Nondestructive estimates of above-ground biomass using terrestrial laser scanning

Published on
March 29, 2016

This year’s Robert May Early Career Researcher Award is won by former PhD student Kim Calders. Kim led the work on the prize winning paper on estimating biomass with terrestrial laser scanning, with an international team of coauthors. The study is an important development in the monitoring of carbon stocks for worldwide climate policy-making.

The Robert May Early Career Researcher Award is named after Robert May, Lord May from Oxford. The prize is awarded annually by the paper Methods in Ecology and Evolution (from the British Ecological Society) to the best paper submitted by an early career author at the start of their research career. Kim Calders was a PhD student and the paper is one of his PhD chapters. His promotor, Martin Herold, is proud of his former student: “This award is given only to one person a year,” he says. “It shows that already our PhD’s are doing excellent research with international visibility and recognition. Kim’s research is a good example of the ‘digitizing nature’ theme of Wageningen University and ESG that was also the topic of this year’s Dies. Our facility for terrestrial laser scanning is continuing work with a priority area now for increasing the precision and detail for measuring and modeling of tropical trees.”

Kim Calders and his colleagues have developed a way to harness ground-based laser technology for use in measurements of vegetation structure of forests. Both carbon stocks and above-ground biomass are important measurements for the initiative on Reducing Emissions from Deforestation and Forest Degradation (REDD) – a programme striving to reduce loss of forests and preserve them for uptake of carbon by trees. Current estimates of tropical forest biomass are based on a relatively small number of directly measured and weighed trees. These destructive methods are time-consuming and are lacking in many parts of the world; particularly in tropical forests where trees can be over 50m tall, complex in structure and can have over 100 tonnes of dry matter biomass per tree. Terrestrial laser scanning is an active remote sensing technique that can measure precise distances by sending out laser energy and then analysing the reflected energy. The method allows us to measure volume of trees directly without having to cut them for estimating biomass. While traditional methods yielded results that may have been off by as much as 37%, the LiDAR method developed by Calders et al. delivers over 90% accuracy.

This paper – which brings together ecologists, remote sensing scientists and mathematicians – is a great example of how international and interdisciplinary collaboration can be a catalyst for significant scientific progress in ecology and forest monitoring. In one recent demonstration of the method, researchers collected laser scan measurements of over 1000 trees in just 10 days. The method is tested in many other regions including tropical forests in Gabon, Peru, Indonesia, Guyana, Ghana and Ethiopia. Here you can find the Wageningen UR Terrestrial Laser Scanning Logbook.