New technique significantly improves ability to map deforestation
Researchers at Edinburgh University have developed a new technique of remote sensing which will lead to a significant advance in our ability to monitor deforestation and land disturbances in tropical forests.
By combining several different methods of remote sensing, Dr Edward Mitchard and Dr Murray Collins of the School of Geosciences at The University of Edinburgh have been able to map biomass data more accurately in order to study the effects of deforestation in tropical forests.
Forests as an important natural resource
Covering around one third of the total land area of the planet, forests play a vital role not only in maintaining animal and plant biodiversity, but also in helping to regulate the earth’s climate by absorbing and storing carbon dioxide from the atmosphere.
However, global deforestation rates are now becoming so high, that deforestation is currently responsible for around 17% of all anthropogenic carbon emissions, and this is becoming a major concern in attempts to combat climate change.
“By cutting down forests we are effectively shooting ourselves in the foot and accelerating the rate of climate change”, says Dr Mitchard, who leads a group of remote sensing and monitoring researchers at the University of Edinburgh, “we’re rapidly cutting down forests, which releases more carbon into the atmosphere and it also stops those forests from being able to take back in carbon dioxide, so it’s a double whammy.”
Reducing deforestation is therefore becoming key in global efforts to decrease carbon emissions and tackle climate change. In response, global projects such as the ‘Reducing Emissions from Deforestation and forest Degradation’ programme (REDD+) have been set up to actively combat deforestation around the world and support the sustainable management of forests. However, in order to effectively reduce deforestation, accurate mapping and monitoring tools are essential.
A unique approach to mapping
In the past, cloud and smoke have obscured optical satellite images and hindered researchers from obtaining accurate data when mapping and monitoring deforestation and forest disturbances. “Historically a lot of people have used optical satellite data to understand deforestation and degradation”, say Dr Collins, “but typically these approaches are beset by problems of cloud cover and also smoke in the dry season. What we’re doing by using radar data, allows us to see through both the cloud and the smoke and also lets us have a much better perception of forest degradation.”
Speaking about a recent study carried out on the Indonesian island of Sumatra, Dr Collins tells us of the importance of this unique approach to remote sensing. “We were looking at a study site, which [had] pretty much year round cloud coverage, and also smoke during the dry season…so using optical data was very, very difficult. Radar data proved to be extremely valuable in extracting information about both the carbon stock in the forest and how it was changing.”
The research also demonstrates for the first time, how synthetic aperture radar (SAR), LiDAR and forest plot data can be combined to improve the accuracy of data. “What we’ve been doing in the Indonesian case, is also integrating some extra data…by integrating all those different data sets we can get quite a complete picture of the forest and also its change over time.”
Implications of the research
This research will contribute significantly to the development of improved forest monitoring technology, which will be essential in the success of programmes such as the REDD+. This is because more accurate biomass data will allow for better monitoring of deforestation bans and zero deforestation pledges, by flagging up areas where deforestation is still occurring. It will also allow policy makers to assess the success of their mitigation strategies in relation to combating deforestation.
“If we’re able to provide accurate information”, says Dr Collins, “then policy makers are better able to understand what policy mechanisms [actually] worked to reduce deforestation…[because] we’re also able to extract information about the structure of the forest itself, [this] allows us to tell things like the amount of biomass in a particular area and from that the amount of carbon. When we know an area of forest that is being degraded or cleared, then we can estimate the amount of [associated] carbon emissions.”
By being able to make reliable estimates of the carbon emissions associated with land use change, this will help to improve climate model simulations, and increase our understanding of the impacts of deforestation and degradation on future climate change.
Speaking to us about the group’s involvement in future projects, Dr Mitchard outlined a collaboration with the European Space Agency. “There is excitement around a new satellite that will be launched in 2021 called Biomass, which will have some involved from the University of Edinburgh. It has been designed to map biomass with very high accuracy across the world and we will be having some input in terms of trial sites, particularly my sites in Gabon. [This is] to see if we can develop the algorithms, so that when the satellite is launched, it can produce estimates straight away from day one, rather than [having to wait] a couple of years.”
Along with this project, both Dr Mitchard and Dr Collins are working on launching SAREDD, an operational service, which looks to provided data on deforestation and degradation to national governments, private corporations and NGOs. “What we’re trying to show”, says Dr Collins, “is that we can map deforestation and forests degradation on a monthly basis across the world using satellite radar data…The next steps for the SAREDD project are to continue with our technological development, but we’re also looking for new users across the world, particularly in Central Africa, Indonesia and Malaysia and in South America.”
Dr Edward Mitchard at the School of Geosciences
Dr Murray Collins at the School of Geosciences
Collins, M. B. and Mitchard, E. T. A.: Integrated radar and lidar analysis reveals extensive loss of remaining intact forest on Sumatra 2007–2010, Biogeosciences, 12, 6637-6653, doi:10.5194/bg-12-6637-2015, 2015.