濒危植物沉水樟的濒危机制研究

Endangering Mechanisms of Cinnamomum micranthum Hayata

2003-2004年对沉水樟生殖物候进行了连续2年的野外定位观测，从沉水樟的生殖繁育过程及其种子品质两方面对其有性生殖过程进行系统研究，以探讨沉水樟种群濒危机制。结果表明：（1）沉水樟的花期长达3个月，而盛花期只有15d左右，杂交指数值为2，繁育系统类型为兼性自交。花粉胚珠比值为244．7～2588，为风媒传粉的自花授粉植物；（2）沉水樟种子横径为0．50～O．83cm，纵径为0．87～1．28cm，结实量比较多，但由于不同物候期重叠，落果率高，果实产量低；（3）沉水樟的生育期长达19个月，其中果实发育期16个月，在漫长的生殖发育过程中易受环境因素影响，种子病虫危害严重，存在严重的空心现象，影响了沉水樟种群的天然更新，这是导致沉水樟种群濒危的主要原因。同时人为破坏和对现代生境不适应也是影响沉水樟种群濒危的原因。

The phenology of Cinnamomum micranthum Hayata was position observed in the field in two consecutive years to study its reproductive system and process and seed quality in order to look for the mechanisms in endangering C. micranthum populations. It was shown that（1）C, micranthum had a threemonth flowering period and a outcross index of 2 belonging to a typical facultative inbred type,its pollen to ovule ratio ranged within 244. 7-2 588 and its pollen dispersal was anemophilous; （2）C. micranthum pro- duced great quantities of seeds that were 0.50-0.83 in transverse diameter and 0.87-1.28 in lengthwise diameter, but because of its overlapped phenophases it had a high fruit-setting rate and a low fruit yield ; （3） C. micranthum needed as long as two years to develop its fruits and thus during such a long developmental period it was liable to be affected by environmental factors and its seeds suffered severe disease and insect damage thereby resulting in their severe hollowness,which was the main reason why C. micranthum was one endangered species. In the meantime,human disturbance and poor adaptability to modern environments were also the reasons for C. micranthum to become endangered.