Studies on the Beef wood (Casuarina equisetifolia Forst.) forests on the sea shore in the northern district of Okinawa Island.

Since Mokumao (Casuarina equisetijolia Forst.) has been planted extensively at the most prospective silvicultural species to protect forests, agricultural products, etc. from damages caused by tids of the Ryukyu Islands. The aim of this study, therefore, was to obtain the data on Mokumao in order to find whether it is useful or not for improving the forests of this country. This research deals with an analysis of the relationship of the growth of various parts of trees from Northern Okinawa with respect to density of stand, wind, and soil influence according to the age of the trees. The analysis is mainly based on the sample trees collected from various forests different with respect to such facters as stand density, wind, and etc. 1. The growth of Mokumao growing lose to the sea is greatly influenced by the typhoons which usually come late spring and fall, and by the winter monsoons. The growth of this tree on the other hand is not greatly influenced by soil type and stand density. The younger trees are severely damaged by these winds. The growth relationship study of trees planted in different areas (1, 2, 3) a which are confonted by very strong wind shows the following results. The slope of growth in area 2 is sharper than that of area 1 and damages by storms are far less in area 2 than in area 1. Although the slope of growth in area 3 is greater than that in area 2, the difference between the two areas is not as remarkable as that of 2 and 1, and the growth of trees in area 3 is not significantly influenced by storms, but it is, on the other hand, greatly influenced by soil type and stand density. 1) Density of crown Weight of green leaves of 1 ha. is 5.09 ton. Width of forest About 5 meters. Age of stand 9. Location Nearest side of sea, Onna son. 2) Density of crown Weight of green leaves of 1ha. is 4.37 ton. Width of forest About 35 meters. Age of stand 9. 3) Density of crown Weight of green leaves of 1ha. is 4.63 ton. Width of forest About 30 meters. Location Next to of 2 district, Onna son