Scientists from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and international collaborators demonstrated a new method for mapping the location and size of trees growing outside of forests. As a result, they’ve discovered billions of trees in arid and semi-arid regions. They are now laying the groundwork for more accurate global measurement of carbon storage on land.
How are they doing this? The scientists are using powerful supercomputers and machine learning algorithms to map the crown diameter – the width of a tree when viewed from above – of more than 1.8 billion trees across an area of more than 500,000 square miles. The team then mapped how tree crown diameter, coverage and density varied depending on rainfall and land use.
With traditional analytical techniques, it would take months to map non-forest trees at this level of detail. With this study, it only took weeks. The use of very-high resolution imagery and powerful artificial intelligence represents a technology breakthrough for mapping and measuring these trees. The study is intended to be first in a series of papers whose goal is not only to map non-forest trees across a wide area, but also to calculate how much carbon they store. This information is vital for understanding Earth’s carbon cycle and how it’s changing over time.
Carbon is one of the primary building blocks for all life on the planet. This element circulates among the land, atmosphere, and oceans via the carbon cycle. Some natural processes and human activities release carbon into the atmosphere while other processes draw it out of the atmosphere and store it in the land or in the ocean. Trees and other vegetation are known as ‘carbon sinks’, meaning they use carbon for growth and store it out of the atmosphere in their trunks, branches, leaves and roots. Human activities, like burning trees and fossil fuels or clearing forested land release carbon into the atmosphere as carbon dioxide. Rising concentrations of atmospheric carbon dioxide are a big problem and a main cause of climate change.
Conservation experts who are working to mitigate climate change and other environmental threats have targeted deforestation for years, but these efforts do not always include trees that grow outside of forests. Not only could these trees be significant carbon sinks, but they also contribute to the ecosystems and economies of nearby human, animal and plant populations.
What the team did was run a powerful computing algorithm called a fully functional convolutional neural network on one of the world’s fastest supercomputers. The team trained the model by manually marking nearly 90,000 individual trees across a variety of terrains, then allowing it to learn which shapes and shadows indicate the presence of trees.
The process of coding the training data took more than a year according to the study’s lead author, Martin Brandt, an assistant professor of geography at the University of Copenhagen. He marked all 89,899 trees by himself and helped supervise training and running the model. Ankit Kariryaa of the University of Bremen led the development of the deep learning computer processing.
Establishing an accurate count of trees in this area provides vital information for researchers, policymakers, and conservationists. Additionally, measuring how tree size and density vary by rainfall with wetter and more populated regions supporting more and larger trees provides important data for on the ground conservation efforts.
After gauging the program’s accuracy by comparing it to both manually coded data and field data from the region, the team ran the program across the full study area. The neural network identified more than 1.8 billion trees, a surprising number for a region often assumed to support little vegetation. The team’s objective is to see how much carbon is isolated in trees in the vast arid and semi-arid portions of the world. They then need to understand the mechanism which drives carbon storage in these areas. Hopefully the information can be used to store more carbon in vegetation by taking more carbon dioxide out of the atmosphere.
We don’t fully comprehend what this research means for climate change but are excited by the results. If trees can survive in arid and semi-arid areas such as these, then there may be hope for the planet yet. We really hope you enjoyed this article as much as we did writing it. As always, we appreciate your support.
