A new study aimed at assessing the impact of woody vines, called lianas, on the global carbon balance has been published earlier this month in the “Journal of Applied Ecology”. The article helps to shed some new light on climate change. Using a lightweight, commercially available drone and camera, a team of researchers at the University of Nottingham have pioneered a novel method of monitoring liana infestation in tropical forest canopies.

Tropical forests and their canopies help mitigate climate change by storing massive quantities of carbon dioxide, thus playing a pivotal role in the global carbon cycle. Proliferation of these long-stemmed woody vines has been found to be detrimental to forest carbon dioxide storage and uptake, with wide-reaching impact on climate change.  Infestation with lianas in tropical forests has been traditionally evaluated from the ground, but this is a time-consuming task, especially when it comes to lianas embedded in the upper tree canopies. These layers are known to store and sequester the most carbon dioxide.

Drone-based surveys are not only more efficient, accurate and cost-effective but also cover significantly larger geographical areas than ground-based surveys. This new method enables quality control of the results, allowing more in-depth monitoring of various changes over time.  The study conducted by Catherine E. Waite and her colleagues at the University of Nottingham in the UK examined, for the first time, the applicability of drone image data to evaluate the extent of woody vine infestation in tropical tree canopies.

By overcoming most of the limitations of remote sensing platforms (such as satellite and manned-airborne platforms), drones can capture remotely sensed data from virtually inaccessible areas at significantly higher resolutions, which allow them to distinguish lianas from trees. Drones have been utilized to study various tree canopy phenomena, but never to monitor canopy-level infestation with lianas.

The team of Nottingham researchers conducted drone-based surveys as well as ground-based surveys (used as a benchmark) in Sepilok Forest Reserve and Danum Valley Conservation Area, both located in Malaysia. They collected image data of the tropical forest canopy with the use of an inexpensive, lightweight DJI Phantom 3 Advanced with an integrated 3-waveband RGB camera, 3-axis gimbal system as well as GPS and GLONASS that enable autonomous flights for around 20 minutes. Seventeen plots across 4 forest types were flown using Map Pilot, the autonomous mapping software.

The findings of this new research suggest that lightweight, inexpensive drones can be used efficiently and accurately to evaluate liana infestation in tropical forests and make this data collection much more accessible. Given the proliferation of woody vines lately, coupled with its huge impacts on the global carbon balance, it is vital to pinpoint where exactly are lianas infesting tropical tree canopies for effective, targeted tropical forest management. And, according to this groundbreaking study, drones can facilitate this vital mission in a timely, efficient and cost effective manner.

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