Quantitative assessment of nitrogen fixation by forest vegetation using Landsat TM data

An approach to use satellite data to estimate quantitatively the fixation of nitrogen by different forest types over river basin ecosystems was proposed and applied to a mountainous area located in the upper reach of Nagara river basin (Gifu Prefecture, Japan) covered predominantly with multiple vegetation types. In addition to satellite data, this approach also involved the use of census data, statistical data and previous results available in the literature as supporting material. With this approach, the annual amounts of nitrogen absorbed by different categories of forest vegetation classified in terms of species and ages using the satellite data were estimated. Validation tests were performed by comparing the satellite data-based estimations (N-satellite) with estimations from a budget model (N-model) and statistics data (N-record), respectively. The estimated N-satellite values coincided well with the values of N-model and were somewhat larger than those of N-record, although the values of N-satellite and N-record were all in the same order of magnitude for respective forest types classified.