Sensing technology identifies trees affected by deadly larch disease

Posted by ap507 at Apr 06, 2017 09:53 AM |
University of Leicester researchers lead study into disease identification and monitoring

Issued by University of Leicester Press Office on 6 April 2017

Images from the project are available here: https://www.dropbox.com/sh/la3wrsc5on1hk8b/AACvlWAZBTrLfjHcu0onyBe7a?dl=0

Researchers from the University of Leicester have used remote sensing technology by Leicestershire-based aerial mapping company Bluesky in order to identify trees affected by a destructive disease. 

Maps collected by airborne Laser sensors have, for the first time, been used to successfully pinpoint individual trees affected by the deadly larch tree disease.

The laser scanning surveys (LiDAR) were undertaken by aerial mapping company Bluesky and used to model tree canopy height as part of a wider study to prove the effective use of the technology for disease identification and monitoring.

Phytophthora ramorum is a fungus-like pathogen which causes extensive damage and mortality to a wide range of trees and other plants. Generically referred to as ramorum, the disease was first discovered in the UK back in 2002 and has now spread to sites from Cornwall to Scotland, causing destruction in high profile areas including Epping Forest and the Forest of Dean.

Professor Heiko Balzter, Director of the Centre for Landscape and Climate Research, lead investigator of the study at the University of Leicester and Co-investigator of the NERC National Centre for Earth Observation, said: “Invasive tree diseases pose a huge threat to Britain's forestry. Diseases like Dutch Elm disease and Sudden Oak Death can wipe entire tree species from our landscapes within a few years. Climate change increases the risk of new tree diseases spreading across the UK.

“We hope that better ways of monitoring the outbreaks and spread of these diseases in our forests will help the Forestry Commission and private land owners to respond more effectively to such outbreaks."

Chloe Barnes, Postgraduate Researcher at the University of Leicester’s Department of Geography and lead author of the study, said: “Current trends suggest that UK forests and woodlands are subject to a greater threat from exotic diseases, such as Larch tree disease, than ever before.

“While the use of LiDAR in forestry applications has become more common, its use to identify individual trees affected by diseases has, until now, been underutilised.”

LiDAR has been used extensively to derive canopy height models (CHMs). It is one of the key datasets used to create Bluesky’s unique National Tree Map.

However, when trees are affected by disease, evidenced by defoliation and dieback, irregularities across the entire canopy add complications to the segmentation of individual tree crowns (ITCs).

Using the Bluesky LiDAR data, sample plots of two study sites in Wales were assessed using different segmentation algorithms. A series of raster format CHMs were computed at different pixel sizes and tested across a range of plantation larch plots in order to perform ITC delineation.

Chloe added: “The three dimensional nature of LiDAR provides structural information on topography, canopy height, tree density and crown dimensions, which we have proved can be used to determine biophysical parameters and inform forest inventories.

“The high resolution and accuracy of the data also enables the extraction of forest parameters associated with individual tree crowns, including the opportunity for the detailed study of forest condition and dynamics.”

Professor Balzter added: “University research in close collaboration with companies like Bluesky provides huge opportunities for turning research outcomes into real-world applications.”

The article, “Individual Tree Crown Delineation from Airborne Laser Scanning for Diseased Larch Forest Stands”, by Barnes, Balzter, Barrett, Eddy, Milner and Suárez is available for download at http://www.mdpi.com/2072-4292/9/3/231

ENDS

Notes to editors:

For more information contact Chloe Barnes on cb482@leicester.ac.uk or Professor Heiko Balzter on hb91@le.ac.uk

www.bluesky-world.com

In order to capture highly accurate LiDAR (Light Detection and Ranging) data, a survey aircraft equipped with a system of lasers is used. Lasers are transmitted to the ground and the time taken for the beam to be bounced back to the aircraft-mounted receivers is recorded. Using the known position of the aircraft (derived from on-board satellite positioning equipment), the time taken for the return of the laser beam and the known value of the speed of light, the distance between the aircraft and ground is calculated.

Readings can also be taken to determine the height of buildings, vegetation and other surface structures such as above ground pipelines, highways, street furniture, power lines and railway tracks.

Bluesky is a specialist in aerial survey including aerial photography, LiDAR and thermal data, using the very latest survey technology, including two UltraCam Eagles and a Teledyne Optech Galaxy LiDAR system integrated with a PhaseOne camera and thermal sensor. An internationally recognised leader with projects extending around the globe, Bluesky is proud to work with prestigious organisations such as Google, the BBC and Government Agencies. 

Bluesky has unrivalled expertise in the creation of seamless, digital aerial photography and maintains national “off the shelf” coverage of aerial photography, DTM and DSM through an ongoing three-year update programme. By purchasing a world first sensor for the simultaneous capture of LiDAR, Thermal and Aerial Photography data, Bluesky is in the enviable position of being able to provide customers with unique and cost effective solutions.

Bluesky is leading the way in developing innovative solutions for environmental applications, including the UK’s first National Tree Map (NTM), solar mapping and citywide ‘heat loss’ maps and is currently developing noise and air quality mapping products. www.bluesky-world.com

About the National Centre for Earth Observation

The National Centre for Earth Observation (NCEO) is a distributed centre with over 80 scientists from UK institutions, led by Professor John Remedios at the University of Leicester. It provides NERC with national capability in Earth observation science and incorporates world-class capabilities in interpretive Earth observation to meet the needs of society through long-term core science and translation of knowledge and environmental data for government and business.

NCEO has world-class capabilities in processing and analysing the vast quantities of data generated by satellites, aircraft and ground-based instruments to monitor and understand global and regional environmental change.

For more information contact jan.fillingham@nceo.ac.uk

https://www.nceo.ac.uk/

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