While rangelands and NASA may seem like an unlikely pair, Lara Prihodko, a college associate professor of animal and range sciences at New Mexico State University, is currently working on two projects featuring the collaboration. Prihodko and other researchers from NMSU’s College of Agricultural, Consumer and Environmental Sciences have turned to satellites to learn more about Earth’s vegetation.
With the ICESat-2 Science Program, which is part of NASA’s Earth Observing Mission, the NMSU team is interested in measurements of woody plants such as shrubs and trees.
“It sounds counterintuitive that a satellite called ICESat-2 that was built to measure ice in the polar regions would be something we would use for rangeland analysis and monitoring,” Prihodko said. “However, ICESat-2 is what we call a photon-counting LiDAR (Light Detection and Ranging) that can measure the precise height of not only the ice or soil surface but also the trees and shrubs growing on the soil. It can be very difficult to measure the low stature, sparse vegetation you find in environments like ours from space, and so our research team, the Savanna Lab, is working to improve those measurements from ICESat-2.”
Prihodko also is working to measure tree height using a waveform LiDAR on the International Space Station, a collabo- ration with Qiuyan Yu, a research assistant professor in the Department of Plant and Environmental Sciences and lead scientist on the Global Ecosystem Dynamics Investigation project. They want to understand the limiting factors for tree height globally.
“In dense forests, it is to some extent much more straightforward to measure many of the properties of the vegetation from space,” Prihodko said. “They are more pronounced in satellite imagery. By contrast, drylands and savannas are more open landscapes with shorter-stature vegetation, which is challenging to measure well from space. We are interested in calculating the carbon stocks in above-ground woody biomass in dryland landscapes, and we needed the measurements of tree and shrub height, so we set out to improve them.”
The NASA-funded projects are challenging because of the sheer size of the datasets they receive, Prihodko said. In addition to the amount of data the team has to evaluate, the material is very complex and has spatial and temporal components that require an assortment of computing techniques.
“Detecting and interpreting the ways that different land-surface components reflect or return energy from the land surface to the sensor requires a lot of different kinds of knowledge about the properties of the land surface, and in the case of LiDAR, the properties of the laser/photon pulse,” she said.
An ACES faculty member since February 2017, Prihodko also is collaborating with Dennis Dye from the Southwest Indian Polytechnic Institute, a public tribal land-grant community college in Albuquerque, to develop a tool to monitor forage resources from space. Featuring research and educational elements, the project aims to create opportunities for SIPI students to interact with NMSU range ecologists.