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

Abstract

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.

Acknowledgments

This research was supported by the Grant in aid of the Ministry of Education, Culture, Sports, Science and Technology of Japan under Grant 11794029. The Library of Gifu Prefecture is also thanked for allowing the sharing of partial original satellite data.

A part of the results displayed in the present article was previously reported by the authors in the Japanese paper: Quantitative assessment of the nitrogen fixation by forest vegetation in the Nagara River basin using Landsat TM data, Journal of the Japan Society of Photogrammetry and Remote Sensing, 42, 12–20, 2003 (in Japanese with English summary).