Humanity is exalted not because we are so far above other living creatures, but because knowing them well elevates the very concept of life. E.O. Wilson, 1984

16 Jul 2016

Borneo Correspondence: Counting Carbon in the Canopy

Six months on, and I am back at Danum Valley Field Centre to continue collecting data for my PhD thesis. And aside from the continuation of my research project, a twist of fate ties this visit to the last. On one of my final days here back in January, with my work coming to a close, and a sense of entitled accomplishment, I allowed myself to lounge around and read the magazines left by passing tourists and researchers. One of these was a National Geographic where a photo editorial focused on the use of remote sensing, or the collection of data using electronic sensors to reveal trends in the world's geographic organisation. Along with images of satellite trajectories and shifting river beds, were images of tree crowns from above, their colours distorted so as to appear in vivid technicolor, a Wonka-Oz-Dr.Seus-esque scene of pink and purple.

Canopy of rainforest in Panama with colour indicating carbon uptake (green slow, pink fast). Photo by Gregory Asner, Carnegie Institution for Science

These images were the work of Greg Asner and his colleagues at the Carnegie Airborne Observatory, who use LIDAR (Light Imaging, Detection and Ranging) technology to scan huge areas of the globe's surface, collecting terrifying amounts of data on its composition. By flying a dual propeller plane shooting lasers down at whatever lies below, and recording the returning light signal, the team are able to detect changes in the chemical make-up of huge areas of the planet’s surface in a short amount of time.  Soaking in the images before me, pictorial representations making seemingly complicated data incredibly easy to interpret, I became inspired by how advanced techniques had made the collection of information of global significance rapid and efficient. I also felt pity for those who have had to spend years of repetitive fieldwork to gather a smidgen of what was being shown here, collected in a single flyby.

And so back to this week, on the ground in Danum, where I started my acclimatization by assisting others working here, getting used to the heat and sweat, to the mosquito bites and wasp stings. Along with botanists working on trees and vines, we trekked to plots of forest to record the size and density of marked trees and lianas or vines. By repeating measures over subsequent years, scientists can determine how a forest is evolving, either as a result of its recovery from logging, or due to changes in global climate. For there it is, a ghoulish presence hanging over everyone’s shoulder, a force which we would prefer to ignore, but whose ramifications will likely impact on all of life on earth: human induced climate change as a result of carbon emissions.

Botanist Julien Engel measures trunk diameter in French Guiana
In recording tree growth, it becomes possible to determine how a forest stores released carbon. Lianas and epiphytes too, long neglected by scientists trying to see the woods through the trees, are now taken into account as influencing not only forest recovery (their choking embrace smothering trees and preventing their growth), but also in storing large amounts of carbon themselves. Thankfully, international governments are beginning acknowledge the threats of climate change. Carbon is now on the global agenda, and with programmes such as the UN’s REDD+ promoting carbon credit schemes and payment to countries for maintaining forest cover, trees equate to top dollar. Carbon creditors, aiming to cash in on this emerging market are placing large investments into projects which aim to strengthen calculations of where carbon is stored and how much of it is there. And when you require funds to fly a laser-firing plane across the globe, working for such investors can prove highly tempting. And so, on my return to Danum, I bump into Greg Asner himself, here with his colleagues to collect leaf samples to enable a better calibration for future forest scans.

The CAO plane flying over the Sierra Navada, California. Photo by Gregory Asner, Carnegie Institution for Science
The team take two approaches; firstly, using LIDAR, they can calculate the height of the canopy from the ground, and its density, and thus an estimation as to how much carbon is held by each tree. This approach, as Greg says, pays the bills, and satisfies partner organisations interested in carbon balances. But is also allows for flight plans to collect more data, using the second approach of spectroscopy, or the analysis of different wavelengths of light returning to the plane’s detectors. Different species of trees have different chemical signals as a result of the physiological make up of their leaves, which absorb and reflect varying levels of light. By collecting leaves from trees which have been scanned, and identifying the species, you can have an effective chemical fingerprint, in theory allowing future flybys to determine not only carbon content, but also species diversity.

Dana Chadwick from CAO preparing leaf specimens
The combination of traditional field techniques such as specimen collection and identification, with more technologically advanced tools such as LIDAR is making waves in how science is performed, and how data is interpreted. Burgeoned by an increasing global conscience and demand for this information, landmark projects such as the Carnigie Airbourne Observatory are able to accomplish tasks which would previously have been unthinkable, but which today are increasingly common. Tropical biologists are now often armed with drones and a GPS, in addition to measuring tools of tradition. With a serendipitous week of inspiration from fellow jungle researchers, I am ready to commence my next 3 months of fieldwork!

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