Remote sensing estimation of forest LAI in close canopy situation. Internet

This study attempts to find a new and better approach to estimate forest LAI in fully closed canopy condition. Although there have been many previous studies to estimate LAI using optical remote sensor data, there are not enough evidences whether the red and near-IR reflectance are still effective to estimate forest LAI in closed canopy situation. In this study, we have conducted a simple correlation analysis between LAI and spectral reflectance at two different settings: 1) spectral measurements on the multiple-layers of leaf samples and 2) Landsat ETM+ reflectance with field-measured LAI on the close canopy forest stands. In both cases, the correlation coefficients between LAI and spectral reflectance were higher in short-wave infrared (SWIR) and visible wavelength regions. Although the near-IR reflectance showed positive correlations with LAI, the correlations strength is weaker than in SWIR and visible region. The higher correlations were found with the spectral reflectance data measured on the simulated vegetation samples than with the ETM+ reflectance on the actual forests. In addition, there was no significant correlation between the forest LAI and NDVI, in particular when the LAI values were over three and full canopy situation. The SWIR reflectance may be important factor to improve the potential of optical remote sensor data to estimate forest LAI in close canopy situation