Spectral characteristics of aboveground biomass, plant coverage, and plant height in Italian ryegrass (Lolium multiflorum L.) meadows

摘要

To investigate the suitability of a hand-held spectro radiometer for estimating grassland productive functions such as aboveground biomass, plant coverage and plant height, spectral characteristics were measured in three Italian ryegrass (Lolium multiflorum L.) meadows in Gifu prefecture. Spectral reflectance in six wavelengths ranging from the visible to the near infrared was measured, and nine vegetation indices were calculated from combinations of spectral data. Leaves in a meadow strongly absorbed blue and red sunlight in the chlorophyll absorption ranges, while strongly reflecting light in the near infrared range. Soil surface conditions as well as vegetation conditions affected these spectral characteristics. It was suggested that grasslandproductive functions show specific spectral characteristics depending on their location and growth stage. The correlation and regression analyses showed that the aboveground biomass (g DM/m~2) was linearly related to the Difference Vegetation Index withr~2 = 0.95 and the K Vegetation Index with r~2 = 0.95, while plant coverage (percent) was linearly related to the Normalized Difference Vegetation Index with r~2 = 0.97. The results suggest that spectral characteristics are suitable for rapidly qualifying vegetation in grassland.