A new space age for tropical forests – but field-workers matter more than ever

A new era of forest monitoring has quite literally taking off, ushering in what scientists are calling the ‘forest space age’. On April 29, ESA launched its revolutionary Biomass mission, the first satellite to carry a P-band radar into space – technology that is set to transform how we understand forests and the carbon they store. Along with other space agencies’ instruments already in orbit or soon to be launched, there has never been so many ‘eyes in the sky’ focused on forests.

Yet, the work of people on the ground –often in the most remote and challenging forest regions – also remains essential.

The ESA Biomass satellite’s P-band synthetic aperture radar is capable of slicing through even the densest forest canopies to measure tree trunks, branches, and stems – which is where most forest carbon is stored. These measurements act as a proxy for carbon storage, the assessment of which is critical to better understanding Earth’s carbon cycle.

Soon, it will be joined by the US–India NISAR mission, an L-band synthetic aperture instrument designed to provide complementary data. Together with NASA’s GEDI lidar system already aboard the International Space Station, the Copernicus Sentinel-1 C-band radar mission and other missions, together they offer an unprecedented view of Earth’s forests.

Meanwhile, ESA’s Climate Change Initiative’s Biomass Project uses long-term data from these different sources to provide a transparent, consistent picture of the state of the world’s forests and assessment of annual biomass change over time. This information is used to understand both carbon cycle and forest dynamics and, when combined with climate models, contribute to improved prediction of future climate change.

Despite their sophistication, spaceborne instruments do not directly measure forest biomass or biodiversity. Ground validation is essential – especially in tropical forests, where the sheer diversity of plant species and ecosystems defies easy classification from space.

“Even the most advanced satellite can’t tell a mahogany from a Brazil nut tree without help from the ground, and there are more than ten thousand tree species in the Amazon alone,” said Professor Oliver Phillips from the University of Leeds, who contributes validation efforts with colleagues

This is where the global network of forest scientists, botanists and technicians comes in – many of whom work in challenging, under-resourced and often dangerous conditions. Long-term, on-the-ground measurements are needed to verify satellite readings, ensure accuracy and maintain consistent records over time.

To support this vital work, researchers from across the forestry, ecology, and remote-sensing fields launched GEO-TREES, a global initiative aimed at uniting these communities and promoting fairer, more equitable scientific partnerships.

ESA’s Biomass Mission Manager, Klaus Scipal, explains, “The aim of GEO-TREES is to establish a sustainable funding mechanism to support ecologists and experts working in the forest to take the tree-by-tree measurements that are needed to validate satellite data products.

“GEO-TREES will implement rigorous ground-validation protocols and push for major investments in the people behind the data – particularly in the Global South, where much of the world’s biodiversity resides.

“Satellites, such as our Biomass, offer a wealth of information to understand our changing world, but we must not forget those working tirelessly on the ground taking in situ measurements, often in difficult conditions, who allow us to have confidence in the data returned from space.”

ESA’s Director of Earth Observation Programmes, Simonetta Cheli, added, “The dedicated teams working in the field to collect vital ground-truth data are important to the success of our missions.

“Their contributions help ensure that our Earth Explorer missions deliver outstanding science – science that lies at the core of our FutureEO programme.”

Read the ESA article: https://www.esa.int/Applications/Observing_the_Earth/FutureEO/Biomass/A_new_space_age_for_forests_but_groundwork_still_matters

The photograph shows measurements being taken of a tree in forest close to Nova Xavantina, Mato Grosso, Brazil. In this case, a tricky balancing act. Credit: Bia Marimon.

Accurately measuring and identifying trees in tropical forests needs skill and courage. To measure the diameter of a giant Ceiba in Colombia’s Pacific Rainforest, three researchers from partner network ‘Col-Tree’ climbed 12 metres. This is the most practical, accurate way to measure large trees when there is no power and scanners are not deployable. Credit: P. Kindler