The main objective of Junttila’s thesis was to investigate the capabilities of multispectral terrestrial lidar in the detection and assessment of tree decline caused by different stressors. This was done by investigating the estimation of a remotely detectable indicator of tree decline, leaf water content (LWC).
The World’s forests are facing novel stress due to climate change. Pest insects and pathogens are shifting towards new latitudes and heat stress is resulting in increased tree mortality and more frequent forest fires globally. Uncertainty in estimating the magnitude of climate change induced forest and tree decline requires new methods for unbiased estimation of tree decline.
The dissertation contributes both to the development of an objective and automatable method for detecting and measuring tree decline in the field, and to the understanding of the relationship between LWC and tree decline with implications to remote sensing.
Due to the extremely high costs of visiting and exploring objects in space, such as the Moon, Mars and other planets, it is crucial to find the right tools and techniques for collecting high-quality data for research. This can be done by making experiments in comparable places on Earth.
Valuable information with LiDAR
The FINESSE scientists have been exploring the Craters of the Moon National Monument and Preserve (CRMO) in the Snake River Plain of Idaho. As a part of the cooperation CoE-LaSR research professor Antero Kukko has been performing technology demonstrations using an FGI originating backpack mobile laser scanning system Akhka-R3.
In a lava field environment the Lidar detects details often more precise than 1 cm point distribution revealing even tiny details of the surface. The collected data enables the producing of high-accuracy topographic maps and provides information on terrain roughness and morphology features of the surveyed area.
The Backpack system developed in FGI has proven to be an efficient tool for fast collection of precise information in lava fields. The findings indicate that in similar conditions, i.e. in Mars, terrestrial and mobile laser scanning are good options for collecting data for further analogy and exploration studies.
The FINESSE program is a consortium of more than 30 research scientists. Their goal is to generate strategic knowledge in preparation for the human and robotic exploration of the Moon, near-Earth asteroids (NEAs) and Phobos & Deimos.
Laser scanning research got recognition among the international media in 2016. Our “sleeping trees” findings and advances in mobile laser scanning gained international audiences both in scientific journals and popular news. Two articles by CoE -LaSR researchers were in the top 10 of GIM International magazine’s most read articles 2016, and a Coe – LaSR cooperation article on birch tree’s day-night cycles was listed as one of the 12 best science stories of the year by The New Scientist.
The articles in GIM International brought insight into topics of personal laser scanners (PLS) and unmanned aerial systems (UAS). The main interest and focus was on the development of new scanning systems and potential applications utilizing them in 3D data collection.
First high performance backpack system Akhka in spotlight
To our knowledge, the Akhka PLS system has been the first backpack system with such high data acquisition capability. After the publication of this article, an updated revision, AkhkaR3, has been released with even higher performance sensors.
New research fields for laser scanning for plant dynamics
The New Scientist story ’Trees seen resting branches while ‘asleep’ for the first time‘ illustrated a novel application of using the high potential of terrestrial laser scanning measurements in the field of chronobiology. The study, a joint international research collaboration with Dr. Eetu Puttonen from NLS FGI and TU Wien, clearly demonstrated circadian movements of silver birch branches and showed for the first time that lidar measurements can detect nocturnal physical changes in trees that resemble a resting or a sleeping pattern.
Above: Overnight movement of a small tree acquired with three different terrestrial laser scanners. Each frame represents the point clouds measured at the shown time with color. The point coloring shows the reflectance of each measured point that were calibrated using an external calibration target. The black point cloud shows the tree’s original posture at sunset.
The results were exciting as they support the use of high resolution terrestrial laser scanning in monitoring plant dynamics with short time intervals and in a non-destructive manner. Additionally, the laser scanning measurements can be scaled up to cover for example several full-grown trees of different species simultaneously with short preparation times.
Sensei, an early unmanned aerial vehicle (UAV) -based laser scanner developed at FGI that has contributed significantly to the emerging mini-UAV laser scanner field, is presented in GEO informatics December issue 8/2013. Read more (page 20).