Estimating foliage biomass in a natural deciduous broad-leaved forest area in a mountainous district

The purpose of this study is estimating the foliage biomass in a natural deciduous broad-leaved forest area dominated by Siebold's beech (Fagus crenata Blume) from topographical factors using a geographic information system (GIS). The study was carried out in Kamikawa Village, Niigata Prefecture in central Japan. First, 23 plots were selected in the area and four litter traps were set in each plot. The dry weight of leaves collected with the litter traps was measured and foliage biomass per ha for each plot was estimated. Then, the relationship between them and the topographical factors was analyzed with quantification theory type I and an equation to predict foliage biomass from elevation, slope and aspect was derived. The elevation was classified into four categories of < 500, 500-750, 750-1000 and > 1000 m, the slope into three categories of < 20, 20-30 and > 30 degrees and the aspect into two categories of north which included 0-45 and 315-360 degrees and south which included 45-315 degrees on the basis of our analyses. The coefficient of determination was 0.606 and the ratio of standard error was 9.9%. The category scores showed that the elevation was the most influential factor, followed by the slope and aspect in this order. The combination of 500-750 m, 20-30 degrees and north was the best condition for foliage biomass in a natural deciduous broad-leaved forest in the district. Finally, the forest map and contours were input into the GIS and a digital elevation model (DEM) was developed for the area from input contours with GIS. A study area was classified in elevation, slope and aspect and also classified in forest type using the forest map. The foliage biomass in deciduous broad-leaved forests was estimated for each cell in the area with the equation and also summation for the whole area was obtained. (C) 2001 Elsevier Science B.V. All rights reserved.