强潮差海域秋茄生长的宜林临界线

Critical tidal level for Kandelia candel forestation in strong tidal range area

以国内最大潮差值的乐清湾西门岛海域为研究地点,选定黄零为1.96、1.66、1.35和1.03m4个高程断面,对各高程上1年生和3年生秋茄(Kandelia candel)幼苗的成活率、生长指标以及污损生物(藤壶)等因子进行了统计分析.结果表明:不同高程内,1年生和3年生秋茄幼苗的生长存在显著性差异;秋茄幼林植株上附生有白脊藤壶(Balanus albicostatus)和纹藤壶(Balanus amphitrite amphitrite)2种藤壶,其中优势种白脊藤壶在黄零1.35m的高程对秋茄的污损最为严重.西门岛秋茄的宜林线为黄零1.66m,即不低于当地平均海平面以上1.29m、每个潮水周期平均淹水时间小于3.65h的潮滩.藤壶、强潮和极端天气是该地区秋茄宜林线明显高于当地平均海平面的主要原因.

Taking Ximen island of Yueqing bay,the biggest tidal range area among the coasts of China,as study site,an investigation was made on the survival rate,growth characteristics,and attached barnacles of 1-and 3-year old Kandelia candel seedlings at the elevations 1.96,1.66,1.35,and 1.03 m above the zero tidal level of Yellow Sea. Significant differences were observed in the survival rate and growth situation of the seedlings among the elevations. There were two barnacle species,Balanus albicostatus and Balanus amphitrite amphitrite,and B. albicostatus was the major species which attached K. candel most seriously at elevation 1.35 m. The critical tidal level for K. candel in the site was 1.66 m above the zero tidal level,i.e.,at least 1.29 m higher than the local mean sea level,and the flooding time per tide cycle being less than 3.65 h. Barnacle,strong tide,and extreme weather event were the main reasons for the higher critical tidal level.