Researchers from University College London and NASA have used laser technology for the first time to measure the biomass of the world's famous giant trees, providing us with an unprecedented 3D structure of trees to help scientists estimate how carbon is absorbed and how it changes with climate change.
Laser technology was used for the first time to measure the volume and biomass of California's giant sequoia tree, the first record made by University College London
Remarks: (University College London, University College London, abbreviated as UCL)
Published in the journal scientific reports > <, this advanced technology gives us an unprecedented 3D picture of the structure of trees, helping scientists to estimate how carbon is absorbed and how it changes with climate change.
Oil painting of a giant redwood tree in California: Albert Bierstadt
Remarks: The painting was created in 1874; Style: Luminism ; Genre: Landscape painting
Material: oil on canvas; Currently located at: Berkshire Museum, Pittsfield, MA, US; Actual dimensions: 133.35 x 109.22 cm
Mat Disney, a professor of earth sciences at University College London and the first author of the study, says that huge trees can be described as disproportionately important, both in terms of aboveground biomass (AGB) and their carbon storage, and in terms of their broad and profound impact on ecological balance systems. At the same time, these trees are also very difficult to measure, belonging to the part of the field of measurement that is not fully represented and the part where the aboveground biomass is not fully studied.
The researchers demonstrated for the first time detailed 3D terrestrial laser scanning (TLS) to assess the above ground biomass (AGB) of the giant coastal sequoia (Sequoia sempervirens) from three different regions of Northern California, which in part represent the most biomassy ecosystems on Earth.
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3D ground laser scanning (TLS) physical map and the results of its measurements of terrain and trees
The contribution of this research result lies in the fact that new progress has been made in the increasingly important study of climate change.
Professor Disney added: "The big question in climate science is the question of increasing CO2 emissions, whether and where, more trees can be planted and how to maximize the protection of existing forests. To answer these questions, scientists first need to understand how carbon is stored in different biological species.
Assessing the size of very large trees and their biomass is an extremely difficult task. In the past, trees could only be weighed after they had been cut down, or they were evaluated using indirect methods, such as remote sensing or manual measurement of trunk diameters to scale up or down, both of which had the potential to have large margins of error.
Working with colleagues at NASA, and with the support of NASA's Carbon Monitoring Systems Project, the researchers used a ground-based laser measurement system to create detailed 3D maps of California's giant sequoia trees. NASA's new space laser emission, GEDI, is a technique for graphicalizing (spatial mapping) of forest carbon from space. And the GEDI team used Professor Disney's work to test and improve the model they used to measure.
Measurement scans of the trees included the 88-metre-tall Independent Colonel Armstrong tree, which has a diameter of 3.39 metres and a mass of about 110 tonnes, equivalent to the mass of 10 double-decker buses.
The researchers also compared the results estimated by terrestrial laser scanning (TLS) with those measured by other techniques, and found that they used 3D contouring of the canopy projection( 3D crown mapping), an advanced technology developed by American botanist Stephen C. Sillett, a kind of climbing expert in a certain proportion, A technique for manually documenting the height and quality of huge sequoia trees in detail.
Professor Disney's team found that their AGB estimates were within a 2 percent margin of error in the 3D crown mapping. Crucially, they also found that both 3D techniques showed that these giant trees were at least 30 percent more massive than the results estimated by current indirect methods.
The researchers also recommend laser technology and 3D crown mapping, which can be used to provide complementary, independent 3D measurements.
Assistant Professor Laura Duncanson, an earth science researcher at NASA and the University of Maryland, the paper's final author and a member of the scientific team at NASA GEDI, said estimating the biomass of giant trees is critical to quantifying their carbon cycle, especially in Earth's most carbon-rich forests. The results of this exciting conceptual study demonstrate the potential advantages of using this technology to measure giant trees, and our next step is to expand globally, with the expectation that GEDI's biomass assessment in high-carbon-density forests around the world can be improved.
This research work was funded by NASA and the Natural Environment Research Council and University College London.
文章来源: “New 3D measurements of large redwood trees for biomass and structure” by Mathias Disney, Andrew Burt, Phil Wilkes, John Armston and Laura Duncanson, 15 October 2020, Scientific Reports. DOI: 10.1038/s41598-020-73733-6
<h1 class="pgc-h-arrow-right">参考资料：VERIS，Estimation of above‐ground biomass of large tropical trees with terrestrial LiDAR</h1>
Jose Gonzalez de Tanago Alvaro Lau Harm Bartholomeus Martin Herold Valerio Avitabile Pasi Raumonen Christopher Martius Rosa C. Goodman Mathias Disney Solichin Manuri Andrew Burt Kim Calders，First published: 25 September 2017 https://doi.org/10.1111/2041-210X.12904
Note: The weight of a biological organism is called biomass