Assessing how changes in our climate are affecting ecosystems and hydrosystems is vitally important – unfortunately, in many ways, assessing these changes is much simpler in woody mountain ranges than it is in the semi-arid ecosystems that dominate much of the west.
The most common tools for conducting large-scale terrain studies are with remote sensing, such as lidar, However, these tools use large or leafy biomass (think: forests) to gauge vegetation and hydrologic changes on a grand scale.
But as geosciences doctoral student Nayani Ilangakoon explained, western ecosystems often contain short-height vegetation structures, like sagebrush, which are critical for balancing global carbon dioxide levels – but aren’t as easily captured by remote sensing and traditional discrete return lidar. Sagebrush also are particularly susceptible to human disturbances and land use, as well as natural disturbances like drought, fire and climate change – all of which impact the ecosystem structure and hence the hydrologic cycle at the local and regional level. Agriculture and municipalities are reliant on western watersheds to survive, so the impacts of future hydrologic changes could be significant.
“There is very limited research going on that tells us how vegetation type and structure influences hydrology in an ecosystem, but we do know disturbances change the hydrocycle and the ecosystem itself,” Ilangakoon said. “It also changes the soil carbon, habitat quality – really everything – so assessing vegetation is critical.”
Reynolds Creek experimental watershed in southwest Idaho shows a range of plant functional types with varying density and structure. The study area also shows a gradient of topography (right), which controls both vegetation and hydrosystems.
There is a silver lining: Ilangakoon recently was selected as one of 69 graduate students (out of a pool of 385 nationally) to be awarded a NASA Earth and Space Science Fellowship for her proposal to analyze data collected in the Owyhee mountains and Colorado’s Grand Mesa using a full-wave form of lidar.
The Owyhee data was collected by NASA for a terrestrial ecology project awarded to Boise State researchers Nancy Glenn and Lejo Flores, while the Colorado data is part of NASA’s SnowEx campaign and includes data from periods when areas have snow coverage and when they have none. Full-waveform lidar can detect the structure of vegetation and other biophysical characteristics with more accuracy, given western states’ unique and sparse terrain.
Ilangakoon’s three-year fellowship includes a $45,000 annual stipend, which covers tuition at Boise State, as well as a stipend, health insurance and travel costs for her project.
“If we can characterize ecosystem structure with low uncertainty, we can predict ecosystem function, and its relationship with snow accumulation, snow water storage, soil moisture and runoff,” she explained.
Ilangakoon’s project dovetails nicely with NASA’s upcoming mission, Global Ecosystem Dynamics Investigation Lidar (or GEDI), during which astronauts will mount a sensor to the international space station to collect lidar data globally. The GEDI mission is to assess global biomass and carbon change.
Some of the information generated from the lidar waveforms (especially the 3D height) can be used to generate both 3D and 2D images to represent the study area vegetation and topographic features.
“That system has a very large footprint, it captures a big area, like 25 meters,” Ilangakoon said. “The system I’m working on is less than 50 centimeters. But we have to evaluate how we can use those systems, like GEDI, to evaluate our ecosystems in the west because we have very low-height vegetation here. I’m analyzing with small-footprint data how we can do this for shrubs and trees. I have a simulated waveform that’s equal to GEDI.”
Boise State graduate student Ann Marie Raymondi spent part of her NASA fellowship at NASA’s Goddard Space Flight Center learning about GEDI and the potential for applications in the western U.S.
Ilangakoon credits geosciences professor Glenn,her Boise State advisor, for her help in preparing her proposal and guiding her through the application process.
BY: CIENNA MADRID PUBLISHED 12:40 PM / JULY 12, 2017