GIS at SEV: Waveform Lidar, RapidEye Remote Sensing and the Southwest Ecological Observatory Network

Currently at SevLTER we are developing GIS capability in terms of providing modern SDE geodatabase driven processing and access for site spatial data and metadata. Perhaps more importantly, we are leveraging remote sensing GIS data to answer questions about ecosystem processes. SevLTER Co-PI Marcy Litvak, UNM PhD candidate Dan Krofcheck, Andrew Fox (NEON) and Amy Neuenschwander (UT-Austin) will utilize waveform lidar remote sensing data acquired in 2011 to characterize vegetation structure and estimate above ground biomass within the tower fetches of a network of 8 eddy covariance towers in NM and TX which represent an ecological gradient from black grama desert grassland on up through spruce-fir coniferous woodlands. The analysis, funded by the NASA ROSES Carbon Cycle program, is intended to reduce uncertainties regarding regional carbon dynamics in the Southwestern US by coupling a more accurate estimate of vegetation structure using full-waveform lidar to direct measurements of ecosystem-atmosphere carbon exchange from the towers. The lidar and tower data will be incorporated into the Community Land Model (CLM), a land surface model  (LSM) using a model-data fusion (MDF) framework to improve regional carbon budgets and predict the response of C dynamics in semi-arid ecosystems to changing climate and disturbance. Litvak, Krofcheck and colleagues from Idaho State University are also exploring means of measuring large changes in ecosystem structure, remotely, and relating those measurements to the change in function of the ecosystem as measured in-situ using eddy covariance techniques. In this case the analysis is constrained to piñon-juniper woodlands found at a pair of tower sites and the GIS data used is a time series of 42 images for both sites using the RapidEye constellation of satellites and classified using NDVI (Normalized Difference Vegetation Index) as a proxy for LAI and NDRE (Normalized Difference Red Edge) as an approximate for Chlorophyll concentrations calculations. At one of the PJ sites, all adult piñon in the tower fetch were girdled to simulate piñon mortality. The massive change in ecosystem structure following the selective mortality of the piñon overstory in the manipulation site has resulted in some drastic changes in ecosystem function which researchers hope can be detected using vegetation indices from the time series GIS dataset.

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