神农架南坡珍稀植物独花兰的物候、繁殖及分布的群落特征

The phenology, reproduction and community characteristics of Changnienia amoena, a rare species in southern part of Shennong-jia Mountain range

神农架南坡独花兰分布的群落一般位于坡度 1 5～ 45°的阴坡 ,海拔范围为 1 30 0～ 1 70 0 m。土壤类型主要为山地黄棕壤 ,p H值 5 .0～ 5 .6。9月中下旬独花兰地下假鳞茎萌芽出土并开始展叶 ,1 1月中下旬抽生花葶 ,次年 3月下旬开花 ,4月下旬至 5月上旬叶片逐渐枯死 ,地下部假鳞茎开始发育 ,9月中下旬假鳞茎发育成熟 ,1 0月下旬至 1 1月上旬果实成熟。独花兰的结实率两年的调查结果差异较大 ,分别为 2 .3%、9.5 %。每株独花兰每年能长出 1～ 3个假鳞茎 ,抽生 1～ 3个叶片和花葶。神农架南坡独花兰主要分布在以化香 ( Platycarya strobilacea)、四照花 ( Dendrobenthamia japonica)、华千金榆 ( Carpinuscordata var.chinen-sis)等为主的落叶阔叶林下以及以箬竹 ( Indocalamustessellatus)灌丛下 ,群落物种组成中北温带成分占绝对优势。群落遭到不同程度的人为干扰 ,随着干扰强度的递增 ,独花兰在不同群落中的个体数量有递减的趋势 ,在郁闭的森林下个体数量最大而箬竹灌丛下最小。人为干扰、结实率低、种子萌发困难是导致独花兰濒危的主要原因 ;建立保护区 ,恢复独花兰分布区的森林植被是保护独花兰的有效途径。

Changnienia amoena is a rare species endemic to China, which belongs to Orchidaceae. In order to understand why this plant has been endangered, we studied the phenology,reproduction and community characteristics of C. amoena populations that occurred in southern part of Shennongjia Mountain range. Thirteen plots were sampled to investigate the community composition. Our results showed that C. amoena generally distributed on shaded slope of 15~45°, with altitudes of 1300~1700m. Its buds emerged to above ground at middle or late September. Scapes took place in the mid-November. Flowers bloomed in mid-March of the next year, and leaves started to shed off in late April or early May. New pseudo-bulbs began to appear in late April or early May and matured at middle or late September. Seed capsules ripened in early November. The fruiting percentage was low and varied from 2.3% to 9.5% in two years. One plant produced 1~3 new pseudo-bulbs thus one plant could produce 1~3 scapes per year. The population of C. amoena in Shennongjia region distributed mainly in those forest patches dominated by Platycarya strobilacea, Dendrobenthamia japonica, and Carpinus cordata var. chinensis. These species belongs to North Temperate floristic elements according to Wu's system. Evergreen species was rare in these patches. All of these forest patches were heavily disturbed, and the population of C. amoena was endangered. The number of plants of C. amoena decreased with the increasing of disturbance intensity. Heavy disturbance, low fruiting rate, and low germinating rate were the major causes resulting in the endangered situation of C. amoena. We suggest establish nature reserve in order to restore forest vegetation and to conserve C. amoena.