CLONAL GROWTH CHARACTERISTICS OF SIX SUBMERGED MACROPHYTES

Submerged macrophytes, an important functional group in freshwater ecosystem, grow underwater and can absorb nutrients via roots and leaves. Clonal growth is the key mechanism for the establishment, maintenance, and expansion of submerged macrophyte populations. It is important to study their clonal patterns and key parameters for modelling population dynamics, community succession and even freshwater ecosystems. The better understanding of clonal growth characteristics is also valuable for the restoration of aquatic vegetation. Herein, clonal patterns of six submerged macrophytes (Potamogeton wrightii, P. distinctus, P. lucens, P. perfoliatus, P. intortifolius, and Vallisneria natans) were studied in a common garden. The clonal growth process and some key parameters (ramet emerging rate, area spreading rate, ramet growth rate, spacer length, ramet height, biomass, etc.) of these macrophytes were monitored. By monitoring the development trend of individual clones, we expect to summarize of the clonal growth patterns of different species, which can provide a reference for the construction of submerged macrophytes population expansion model and community model, it also provides scientific support for submerged vegetation restoration. We found that new ramets emerged 28 days after planting. V. natans represents the highest ramet emerging rate (1.09 ramets/d) and the lowest ramet growth rate (0.2 cm/d) among the 6 species. Potamogeton species had a higher ramet growth rate and a relative lower ramet emerging rate, but the lowest ramet emerging rate and ramet growth rate were both found in P. lucens. The area spreading rate varied significantly among the 6species. P. perfoliatus had a much stronger area occupation capacity than other plants. We also illustrated an abnormal “node” on stolon in Potamogeton species, which will strengthen their area occupation capacity. However, there was no “node” on Vallisneria stolons. This characteristic will greatly shape the different clonal growth patterns of these submerged macrophytes.