六种沉水植物的克隆生长特征

为构建种群动态模型以指导沉水植被修复工程实践, 研究采用同质园实验方法对6种常见沉水植物(竹叶眼子菜(Potamogeton wrightii)、眼子菜(P. distinctus)、光叶眼子菜(P. lucens)、穿叶眼子菜(P. perfoliatus)、扭叶眼子菜(P. intortifolius)和苦草(Vallisneria natans)的克隆生长模式进行了连续观测研究, 获取了分株形成速率、空间扩张速率、株高增加速率等种群扩张动态参数，及分株数、间隔子长度、分株高度等克隆构件特征参数。结果表明, 6种沉水植物的分株数从28d开始增长, 其中苦草的分株形成速率最高, 平均为1.09株/d, 分株形成最大速率出现在55d之后; 穿叶眼子菜和扭叶眼子菜的分株形成速率低于苦草, 但是高于竹叶眼子菜、眼子菜和光叶眼子菜, 最大速率出现在41d之后。虽然苦草的分株最多, 但是分株的株高最低, 其株高增长速率均值为0.2 cm/d。眼子菜属物种中竹叶眼子菜和眼子菜株高增长速率最高, 光叶眼子菜的株高增长速率和分株形成速率都最低。克隆系占据面积随时间的扩张速率为穿叶眼子菜(113.22 cm2/d)>扭叶眼子菜(71.70 cm2/d)>苦草(35.48 cm2/d)>竹叶眼子菜(12.09 cm2/d)>眼子菜(3.07 cm2/d)>光叶眼子菜(0.53 cm2/d)。此外, 研究还发现眼子菜属植物普遍表现出匍匐茎上“节”的形成, 而苦草则不具备这种特性, 匍匐茎“节”的形成及随之形成的不定根在眼子菜属植物空间扩张过程中具有重要的生态功能, 并在种群构建方面与苦草等其他物种发生分异。基于眼子菜属植物匍匐茎上的“节”可以形成跳跃性的分株, 在种群面积扩张方面更具优势; 而苦草形成分株的数量更多、速度更快, 在提高种群密度保障种群稳定方面更有优势。

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.