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Harvard Forest REU Symposium Abstract 2013

  • Title: Assessing and modeling the urban heat island’s impact on deciduous vegetation phenology with Landsat
  • Author: David L Miller (Boston University)
  • Abstract:

    Deciduous vegetation phenology is directly affected by climate dynamics, and is a control on energy and carbon resources in forest ecosystems. It is responsive to temperature variations, such as those resulting from the urban heat island (UHI). Satellite remote sensing can evaluate interannual trends in the magnitude of the UHI’s effect on phenology. Here, we used all available Landsat TM/ETM+ data from 1982-2011 to approximate yearly changes in spring and fall phenology of deciduous broadleaf forest, and quantified the intensity of the UHI with land surface temperature measurements for the Boston, MA metropolitan area. We have found that start of season (SOS) averages 8 days earlier and end of season 8 days later in high-temperature urban areas relative to nearby rural areas. In addition, we utilized daily air temperature data to predict SOS along the urban-to-rural gradient, and such models are capable of approximating interannual changes in SOS. We used Monte Carlo methods to seek parameters for a growing degree day model, the chosen model having a temperature threshold of 5° C, start day of year 90, and a GDD sum of approximately 225. When compared against Landsat-estimated SOS, the model had an RMSE = 7.4 days and R^2 = 0.25 for 1999 onward. These results enhance the spatial resolution of the UHI’s impacts, and the UHI provides a unique glimpse at how forests may develop in the near future with increased temperatures.

  • Research Category: Ecological Informatics and Modelling; Group Projects

  • Figures:
  • DavidMiller-abstractpic.jpg