苏北海滨湿地互花米草无性分株扩张能力

摘要

在新洋港滩涂由海向陆建立样地:光滩(mudflat)、零星互花米草(Spartina alternifiora)斑块(SAP)、稳定互花米草滩下边缘(SAFI)、2003年互花米草定居处(SAF03)、1989年互花米草定居处(SAF89)、碱蓬(Suaeda salsa)滩(SS)及禾草滩(GF),各样地原位栽培9株生长无差异的互花米草分蘖幼苗(1 m×1 m样方,3次重复),分析互花米草生长指标和繁殖成功率,研究互花米草在苏北海滨湿地的扩张能力.结果表明:(1)mudflat处互花米草分蘖幼苗存活率为7.8%,极显著低于其他样地,SAP、SAFI、SAF03、SAF89、SS和GF样地互花米草存活率分别为88.9%、77.8%、60.0%、81.1%、0和66.6%;(2)mudflat处根状茎数量显著高于其他样地,但互花米草种子千粒重显著低于其他样地,127 d时mudflat、SAP、SAFI、SAF03、SAF89及GF处互花米草数量比原先存活的互花米草数量分别增加了24.8、19.7、30.2、6.7、5.8和3.0倍;(3)SAP、SAFI及SAF89间总生物量无显著差异(P＞0.05),且显著高于其他样地,并表现出以SAFI为中心,分别向海洋和陆地递减的趋势,mudflat与GF处穗生物量分配低,根状茎生物量分配高.结果显示受潮汐、土壤水分和风浪影响,互花米草在研究区内近海潮滩带有较强的扩张能力,但光滩处植株矮小,且在近海潮滩带与近岸潮滩带两端更趋向于选择无性繁殖方式,而中部潮滩带则是以有性繁殖和无性繁殖相结合的方式来进行种群延续和扩张.%Seven plots were laid out from sea to land along the intertidal gradient on tideland of the coast of Xinyanggang,North Jiangsu and labeled as mudflat, Spartina alterniflora patch ( SAP), lower edge of stable S. alternifiora flat ( SAFI),S. alternifiora flat 2003( SAF03), S. alterniflora flat 1989(SAF89), Suaeda salsa (SS) and grass flat (GF). In each plot ( 1 m × 1 m in quadrat, 3 replicates), 9 S. alterniflora tiller seedlings, similar in growth for all the plots, were cultivated in situ for observation of their breeding success rate and hence study on their expansion ability in the coastal wetland of North Jiangsu. Results show that ( 1 ) The survival rate of the seedlings was 7.8％ in mudflat, significantly lower than in the others except SS (P ＜ 0. 05 ) and was 88. 9％, 77.8％, 60. 0％, 81.1％, 0 and 66. 6％ in SAP, SAFI,SAF03, SAF89, SS and GF, respectively; (2) Number of rhizomes of the plants was significantly higher in mudflat than in the others, but thousand grain weight (TGW) of the plants in mudflat was significant lower than in the other plots (P＜ 0. 05); On D127 the number of the plants increased by 24. 8 times in mudflat, by 19. 7 times in SAP, by 30. 2 times in SAFI, by 6. 7 times in SAF03, by 5. 8 times in SAF89 and by 3.0 times in GF over the number of the plants that survived at the first phase; (3) SAP, SAFI and SAF89 was significantly higher in total biomass of the plants than the other plots and differed very slightly between them, displaying a trend with SAFI being the summit declining towards the land and the sea; The plants in mudflat and GF were low in spike biomass, but high in rhiome biomass. It was also found that S. alterniflora in the area close to the sea was rather stronger in expansion ability as affccted by tide, soil moisture content, wind and waves, and the plants in mudflat were dwarf. For reproduction and expansion of the population, it is more advisable to choose asexual reproductive strategy in areas close to the sea and to the land, and a mixed strategy of sexual and asexual reproductions at the central belt of the tidal flatland.