水盾草(Cabomba caroliniana)入侵对沉水植物群落物种多样性组成的影响

采用群落学样方调查法, 对中国的水生入侵种水盾草所侵入的沉水植物群落进行研究.主要以28个样地（包括4个对照样地）为调查对象, 并将道场、太湖、陶堰、柯岩、方桥和五常6个作为固定样地进行每个季度的调查.α、β多样性测度公式分析, 结果表明, （1） 各个调查群落的物种组成差异都较大, 物种数目不等; 固定样地大多在不同季节中物种数目有所变化, 春夏季多, 冬季少. （2） 一般样地的3个α多样性指数中, Simpson指数和Shannon- Wiener指数变化较为一致, Pielou均匀度指数变化不太一致.物种多样性与水盾草的入侵程度有关, 水盾草优势程度越高, 物种多样性就越低.（3） 对照样地？？多样性指数与相应的一般样地比较, 多样性也与优势度相关.（4） 固定样地？？多样性指数一般冬季较其他三个季度低, 但2001年与2002年没有大的差异.（5）βT多样性指数显示, 在0.4-2.4m水深, 种类组成都有所改变, 在0.4-0.8m和0.8-1.2m种类改变较多, 且以稀有种类为主.水盾草对本土水生植物有负面影响, 应引起高度重视, 进行相关研究.     

Invasion and spreading of Cabomba caroliniana revealed by RAPD markers

Applying randomly amplified polymorphic DNA （RAPD）, the genetic variation of Cabomba caroliniana Gray （cabomba or fanwort）, a new alien plant in China, was analyzed in this paper. Total 143 bands, including 47 polymorphic bands, were amplified from 23 primers in 20 samples. The sampling distance was large, but its genetic diversity was low. The main results were that： （1） Cabomba, which grew and dispersed mainly in fragment, was an abundant and dominant species in freshwater, and its main dispersal mechanism was vegetative reproduction. （2） Cabomba was originally introduced into China as an aquarium submerged plant. Somehow, those discarded cabomba became invasive species in the areas of Hangzhou, Shanghai, and Meicheng, and other places. （3） Although the level of genetic diversity in cabomba was low, their rapid dispersion and propagation could seriously harm to local aquatic community. Therefore, specific measure should be used to control cabomba from uncontrolled spreading and damage to local vegetation communities.     

浙江古田山自然保护区常绿阔叶林群落特征

在对古田山自然保护区森林植被广泛调查的基础上，详细分析了常绿阔叶林群落特征，从该区森林植被的外貌特征、群落结构和种类组成上看，均具有我国典型亚热带常绿阔叶林的基本性质。