Huemmrich, Karl (Fred): NASA GSFC / UMBC (Project Lead)
Campbell, Petya: NASA GSFC / UMBC JCET (Co-Investigator)
Middleton, Elizabeth (Betsy): NASA GSFC (Co-Investigator)
Tweedie, Craig: University of Texas at El Paso (Co-Investigator)
Vargas Zesati, Sergio: University of Texas at El Paso (Post-Doc)
Nwigboji, Ifeanyi: University of Texas at El Paso (Student-Graduate)
Project Funding:
2016 - 2020
NRA: 2016 NASA: Terrestrial Ecology
Funded by NASA
Abstract:
Long-term satellite data records show greening of high latitude terrestrial ecosystems based on change in NDVI with strong trends in the coastal arctic. This proposal is directed at investigating how changes in biodiversity and tundra carbon and energy balance are related to the change in NDVI. Tundra vegetation groups into several different plant functional types (PFT) such as vascular plants, lichens, and mosses. These PFT have very different physiological responses and thus lead to differential growth rates, carbon fluxes (GPP), and energy balance under varying environmental conditions. The distribution of these PFTs over the arctic landscape is key to describing patterns of biodiversity and carbon fluxes and understanding responses to climate change. Spatial distributions of vegetation functional types are strongly related to surface microtopography with surface hydrology being a significant controlling factor. Warming and melting permafrost alter surface hydrology (wetting or drying), with moisture affecting surface-atmosphere fluxes and albedo.
Resulting changes in PFT distribution and surface hydrology impact ecosystem function, which will, in turn, require changes in how these systems are modeled as well as the interpretation of remotely sensed signals. Key drivers for remotely sensed spectral reflectance are vegetation structure, physiology, and phenology, which are all factors that describe plant functional traits thus providing physical links between remote sensing and plant physiology. We will utilize small-plot measurements of spectral reflectance and carbon fluxes to describe the spectral characteristics and light use efficiency of different PFTs. These data will be used to develop spectral unmixing approaches for describing the fractional coverage of the tundra PFT that will be applied to the AVIRIS and other aircraft imagery from the ABoVE airborne data collection. We will use the PFT information to parameterize models of carbon and energy fluxes, testing the results against flux tower measurements. The spatial change encountered along the flight lines will be used to examine how relationships between NDVI and carbon fluxes vary to evaluate how a greening NDVI signal relates to changing tundra biodiversity and carbon fluxes.
Publications:
Huemmrich, K. F., Gamon, J., Campbell, P., Mora, M., Vargas Zesati, S. A., Almanza, B., Tweedie, C. E. 2023. 20 years of change in Tundra NDVI from coupled field and satellite observations. Environmental Research Letters. DOI: 10.1088/1748-9326/acee17
More details may be found in the following project profile(s):
