Assessing whether Japanese National Forest Inventory Plots Were Re-measured:

Analysis in Private Forests of the Toyama Prefecture, Japan

Abstract

　Forest dynamics can be documented in detail by repeatedly measuring permanent plots. The Japanese National Forest Inventory (NFI) aims to estimate forest resources and dynamics over large regions. NFI plots were established on a 4-km national grid and were expected to be re-measured every 5 years. In private forests of the Toyama Prefecture, a plot was established during the first NFI in each of the 101 grid points (1999－2003) . To clarify data availability for analyzing forest dynamics at a prefecture level, this study examined whether these 101 plots had been re-measured until the third NFI (2009－2013) . Twelve plots were abandoned because of difficulty in accessibility; thus, the third NFI measurement was not performed. During the second or third NFI measurement, locations of 11 plots could not be found; thus, alternative new plots were established at different locations. Plot shapes were converted from square to circle at a single location in 20 plots. Data from these transformed plots can sometimes be regarded as equivalent to data from re-measuring plots. Only 58 plots were re-measured; therefore, data were flawed regarding analysis of forest dynamics. Provisions for future NFI measurement to enhance data continuity and availability were discussed.