洱海湖滨带不同基底高程下菰出苗及生长特征

Emergence and Growth Characteristics of Zizania caducifiora in Different Base Elevations in Erhai Lakeshore

为研究洱海不同类型湖滨带菰(Zizania caduciflora)的出苗及生长的特征,在2010年3月和6月(菰的主要出苗和生长季节)调查洱海湖湾型和非湖湾型湖滨带不同基底高程上菰生物量、密度、植株叶片数、植株高度等的变化,分析洱海水位变化的影响.结果表明:随着湖滨带基底高程的降低,洱海湖滨带菰的密度、生物量、单株叶片数呈先增高后快速降低趋势,株高则呈增大后基本不变的趋势;从株密度及生物量看,随着3—6月洱海水位的降低,湖湾型和非湖湾型湖滨带菰生长的最适基底高程都随之下降,3月为1 964.85 m,6月为1 964.55 m,所对应的水深均为0.3 m.3月和6月湖湾型湖滨带能够出苗良好的基底高程比非湖湾型分别低了0.3和0.6 m;随着水位的下降,湖湾型湖滨带菰出苗良好的范围向水下延伸,但在非湖湾型湖滨带,出苗良好的最低高程几乎不变.湖湾型和非湖湾型湖滨带菰出苗和生长的差异显示出其影响因素不同,在湖湾型湖滨带,水深动态变化是主要影响因子,而在非湖湾型湖滨带,风浪作用和水深动态变化存在共同作用.

Emergent aquatic plants are the most important plants in riparian areas. Effects of water level on biomass, density, leaf number and plant height of Zizania caduc^fiora were investigated in Erhai lakeshore in March and June, 2010. The results showed that plant density, biomass and plant leaf number of Z. caducifiora increased first and then decreased, while the plant height increased and remained stable with the base elevation decreased. The best base elevation for emergence and growth of Z. caducifiora in March and in June were 1964. 85 m and 1964. 55 m respectively in O. 3 m water depth with no significant difference between in and out lake bays. However, the lowest base elevation （ 1963.65 m） for Z. caducifiora in lakeshore in lake bays was 0.3 and 0. 6 m smaller than those out of bays. In addition, the plant height of Z. caducifiora in lake bays was significantly higher than those out of bays. The differences between lakeshores in and out lake bays indicated that wave could greatly inhibit the emergence and growth of Z. caducifiora in lakeshore.