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Harvard Forest Symposium Abstract 2013

• Title: Canopy Phenology, Remote Sensing, and Microclimate.
• Primary Author: Mark Friedl (Boston University)
• Abstract:

  The goals of this research project are (1) to develop improved methods for monitoring phenology from multiple remote sensing sources, and (2) to use data acquired through this effort to improve models of phenology at scales commensurate with large-scale ecosystem models. To achieve this goal, we are collecting long-term measurements that quantify how above and below canopy radiation fluxes vary as a function of seasonal leaf dynamics. Specifically, we are continuously measuring above- and below-canopy radiation fluxes in both the PAR and solar spectral bands. Time series of these measurements provide surrogate measures of canopy leaf area dynamics, and directly characterize the shortwave radiation component of the surface energy balance. These measurements also complement ongoing microclimate and eddy covariance measurements of water, energy, and carbon exchange at the EMS tower. Core measurements being collected focus on photosynthetically active radiation (PAR) measured using LI190SB LI-COR quantum radiation sensors. Five below-canopy sensors mounted on posts approximately 0.5 meters above the ground surface and located roughly 20-m from the walk-up tower at equidistant spacing measure downwelling PAR below the forest canopy. Above-canopy quantum sensors measure upwelling and downwelling PAR, and are mounted on a boom extended from the tower at a height of 23-m. Downwelling and upwelling solar radiation measurements are also recorded using a Kipp and Zonen thermopile pyranometer, and global (total) and diffuse PAR measurements are measured using a BF3 sunshine sensor (both at 23-m). Soil temperatures at 20-cm depth are measured with Campbell Scientific 107-L probes in four locations co-located with PAR sensors. Air temperatures are measured using a shaded CS107-L probe at 23-m. Previous field efforts were based at the old walk-up tower site adjacent to the EMS tower (the location of the new NEON tower). Field data collection is currently suspended, but we plan to resume these activities when construction of the new walk-up tower adjacent to the NEON site is complete. Data collected through this effort will be used in combination with visual observations of phenology collected by Harvard Forest staff, webcam imagery collected by Andrew Richardson’s group, and remote sensing measurements from both Landsat and MODIS to model phenology at local to regional scales.

• Research Category: Ecological Informatics and Modelling
  Forest-Atmosphere Exchange