互花米草盐沼潮沟地貌特征

The tidal creek character in salt marsh of Spartina alterniflora Loisel on strong tide coast

互花米草是我国从国外引进的能在淤泥质潮滩的高潮带下部和中潮带上部生长的禾木科植物 ,由于其植株高大、群落盖度高、根系发达等生物学特性 ,其对潮流动力特征有显著的影响。本文通过对江苏省东台市笆斗垦区外互花米草盐沼地的潮沟形态调查 ,发现互花米草盐沼潮沟具有以下一些特征 :潮沟密度大 ,可达 50km/km2 以上 ;潮沟的宽深比小 ,大多在8以下 ;沿岸堤发育 ,且多呈不对称状 ;一级主潮沟与主潮沟接头处普遍呈逆弧形 ;盐沼外侧边缘发育有明显的陡坎冲沟。分析认为这些特征主要与互花米草发达的根系和致密的植株等生物学特性有关 ,发达的根系增加了盐沼滩面的稳定性 ,而互花米草高大的植株增加了对潮水运动的阻力 ,提高了滩面落潮水的归槽水位 ,改变了潮流的泥沙沉积地点和涨、落潮流的流向 ,从而形成比较特别的互花米草盐沼潮沟特征。

Spartina alterniflora Loisel is introduced from the USA to China and it is a new adventitious species of plant to Chinese environment, which can occupy vast areas between mean sea level and mean high level with many special biological characteristics, such as high plant, great community coverage and robust root. By the influence of the interaction between the tidal current and Spartina alterniflora Loisel, the particular landform configuration is forming. There has formed many Spartina alterniflora salt marsh on Jiangsu coast since the planting of Spartina alterniflora Loisel in 1982, especially in the tidal flat outside of Badou Reclaim region, Dongtai County, which has developed a mature salt marsh with the mature and integrated channel system. By field investigations and interpretation of remote sensing imageries of Badou Reclaimed region, many particular channel characters in the salt marsh of Spartina alterniflora Loisel are identified: (1) high density channels, which can reach 50km/km 2; (2) small width-depth ratio, which is often smaller than 8; (3) remarkable creek bank; and (4) obvious gulch outside edge of the salt marsh. Combining the survey result of tidal current in Spartina alterniflora Loisel salt marsh, reasons accountable for the formation of the particular channel characters mentioned above in the salt marsh of Spartina alterniflora Loisel are analysed.One of the important reasons is attributed to the substantial soil and ebb-dominance current resulting from the special biological characteristics, such as high plant, great community coverage, robust root in the salt marsh of Spartina alterniflora Loisel.etc.