Geremew Addisie, Stiers Iris, Sierens Tim, Kefalew Alemayehu, Triest Ludwig
Laboratory of Plant Biology and Nature Management (APNA), Department of Biology, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
Department of Plant Biology and Biodiversity Management, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia.
PLoS One. 2018 Jan 16;13(1):e0190810. doi: 10.1371/journal.pone.0190810. eCollection 2018.
Land degradation and soil erosion in the upper catchments of tropical lakes fringed by papyrus vegetation can result in a sediment load gradient from land to lakeward. Understanding the dynamics of clonal modules (ramets and genets) and growth strategies of plants on such a gradient in both space and time is critical for exploring a species adaptation and processes regulating population structure and differentiation. We assessed the spatial and temporal dynamics in clonal growth, diversity, and structure of an emergent macrophyte, Cyperus papyrus (papyrus), in response to two contrasting sedimentation regimes by combining morphological traits and genotype data using 20 microsatellite markers. A total of 636 ramets from six permanent plots (18 x 30 m) in three Ethiopian papyrus swamps, each with discrete sedimentation regimes (high vs. low) were sampled for two years. We found that ramets under the high sedimentation regime (HSR) were significantly clumped and denser than the sparse and spreading ramets under the low sedimentation regime (LSR). The HSR resulted in significantly different ramets with short culm height and girth diameter as compared to the LSR. These results indicated that C. papyrus ameliorates the effect of sedimentation by shifting clonal growth strategy from guerrilla (in LSR) to phalanx (in HSR). Clonal richness, size, dominance, and clonal subrange differed significantly between sediment regimes and studied time periods. Each swamp under HSR revealed a significantly high clonal richness (R = 0.80) as compared to the LSR (R = 0.48). Such discrepancy in clonal richness reflected the occurrence of initial and repeated seedling recruitment strategies as a response to different sedimentation regimes. Overall, our spatial and short-term temporal observations highlighted that HSR enhances clonal richness and decreases clonal subrange owing to repeated seedling recruitment and genets turnover.
在纸莎草植被环绕的热带湖泊上游集水区，土地退化和土壤侵蚀会导致从陆地到湖泊方向的沉积物负荷梯度。了解克隆模块（分株和基株）的动态以及植物在这种梯度上的时空生长策略，对于探索物种适应性以及调节种群结构和分化的过程至关重要。我们通过使用20个微卫星标记结合形态特征和基因型数据，评估了一种挺水大型植物纸莎草在两种截然不同的沉积条件下，其克隆生长、多样性和结构的时空动态。在埃塞俄比亚的三个纸莎草沼泽中，选取了六个永久样地（18×30米），每个样地具有不同的沉积条件（高沉积与低沉积），共采集了636个分株，持续两年。我们发现，高沉积条件下的分株明显聚集且比低沉积条件下稀疏分散的分株更为密集。与低沉积条件相比，高沉积条件导致分株的茎高和茎围显著不同。这些结果表明，纸莎草通过将克隆生长策略从游击型（低沉积条件下）转变为密集型（高沉积条件下）来减轻沉积的影响。克隆丰富度、大小、优势度和克隆亚范围在沉积条件和研究时间段之间存在显著差异。与低沉积条件（R = 0.48）相比，高沉积条件下每个沼泽的克隆丰富度显著更高（R = 0.80）。克隆丰富度的这种差异反映了作为对不同沉积条件的响应，初始和重复的幼苗招募策略的发生。总体而言，我们的空间和短期时间观测结果突出表明，由于重复的幼苗招募和基株更替，高沉积条件增强了克隆丰富度并减小了克隆亚范围。
