敦煌阳关湿地芦苇克隆构件空间拓展策略及其对土壤环境因子的响应

Spatial expansion strategy and soil environmental response of the clonal architectures for Phragmites australis in Yangguan wetland of Dunhuang

空间拓展是克隆植物响应环境的生态适应和权衡维度,以内陆盐沼湿地典型代表敦煌阳关国家级自然保护区内的芦苇(Phragmites australis)为研究对象,基于水库距离远近和芦苇种群的密度与盖度,设置了近水区(500 m)、过渡区(1500 m)、荒漠区(2500 m)3个不同的采样梯度,研究了环境异质条件下芦苇克隆构件空间拓展策略及其对土壤环境因子的响应。结果表明:(1)芦苇克隆构件在异质环境条件下差异显著,初级根茎条数、根茎节间长、间隔子长、分枝角度呈现"同增同涨"的协同进化关系(P<0.01),而与分株数呈现"此消彼长"的权衡关系(P<0.01)。(2)且随着种群的密度降低,芦苇在空间拓展过程中呈现从"密集型"转"游击型"的生存策略。(3)冗余分析显示土壤水分、pH值、盐分是克隆构件空间拓展的主要驱动力,其中各层土壤水分、深层土壤pH值和盐分是芦苇空间拓展最重要的环境因子。明晰内陆河湿地芦苇克隆构件空间拓展策略及主要的环境驱动力,能为干旱脆弱敏感区湿地保护和生态恢复提供借鉴意义。

Spatial expansion is the ecological adaptation and trade-off decision of clonal plants in response to the environment. In order to study the spatial expansion strategy of clonal architectures and its response to soil environmental factors under heterogeneous conditions, Phragmites australis in Yangguan National Nature Reserve(Dunhuang, China) with a typical inland salt marsh wetland was selected as the research object. Three different sampling sites including near water zone(500 m), transition zone(1500 m) and desert zone(2500 m) were set up. The results showed that:(1) The features of the clonal architectures of Phragmites australis differed significantly in heterogeneous environment, and the co-evolutionary relationship of architectures showed significantly positive correlation with the primary rhizome number, rhizome internode length, spacer length and branch angle(P<0.01), and negative correlation with the ramet number(P<0.01).(2) Phragmites australis presented a survival strategy from "phalanx" to "guerrilla" during spatial expansion with gradual decreases of population density.(3) Soil water, pH value and salt were the main driving forces of spatial expansion of clonal architectures based on redundancy analysis. Specifically, water in each soil layer, pH value and salt in deep soil were the most important soil environmental factors driving the spatial expansion of Phragmites australis. This study provides a scientific basis and case reference for protection management and ecological restoration of inland river wetlands.