How Satellites Transform Biodiversity Monitoring in Tropical Forests

There is something almost magical about viewing a forest from orbit. Satellites positioned hundreds of kilometres above Earth can now monitor the canopy, calculate biomass and even show how a forest functions and recovers following a storm.

Scientists have become remarkably capable of doing this. Yet a major new review highlights an important limitation: despite everything satellites can observe, they remain largely unable to answer some of the most basic questions about what is actually living below.

Jesús Aguirre-Gutiérrez, an associate professor at the University of Oxford, led the review. Its co-authors are based in the UK, Mexico, the USA, South Africa and Japan.

Countries have a data problem

Behind the science lies a very practical challenge.

Nations that joined the Kunming–Montreal Global Biodiversity Framework - the agreement associated with the widely known target to protect 30 per cent of land and sea by 2030 - require a consistent method for measuring whether biodiversity is genuinely improving.

This is difficult even close to home. Across remote, vast or almost inaccessible landscapes, it becomes an enormous challenge.

Satellites, LiDAR, radar and airborne sensors are helping to fill this gap.

The review brings together current knowledge of how such technologies are being used to monitor ecosystem change at scale. They offer what field surveys cannot: consistent, near-continuous observation across immense areas of the planet at the same time.

Why rainforests get the spotlight

Tropical forests provide the review’s main example, for understandable reasons. They contain around half of the world’s terrestrial biodiversity despite occupying only a small fraction of Earth’s land area.

Meanwhile, these forests face increasing pressure from climate change, land clearance and wider disturbance.

Satellites are becoming particularly effective at monitoring forest structure, biomass, canopy characteristics and the way these ecosystems function.

This information enables researchers to address a question that is otherwise exceptionally difficult to quantify: how effectively a forest recovers after damage, withstands additional disturbance and adjusts as surrounding conditions change.

That is essentially what ecologists mean by resilience, and space is proving to be an unexpectedly useful viewpoint from which to observe it.

Reading between the pixels

Satellites can also serve as indirect indicators of biodiversity itself, providing clues about functional and taxonomic diversity.

To a more limited degree, satellite information can also suggest patterns in genetic and evolutionary diversity.

These proxy signals are becoming increasingly valuable for initiatives such as Essential Biodiversity Variables, which seeks to standardise biodiversity measurement regardless of the tools or data sources used.

However, a proxy remains only a proxy. The review makes clear that remote sensing, however capable it becomes, cannot independently provide a complete picture of biodiversity.

What satellites still can’t see

Several of biodiversity’s most fundamental questions remain effectively invisible from orbit.

With current technology, species turnover, evolutionary history and genetic diversity cannot be clearly detected in satellite data. They still depend on work on the ground, with researchers counting, sampling and observing directly.

Satellite data and field ecology are therefore not rival approaches but complementary methods. Without either one, biodiversity assessments begin to break down.

“Remote sensing is transforming how we can observe biodiversity and ecosystem change at large scales,” Aguirre-Gutiérrez said.

“Satellites now provide unprecedented information on forest structure and function, helping us understand how ecosystems respond to disturbance.”

“However, this is not a complete solution. Many dimensions of biodiversity are still difficult to observe directly from space, which is why combining satellite data with field observations remains essential.”

“Future satellite missions will continue to expand what we can measure, but biodiversity monitoring will always depend on integrating multiple sources of evidence.”

The next generation of satellites

The review identifies an approaching new generation of satellite missions and more precise sensor technologies, including improved hyperspectral imaging, more advanced LiDAR and enhanced radar systems.

Over coming years, these improvements should significantly broaden what can be measured from orbit, reducing some existing gaps in structural and functional monitoring.

The more profound questions around genetics and evolution, however, are likely to remain beyond satellites’ reach for some time.

Why a study like this matters

Forests account for roughly 31 per cent of the planet’s land surface and have an enormous role in climate regulation. Their condition is therefore central to whether the world can meet its conservation goals at all.

However, biodiversity monitoring worldwide is currently uneven and incomplete, particularly in tropical regions - precisely where satellite data could, in theory, offer the greatest support.

The authors do not present satellites as a silver bullet, regardless of how rapidly the technology advances.

For the Global Biodiversity Framework to work in practice, remote sensing, field ecology and newer systems such as Essential Biodiversity Variables must be combined rather than relying entirely on any one method.

As Aguirre-Gutiérrez concluded, biodiversity monitoring will always rely on integrating multiple sources of evidence, however sharp the eventual view from space becomes.