海岸草本植物细根、叶片功能性状及其与土壤因子的关系

植物根、叶是对环境敏感性最高的器官,探究根叶功能性状之间的相互关系以及对环境因子的响应,有助于揭示植物对资源的利用状况及其对环境的适生策略。为探讨沿海植物的适应策略,该文以平潭岛砂质海岸草本植物为研究对象,由海及陆设置了3个距离梯度,选取6个叶功能性状和5个细根功能性状指标,分析海岸植物叶片与细根功能性状及其对土壤因子的响应。结果表明:(1)根、叶功能性状变异系数幅度在潮间带最小,在距高海潮线30～60 m的梯度上最大。单叶面积、叶磷含量、根平均直径、根组织密度、根磷含量随着由海到陆的距离增加呈上升趋势; 叶干物质含量、叶组织密度、比根长、比根面积呈下降趋势。(2)植物通过性状组合,在生长与防御间进行资源分配的权衡,表现在叶性状间、根性状间以及根-叶性状间具不同程度的相关性。其中,在地上-地下对应性状中,叶厚与根平均直径、叶磷含量与根磷含量呈极显著正相关; 而比叶面积与比根面积、比根长,叶组织密度与根组织密度均未表现出显著的相关性。(3)土壤因子对海岸植物功能性状变化的解释度为52.05%,其中土壤含盐量的影响最大,其次是土壤含水量、电导率、pH值。总体而言,在恶劣的海岸环境下,由海向陆土壤含盐量、电导率、含水量及pH值逐渐下降,整体为低磷高盐碱,植物表现为不同的生存策略:距海近的植物采取“叶片资源保守型、根系资源获取型”策略; 距海远的植物则采取“叶片资源获取型、根系资源保守型”。该研究结果为了解海岸草本植物对环境梯度变化的响应机制和适应性提供了一定参考价值,同时也利于通过分析土壤等环境特性按梯度筛选栽种适宜的物种,促进海岸植物的恢复和保护。

Fine root and leaf functional traits of coastal herbs and their relationship with soil factors

Leaf and root are the most sensitive organs to environment, exploring the relationship between root and leaf functional traits and their responses to environmental factors is helpful to reveal the utilization of resources by plants and their adaption trategies to environment. In order to explore the adaptive strategies of coastal plants, the sandy coastal herbaceous plants in Pingtan Island were taken as the research object. Three distance gradients were set up from sea and land. Six leaf function traits, leaf thickness, individual leaf area, leaf dry matter content, specific leaf area, leaf tissue density, leaf phosphorus content, and five fine root function traits, root average diameter, root tissue density, specific root length, specific root area, root phosphorus content, were measured to analyze the function traits of leaf and root of coastal plants and their responses to soil factors. The results were as follows:(1)The variation coefficient amplitude of root and leaf function traits in intertidal zone was the smallest, and it was the largest on the gradient 30-60 m away from the high tide line. The individual leaf area, leaf phosphorus content, root average diameter, root tissue density, and root phosphorus content increased with the distance from sea to land; the leaf dry matter content, leaf tissue density, specific root length and specific root area decreased.(2)Plants balanced resource allocation between growth and defense through traits combination, which showed that there were different degrees of correlation among leaf traits, root traits and root-leaf traits. Among the aboveground and underground corresponding traits, leaf thickness-root average diameter, leaf-root phosphorus content were significantly positively correlated. Specific leaf area with specific root length, specific root area, leaf tissue density-root tissue density had no significant correlation.(3)The interpretation degree of soil factors to the changes of coastal plant functional properties was 52.05%, of which the soil salt content had the greatest impact, followed by soil water content, soil electrical conductivity and soil pH value. In conclusion, in the harsh coastal environment, the soil salt content, soil electrical conductivity, soil water content and soil pH value decreased gradually from sea to land, and the overall environment is low in phosphorus and high in salinity. The plants have shown different survival strategies: plants closer to the sea adopted the strategy of leaf resource conservation type and root resource acquisition type; the farther away from the sea, the strategy of leaf resource acquisition type and root resource conservation type is adopted. The results of this study can provide a certain reference value for understanding the response mechanism and adaptability of coastal herbs to environmental gradient changes, which is conducive to the analysis of soil and other environmental characteristics to screen and plant suitable species according to gradient, and promote the restoration and protection of coastal plants.