苏北潮滩群落交错带互花米草斑块与土著种竞争关系研究

Relative competitive ability of Spartina alterniflora patches to native species in tidal zone ecotone of north Jiangsu

选取盐城滨海湿地典型滩地(互花米草与碱蓬交错区、碱蓬滩)互花米草斑块,研究互花米草和本地种的生长特征、斑块微生境变化和互花米草与本地种的相对竞争力。结果表明:①和本地土著种碱蓬Suaeda salsa、芦苇Phragmites australis相比,入侵种互花米草Spartina alterniflora能更有效地改善微生境,其发达根系能够提高土壤含水量,互花米草的耐盐特性和泌盐作用能够使得互花米草在高盐度环境中生存,并有效的降低土壤盐度;②在互花米草与碱蓬交错区,从互花米草斑块边缘到中心,碱蓬的长势显著变弱,互花米草的长势显著增强,互花米草与碱蓬的相对竞争力为1.94±0.94,互花米草的竞争能力明显强于碱蓬;③在碱蓬滩,从互花米草斑块边缘到中心,碱蓬、芦苇的长势显著变弱,互花米草的长势显著增强,互花米草与碱蓬的相对竞争力为0.87±0.30,互花米草与碱蓬之间的竞争相对平衡;④因此,互花米草可能通过种间竞争不断侵蚀碱蓬生境,从而取代当地土著植被碱蓬和芦苇。

The Spartina alterniflora patches on tidal flate in North Jiangsuwas selected to study the growth situation of S.alterniflora and native plants,the habitat changes within the patches and the relative competitive ability between S.alterniflora and native species.The results indicated that： ① compared with the two native species（Suaeda salsa and Phragmites australis）,the exotic S.alterniflora could effectively improve the microhabitat,e.g.increase soil water content and reduce soil salinity as a result of its salt resistance and characters of ions secretion;② in ecotone,from frontier to inner of the S.alterniflora patch,the growth index of S.salsa significantly decreased while that of S.alterniflor significantly increased.Relative competitive ability of S.alterniflora was 1.94±0.94,indicating the higher dominance of it than S.salsa.③ On Suaeda flat,from frontier to inner of the S.alterniflora patch,the growth index of S.salsa and P.australis significantly decreased while that of S.alterniflor significantly increased.Relative competitive ability of S.alterniflora was 0.87±0.30,indicating the similar dominance between the exotic and the native plants.④Therefore,it is possible that S.salsa and P.australis would be replaced by S.alterniflora.