Imagine farmers growing crops not for food but to sequester carbon dioxide. Under the state’s cap-and-trade program, such scenarios are possible, though there are many details to hash out – not the least of which is putting hard numbers to the carbon-credit value of different types of vegetation. In research that may help in this effort, the Delta Science Fellow is attempting to develop a method for calculating vegetative cover (“leaf area index”) in key wetlands of the Sacramento- San Joaquin River Delta, using NASA Landsat satellite images.
Her work to date has focused on collecting fish-eye images and light-intensity readings of plant communities at freshwater marshes on Twitchell Island and Sherman Island and tidal wetlands at Suisun Marsh. From these data, she is able to calculate local estimates of leaf area index. At present, these field estimates of leaf area index are being compared to Landsat satellite-based metrics for the same areas, and preliminary results indicate significant correlations between field and satellite estimations. Once the techniques for estimating LAI from satellite data are refined, scientists will be able to use the Landsat images to reconstruct vegetative cover and density over a 30-year period for the entire delta. This reconstruction will facilitate an ongoing NASA-funded study to quantify net carbon fluxes in wetlands in the delta. Other applications of the project include being able to better monitor trends in wetland bird habitat quality and recovery trajectories for various habitat restoration projects.
Research mentor: Peng Gong, Department of Environmental Science, Policy, and Management, UC Berkeley
Community mentor: Kristin Byrd, USGS Western Geographic Science Center