基于光补偿深度的白洋淀沉水植物修复技术

Remediation technology of submerged plants in Baiyangdian Lake based on light compensation depth

沉水植物是浅水湖泊生态恢复的关键。为实现浅水湖泊沉水植物修复,对白洋淀淀区沉水植物历年变化和2018年现状进行了调研分析,并于2019年3月和5月测定了水下光场的变化;在考察水下光场、沉水植物耐污性和光敏感性的基础上,确定了沉水植物群落2个阶段(耐污种+中等耐污种和敏感种)恢复方案。结果表明:以2018年春、夏、秋3季调研的沉水植物群落为目标,测定的群落光补偿点和群落组成与优势物种的种类具有相关性,植物比例对其群落光补偿点的影响不大,如龙须眼子菜+金鱼藻的搭配,以龙须眼子菜为优势种(2∶1和50∶1)的群落光补偿点的光强分别为22.46μmol·(m2·s)^-1和26.05μmol·(m2·s)^-1,以金鱼藻为优势种(1∶2和1∶5)的群落光补偿点的光强分别为35.01μmol·(m2·s)^-1和37.79μmol·(m2·s)^-1;白洋淀水下光衰减系数呈现东低西高的趋势,且与叶绿素a和总悬浮物空间变化趋势一致,其中叶绿素的影响较大,高值区存在于人为干扰较多区域,低值区人为干扰较少;沉水植物种群(群落)光补偿深度与透明度符合线性回归模型,且其显著性较高(大部分R2>0.74);利用沉水植物种群(群落)光补偿深度和实际水深的比值评估第一阶段白洋淀修复区域,并通过前期光衰减系数与叶绿素a、悬浮物和DOC的相关性分析,确定可通过降低水体中叶绿素a和悬浮物含量,从而提高沉水植物光补偿深度,进而实现沉水植物群落恢复。以上研究结果可为白洋淀及北方湖泊的生态治理提供参考。

Submerged plants are the key to the ecological restoration of shallow lakes.In this study,submerged plants in Baiyangdian Lake area were sampled in 2018 and compared with its history.The changes of the underwater light field were also analyzed in March and May 2019.Considering the underwater light field,antipollution and light sensitivity of submerged plants,a two-phase restoration plan for submerged plant communities(stain-resistant+medium-tolerant and sensitive species)was determined.The results showed that the submerged plant community surveyed in the spring,summer and autumn of 2018 were taken as research target,the correlation between the measured light compensation point of the community and its composition and the dominant species were determined,and the plant proportion has slight effect on the light compensation point of its community.For example,the combination of P.pectinatus+Ceratophyllum,the light intensities of the community light compensation point with P.pectinatus as the dominant species(2∶1 and 50∶1)were 22.46μmol·(m2·s)^-1 and 26.05μmol·(m2·s)^-1,respectively.The light intensities of the community light compensation point with Ceratophyllum as the dominant species(1∶2 and 1∶5)were 35.01μmol·(m2·s)^-1 and 37.79μmol·(m2·s)^-1,respectively.The results of the underwater light field showed the light attenuation coefficient had a trend of low values in the east and high values in the west.This spatial variation trend was similar to that of chlorophyll a and total suspended matter.Of which,the effect of chlorophyll was greater.The high-value regions had more human interference,while the low-value regions had less human interference.The depth of light compensation and the transparency of submerged plant populations(communities)showed significant linear positive correlation(most R2 values were higher than 0.74).The ratio of light compensation depth of submerged plant population(community)to actual water depth was used to evaluate the first stage of Baiyangdian restoration area,and through the correlation analysis of early light attenuation coefficient with chlorophyll a,suspended matter and DOC,it was determined that chlorophyll a and suspended matter content in the water body could be reduced,so as to increase the depth of light compensation of submerged plants,and then achieve the restoration of submerged plant communities.The above research results can provide a reference for the ecological management of Baiyangdian and northern lakes.