from shoots higher in the tree suppress these buds. But when the tree loses canopy leaves due to <a href="https://www.nature.com/articles/ncomms1191" target="_blank">fire</a>, drought or insect attack, the hormone levels drop, allowing the buds to sprout.
<h2>Insect influx</h2>
This summer’s fires left in their wake a mass of decaying animal carcasses, logs and tree trunks. While such a loss can be devastating for many species – particularly those that were already vulnerable – many insects thrive in these conditions.
For example, <a href="http://forensicentomologist.com/wp-content/uploads/2008/06/4.pdf" target="_blank">flies</a> lay eggs in the animal carcasses; when the maggots hatch, the rotting flesh provides an ample food source. This process helps break down the animal’s body – reducing bacteria, disease and bad smells. Flies are important decomposers and their increased numbers also provide food for birds, reptiles and other species.
Similarly, <a href="https://theconversation.com/wood-beetles-are-natures-recyclers-with-a-little-help-from-fungi-76029" target="_blank">beetles</a> such as the <a href="https://www.anbg.gov.au/gardens/visiting/exploring/fauna/insects/beetles-ANBG" target="_blank">grey furrowed rosechafer</a>, whose grubs feed on decaying logs and tree trunks, add nutrients to the soil when they defecate which helps plants grow again.
<a href="https://www.sciencedirect.com/science/article/abs/pii/S0378112705003130" target="_blank">Insects also benefit</a> from the mass of new leaves on trunks and branches. For example, native <a href="https://www.urban.com.au/property-observer" target="_blank">psyllids</a> – an insect similar to aphids – feed on the sap from leaves and so thrive on the fresh growth.
<img src="https://images.theconversation.com/files/315623/original/file-20200217-10985-k5e7fc.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="">
Animal carcasses are a sad consequence of bushfire, but provide a boon to some insect species. Sean Davey/AAP
<h2>Then come the birds</h2>
Once insects start to move back into an area from forested areas nearby, the birds that eat them will follow.
An increase in psyllids encourages honeyeaters – such as bell miners and <a href="https://ro.uow.edu.au/cgi/viewcontent.cgi?article=1145&amp;context=thsci" target="_blank">noisy miners</a> – to return. These birds are considered <a href="https://www.sciencedirect.com/science/article/abs/pii/S0378112705003130" target="_blank">pests</a>.
A <a href="http://www.publish.csiro.au/pc/PC970221" target="_blank">CSIRO study</a> after bushfires in Victoria’s East Gippsland in 1983 found several native bird species – flame and scarlet robins, the buff-rumped thornbill and superb fairy-wren – increased quickly to levels greater than before fire. As shrubs in the understorey regrow, other species will move in, slowly increasing biodiversity. 
Since the recent <a href="https://www.nbnnews.com.au/2019/11/12/watch-and-act-bushfire-burning-in-moonbi-north-of-tamworth/" target="_blank">bushfire in woodland near Moonbi in New South Wales</a>, numerous bird species have returned. On a visit over this past weekend, I observed currawongs landing in the canopy, saw fairy wrens darting in and out of foliage sprouting from the ground, and heard peep wrens in tufts of foliage on bark and high branches.
Honeyeaters moved between burnt and intact trees on the edge of the blackened forest and butterflies visited new plants flowering after recent rain.
<img src="https://images.theconversation.com/files/315627/original/file-20200217-11023-c6ad0s.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="">
The presence of the currawong, while a pest species, shows birdlife is returning to the bush. Flickr, <a class="license" href="http://creativecommons.org/licenses/by/4.0/" target="_blank">CC BY</a>
<h2>Weeds can help</h2>
<a href="https://www.propertyobserver.com.au/https://www.sciencedirect.com/science/article/abs/pii/0006320795900616" target="_blank">Weeds</a> usually benefit when fire opens up the tree canopy and lets in light. While this has a downside – preventing native plants from regenerating – weeds can also provide cover for native animal species.
A study I co-authored in 2018 found highly invasive <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1442-8903.2011.00600.x" target="_blank">Lantana camara</a> provided habitat for <a href="https://www.publish.csiro.au/AM/AM17003" target="_blank">small mammals</a> such as the brown rat in some forests. Mammal numbers in areas where lantana was present were greater than where it was absent.
<a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-3180.2011.00869.x" target="_blank">Lantana</a> often grows quickly after fire due to the increase in light and its ability to <a href="https://link.springer.com/article/10.1023/A:1009707404802" target="_blank">suppress</a> other plant growth.
<img src="https://images.theconversation.com/files/315628/original/file-20200217-10985-od7u07.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="">
Lantana provides cover for animal species. Flickr, <a class="license" href="http://creativecommons.org/licenses/by/4.0/" target="_blank">CC BY</a>
<h2>Is there hope for threatened species?</h2>
Generalist species – those that thrive in a variety of environments – can adapt to burnt forest. But specialist species need particular features of an ecosystem to survive, and are far less resilient.
The critically endangered <a href="https://books.google.com.au/books?hl=en&amp;lr=&amp;id=hF2sMDVZztIC&amp;oi=fnd&amp;pg=PR7&amp;ots=5Uri8BWkcm&amp;sig=UKvmQHpO-9hWvqK5pYEfB6hSIEU&amp;redir_esc=y#v=onepage&amp;q&amp;f=false" target="_blank">Leadbeater’s possum</a> lives only in <a href="https://www.wildlife.vic.gov.au/our-wildlife/leadbeaters-possum" target="_blank">small pockets of forest</a> in Victoria.
It requires large fires to create a specific habitat: big dead trees provide hollows for shelter and nesting, and insects feeding on burnt wood and carcasses provide a food source.
But for the Leadbeater’s possum to benefit from the fire regime, bushfires should be infrequent – perhaps every 75 years – allowing time for the forest to grow back. If fires are too frequent, larger trees will not have time to establish and hollows will not be created, causing the species’ numbers to decline.
Similarly in NSW, at least 50% and up to 80% of the habitat of threatened species such as the vulnerable rufous scrub-bird was burnt in the recent fires, an environmental department analysis <a href="https://www.environment.gov.au/biodiversity/bushfire-recovery/research-and-resources">found</a>.
<h2>Looking ahead</h2>
Only time will tell whether biodiversity in these areas is forever damaged, or will return to its former state.
Large fires may benefit some native species but they also provide food and shelter for predatory species, such as <a href="https://theconversation.com/hunter-hunted-when-the-world-catches-on-fire-how-do-predators-respond-126280" target="_blank">feral cats and foxes</a>. The newly open forest leaves many native mammals exposed, changing the foodweb, or feeding relationships, in an ecosystem.
This means we may see a change in the types of birds, reptiles and mammals found in forests after the fires. And if these areas don’t eventually return to their pre-fire state, these environments may be changed forever – and extinctions will be imminent.
<a href="https://theconversation.com/profiles/kathryn-teare-ada-lambert-186436" target="_blank">Kathryn Teare Ada Lambert</a>, Adjunct Lecturer/ Ecologist, <a href="https://theconversation.com/institutions/university-of-new-england-919" target="_blank">University of New England</a>
This article is republished from <a href="http://theconversation.com" target="_blank">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/these-plants-and-animals-are-now-flourishing-as-life-creeps-back-after-bushfires-130293" target="_blank">original article</a>.
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j.ballantyne1990-6AQqhLzZaK

These plants and animals are now flourishing as life creeps back after bushfires

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GUEST OBSERVATION
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?
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 “improvement” 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 <a href="http://www.environment.gov.au/biodiversity/threatened/conservation-advices/natural-temperate-grassland-southern-tablelands" target="_blank">natural temperate grassland of the Southern Tablelands</a>) 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.
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.
<a href="https://images.theconversation.com/files/286192/original/file-20190730-43136-1v4usvm.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/286192/original/file-20190730-43136-1v4usvm.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt=""></a>
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, <a href="http://creativecommons.org/licenses/by-nc-sa/4.0/" target="_blank">CC BY-NC-SA</a>
A fraction remain
It is estimated <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1442-8903.2007.00363" target="_blank">only 0.5%</a> of the area that would once have been natural temperate grasslands in the Southern Tablelands remains. The rest has been gradually “improved” <a href="https://www.propertyobserver.com.au/https://trove.nla.gov.au/work/11035501?selectedversion=NBD25432907" target="_blank">since the mid-nineteenth century</a> 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 <a href="https://www.propertyobserver.com.au/https://trove.nla.gov.au/work/11035501?selectedversion=NBD25432907">spread non-native weeds</a>.
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.
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 <a href="https://www.environment.nsw.gov.au/threatenedSpeciesApp/profile.aspx?id=20260" target="_blank">classified as critically endangered and federally protected</a>. Furthermore, many of the <a href="http://www.environment.gov.au/biodiversity/threatened/conservation-advices/natural-temperate-grassland-southern-tablelands" target="_blank">distinct plants and animals</a> that still live in these grasslands are classified as vulnerable or endangered.
<a href="https://images.theconversation.com/files/286193/original/file-20190730-186833-i4fw9q.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/286193/original/file-20190730-186833-i4fw9q.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt=""></a>
The pink-tailed worm lizard is one of the rare species living in the native grasslands of the Southern Tablelands. <a href="https://commons.wikimedia.org/wiki/File:Pink-tailed_Worm-lizard_(Aprasia_parapulchella)_(9106371285).jpg" target="_blank">Matt Clancy/Wikimedia Commons</a>, <a href="http://creativecommons.org/licenses/by-sa/4.0/" target="_blank">CC BY-SA</a>
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.
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.<img src="https://counter.theconversation.com/content/121181/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1">
Mike Letnic, Professor, Centre for Ecosystem Science, UNSW
This article is republished from <a href="http://theconversation.com" target="_blank">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/what-are-native-grasslands-and-why-do-they-matter-121181" target="_blank">original article</a>.
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What are native grasslands, and why do they matter?

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<img src="https://counter.theconversation.edu.au/content/57114/count.gif" alt="The Conversation" width="1" height="1">
GUEST OBSERVER
Fish are the most threatened group among Earth’s freshwater vertebrates. On average, freshwater fish populations have declined by 76 percent over the past 40 years. Damaged fish communities and declining fisheries characterise global freshwater environments, including those in Australia.
Fish migrate to complete their life cycles, but water-resource developments disrupt river connectivity and migrations, threatening biological diversity and fisheries.
Millions of dams, weirs and smaller barriers – for storage and irrigation, road and rail transport and hydropower schemes – block the migration of fish in rivers worldwide.
These barriers serve our needs for water supply, transport and energy. But, by obstructing fish migrations, they also degrade ecological integrity and reduce food security.
This is bad news for those who depend on fish for food. For example, in the Mekong River fish supply over 70% of the people’s animal protein, but catches are falling drastically following dam building.
In our paper published today in CSIRO’s Marine and Freshwater Research, we take stock of the impact these barriers have on our freshwater fish, most (perhaps all) of which migrate, and how we can help them.
<h2>Dam it all</h2>
There are countless barriers across Australia’s rivers. Roughly 10,000 barriers of all kinds obstruct flows in the Murray-Darling Basin. Flow is unobstructed in less than half of the basin’s watercourse length.
Native fish numbers in the basin’s rivers have declined by an estimated 90% through habitat fragmentation by barriers together with altered flows, overfishing, coldwater pollution and invasive species.
Similar problems also affect coastal river systems. One or more barriers obstruct 49% of rivers in southeast Australia.
Local species extinctions and loss of biodiversity have occurred nationwide in developed regions, especially upstream of large dams.
<h2>Overcoming barriers</h2>
One way to help fish overcome barriers is to build fishways (or “fish ladders”).
Fishways are designed to aid fish travelling upstream or downstream at high (dams, weirs) or low (road crossings, barrages) barriers. These are classed as “technical”, with hard-engineering designs, or “nature-like”, mimicking natural stream channels.
Recognition that dams threaten freshwater fish communities lagged well behind their construction. Nonetheless, European and American observations of declining fisheries for species moving from the sea to breed in rivers prompted early attempts in Australia to provide for fish passage.
The first Australian fishway was built near Sydney in 1913. By 1985, 52 had been built, but they adopted Northern Hemisphere designs for salmon and trout. These were unsuitable for Australian species, which rarely leap at barriers, and their flow velocities, turbulence and other aspects were excessive.
Seeing the failure of these fishways, New South Wales Fisheries sought advice in 1982 from George Eicher, an American expert, who advised on research to create designs for local species.
This led to expanding fishways research and construction in eastern states. The result was markedly improved performance, for example in the Murray-Darling’s Sea to Hume program.
<h2>Fishway performance</h2>
Our research shows that regrettably few Australian fishways have yet been shown to meet ideal ecological criteria for mitigating the impact of barriers. Furthermore, fishways are in place at relatively few sites.
In NSW, for example, only about 172 in total serve several thousand weirs and 123 dams. They can be expensive to build and operate, so costs retard mitigation at numerous important sites.
Fishways have seldom been built on dams (fewer than 3% of Australia’s 500 high dams have one); they have generally cost tens of millions of dollars; and most operate, with limited effectiveness, for less than 50% of the time. The need for much greater investment in innovation, research and development is pressing.
<h2>How to store water and also rehabilitate fish</h2>
To reduce the impact of dams on fish we need to look at resolving problems at river-basin scale; improving our management of barriers, environmental flows and water quality; removing barriers; and developing improved fishway designs.
One way to accelerate improvements nationally would be to pass legislation for routinely re-licensing waterway barriers at regular intervals. This would mean that older barriers are re-evaluated and upgraded or removed where necessary. Under the NSW Weir Removal Program, 14 redundant weirs have already been removed, with others under assessment.
We are developing an innovative pump fishway concept at UNSW Australia. It combines aquaculture fish-pumping methods for safe fish transfer with existing fishway technology.
We hope the project may help transform past practices through less-costly modular construction, adaptability to a wide range of barriers and improved effectiveness.
Better fishway developments will mean that we can store and supply much-needed water while also restoring fish migrations. This will be increasingly important as climate change reduces streamflows in many regions, and will help rehabilitate fish populations.
John Harris is adjunct associate professor, Centre for Ecosystem Science, UNSW Australia and can be contacted <a href="https://theconversation.com/profiles/john-harris-94224" target="_blank">here.</a>
Bill Peirson is adjunct, Water Research Laboratory, School of Civil and Environmental Engineering, UNSW Australia and can be contacted <a href="https://theconversation.com/profiles/bill-peirson-277095" target="_blank">here</a>.
Richard Kingsford is professor, School of Biological, Earth and Environmental Sciences, UNSW Australia and can be contacted <a href="https://theconversation.com/profiles/richard-kingsford-134" target="_blank">here</a>.
All are authors for The Conversation.
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