NEON

Phenology from Space


The high-resolution images from Canopy Height from Space can be integrated with satellite imagery that is gathered more frequently. We will use data collected from MODIS. One common ecological process that can be observed from space is phenology (or seasonal patterns) of plants. Multi-band satellite imagery can be processed to provide a vegetation index of greenness called NDVI. NDVI values range from -1.0 to 1.0, where negative values indicate clouds, snow, and water; bare soil returns values from 0.1 to 0.2; and green vegetation returns values greater than 0.3.

Download HARV_NDVI and SJER_NDVI and place them in a folder with the NEON airborne data. The zip contain folders with a year’s worth of NDVI sampling from MODIS. The files are in order (and named) by date and can be organized implicitly by sampling period for analysis.

  1. Plot the whole-raster mean NDVI (cellStats()) for Harvard Forest and SJER through time using different colors for the two sites.
  2. Plot the mean NDVI of the plot_locations (extract()) for Harvard Forest and SJER through time using different colors for the two sites.
  3. Describe the differences in vegetation structure (chm) from Canopy Height from Space and seasonal phenology (NDVI) that you observe in this analysis in a comment. Also, describe the impact of the different mean calculations on the analysis.

Optional challenge: Extract sampling_day from the NDVI file_name and include that with your data.frame for graphing.

[click here for output] [click here for output]