Weighing trees with lasers: reducing uncertainty in tropical forest biomass and allometry

Lead Research Organisation: University College London
Department Name: Geography

Abstract

Measuring the volume and structure of a tree accurately allows us to calculate the total above-ground carbon (C) stored in the tree, a very important property. Trees remove CO2 from the atmosphere during photosynthesis and can store this C for decades or even centuries until the tree dies, when some of it is released back to the atmosphere through decomposition. Tropical forests store around half of all above-ground terrestrial C, but are at particular risk due to deforestation and degradation, as well as from changing rainfall and temperature patterns. Surprisingly, our knowledge of tropical forest C stocks is quite poor, and errors in these stocks are large and uncertain. This uncertainty feeds into estimates of CO2 emissions due to deforestation, degradation and land use change. We will address this major uncertainty in the terrestrial C cycle by deploying a new, NERC-funded terrestrial laser scanner (TLS) to scan 1000s of trees in tropical forests on three continents: Amazonia, the Congo Basin and SE Asia. The laser data will allow us to measure 3D tree volume and biomass non-destructively to within a few percent of the best current estimates, made by destructive harvesting and weighing. The current, large uncertainties arise because weighing a tree is extremely difficult: tropical trees may be over 50m tall, and weigh 100 tonnes or more. Harvesting also precludes revisiting trees over time to measure change. In practice, a small sample of trees that have been harvested and weighed are related to easy-to-measure parameters of diameter and height, using empirical 'allometric' (size-to-mass) relationships. These relationships are then used to translate diameter and height measurements made over wider areas into estimates of biomass. Allometry is also the only way to infer biomass at very large (pan-tropical) scales, from remote sensing measurements. Unfortunately, the sample of harvested trees underpinning global allometric relationships is geographically limited, and contains very few large trees. Current estimates of tropical forest C stocks from satellite and ground data, all based on these very limited allometry samples, diverge significantly in size and pattern, leading to heated debate as to why this should be.

We hope to settle this debate, given that our lidar-derived estimates of biomass are completely independent of allometry and unbiased in terms of tree size. We will 'weigh' more trees than are currently included in all global pan-tropical allometries and quantify uncertainty in the allometry models. We will also test assumptions made in allometric models regarding tree shape and wood density. Our measurements will also answer fundamental questions about geographical differences in structural characteristics across tropical forests. Our data will be vital for testing new estimates of biomass from remote sensing; the UK-led ESA BIOMASS RADAR and NASA GEDI laser missions will both estimate pan-tropical C stocks by relying on allometric relationships between forest height and biomass. Our work will feed into these two missions through long-standing collaborations with the lead scientists. More generally, the large number of tree measurements we will collect would be of great interest to researchers in tropical ecology, forestry, biodiversity, remote sensing and C mapping, among others.

A key aim of the project is to ensure the widest use of our results, by making our data and tools publicly available. We will work with partners to explore routes for commercial developments and input into government policy, particularly relating to forest management and C mapping and mitigation. Lastly, we will make our work accessible through a range of outreach activities, including developing links between a school in the Amazon and UK schools, to raise awareness of scientific, conservation and policy issues surrounding tropical forests.

Planned Impact

We target four groups of users with interests in C stocks, biomass, tree structure and tropical forests more generally to maximise the impact of our work: users of data and tools; commercial sector; policymakers; wider public.

Users of data and tools includes forestry sector, conservation, land management, other researchers. We will make TLS data, derived tree structure and analysis tools publicly available. We will integrate the TLS-derived tree measurements into the database coordinated by co-I S. Lewis (www.forestplots.net), including data query and analysis tools. Timescale: 1 year for database integration. TLS data will be archived at NEODC/CEMS and also provided to the TLS International Interest Group (TLSIIG) via PP Strahler, for community use. All code used to process the TLS data will be put on github to enable other researchers to process and analyse them. Timescale: project duration, ongoing.

Policymakers: we will address issues of direct policy relevance: C cycle uncertainty, forest inventory and management policy. These issues are core to government response to climate change, particularly UN Reducing Emissions from Deforestation and Degradation (REDD+). This impact will be via PPs Herold, SAC, Forest Research, and ongoing collaborations with government agencies e.g. S. Lewis in Gabon (calibrating and validating national estimates of forest C stocks from airborne lidar for conservation and REDD+ readiness). We will work with PP Forest Research to test and improve existing UK forest inventory methods. Timescale: 1-2 years to show benefit of TLS methods; ongoing if demonstrated. Our data will add value to UK investment in the forthcoming ESA BIOMASS mission, through calibration and testing of retrievals (and via PP Quegan). Results will also feed into calibration and development for the NASA GEDI lidar mission (PP Dubayah). Timescale: 1-2 years for testing BIOMASS retrievals; 5+ years, for REDD+ positioning, and inclusion in BIOMASS, GEDI.

Commercial: we identify various opportunities for commercial exploitation of C stock mapping technology. Our allometry-free AGB estimates will enable PP Carbomap to assess their new airborne lidar-derived C stock estimates. Timescale: 1 year to provide 3D tree models; ongoing for testing new technology and retrievals. PP Planet Labs will work with us to test the feasibility of area-based C stock measurements using high spatial and temporal resolution satellite data: Timescale: 6 months. PP SAC will identify routes to policy and commercial data exploitation opportunities, including data hosting via the CEMS facility. Timescale: project duration. PP Skycap will explore UAV-based measurements of canopy height and cover, and how new low-cost lidar instruments might be used in this context. Timescale: project duration for development and then ongoing for commercial exploitation. PPs Herold and Schaaf will provide low-cost lidar instruments that we will test for biomass estimation. Such instruments may find much wider use in C stock mapping, eg in REDD+ activities, and we will exploit existing links with manufacturers and suppliers to develop these opportunities. Timescale: 1 year for demonstration; ongoing for exploitation.

Wider public: The project will provide a unique view of tropical forests that is particularly suited to engaging wider interest, due to its inherently visual nature. We will build on established links between a school in the Brazilian Amazon and UK schools to develop reciprocal work programmes and teaching materials to highlight environment, climate and biodiversity issues. PP Burkitt will develop web-based 3D visualisation of the TLS data. The PI and co-Is will expand existing outreach activities, such as the PI blog and involvement in TV (BBC, Reuters) and online teaching (ESA online) activities. Timescale: 1 year to set up school partnerships then self-sustaining; 1 year for visualisation; ongoing for other activities.

Publications

10 25 50
 
Description We have shown that our new approach to measuring forest biomass (weighing trees), particularly in the tropics, can provide much improved estimates of forest carbon stocks. We have also found that current estimates appear to be an underestimate of perhaps as much as 20%. This has potentially important implications for scientific understanding of tropical forest C budgets and climate, as well as for policies aimed at protecting these forests through investment in keeping C locked up and reducing deforestation.
Exploitation Route These methods are underpinning new satellite estimates, and are likely to be taken up in policy recommendations as to how to measure and quantify forests. We are also providing tools and data to allow other people to use these methods. The data are also of wide interest in showing trees and forests in a way that is accessible to the public, as witnessed by the media interest in this work.
Sectors Creative Economy,Digital/Communication/Information Technologies (including Software),Education,Environment,Culture, Heritage, Museums and Collections

URL http://disneytls.blogspot.co.uk/
 
Description Measurements made as part of the project have featured widely in media (documentaries), exhibitions, and other outreach activities and press.
First Year Of Impact 2016
Sector Creative Economy,Digital/Communication/Information Technologies (including Software),Education,Environment,Culture, Heritage, Museums and Collections
Impact Types Cultural,Societal,Policy & public services

 
Description Better measurement of forests for eg REDD+ reporting
Geographic Reach Multiple continents/international 
Policy Influence Type Citation in other policy documents
URL http://www.gofcgold.wur.nl/redd/
 
Description Discovery science
Amount £250,000 (GBP)
Funding ID NE/P011780/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 10/2017 
End 09/2020
 
Description EU Horizon 20:20
Amount € 244,000 (EUR)
Funding ID 757526 
Organisation European Commission 
Department Horizon 2020
Sector Public
Country European Union (EU)
Start 01/2018 
End 12/2021
 
Description NASA ROSES CMS
Amount $5,000 (USD)
Organisation National Aeronautics and Space Administration (NASA) 
Sector Public
Country United States
Start 06/2016 
End 05/2019
 
Description NCEO studentship
Amount £85,000 (GBP)
Organisation National Centre for Earth Observation 
Sector Academic/University
Country United Kingdom
Start 09/2015 
End 03/2019
 
Description NERC capital equipment bid: ZEB
Amount £31,600 (GBP)
Funding ID c7 
Organisation National Centre for Earth Observation 
Sector Academic/University
Country United Kingdom
Start 02/2016 
End 04/2016
 
Description NERC laser scanning
Amount £630,000 (GBP)
Funding ID NE/N00373X/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 11/2015 
End 10/2018
 
Title Lidar data processing tools 
Description Tools for processing 3D terrestrial laser scanner data, to extract individual separate individual trees from larger point clouds covering forested areas. 
Type Of Material Improvements to research infrastructure 
Year Produced 2015 
Provided To Others? Yes  
Impact Provided ability to justify applciations for futher funding eg successful NERC Standard Grant application, CNRS collaboration in French Guiana, ESA funding to participate in ESA BIOMASS cal/val campaign, to collect laser scan data in Ghana and process into individual tree structure models. 
 
Title New collection & dissemination of RT modelling tools and resources 
Description Collection of radiative transfer modelling tools and resources for NCEO, and wider, research community 
Type Of Material Improvements to research infrastructure 
Year Produced 2017 
Provided To Others? Yes  
Impact Many requests for information on tools, and training possibilities, as well as new research collaborations. 
URL https://www.nceo.ac.uk/data-tools/land-tools/
 
Title Treeseg 
Description New code to extract 3D trees from lidar point clouds collected in forest environments. 
Type Of Material Improvements to research infrastructure 
Year Produced 2017 
Provided To Others? Yes  
Impact Code and algorithms developed as part of Andy Burt's PhD and our ongoing lidar work. Many requests for the code, so we have now made it available with examples and tests. Being downloaded quite frequently, leading to more potential collaboration opportunities. 
URL https://github.com/apburt/treeseg
 
Title 3D lidar tree point clouds and models 
Description A collection of 3D trees as used in the p 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact None as yet. 
 
Description CNRS 
Organisation National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS)
Country France 
Sector Public 
PI Contribution To visit and deploy our terrestrial laser scanner at the CNRS field site at Nouragues, French Guiana, as part of CNRS-funded ongoing work.
Collaborator Contribution Provide funding for travel, subsistence, logistical help and accommodation, permits etc.
Impact 3D laser data for French Guiana plot, to be shared with partners and wider collaborators. Multi-disciplinary: remote sensing, engineering, ecology, forestry, climate.
Start Year 2015
 
Description Collaboration with EOLDAS 
Organisation University College London
Country United Kingdom 
Sector Academic/University 
PI Contribution We are providing new EO data products at high resolution over the UK, including agriculture and land use data.
Collaborator Contribution The European Space Agency EOLDAS (Earth Observation Land Data Assimilation System) team are providing expertise and tools to transform our satellite data into new, consistent EO products over the UK, which can be used by the GREENHOUSE modelling team.
Impact A new estimate of surface reflectance over the uk from multiple satellite sources. Conference papers reporting first results of this.
Start Year 2013
 
Description Collaboration with Univ. of Edinburgh 
Organisation University of Edinburgh
Department School of Geosciences Edinburgh
Country United Kingdom 
Sector Academic/University 
PI Contribution To scan forest plot in Brazil using NERC-funded terrestrial laser scanner, process data, and share results.
Collaborator Contribution Providing funds for travel and subsistence, logistic help and research collaboration.
Impact 3D visualisation of drought experiment; demonstration of lidar capability. Multi-disciplinary: remote sensing, ecology, forestry, climate.
Start Year 2013
 
Description ESA BIOMASS 
Organisation European Space Agency
Country France 
Sector Public 
PI Contribution To visit calibration/validation sites for ESA BIOMASS mission.
Collaborator Contribution Provide funds for travel to, and scanning of ESA BIOMASS cal/val sites.
Impact Field visit to Ghana to scan AfriSCAT calibration site (TBC 2016). Multi-disciplinary: remote sensing, engineering, ecology, forestry, climate.
Start Year 2015
 
Description NASA GEDI 
Organisation National Aeronautics and Space Administration (NASA)
Country United States 
Sector Public 
PI Contribution Calibration & validation work with the NASA GEDI team.
Collaborator Contribution Providing funding for fieldwork in US and Gabon.
Impact Generation of datasets and modelling tools for NASA GEDI team, and wider community of biomass research. Collaboration is multi-disciplinary as has science focus, but for policy delivery (via feeding into REDD+ MRV schemes).
Start Year 2017
 
Description Amazon FACE exhibition, Washington DC 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Supporters
Results and Impact Invited and funded to participate in an exhibition of our work done as part of the multi-million dollar Amazon FACE CO2 experiment in the Amazon rainforest, near Manaus in Brazil. The exhibition took place in the Inter American Development Bank HQ, Washington DC, June 2017. The exhibition was intended to showcase progress in the FACE project, and potentially secure further funding for continued research at the Amazon FACE experiment.
Year(s) Of Engagement Activity 2017
URL http://amazonface.org/news/5935e65df655c4d0226c643c
 
Description BBC documentary: Judi Dench: My Passion for Trees 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Invited to participate in a flagship documentary exploring the trees in Dame Judi Dench's garden, as part of an exploration of her love of trees. Scanned an oak tree in her garden, and then presented the results to her during various interviews and pieces to camera. Featured in premiere screening at Kew introduced by the director of Kew Gardens, and then featured in many places in the national press. Broadcast at Xmas prime time (BBC1 20/12/2017) reaching an audience over 4 million people. Tree data featured in BBC Arts Facebook page, viewed by > 45k people as of Feb 2018: https://www.facebook.com/BBCArtsOnline/videos/2403675943190879/
Year(s) Of Engagement Activity 2017
URL http://disneytls.blogspot.co.uk/2017/10/bbc-docs-featuring-our-work.html
 
Description BBC documentary: Life and Death on Your Lawn 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Use of the terrestrial laser scanning to illustrate the structure of trees and estimate the leaf area of trees in a suburban garden. Part of a 90 minute BBC 2 documentry, presented by Chris Packham, on the hidden biodiversity of suburban gardens. Seen by > 1m people and featured in the national press.
Year(s) Of Engagement Activity 2017
URL http://disneytls.blogspot.co.uk/2017/10/bbc-docs-featuring-our-work.html
 
Description CEOS biomass protocol 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited to co-lead the CEOS Working Group on Calibration and Validation (WGCV) for above ground biomass. The CEOS WGCV groups develop consensus protocols on international standards for earth observation products. My work on lidar measurement of biomass, particularly in tropical forests, has led to this invitation. The role involves leading the development of a protocol to allow new satellite observations of biomass to be calibrated and validated in such a way that they are as widely-used as possible by researchers and policy-makers alike.
Year(s) Of Engagement Activity 2017
URL https://lpvs.gsfc.nasa.gov/Biomass/AGB_home.html
 
Description GEO BON Ecosystem Function Group 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited to sit on GEO BON Ecosystem Function Working Group. The aim of the Working groups (WGs) centred on Essential Biodiversity Variables (EBVs) are expected to deliver on four fronts over the coming three years: (1) identify research opportunities (relevant to ecosystem functions) supporting the identification/implementation of EBVs; (2) derive/identify potential datasets; (3) articulate the links between these EBVs and global indicators; and (4) provide guidance to national biodiversity networks in terms of in situ monitoring of these EBVs (through, eg, the production of reports/guidelines).
Year(s) Of Engagement Activity 2017,2018
URL http://geobon.org/working-groups/ecosystem-function/
 
Description Laser scanning blog 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Providing background and examples of my work in laser scanning for a wider audience. Has led to many media requests, school talk requests, participation in workshops etc.
Year(s) Of Engagement Activity 2014,2015,2016
URL http://disneytls.blogspot.co.uk/
 
Description Press activities around new papers on Weighing Trees with Lasers 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Press release around release of new papers on laser measurements of forests, featuring in a series of papers in the Royal Society Interface journal, coming out of our themed meeting in February 2017. My work featured on the cover of the journal and an accompanying press release by UCL was picked up widely by the print and broadcast media, including: BBC and Sky radio, Sky News, Independent, Mail Online, BT news etc., leading to various radio and print interviews.
Year(s) Of Engagement Activity 2018
URL http://disneytls.blogspot.co.uk/2018/02/royal-society-super-special-issue-on-tls.html
 
Description Royal Society Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact A Royal Society-funded workshop on 'The terrestrial laser scanning revolution in forest ecology'. Co-organised the meeting, secured funding from the Royal Society, and then acted as joint associate editor for the resulting special issue of the Royal Society journal. Aimed to showcase widely the new opportunities for TLS measurements in ecology.
Year(s) Of Engagement Activity 2017
URL https://royalsociety.org/science-events-and-lectures/2017/02/forest-ecology/
 
Description Schools visits 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Multiple schools visits including: Jubilee Primary School, Hackney; City and Islington Academy, Islington (GCSE and A-level); Bedford School, Bedford (across lower school and 6th form). In all cases I was invited to talk about my work in tropical forests primarily, to show the audience what tropical forests look like, how we measure them and why these measurements are important - in some cases to address specific curricular aspects such as climate, carbon cycle, photosynthesis, forests etc. In each case I have been invited back again.
Year(s) Of Engagement Activity 2015,2016
 
Description Victoria and Albert Museum 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Our lidar data from a tropical forest in Brazil is featuring as part of a major new exhibition at the V&A, The Future Starts Here, as well as in the book accompanying the exhibition. The exhibition "will bring together more than 100 objects as a landscape of possibilities for the near future." - as part of this, scientific measurements which are allowing us to see the world in new ways are explored. Our data are used to show the possibilities for measuring forests, understanding tropical climates, and showing audiences what being in such a forest is like. The hope is it will help to raise awareness of the structural complexity and beauty of these environments, potentially allowing us to see their 'value' in new ways.
Year(s) Of Engagement Activity 2018
URL https://www.vam.ac.uk/exhibitions/the-future-starts-here#intro