Japanese Cedar (Chamaecyparis obtusa) Grown in China

Chamaecyparis obtusa Endl.,introduced from Japan,has become one of the important tree species for plantations in subtropical zones in China. In this paper,the geographical distribution,biology,ecology,genetics,and silvics were studied and reviewed for the species. The results showed that:(1)it is a fast-growing tree with shallow roots,the annual increment is 50 cm for tree height and 0.6 cm for DBH;(2) it can be planted in a variety of ecozones,but best planted in warm and humid sites although it can tolerate a minimum air temperature of -25℃,with soil pH 5.0～7.2;(3) the slope and altitude have significant influence on its growth rate;(4) it releases dormancy and begins to grow in Spring when the air temperature reaches 10℃ and 15℃ respectively;(5) it can be propagated by seeds or by cuttings,the germination percentage is 30%～40%;(6) the initial planting space is from 1.5 m×1.5 m to 2.0 m× 2.0 m,but less than 3000 trees per hectare is preferred. Finally,it is pointed out that for Japanese cedar in China,the major problems are the narrow genetic base for plantations,and only pure stands have been established,which is apt to lead to site decline.