基于光补偿深度的蠡湖沉水植物恢复区划分

为分析蠡湖沉水植物恢复的光补偿深度和透明度条件,根据2012年4月和2013年4月蠡湖水下PAR(光合有效辐射)强度、ρ(SS)、透明度等监测数据以及沉水植物相关资料,探讨了沉水植物光补偿深度的空间分布特征及其影响因素. 结果表明:水下PAR强度随水深呈指数递减,α(光衰减系数)在0.97~6.04 m-1之间变化；光补偿深度空间分布格局均表现为西蠡湖大于东蠡湖、沿岸大于湖心的趋势,并且与水体透明度呈显著正相关；狐尾藻、金鱼藻、菹草、黑藻、苦草的光补偿深度及水体真光层深度分别是透明度的1.83、1.92、2.05、2.12、2.57和3.04倍. 回归分析表明,光补偿深度主要受ρ(SS)影响,其次为ρ(Chla). 以沉水植物群落光补偿深度(水体真光层深度)与水深的比值作为划分沉水植物群落恢复区域的参考依据,将蠡湖水域初步划分为“适宜区”“过渡区”和“暂不适宜区”,其中“适宜区”占蠡湖水域面积的29%. 

Division of Submerged Aquatic Vegetation Restoration Region in Lihu Lake Based on Light Compensation Depth

To investigate the appropriate light compensation depth and transparency to restore the submerged plants in Lihu Lake, spatial distribution characteristics and impacting factors of light compensation depth of submerged plants were analyzed based on relevant references about submerged plants and monitoring data of PAR(photosynthetically active radiation) intensity below the surface, ρ(SS) and transparency in April 2012 and 2013. The results showed that PAR intensity below the surface decreased with water depth, and the light attenuation coefficient α ranged from 0.97 to 6.04 m-1. Light compensation depths in the western part of Lihu Lake and coastal areas were deeper than those in the eastern and central areas, respectively. Light compensation depth was significantly and positively correlated with transparency. Light compensation depth of Myriophyllum verticillatum, Ceratophyllum demersum, Potamogeton crispus, Hydrilla verticillata, Vallisneria natans and submerged plant communities was 1.83,1.92,2.05,2.12,2.57 and 3.04 times that of transparency, respectively. Multivariate regression analysis showed that ρ(SS) was the most important factor affecting light compensation depth, followed by ρ(Chla). With the ratio of light compensation depth (euphotic depth of water) and water depth as references for division of submerged plant restoration areas, Lihu Lake waters was divided into “suitable area” “transition area” and “temporarily unsuitable area”, in which the “suitable area” accounted for 29% of the Lihu Lake water area.