异质生境空心莲子草植物群落组成及物种多样性研究

研究草海湿地空心莲子草（Alternanthera philoxeroides）入侵对异质生境植物群落生活型、物种组成、重要值及物种多样性的影响,结果表明,①异质生境中群落生活型组成比例有差异,水生生境地面芽植物（H）∶隐芽植物（Cr）∶一年生植物（Th）为56∶38∶6;湿生生境为43∶36∶21。②异质生境中物种组成差异明显,水生生境试验样方包含9科13属16种,对照样方（无空心莲子草入侵）包含10科19属23种;湿生生境试验样方包含8科14属14种,对照样方有10科19属22种。空心莲子草入侵不同生境后群落内物种重要值变化及差异均较大,部分乡土物种在试验样方中减少甚至消失,水生生境和湿生生境群落中分别有30.44%、36.36%物种消失。③异质生境中空心莲子草重要值与物种多样性指数、生态优势度指数、均匀度指数均呈二项式函数关系;两种生境的多样性指数和均匀度指数均表现为随空心莲子草重要值先增加后减少,生态优势度指数均为先减少后增加,空心莲子草入侵对乡土植物群落物种多样性产生正向影响和负向影响,在群落中其重要值达25.8（水生生境）、18.9（湿生生境）时,是乡土植物多样性下降的临界点。

Impacts of the invasion ofAlternathera philoxeroides on species composition and diversity of heterogeneous habitat in Caohai wetland

Impacts of the invasion of Alternanthera philoxeroides on heterogeneous habitat community species life forms, species composition, important value and species diversity in Caohai wetland were studied. The results showed that, （1）The ratio of species life form was different in heterogeneous habitats. The composition ratio of hemicryptophyte, eryptophyte and therophyte in aquatic habitat is 56：38：6, while it is 43：36：21 in wet habitat. （2）Species composition was significantly different in heterogeneous habitat. There were 9 families, 13 genera and 16 species in test plots, and 10 families, 19 genera and 23 species in random sites which were located in the aquatic habitat and had no invasion ofAlternanthera philoxeroides; while there were 8 families, 14 genera and 14 species in test plots, but 10 families, 19 genera and 22 species in random sites in the wet habitat. After the invasion of Alternanthera philoxeroides in both habitats, the important value of species have changed greatly and the differences between them were larger. In addition, some native species decreased and even disappeared in test plots. The proportion of native species disappeared in aquatic habitat and wetland habitat was 30.44%, 36.36% respectively. （~Relationship between important value of AIternanthera philoxeroides and species diversity index, Shannon-wiener index and pielou index all showed a binomial function changes in both habitats. Simpson index and pielou index were all increased with the important value of Alternanthera philoxeroides and then decreased, shannon-wiener index were decreased and then increased in both habitats. Therefore, the invasion of Alternanthera philoxeroides had positive effect and negative effect on species diversity of native vegetation communities. The important value of 25.8 （in aquatic habitat） and 18.9 （in wet habitat）is a critical point of native plant species diversity decreased.