Lake Dianchi is a typical large, shallow, eutrophic plateau lake. A nuisance cyanobacterial bloom has frequently appeared in this lake since the 1990s. Large amounts of money have been invested for Lake Dianchi in improving waste water treatment and restoring submerged macrophytes since the 2000s. Despite all these attempts, eutrophication remains a major problem, and submerged macrophytes have responded slowly to restoration. In the coming decade, restoration ecologists will have to develop concepts including the reduction of external nutrient loading and the establishment of internal restoration measures to improve the ecological quality of the lake. Decision support schemes to restore the submerged vegetation of Lake Dianchi are, therefore, a pressing need.

Prof. LIU Guihua and his research associate Dr. LU Jing at Wuhan Botanical Garden have compiled the history of submerged vegetation and environmental conditions in Lake Dianchi since 1960s and conducted a sediment seed bank assay by sampling different sediment strata to examine the natural restoration potential of submerged macrophytes in Lake Dianchi. They revealed the temporal and spatial sequence of submerged macrophytes’ disappearance in Lake Dianchi.

Their results indicate that phosphorus concentrations have increased by 28 times in the lake since 1961 and macrophytes that used to grow at 5–6.5 m are now confined to water less than 3 m deep. Many species had disappeared by 1978 and a former 17 species and 88% cover in 1961 was reduced to 9 species in three turbidity-tolerant communities with only 2% cover by 2010. The remaining seed bank was dominated by two species, still present in the lake and many former species, which had been very abundant, were not found as seeds. Based on the findings above, they also proposed a possible path of eco-restoration of submerged macrophytes in Lake Dianchi.

This study has been published in Ecological Engineering (2012, 39: 95-103) entitled “Using sediment seed banks and historical vegetation change data to develop restoration criteria for a eutrophic lake in China”. This research was funded by National Natural Science Foundation of China.