苏北滨海湿地互花米草两种繁殖体与本地种竞争能力分析

Competitive Ability of Two Propagules of Spartina alterniflora With Native Species in the Coastal Wetlands of North Jiangsu

在碱蓬滩选取互花米草斑块,由外向内分为外围(A)、外侧(B)、内侧(C)、中心(D)四个取样点,研究互花米草实生苗、分蘖苗与本地植物碱蓬、芦苇的相对竞争力,探讨互花米草在碱蓬滩地入侵扩张的趋势。结果表明:1)在斑块B点处,互花米草实生苗与碱蓬相对竞争力高于互花米草分蘖苗与碱蓬相对竞争力;在斑块C点处,互花米草实生苗与碱蓬相对竞争力低于互花米草分蘖苗与碱蓬相对竞争力;多样性指数分析表现为:B点>C点>A点>D点;在互花米草斑块B点处重要值大小表现为:互花米草实生苗>碱蓬>芦苇实生苗>互花米草分蘖苗,在互花米草斑块C点处重要值大小表现为:互花米草分蘖苗>芦苇实生苗>互花米草实生苗>碱蓬。因此,碱蓬滩互花米草斑块主要是通过实生苗入侵新生境,向外扩张,通过互花米草分蘖苗维持种群的稳定。2)在斑块B点,芦苇实生苗与互花米草实生苗的相对竞争力相当,大于互花米草分蘖苗的相对竞争力,但在斑块C点处,互花米草分蘖苗高于芦苇实生苗。碱蓬与本地种芦苇也产生了竞争关系,并很有可能被芦苇和互花米草共同取代。3)互花米草实生苗与碱蓬的相对竞争力与滩涂微生境土壤含水量、土壤全盐量负相关(P<0.01),与土壤pH正相关(P<0.01);互花米草分蘖苗与碱蓬的相对竞争力与土壤含水量、土壤全盐量正相关(P<0.05),与土壤pH负相关(P<0.01)。碱蓬滩斑块处的含水量、盐度适合互花米草的定居、扩张。

The relatively competitive ability of S. alterniflora seedling and S. alterniflora tiller with Suaeda and reed was studied and to discuss the invasion trend of S. alterniflora into the Suaeda salsa flat was discussed by selecting S. alterniflora patch in the Suaeda flat and dividing them into four sampling sites, periphery（A）, outside（B）, inside（C） and center （D）. The results show that. （1） in site B the com- petitive ability of S. alterniflora seedling with Suaeda is higher than that of S. alterniflora tiller with Suaeda, while in site C the situation is just opposite. The diversity indices occurring in the sampling sites show an order of B〉C〉A〉D. The significant values show an order of S. alterniflora seedling〉Suaeda 〉reeds〉S. alterniflora tiller in site B, and S. alterniflora tiller〉 reeds〉 S. alterniflora seedling〉 Suaeda in site C. These indicate that S. alterniflora invades into the Suaeda flat mainly by seedling and the population in the patch is kept stable mainly by tiller; （2） in site B, the competitive ability of reeds is comparable with that of S. alterniflora seedling, but higher than that of S. alterniflora tiller. In site C, however, the competitive ability of S. alterniflora tiller is higher than that of reeds, indicating that Suae- da might have a competing relation with native reed and could be replaced by both S. alterniflora and reed; and （3） The competitive ability of S. alterniflora seedling with Suaeda has a negative correlation to water content and total salinity of the flat soil （P〈0.01） and a positive correlation to pH of the flat soil （P〈0.01）. However, the competitive ability of S. alterniflora tiller with Suaeda has a positive correla- tion to water content and total salinity of the flat soil （P〈0.05） and a negative correlation to pH of the flat soil （P〈0.01）. The water content and salinity of the soil in the Suaeda flat may possibly be favoura- ble for S. alterniflora to settle down and to expand .