摘要
对金沙江干热河谷攀枝花苏铁（Ｃｙｃａｓ ｐａｎｚｈｉｈｕａｅｎｓｉｓ Ｌ． Ｚｈｏｕ ｅｔ Ｓ． Ｙ． Ｙａｎｇ）种群进行野外调查和定位观察，结果表明：成年植株的雌雄比接近１ｖ１，但开花季节雌雄球花的比例是偏雄性的。雌雄植株在树干大小、叶数、叶大小和无性系小株数目等方面差异不大。叶数、叶长、叶宽、茎直径等随植株年龄的增高而增加。树干３０—４０ ｃｍ 高的植株平均营养叶数和茎直径已基本恒定。树干高１０ ｃｍ 的植株营养叶的长度不再增加。５年以上的植株叶片停止加宽。７０％ 成年攀枝花苏铁萌生无性系，平均每株萌生２．８个无性系小株；具无性系小株植株的比例和单位植株无性系小株的数量都随茎的长高而增加。树干高度与其生长单元数成线性相关，用统计生长单元数的方法可推算植株年龄。营养叶的存活曲线是Ｄｅｅｖｅｙ Ｉ型，大多数的叶片可在植株上存活两个生长单元，随后叶片的死亡率明显增加；
Cycas panzhihuaensis L. Zhou et S. Y. Yang is a rare and endangered Cycad that grows in dry hot valley of Jinsha River. The biological properties, trunk anatomy and growth patterns were studied by field investigation and location observation. The results showed as follows: The sex ratio of cones was strongly male based on reproductive episode. There were no significant sexual differences in leaf number, leaf size, trunk size and ramet number. More than 70% of the adult plants produce ramets, with a mean number of ramets per adult plant of about 2 8. The proportion of individuals with ramets and the number of ramets was positively correlated with trunk height. Maximum mean trunk diameter and mean number of leaves were reached when the plant reached 30—40 cm tall. Further increase of leaf width ceased when the plant reached 5 years old. Leaf reached its maximum length when the trunk was 10 cm tall. Growth units of trunk showed a linear relationship with height. The estimated age could be obtained by counting growth units of the trunk. The survival curve of leaves was well described by Deevey typeⅠ. The survival time of many leaves was two growth units. The rate of leaf mortality abruptly increased after two growth units. Few leaves could survive five units.
基金
国家自然科学基金
关键词
攀枝花
苏铁
生物学特性
树干解剖
生长模式
Cycas panzhihuaensis
Biological properties
Trunk anatomy
Growth patterns
