Lemurs are the world’s most endangered mammals, but planting trees can help save them



Black-and-white ruffed lemurs are important indicators of rainforest health.
Franck Rabenahy, CC BY-ND

Andrea L. Baden, Hunter College

Madagascar, the world’s fourth-largest island, is a global biodiversity hotspot.
Andrea Baden

The island of Madagascar off the southeastern coast of Africa hosts at least 12,000 plant species and 700 vertebrate species, 80% to 90% of which are found nowhere else on Earth.

Isolated for the last 88 million years and covering an area approximately the size of the northeastern United States, Madagascar is one of the world’s hottest biodiversity hotspots. Its island-wide species diversity is striking, but its tropical forest biodiversity is truly exceptional.

Sadly, human activities are ravaging tropical forests worldwide. Habitat fragmentation, over-harvesting of wood and other forest products, over-hunting, invasive species, pollution and climate change are depleting many of these forests’ native species.

Among these threats, climate change receives special attention because of its global reach. But in my research, I have found that in Madagascar it is not the dominant reason for species decline, although of course it’s an important long-term factor.

As a primatologist and lemur specialist, I study how human pressures affect Madagascar’s highly diverse and endemic signature species. In two recent studies, colleagues and I have found that in particular, the ruffed lemur – an important seed disperser and indicator of rainforest health – is being disproportionately impacted by human activities. Importantly, habitat loss is driving ruffed lemurs’ distributions and genetic health. These findings will be key to helping save them.

Deforestation from slash-and-burn agriculture in the peripheral zones of Ranomafana National Park, Madagascar.
Nina Beeby/Ranomafana Ruffed Lemur Project, CC BY-ND

The forest is disappearing

Madagascar has lost nearly half (44%) of its forests within the last 60 years, largely due to slash-and-burn agriculture – known locally as “tavy” – and charcoal production. Habitat loss and fragmentation runs throughout Madagascar’s history, and the rates of change are staggering.

This destruction threatens Madagascar’s biodiversity and its human population. Nearly 50% of the country’s remaining forest is now located within 300 feet (100 meters) of an unforested area. Deforestation, illegal hunting and collection for the pet trade are pushing many species toward the brink of extinction.

In fact, the International Union for Conservation of Nature estimates that 95% of Madagascar’s lemurs are now threatened, making them the world’s most endangered mammals. Pressure on Madagascar’s biodiversity has significantly increased over the last decade.

A red ruffed lemur, one of two Varecia species endemic to Madagascar.
Varecia Garbutt, CC BY-ND

Deforestation threatens ruffed lemur survival

In a newly published study, climate scientist Toni Lyn Morelli, species distribution expert Adam Smith and I worked with 19 other researchers to study how deforestation and climate change will affect two critically endangered ruffed lemur species over the next century. Using combinations of different deforestation and climate change scenarios, we estimate that suitable rainforest habitat could be reduced by as much as 93%.

If left unchecked, deforestation alone could effectively eliminate ruffed lemurs’ entire eastern rainforest habitat and with it, the animals themselves. In sum, for these lemurs the effects of forest loss will outpace climate change.

But we also found that if current protected areas lose no more forest, climate change and deforestation outside of parks will reduce suitable habitat by only 62%. This means that maintaining and enhancing the integrity of protected areas will be essential for saving Madagascar’s rainforest habitats.

Warm colors indicate areas where lemurs can move about readily, which promotes genetic diversity; cool colors indicate areas where they are more constrained and less able to mate with members of other population groups.
Baden et al. (2019), Nature Scientific Reports, CC BY-ND

In a study published in November 2019, my colleagues and I showed that ruffed lemurs depend on habitat cover to survive. We investigated natural and human-caused impediments that prevent the lemurs from spreading across their range, and tracked the movement of their genes as they ranged between habitats and reproduced. This movement, known as gene flow, is important for maintaining genetic variability within populations, allowing lemurs to adapt to their ever-changing environments.

Based on this analysis, we parsed out which landscape variables – including rivers, elevation, roads, habitat quality and human population density – best explained gene flow in ruffed lemurs. We found that human activity was the best predictor of ruffed lemurs’ population structure and gene flow. Deforestation alongside human communities was the most significant barrier.

Taken together, these and other lines of evidence show that deforestation poses an imminent threat to conservation on Madagascar. Based on our projections, habitat loss is a more immediate threat to lemurs than climate change, at least in the immediate future.

In 1961 naturalist David Attenborough filmed ruffed lemurs for the BBC.

This matters not only for lemurs, but also for other plants and animals in the areas where lemurs are found. The same is true at the global level: More than one-third (about 36.5%) of Earth’s plant species are exceedingly rare and disproportionately affected by human use of land. Regions where the most rare species live are experiencing higher levels of human impact.

Crisis can drive conservation

Scientists have warned that the fate of Madagascar’s rich natural heritage hangs in the balance. Results from our work suggest that strengthening protected areas and reforestation efforts will help to mitigate this devastation while environmentalists work toward long-term solutions for curbing the runaway greenhouse gas emissions that drive climate change.

A young woman participates in reforestation efforts in Kianjavato, Madagascar.
Brittani Robertson/Madagascar Biodiversity Partnership, CC BY-ND

Already, nonprofits are working hard toward these goals. A partnership between Dr. Edward E. Louis Jr., founder of Madagascar Biodiversity Partnership and director of Conservation Genetics at Omaha’s Henry Doorly Zoo, and the Arbor Day Foundation’s Plant Madagascar project has replanted nearly 3 million trees throughout Kianjavato, one region identified by our study. Members of Centre ValBio’s reforestation team – a nonprofit based just outside of Ranomafana National Park that facilitates our ruffed lemur research – are following suit.

At an international conference in Nairobi earlier this year, Madagascar’s president, Andry Rajoelina, promised to reforest 40,000 hectares (99,000 acres) every year for the next five years – the equivalent of 75,000 football fields. This commitment, while encouraging, unfortunately lacks a coherent implementation plan.

Our projections highlight areas of habitat persistence, as well as areas where ruffed lemurs could experience near-complete habitat loss or genetic isolation in the not-so-distant future. Lemurs are an effective indicator of total non-primate community richness in Madagascar, which is another way of saying that protecting lemurs will protect biodiversity. Our results can help pinpoint where to start.

[ Like what you’ve read? Want more? Sign up for The Conversation’s daily newsletter. ]The Conversation

Andrea L. Baden, Assistant Professor of Anthropology, Hunter College

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

Entire hillsides of trees turned brown this summer. Is it the start of ecosystem collapse?



Rachael Nolan, CC BY-NC

Rachael Helene Nolan, Western Sydney University; Belinda Medlyn, Western Sydney University; Brendan Choat, Western Sydney University, and Rhiannon Smith, University of New England

The drought in eastern Australia was a significant driver of this season’s unprecedented bushfires. But it also caused another, less well known environmental calamity this summer: entire hillsides of trees turned from green to brown.

We’ve observed extensive canopy dieback from southeast Queensland down to Canberra. Reports of more dead and dying trees from other regions across Australia are flowing in through the citizen science project, the Dead Tree Detective.




Read more:
Drought and climate change were the kindling, and now the east coast is ablaze


A few dead trees are not an unusual sight during a drought. But in some places, it is the first time in living memory so much canopy has died off.

Ecologists are now pondering the implications. There are warnings that some Australian tree species could disappear from large parts of their ranges as the climate changes. Could we be witnessing the start of ecosystem collapse?

Extensive canopy dieback in Kains Flat, NSW, January 2020.
Matt Herbert

Why are canopies dying now?

Much of eastern Australia has been in drought since the start of 2017. While this drought is not yet as long as the Millennium Drought, it appears to be more intense. Many areas have received the lowest rainfall on record, including long periods of time with no rainfall. This has been coupled with above-average temperatures and extreme heatwaves.

The higher the temperature, the greater the moisture loss from leaves. This is usually good for a tree because it cools the canopy. But if there is not enough water in the soil, the increased water loss can push trees over a threshold, causing extensive leaf “scorching”, or browning. The extensive canopy dieback we have observed this summer suggests that the soil had finally become too dry for many trees.

Widespread rainfall deciciencies and higher temperatures across many parts of Australia.
Bureau of Meteorology

Are the trees dead?

Brown or bare trees are not necessarily dead. Many eucalypts can lose all their leaves but resprout after rain.

Many parts of eastern Australia are now flushed with green after rain. In these areas, it will be important to assess the extent of tree recovery. If trees are not showing signs of recovery after significant rainfall, they’re unlikely to survive. In some cases carbohydrate reserves – which trees need to resprout new leaves – may be too depleted for trees to recover.

Snowgums in the New England area resprouting in March 2020, following heavy rain. The trees lost most of their canopy during drought in 2019.
Trevor Stace, University of New England

The drought may also hinder post-fire recovery. Most eucalypt forests eventually recover from bushfires by resprouting new leaves. Some forests also recover when fire triggers seedlings to germinate.

But it’s likely that some forests now recovering from fire were already struggling with canopy dieback. So these two disturbances will test how resilient our forests are to back-to-back drought and bushfire.

Trees recovering from drought and/or fire may also enter the “dieback spiral”. The new flush of leaves following rain can make a particularly tasty meal for insects. Trees will then attempt to grow more foliage in response, but their ability to keep producing new leaves gradually declines as they deplete their carbohydrate reserves, and they can die.

Dieback spiral has led to extensive tree loss in the past, including in the New England area of NSW.

Should we be worried?

The capacity of eucalypts to resprout makes them naturally resilient to extended drought. There are some records of canopy dieback from severe droughts in the past, such as the Federation Drought. We assume (although we don’t know for sure) the forests recovered after these events. So they may bounce back after the current drought.

However, it’s hard not to be concerned. Climate change will bring increased drought, heatwaves and fires that could, over time, see extensive losses of trees across the landscape – as happened on the Monaro High Plain after the Millennium Drought.




Read more:
Are more Aussie trees dying of drought? Scientists need your help spotting dead trees


Australian research in 2016 warned that due to climate change, the habitat of 90% of eucalypt species could decline and 16 species were expected to lose their home environments within 60 years.

Such a change would have huge consequences for how ecosystems function – reducing the capacity for ecosystem services such as carbon storage, altering catchment water resources and reducing habitat for native animals.

Some trees resprouted new leaves after losing their canopy. But in some cases these leaves are now dying, like on these scribbly gums in the NSW Pilliga in August 2019.
Rachael Nolan

Where to from here?

Records of dead and dying trees on the Dead Tree Detective map.
Dead Tree Detective

Landholders can help bush on their property recover after drought, by protecting germinating seedlings from livestock and collecting local seed for later revegetation. Trees that appear dead should not be cut down as they may recover, and even if dead can provide valuable animal habitat.

Most importantly, however, we need to monitor trees carefully to see where they’ve died, and where they are recovering. A citizen science project, the Dead Tree Detective, is helping map the extent of tree die-off across Australia.

People send in photos of dead and dying trees – to date, over 267 records have been uploaded. These records can be used to target where to monitor forests during drought, including on-ground assessments of tree health and quantifying the physiological responses of trees to drought stress.

There is no ongoing forest health monitoring program in Australia, so this dataset is invaluable in helping us determine exactly how vulnerable Australia’s forests are to the double whammy of severe drought and bushfires.The Conversation

Rachael Helene Nolan, Postdoctoral research fellow, Western Sydney University; Belinda Medlyn, Professor, Western Sydney University; Brendan Choat, Associate Professor, Western Sydney University, and Rhiannon Smith, Research Fellow, University of New England

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

Thousands of city trees have been lost to development, when we need them more than ever


Thami Croeser, RMIT University; Camilo Ordóñez, University of Melbourne, and Rodney van der Ree, University of Melbourne

Climate change is on everyone’s lips this summer. We’ve had bushfires, smoke haze, heatwaves, flooding, mass protests and a National Climate Emergency Summit, all within a few months. The search is on for solutions. Trees often feature prominently when talking about solutions, but our research shows trees are being lost to big developments – about 2,000 within a decade in inner Melbourne.

Big development isn’t the only challenge for urban tree cover. During the period covered by our newly published study, the inner city lost a further 8,000 street trees to a variety of causes – vandals, establishment failures of young trees, drought, smaller developments and vehicle damage.

Still, thanks to a program that plants 3,000 trees a year, canopy growth has kept just ahead of losses in the City of Melbourne.




Read more:
Our cities need more trees, but some commonly planted ones won’t survive climate change


Canopy cover is crucial for keeping urban areas liveable, shading our streets to help us cope with hot weather and to counter the powerful urban heat island effect. Trees can also be a flood-proofing tool.

Trees add beauty and character to our streets, and (so far) they’re not a political wedge issue in the ongoing culture war that is Australian climate policy. In short, they’re a very good idea, at just the right time.

Counting the trees lost to development

The thing is, this good idea happens in the midst of a construction boom. In Melbourne alone, this includes thousands of new dwellings and billions of dollars of new infrastructure. Many of the new buildings are very large – there’s a handy open database that shows these developments.

This map shows the scale of development under way in the inner city.
City of Melbourne

Next time you’re walking past a large construction site, look for empty tree pits – the square holes in footpaths where trees have been removed. Maybe you’ve already seen these and wondered what all the construction means for our trees. Well, now we know.

Our study puts a number on the impact of major development on city trees. In the City of Melbourne – that’s just the innermost suburbs and the CBD – major developments cost our streets about 2,000 trees from 2008-2017.

Using council databases and a mapping tool, we tracked removals of trees within ten metres of hundreds of major developments. We found much higher rates of tree removal around major development sites than in control sites that weren’t developed.

An example of our analysis, comparing tree losses around sites with major development (orange) to control sites (blue). Trees within 10m of major developments were much more likely to be removed.
https://doi.org/10.1016/j.scs.2020.102096

Even with the City of Melbourne’s robust tree-protection rules, trees can be removed or damaged due to site access needs, scaffolding, compacted soil, root conflicts with services access, and even the occasional poisoning.

The City of Melbourne invited artist Louise Lavarack to create a roadside memorial to a poisoned plane tree, which was then shrouded in gauze bandages.
Tony & Wayne/Flickr, CC BY-NC



Read more:
We’re investing heavily in urban greening, so how are our cities doing?


Tree protection limits losses

The silver lining in this story is that the city council’s tree-protection policy seems to be quite effective at saving our bigger trees. The vast majority of removals we saw were of trees with trunks less than 30cm thick. Only one in 20 of the trees lost was a large mature tree over 60cm thick.

This may partly reflect the fact that the council charges developers for not only tree replacement but also the dollar equivalent of lost amenity and ecological values. It gets very expensive to remove a large tree once you factor in all the valuable services it provides. When a tree is a metre thick, costs can exceed $100,000 – and that’s if there are no alternatives to removal.

The protection of bigger trees means Melbourne retained canopy fairly well, despite losing over 2,000 trees. Only 8% of city-wide canopy losses during our study period happened near major development sites. This modest loss is still serious, as removals are having more of an impact on future canopy growth than current cover.




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How tree bonds can help preserve the urban forest


Lessons for our cities

While Melbourne-centric, there are lessons in this study for cities everywhere. Robust policies to protect and retain trees backed up by clear financial incentives are valuable, as even well-resourced councils with strong policy face an uphill battle when development gets intense.

Our findings highlight that retaining and establishing young trees is especially difficult. This is troubling given these are the trees that must deliver the canopy that will in future shelter the streets in which we live and work.




Read more:
Keeping the city cool isn’t just about tree cover – it calls for a commons-based climate response


Improved investments in how young trees are planted and how long we look after them can help. For example, in a promising local study, researchers showed that trees planted in a way that catches rainwater run-off from roads grow twice as fast, provided planting design avoids waterlogging.

Finally, in the context of rapid development, buildings themselves can play a positive role. Green roofs, green walls and rain gardens are just a few of the ways developments can help our cities deal with both heat and flooding.

There are plenty of precedents overseas. In Berlin, laws requiring building greening have resulted in 4 million square metres of green roof area – three times the area of Melbourne’s Hoddle Grid. In Singapore, developments must include vegetation with leaf area up to four times the development’s site area, using green roofs and walls. Tokyo has required green roofs on new buildings for nearly 20 years.

The solutions are out there, and urban greening is rising in profile. Recent commitments in Melbourne, Canberra and Adelaide are promising. Our study findings are a reminder that, even for the willing, we’ll have to take two steps forward, because there’s inevitably going to be one step back.




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For green cities to become mainstream, we need to learn from local success stories and scale up


The Conversation


Thami Croeser, Research Officer, Centre for Urban Research, RMIT University; Camilo Ordóñez, Research Fellow, School of Ecosystem and Forest Sciences, University of Melbourne, and Rodney van der Ree, Adjunct Associate Professor, School of BioSciences. National Technical Executive – Ecology, WSP Pty Ltd, University of Melbourne

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

Here are 5 practical ways trees can help us survive climate change



Shutterstock

Gregory Moore, University of Melbourne

As the brutal reality of climate change dawned this summer, you may have asked yourself a hard question: am I well-prepared to live in a warmer world?

There are many ways we can ready ourselves for climate change. I’m an urban forestry scientist, and since the 1980s I’ve been preparing students to work with trees as the planet warms.

In Australia, trees and urban ecosystems must be at the heart of our climate change response.

Governments have a big role to play – but here are five actions everyday Australians can take as well.




Read more:
Go native: why we need ‘wildlife allotments’ to bring species back to the ‘burbs


1. Plant trees to cool your home

At the current rate of warming, the number of days above 40℃ in cities including Melbourne and Brisbane, will double by 2050 – even if we manage to limit future temperature rises to 2℃.

Trees can help cool your home. Two medium-sized trees (8-10m tall) to the north or northwest of a house can lower the temperature inside by several degrees, saving you hundreds of dollars in power costs each year.

Trees can cool your home by several degrees.
Shutterstock

Green roofs and walls can reduce urban temperatures, but are costly to install and maintain. Climbing plants, such as vines on a pergola, can provide great shade, too.

Trees also suck up carbon dioxide and extend the life of the paint on your external walls.

2. Keep your street trees alive

Climate change poses a real threat to many street trees. But it’s in everyone’s interests to keep trees on your nature strip alive.

Adequate tree canopy cover is the least costly, most sustainable way of cooling our cities. Trees cool the surrounding air when their leaves transpire and the water evaporates. Shade from trees can also triple the lifespan of bitumen, which can save governments millions each year in road resurfacing.

Tree roots also soak up water after storms, which will become more extreme in a warming climate. In fact, estimates suggest trees can hold up to 40% of the rainwater that hits them.

But tree canopy cover is declining in Australia. In Melbourne, for instance, it falls by 1-1.5% annually, mainly due to tree removals on private land.

Governments are removing trees from public and private land at the time we need them most.
Shutterstock

This shows state laws fail to recognise the value of trees, and we’re losing them when we need them most.

Infrastructure works such as level crossing removals have removed trees in places such as the Gandolfo Gardens in Melbourne’s inner north, despite community and political opposition. Some of these trees were more than a century old.

So what can you do to help? Ask your local council if they keep a register of important trees of your suburb, and whether those trees are protected by local planning schemes. Depending on the council, you can even nominate a tree for protection and significant status.

But once a development has been approved, it’s usually too late to save even special trees.

3. Green our rural areas

Outside cities, we must preserve remnant vegetation and revegetate less productive agricultural land. This will provide shade and moderate increasingly strong winds, caused by climate change.

Planting along creeks can lower water temperatures, which keeps sensitive native fish healthy and reduces riverbank erosion.

Strategically planting windbreaks and preserving roadside vegetation are good ways to improve rural canopy cover. This can also increase farm production, reduce stock losses and prevent erosion.

To help, work with groups like Landcare and Greening Australia to vegetate roadsides and river banks.

4. Make plants part of your bushfire plan

Climate change is bringing earlier fire seasons and more intense, frequent fires. Fires will occur where they hadn’t in the past, such as suburban areas. We saw this in the Melbourne suburbs of Bundoora, Mill Park, Plenty and Greensborough in December last year.

It’s important to have a fire-smart garden. It might seem counter-intuitive to plant trees around the house to fortify your fire defences, but some plants actually help reduce the spread of fire – through their less flammable leaves and summer green foliage – and screen your house from embers.




Read more:
Low flammability plants could help our homes survive bushfires


Depending on where you live, suitable trees to plant include crepe myrtle, the hybrid flame tree, Persian ironwood, some fruit trees and even some native eucalypts.

Gardens play a role in mitigating fire risk to your home.
Shutterstock

If you’re in a bushfire-prone area, landscape your garden by strategically planting trees, making sure their canopies don’t overhang the house. Also ensure shrubs do not grow under trees, as they might feed fire up into the canopy.

And in bad fire conditions, rake your garden to put distance between fuel and your home.




Read more:
Keeping the city cool isn’t just about tree cover – it calls for a commons-based climate response


5. What if my trees fall during storms?

The fear of a whole tree falling over during storms, or shedding large limbs, is understandable. Human injury or death from trees is extremely rare, but tragedies do occur.

Make sure your trees are healthy, and their root systems are not disturbed when utility services such as plumbing, gas supplies and communication cables are installed.

Coping with a warming world

Urban trees are not just ornaments, but vital infrastructure. They make cities liveable and sustainable and they allow citizens to live healthier and longer lives.

For centuries these silent witnesses to urban development have been helping our environment. Urban ecosystems depend on a healthy urban forest for their survival, and so do we.The Conversation

Gregory Moore, Doctor of Botany, University of Melbourne

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

Trees can add $50,000 value to a Sydney house, so you might want to put down that chainsaw



Allowing residents to remove trees within three metres of buildings or ‘ancillary structures’ could dramatically alter the green infrastructure of dense inner Sydney suburbs like Rozelle.
Tom Casey/Shutterstock

Sara Wilkinson, University of Technology Sydney; Agnieszka Zalejska-Jonsson, KTH Royal Institute of Technology, and Sumita Ghosh, University of Technology Sydney

Sydney’s Inner West Council has a new policy that it is reported means “residents will no longer need to seek council approval to prune or remove trees within three metres of an existing home or structure”. Hold on, don’t reach for that chainsaw yet, because research shows good green infrastructure – trees, green roofs and walls – can add value to your home.

Green infrastructure offers significant, economic, social and environmental benefits. Urban greening is particularly important in dense urban areas like Sydney’s Inner West. Among its benefits, green infrastructure:

Some of these benefits accrue to owners/occupiers, whereas others provide wider societal benefits.




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Higher-density cities need greening to stay healthy and liveable


A 2017 study focusing on three Sydney suburbs found a 10% increase in street tree canopy could increase property values by A$50,000 on average. And the shading effect of trees can reduce energy bills by up to A$800 a year in Sydney. So retaining your green infrastructure – your trees, that is – can deliver direct financial gains.

On a larger scale, a collaborative project with Horticulture Innovation Australia Limited compared carbon and economic benefits from urban trees considering different landuses along sections of two roads in Sydney. Higher benefits were recorded for the Pacific Highway, with 106 trees per hectare and 58.6% residential land use, compared to Parramatta Road, with 70 trees per hectare and 15.8% residential.

For the Pacific Highway section, total carbon storage and the structural value of trees (the cost of replacing a tree with a similar tree) were estimated at A$1.64 million and A$640 million respectively. Trees were also valuable for carbon sequestration and removing air pollution.

Tree species, age, health and density, as well as land use, are key indicators for financial and wider ecosystem benefits. Specifically, urban trees in private yards in residential areas are vital in providing individual landowner and collective government/non-government benefits.

Take away the trees close to these houses in Marrickville, in Sydney’s Inner West, and how much would be left?
Graeme Bartlett/Wikipedia, CC BY-SA

Challenges of growth

As populations grow, cities increase density, with less green infrastructure. The loss of greenery affects the natural environment and both human and non-human well-being.




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We’re investing heavily in urban greening, so how are our cities doing?


Tree canopy cover across Greater Sydney plummets closer to the city centre.
© State of New South Wales through the Greater Sydney Commission. Data: SPOT5 Woody Extent and Foliage Projective Cover (FPH) 5-10m, 2011, NSW Office of Environment and Heritage

Trees and other green infrastructure reduce some impacts of urban density. However, policies, government incentives and national priorities can produce progress in urban greening or lead to setbacks. In the case of the Inner West Council, for instance, the inability to fund monitoring of changes in tree cover could lead to reductions at the very time when we need more canopy cover.

Key concerns include installation and maintenance costs of green infrastructure (trees, green roofs and walls) in property development, and tree root damage. Knowledge and skills are needed to maintain green infrastructure. As a result, developers often consider other options more feasible.

In the short and long term, multiple performance benefits and economic and environmental values are needed to establish the viability of green infrastructure.




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Australian cities are lagging behind in greening up their buildings


Learning from Stockholm

Stockholm shares many issues found in Australian cities. Stockholm houses over 20% of Sweden’s inhabitants, is increasing in density and redeveloping land to house a growing population. Aiming to be fossil-free by 2050, Stockholm acknowledges the built environment’s role in limiting climate change and its impacts.

In a research project we intend to use virtual reality (VR) and electroencephalogram (EEG) technology to assess perceptions of green infrastructure and reactions to it in various spaces.

Our project combines VR with EEG hardware, which measures human reactions to stimuli, to learn how people perceive and value green infrastructure in residential development.

Identifying all the value of green infrastructure

The many benefits of green infrastructure are both tangible and non-tangible. Economic benefits include:

  • those that directly benefit owners, occupants or investors – stormwater, increased property values and energy savings
  • other financial impacts – greenhouse gas savings, market-based savings and community benefits.



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If planners understand it’s cool to green cities, what’s stopping them?


The various approaches to evaluating net value present a challenge in quantifying the value of green infrastructure. The most common – cost-benefit analysis, triple bottom line, life cycle assessment and life cycle costing – are all inadequate for evaluating trade-offs between economic and environmental performance. Conventional cost-benefit analysis is insufficient for investment analysis, as it doesn’t include environmental costs and benefits.

This is salient for green infrastructure, as owners/investors incur substantial direct costs, whereas various shareholders share the value. Perhaps, in recognition of the shared value, a range of subsidies could be adopted to compensate investors. Discounted rates anyone?

Recent efforts to evaluate the business case for green infrastructure include attempts to identify and quantify the creation of economic, environment and community/social value. However, an approach that includes a more comprehensive set of value drivers is needed to do this. This is the gap we aim to fill.

The results of experiments using VR and EEG technology and semi-structured interviews will provide a comprehensive understanding of green infrastructure. This will be correlated with capital and rental values to determine various degrees of willingness to pay.

With this knowledge, property developers in Sweden and Australia will be able to make a more informed and holistic business case for increasing green infrastructure for more liveable, healthy cities.

Maybe we can then persuade more people, including those in the Inner West, to hang onto their trees and leave the chainsaws in the garage.The Conversation

Sara Wilkinson, Professor, School of the Built Environment, University of Technology Sydney; Agnieszka Zalejska-Jonsson, Researcher, Division of Building and Real Estate Economics, KTH Royal Institute of Technology, and Sumita Ghosh, Associate Professor in Planning, School of the Built Environment, University of Technology Sydney

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

When tree planting actually damages ecosystems



Giraffes prefer the open space and scattered trees of the African savanna.
Volodymyr Burdiak/Shutterstock

Kate Parr, University of Liverpool and Caroline Lehmann, University of Edinburgh

Tree planting has been widely promoted as a solution to climate change, because plants absorb the climate-warming gases from Earth’s atmosphere as they grow. World leaders have already committed to restoring 350m hectares of forest by 2030 and a recent report suggested that reforesting a billion hectares of land could store a massive 205 gigatonnes of carbon – two thirds of all the carbon released into the atmosphere since the Industrial Revolution.

Many of those trees could be planted in tropical grassy biomes according to the report. These are the savannas and grasslands that cover large swathes of the globe and have a grassy ground layer and variable tree cover. Like forests, these ecosystems play a major role in the global carbon balance. Studies have estimated that grasslands store up to 30% of the world’s carbon that’s tied up in soil. Covering 20% of Earth’s land surface, they contain huge reserves of biodiversity, comparable in areas to tropical forest. These are the landscapes with lions, elephants and vast herds of wildebeest.

Gorongosa, Mozambique. The habitat here is open, well-lit and with few trees.
Caroline Lehmann, Author provided

Savannas and grasslands are home to nearly one billion people, many of whom raise livestock and grow crops. Tropical grassy biomes were the cradle of humankind – where modern humans first evolved – and they are where important food crops such as millet and sorghum originated, which millions eat today. And, yet among the usual threats of climate change and wildlife habitat loss, these ecosystems face a new threat – tree planting.

It might sound like a good idea, but planting trees here would be damaging. Unlike forests, ecosystems in the tropics that are dominated by grass can be degraded not only by losing trees, but by gaining them too.




Read more:
Reforesting an area the size of the US needed to help avert climate breakdown, say researchers – are they right?


Where more trees isn’t the answer

Increasing the tree cover in savanna and grassland can mean plant and animal species which prefer open, well-lit environments are pushed out. Studies from South Africa, Australia and Brazil indicate that unique biodiversity is lost as tree cover increases.

This is because adding trees can alter how these grassy ecosystems function. More trees means fires are less likely, but regular fire removes vegetation that shades ground layer plants. Not only do herbivores like zebra and antelope that feed on grass have less to eat, but more trees may also increase their risk of being eaten as predators have more cover.

A mosaic of grassland and forest in Gabon.
Kate Parr, Author provided

More trees can also reduce the amount of water in streams and rivers. As a result of humans suppressing wildfires in the Brazilian savannas, tree cover increased and the amount of rain reaching the ground shrank. One study found that in grasslands, shrublands and cropland worldwide where forests were created, streams shrank by 52% and 13% of all streams dried up completely for at least a year.

Grassy ecosystems in the tropics provide surface water for people to drink and grazing land for their livestock, not to mention fuel, food, building materials and medicinal plants. Tree planting here could harm the livelihoods of millions.

Losing ancient grassy ecosystems to forests won’t necessarily be a net benefit to the climate either. Landscapes covered by forest tend to be darker in colour than savanna and grassland, which might mean they also absorb more heat. As drought and wildfires become more frequent, grasslands may be a more reliable carbon sink than forests.




Read more:
Exaggerating how much CO₂ can be absorbed by tree planting risks deterring crucial climate action


Redefine forests

How have we reached the point where the unique tropical savannas and grasslands of the world are viewed as suitable for wholesale “restoration” as forests?

At the root of the problem is that these grassy ecosystems are fundamentally misunderstood. The Food and Agricultural Organisation of the UN defines any area that’s half a hectare in size with more than 10% tree cover as forest. This assumes that landscapes like an African savanna are degraded because they have fewer trees and so need to be reforested. The grassy ground layer houses a unique range of species, but the assumption that forests are more important threatens grassy ecosystems across the tropics and beyond, including in Madagascar, India and Brazil.

A flowering aloe in Madagascan grassland.
Caroline Lehmann, Author provided

“Forest” should be redefined to ensure savannas and grasslands are recognised as important systems in their own right, with their own irreplaceable benefits to people and other species. It’s essential people know what degradation looks like in open, sunlit ecosystems with fewer trees, so as to restore ecosystems that are actually degraded with more sensitivity.

Calls for global tree planting programmes to cool the climate need to think carefully about the real implications for all of Earth’s ecosystems. The right trees need to be planted in the right places. Otherwise, we risk a situation where we miss the savanna for the trees, and these ancient grassy ecosystems are lost forever.The Conversation

Kate Parr, Professor of Tropical Ecology, University of Liverpool and Caroline Lehmann, Senior Lecturer in Biogeography, University of Edinburgh

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