Effects Of Density, Water Depth And Species Diversity On The Growth Of Submerged Macrophytes

Hydrophytes, especially the submerged macrophytes, are important primary producer and main contributor to the subprime productivity in the water ecosystem. Improper agriculture and industry practices have led to deteriorated water quality. The quantity of many kinds of hydrophytes, especially submerged macrophytes, have declined and even disappeared. Thus, we should make some measures to restore and regenerate submerged macrophytes. Density, water depth and species diversity are important factors for the recovery of the submerged macrophyte in wetland restoration project. Few studies about the factors mentioned above have been done. In this research some experiments were designed to test the effects of density, water depth and species diversity on growth of submerged macrophytes, which indicated some information to recover the submerged macrophyte.A field experiment was set up to test the effect of initial density on macrophyte population with five density levels. The results indicated that population’s biomass, number of nodes and shoot length increased significantly as density increased. While individuals performance decreased significantly as density increased. Therefore, individual’s growth is inhibited when density become higher.A field experiment was conducted to learn how density and water level fluctuation affect macrophyte population, we used a macrophyte Ceratophyllum demersum as the experimental subject. Water level fluctuation did not have significant effect on C. demersum, density had a positive effect on C. demersum’s population performance, while density had insignificant effect on C. demersum’s individuals.An experiment was conducted with three density levels and two water depth levels to test effects of water depth and density on macrophyte community, results indicated that community production decreased significantly as water depth went up, community evenness increased as water depth went up; density had a positive effect on community production, yet C. demersum individual’s growth were not affected significantly, density had a negative effect on community evenness. There were interactions of water depth and density on H. verticilata.In another field experiment, different kinds of macrophytes were planted together to test effects of species biodiversity on macrophyte community, results indicated that species biodiversity had insignificant effect on macrophyte community and individuals.This research show that low water depth is beneficial for the reconstruction of macrophyte; population’s production increases as density grows, while individuals growth is inhibited; this research provide theory bases for the recovery of submerged macrophyte.