Preparing a tree planting zone map for landscaping in the southern part of Japan

Abstract

The purposes of this study are 1) to define a dominant temperature factor which governs tree planting distributions and 2) on the basis of the factor, to prepare a tree planting zone map for landscaping for the southern part of Japan. The results are as follows.
(1) A limmiting factor in the north: It was found that the dominant temperature factor which limits tree planting distributions northerly in the southern part of Japan was different from that in the northern part of Japan, Hokkaido. That is, in Hokkaido, the distributions are dominantly limited by average annual minimum temperature rather than “Index of Warmth” due to the sharp fall in the former as compared with the latter. In the southern part of Japan, however, “Index of Warmth” which indicates the degree of warmth during the growing seasons, is the dominant limiting factor in the north.
(2) A limiting factor in the south:“Index of Warmth” was found to be the most dominant factor limiting tree planting distributions in the south among the three possible factors compared; average annual minimum temperature, “Index of Warmth” and August average maximum temperature.
(3) According to the above facts, a tree planting zone map for the southern part of Japan was prepared on the basis of “Index of Warmth, ” a common factor dominantly governing both northern and southern limits of the distributions. A total of 318 tree species were assigned according to the zones in which they will normally grow.
*Calculated by suming the normal monthly mean temperatures minus 5°C of all months with a mean temperature above 5°C.