日本扁柏生物学及其引种研究

Japanese Cedar ( Chamaecyparis obtusa ) Grown in China

日本扁柏是优良用材、荒山绿化和园林观赏树种 ,世界各国广为引种栽培 ,已成为我国长江中下游地区中、高山地带的重要造林树种。对其地理分布、生物生态学特性、栽培技术等进行了研究总结。结果表明 ,日本扁柏是一个喜温暖湿润的浅根性树种 ,生长快 ,适应性强 ,繁殖容易 ,病虫害少。适合中性至微酸性土壤 ,可耐 - 2 5℃低温。较喜光 ,幼时稍耐庇荫。春季日均温大于 10℃时开始萌动 ,超过 15℃时开始生长 ;生长具明显的坡向和坡位效应 ;树高速生期为 10～ 2 0 a,>5 0 cm·a-1;胸径速生期 2 0～ 30 a,>0 .6cm· a-1;材积速生期 30～ 40 a。可进行种子或扦插繁殖 ,结实有丰歉年 ,种子发芽率 30 %～ 40 %。造林密度为 2 5 0 0～ 45 0 0株· hm-2 ,以不超过 30 0 0株· hm-2为好。目前我国引种栽培日本扁柏的主要问题是 :( 1)遗传基础狭窄 ,需引进更多的种源和家系 ;( 2 )大多为纯林 。

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 3 000 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.