土壤水分条件对克隆植物互花米草表型可塑性的影响

在互花米草草滩挖掘沙蚕是海岸带常见的行为,会造成土壤结构松散,蓄水能力下降,局部土壤水分含量低.能否利用这些条件,降低互花米草种群的入侵性,并进而对互花米草的控制提供对策是一个重要的生态学命题.为此,实验模拟3种不同土壤蓄水条件,并测定互花米草在该条件下的形态与存活指标、克隆特征参数及生物量积累与分配格局.结果表明:土壤水分条件对互花米草的叶长和根状茎生物量均没有显著影响(p> 0.05);而其株高、分枝强度、克隆存活数、克隆存活率及地上生物量在各土壤水分条件间差异显著(p< 0.05);在低水分条件下,互花米草的芽数、基茎粗、地上生物量比和叶生物量比均显著低于其他两组处理(p< 0.05),地下生物量比则显著高于其他两组处理(p< 0.05);在中等水分条件下,互花米草的根状茎长、根状茎节数、地下生物量和茎生物量比与其他两组处理差异不显著(p> 0.05),而在其他两组处理间差异显著(p< 0.05);在高水分条件下,总生物量、茎生物量和根生物量显著高于其他两组处理(p< 0.05),根状茎生物量比则显著低于其他两组处理(p< 0.05),而这些指标在其他两组处理间均差异不显著(p> 0.05).由此推断,土壤水分条件适中有利于互花米草的生长扩张以占领有利的资源环境,而土壤水分条件低则抑制互花米草的生长繁殖,影响其种群延续.

Effect of soil-water condition on morphological plasticity of clonal plant Spartina alterniflora

A common phenomenon in the coastal zone, excavating clamworms on the beach covered with Spartina alterniflora, will create a loose soil structure, reduce the ability of the soil to store water, and ultimately cause a low soil-water condition. Whether we can use these conditions to reduce the invasiveness of Spartina alterniflora, and then provide a solution to control Spartina alterniflora, is an important topic of ecology. Therefore, we simulated three different soil-water conditions, and then measured several parameters of Spartina alterniflora under these conditions, including the morphological and survival parameters, clonal parameters and biomass accumulation and allocation. The results showed that: the soil-water condition had no significant effect on the leaf length and rhizome biomass of Spartina alterniflora (p> 0.05),while it had significant effect on the culm height, branching intensity, clonal number alive, survival rate of clones and above-ground biomass (p< 0.05); in low soil-water condition, shoot number, stem diameter, above-ground biomass allocation and leaf biomass allocation were significantly lower than the other two groups (p< 0.05),while the under-ground biomass allocation was significantly higher than the other two groups (p< 0.05); in medium soil-water condition, rhizome length, rhizome node number, above-ground biomass and stem biomass allocation were not significantly different from the other two groups (p> 0.05), while significant differences showed between the other two groups (p< 0.05); in high soil-water condition, total biomass, stem biomass and root biomass were significantly higher than the other two groups (p< 0.05), and the rhizome biomass allocation was significantly lower than the other two groups (p< 0.05), while these parameters showed no significant differences between the other two groups (p> 0.05). Consequently, we can conclude that moderate soil-water condition benefits the growth and spread of Spartina alterniflora, while low soil soil-water condition inhibits the growth and reproduction of Spartina alterniflora, and thus impacts the continue of its population expansion.