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The world around us is always changing. In a lot of ways, it’s changing for the better, as each passing year brings advances in technology, more effective medicine and new ways of communicating with each other.
Zoom out a little, though, and it’s clear that our planet is also going through some very concerning shifts.
Since 1990, we’ve lost 420 million hectares of forest through conversion to other land uses. Even though the rate of human-led deforestation is slowing, we’re still losing 10 million more hectares worth of trees each year.
As we increasingly contend with bushfires, floods and other hallmarks of climate change, the loss of our natural environment is felt even more strongly – and the search for a solution becomes more urgent.
Considering the mass-deforestation that has occurred in recent years, an important question is being pondered across the globe: can planting more trees help our environment? And, if so, how can we get started? To help us answer these questions and more, we sat down with Deakin University lecturer in conservation and sustainability, Dr Carla Archibald.
Trees play a vital role in our world. One of the biggest benefits of trees comes from ‘evapotranspiration’ – a process of absorbing moisture from the soil and evaporating it through leaves, cooling air and soil. As Archibald explains, though, the positive environmental role of trees goes much deeper.
‘The positive effects that tree planting can have on the environment aren’t only the direct impacts that that tree might have on water, on habitat, on climate regulation, but there’s also broader, more indirect benefits human wellbeing, economic benefits and social impacts,’ Archibald says. ‘From a research perspective, we call these benefits ecosystem services.’
One of the big ‘ecosystem service roles’ that trees play in our climate is absorbing carbon.
‘That helps regulate the climate, not only locally – so for example, alleviating heat island effects in urban areas – but also globally,’ Archibald says. ‘Because carbon is a universal service, something emitted or sequestered in one place has benefits in other places – regionally, nationally and globally.’
And while recent studies suggest that cutting fossil fuel use is more urgent than forestation, Archibald says that planting trees is still helpful for the environment. Plenty of projects have cropped up with the purpose of growing forests on a massive scale – 3 million trees, 20 million trees, 1 billion trees spring to mind – but planting trees on a more localised scale can also help the environment.
‘There are different benefits that trees can have and tree planting as an action can have to control the effects of climate change,’ Archibald says. ‘Locally, planting trees can help alleviate more localised impacts of climate change – extreme weather events, for example, drought, flood, erosion at a local level.’
Climate change is everyone’s problem, and planting trees is one way to fight the issue both locally and globally.
As Archibald explains, though, the benefits of planting trees – and the negatives of losing them – go beyond climate.
‘The less trees around, the hotter it can get, as there’s less shade, less water retention in the soil, and that can not only impact the climate in a local and global context, but it could also have flow-on effects to biodiversity and to people,’ Archibald says. ‘So, if there are less trees around in places where there once was trees, and that destabilises soil, or makes it so the soil is unable to retain enough moisture, that is likley having consequences to species that call that place home or to agricultural production, and that could lead to lower crop yields, for example.’
That last point about agriculture ties into Archibald’s own research and her focus at Deakin University: looking at the ways in which protecting and planting more trees can have positive benefits for farmland.
‘What we do at Deakin is focus on, how can we make this campus that we work on, or farms that we might produce food on, better for nature, while also allowing us to kind of seek other needs, whether that be farming or education?’ she says. ‘Some of the work that I’ve been doing with colleagues in Brazil has looked at the benefits that having small, isolated paddock trees or planting along fence lines and in farming landscapes benefit biodiversity. With some of that research, we found that even these small tree planting efforts or tree protection efforts can double the ecological connectivity in fragmented farming landscapes.’
Climate change would be a much simpler problem to address if we could just figure out how many trees need to be planted to offset carbon emissions. Unfortunately, the answer isn’t as easy as just calculating our total carbon emissions, figuring out how much carbon each tree holds, and then planting that many.
The issue is incredibly complex – and it’s something that Archibald is working on in her research. By using a powerful computer model known as the Land Use Trade-Offs Model 2, she and her colleagues, led by Prof Brett Bryan, hope to help Australia meet its climate targets by analysing Australian farmland and a whole host of tree- and climate-related variables.
‘What that model does is it simulates how the land use sector works in Australia,’ she says. ‘It breaks up Australia into pixels, and it assigns farm types to each pixel based on the primary farming activity that happens there. And then we add lots of information about rainfall, whether tree planting is suitable there, how much benefit you would get, how much it would cost, the biodiversity benefit – all of these things. And using this model, we can simulate the feasibility of Australia meeting its net zero emissions targets by 2050.’
As Archibald explains, the reason for the complex relationship between trees and carbon sequestration – and the powerful computer modelling – is that the effectiveness of tree planting depends on variables like the type of tree, tree management and where the tree is planted. Despite this, the outlook from the modelling is positive.
‘Preliminary results from this modelling effort suggests that it’s possible for Australia to achieve nature positive – which is this idea that we can sequester and benefit the environment in Australia more than we are damaging it, by 2050,’ Archibald says. ‘But to get there, we will likley need quite a large-scale change, not only through tree planting, but also through protecting existing areas. We want to avoid loss first, and then we can plant trees.’
Let’s put everything in perspective. Clearly, the relationship between tree planting and carbon emissions is complex, and ‘solving’ climate change is a challenge for all of us. Despite this, Archibald says we can all still make a positive change by planting more trees ourselves.
‘Planting trees as an individual will always have a benefit,’ she says. ‘Carbon is a universal service, so if you plant a tree somewhere, that will have benefits universally.’
So, how do we plant a tree here in Australia, then? Luckily, the South Australian government provides a six-step process that’s easy to follow:
Archibald says that planting trees is just one way that we as individuals can be more environmentally friendly. How we vote, where we invest our money, and other forms of land rehabilitation are all great ways to make a difference. She will be exploring some of these question through her recent government fellowship.
The important thing to remember, though, is that by making small efforts, we can all help improve our planet. And, if you do want to plant a tree anywhere, Archibald says it’s important to just go in with a good attitude and try your best.
‘Give it a go, it’ll be alright,’ she says. ‘Even if you have a balcony, just doing something will help contribute to climate sequestration.’
Lecturer, Conservation and Sustainability
Deakin University
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