Assessing Potential Distribution of Beech ( Fagus crenata) in Central Japan

Abstract

Two different predicitve distribution models, the one for forests and the other for individuals, of Fagus crenata were developed in central Japan. Four climatic variables were used as predictor variables and two different types of vegetation data sets were respectively used as response variables. Tree-Based Models were adopted for the model development. The dataset for the F. crenata forests was 1-km2 vegetation data based on an actual vegetation map, and the other dataset for F. crenata individuals was obtainded from over 4.500 Phytosocialogical Relevé Data Base (PRDB). Predicted presence/absence of F. crenata forests and individuals for every 1-km2 grid square were classified into four groups. Grid sqaures classified as "F. cenata forest absence" and "F. crenata indivudal prensence" covered 5.6% of the study area. These areas consist of reltively higher proportions of deciduous Quercus crispula-Castaneae crenata fores and Q. serrata-Cerasus verecunda forest at low elevations, and Abies mariesii fores and Betula ermaniii forest at hig elevations. Two important threshold warmth index (WI) values for. F creanta indivudals were found to be 38.5 and 93.2. This was wider tha the WI range of 46.2 and 87.8, which were found in the F. crenata dominant forest model. These findings revealed that PRDB is a useful source for modeling plant species ditributions and for impact assessment studies of climate change.