Remote sensing of LAI-FPAR fluctuations and Synchrotron EXAFS-XANES studies of metal absorption under stress

The fluctuations of leaf area index (LAI) and Fraction of Photosynthetically Active Radiation (FPAR) as reported by the MODIS 8-day product MOD15A2 over a section of Harriman State Park, New York were studied with reference to another nearby local park. The area selected for study, a seven km square grid with one km resolution, is known for its biodiversity. Time series data points were generated using the sums of the grid's 49 pixel measurements for each of the 46 entries that make up the annual time series. A quadratic relation has been observed that suggests that LAI/FPAR is proportional to FPAR if FPAR is considered as the forcing parameter via chlorophyll (a, b, c, d and f), in an application model for the study of biodiversity. The LAI annual time series from 2000 to 2009 follows the corresponding FPAR annual time series as expected, but with different proportionality ratios in different seasons. The fractal analysis results of the time series data suggest that the LAI sequences have a lower fractal dimension (~1.35) than those of the FPAR sequences (~1.55), consistent with the idea that biological systems are capable of regulating fluctuation. The regression of LAI sequence fractal dimension versus FPAR sequence fractal dimension exhibits an R-square of about 0.7 (N =10). The observed regression outlier for the year 2009 could be indicative of the presence of additional factors. Synchrotron EXAFS and XANES investigations of leaf samples reveal data consistent with metal absorption under stress. Further studies of absorption under stress using remote sensing data are warranted.