Tuesday, 30 July 2019

Book alert!

The work of our group features in several chapters in a new book describing the new opportunities and challenges for measuring the biomass of forests from space. The book, "Forest properties and carbon cycle studies from Earth Observations", edited by Klaus Scipal, Anny Cazenave, Teodolina Lopez (ISSN: 0169-3298 (Print) 1573-0956 (Online)) is a Special Issue of Surveys in Geophysics (vol 40, issue 4) and is the outcome of a Workshop on “Space-Based Measurement of Forest Properties for Carbon Cycle Research” held at the International Space Science Institute (ISSI) in Bern, Switzerland, from 6 to 9 November 2017.

The ISSI workshop pulled together experts from various fields and space agencies to discuss key science questions, community needs and new technologies for estimating forest biomass from space. The book summarises the state-of-the-art in space-based observations of biomass including new space-based radar and lidar (laser) instruments being launched now and over the coming few years. In addition, there is an exploration of the various challenges to making best use of these new observations, both scientifically and in terms of policy aimed at reducing emissions due to deforestation and degradation.

I led a chapter on terrestrial laser scanning as a key tool for improved calibration and validation (cal/val) of satellite observations of biomass.
Figure from Disney et al. (2019): TLS of 3 contrasting forest types, with each individual tree coloured separately. Top to bottom: Wytham Woods, UK; Caxiuanã, Brazil; Lopé, Gabon.
I also contributed to a chapter by Laura Duncanson on new cal/val protocols for biomass, and to a chapter by Jerome Chave on the importance of more and better ground data to underpin these space missions.

Figure from Chave et al. (2019) illustrating the Super Site concept for ground-based data collection for cal/val of new EO missions providing biomass estimates.
The book is aimed at a general audience of those interested in carbon cycle science, but will be of particular interest to people at the interface of science and policy. The success of initiatives such as the UN REDD+ program to reduce deforestation and degradation will rely on the observations and methods described in the book.

Wednesday, 17 April 2019

Tallest trees, new publications and Hardy Ash revisited ...

We've been involved in some exciting work measuring what is likely to be the tallest tree ever measured in the tropics, in the rainforests of Sabah, Malaysian Borneo. The tree, nicknamed “Menara” or Malay for “tower”, may also be the tallest angiosperm (flowering plant) in the world, a title currently held by "Centurion", a Eucalyptus regnansin Tasmania, Australia, measured at 99.67 m in 2016. Menara is a Shorea faguetiana (common name Yellow Meranti), of the Dipterocarpaceae family that dominates the humid lowland rainforests of SE Asia, and is 100.8 m from top to ground. It was originally identified in airborne lidar by a team from Nottingham University and partners including the South East Asia Rainforest Research Partnership) in 2014. The tree was then located on the ground by a Malaysian team and climbed and measured by Unding Jami. Phil then helped train local researchers to operate our laser scanner, in conjunction with a team from Oxford University led by Allie Shenkin. 
The view from the bottom of the tallest tropical tree in the world
'Menara', picture by Unding Jami. See https://www.eci.ox.ac.uk/news/2019/0408.html.
Allie also produced some amazing visualisations of the tree using the TLS and drone data. More pictures soon when the paper on this comes out.

We've been busy at the start of spring preparing for new campaigns in Peru, Gabon, the UK and in Germany. This means piecing together the jigsaw of travel plans and logistics, which Andy and Phil are leading. The German work will be in support of an ESA campaign in Kermeter, Germany later in the year, where airborne P-band radar and lidar data are being collected as part the lead up to the BIOMASS mission in 2021.

Matheus has defended his PhD, and passed with minor corrections - of course! Examined by Prof. Mark Danson from Salford, and Prof. Peter Muller from MSSL here at UCL, they were both impressed by his work. Matheus has already published 5 papers before submitting his PhD, including the most recent one in MEE summarising his leaf-wood separation work. This is a really excellent paper, providing a significant advance in what we're able to do with TLS data and opening up lots of new areas of exploring tree structure and function.

We've had a few other new papers out since the last post, perhaps most notably one of a collection by various authors on forest biomass, in an edited volume that is coming out in Surveys in Geophysics: Forest Biomass and Structure from Space. This book arises out of the ISSI-organised meeting in Bern in late 2017 and will be an excellent resource, as it will contain a really useful summary of the state-of-the-art in the field. Our first contribution is the chapter "Innovations in ground and airborne technologies as reference and for training and validation: Terrestrial Laser Scanning (TLS)".

Figure 1 from Disney et al. (2019) showing various examples of TLS point clouds.
Meanwhile I've been out and about doing various talks, including an invitation to speak as part of the lunch-time lecture series to staff at Kew Gardens (including a live feed to the Kew Millenium Seedbank at Wakehurst Place, Sussex). This was a real honour and slightly nerve-wracking as talking about trees to the Kew experts seems a little like teaching your grandmother to suck eggs as the expression goes. I also recently appeared via video link to speak as part of the Climate Conversations lecture series at Lawrence Berkeley National Laboratory, SF - another fun and interesting experience. Last but by no means least I was invited to my daughter's school in Hackney to talk about their current topics, trees and the Amazon - it's always fun to try out new material on a tough crowd - if it's not snappy they lose interest pretty quickly.

News from the GEDI mission - things are looking very good so far and the first release of data is pretty impressive. Glad to see they're continuing to rinse the Star Wars link for all it's worth :-) Can't wait to start seeing some of these data over our sites - this is going to be fascinating.

GEDI returns over US, from: https://earthobservatory.nasa.gov/images/144818/return-of-the-gedis-first-data 

Lastly, Phil went back to scan the Hardy Ash in Old Pancras Church yard following some remedial tree pruning work. See the details here, but also Phil's Sketchfab model below.

Monday, 25 February 2019

Vegetable monsters

We've been keeping an eye out for unusual urban trees we can potentially scan. This is partly to build up a collection of the 3D tree structures in more extreme environments, extreme in this case being the level of pressure and management they are likely to have undergone. More generally, this is part of understanding the wider issue of urban tree cover, and how and why some trees survive and thrive. Mostly this is down to management and preservation but of course that reflects what has been planted in the first place and why.

Phil was alerted to these amazing redwoods on Canons Drive, Stanmore via twitter - the go-to research tool for urban forests, obvs! This private drive has an avenue of sequoias (or Wellingtonia - see below for some history of that name) planted by the Duke of Chandos. How we ended up with sequoias in the UK is an interesting bit of history as well; clearly the Duke of Chandos wanted to build an estate that was right on the cutting edge of the latest horticultural fad.

Phil, KC and I spent a morning admiring the trees and scanning up the drive. The tallest is around 33 m and you can see from the figure below the range of shapes. This is another great illustration of the variety of 3D structure we see from particular species in the same climate, but under different other external pressures.

Extracted point clouds of the Canons Drive sequoias (P. Wilkes)

Phil has also produced a rather nice flythrough down the drive based on these data.
Canon St Giant redwoods from Phil Wilkes on Vimeo.