Northern Arizona University monitors biodiversity in US with space lidar

In a recently published first-of-its-kind study, Northern Arizona University (NAU) research professor Chris Hakkenberg shows how laser-based technologies can mitigate the impact of global biodiversity loss: by monitoring biodiversity across the United States using NASA’s Global Ecosystem Dynamics Investigation (GEDI) space-borne lidar — which can detect 3D forest structure from the International Space Station.

The study was inspired by coordinated international efforts, including the Convention on Biological Diversity’s plea to scientists to explore using satellite remote sensing to monitor trends in global biodiversity. The work is described in Environmental Research: Ecology.

Hakkenberg says the research shows it is possible to go beyond conventional 2D imaging and use the entire 3D structure of forests to predict habitat for plants and animals. “We are using space-borne lidar to estimate the entire 3D structure of forests which we can then use to predict the biodiversity contained within,” he said.

“We can go beyond just measuring tree heights but also get a clear picture of the entire vertical distribution of branches, leaves and needles from the ground to the top of the canopy.”

Linking structure and biodiversity

Because forest structure is related to variation in the size and form of different species of trees, Hakkenberg and colleagues were able to use 3D waveform profiles of forest structure to model a relationship between tree structure and tree biodiversity measured with field data from the National Ecological Observation Network across the United States.

“While attention to biodiversity-structure relationships has been growing in the international research communities over the last decade, it has generally focused on tree species diversity because trees form the essential building blocks of forests and are large enough to be detected from space,” Hakkenberg said.

“But what was really interesting about our findings is that these biodiversity-structure relationships extend to plant biodiversity too. Even though we can’t directly detect individual ground plants from the space-borne platform, we can predict the diversity of those plants from the 3D characteristics of the trees that surround them.”

Monitoring biodiversity across the United States using NASA’s GEDI space lidar.

Over the coming years, increasing amounts of remote sensing data from airplanes and space-borne sensors will be paired with field observations, providing scientists with efficient ways to monitor biodiversity at global scales. Through these detailed maps, more can be learned about biodiversity loss and thus where to shift efforts to slow and eventually stop it.

Hakkenberg and his colleagues from the School of Informatics, Computing, and Cyber Systems, including research associate Pat Burns; research professors Patrick Jantz and Zaneta Kaszta; Regent’s professor Scott Goetz; and graduate students Colin Quinn and Melissa Rose, are excited about their findings.

They hope this study moves the needle on continental-scale biodiversity research by employing state-of-the-art NASA technologies and brings increased attention to biodiversity loss.

“It is extremely urgent that we devise better ways to map and monitor biodiversity at large scales, like we do for climate change,” Hakkenberg said. “This study is a part of that greater effort, giving us a fighting chance to address these issues before it’s too late.”