Wang Zhengjun, Gong Huili, Zhang Jing
College of Life Sciences, Capital Normal University, Beijing, China.
College of Resources Environment and Tourism, Capital Normal University, Beijing, China.
PLoS One. 2015 Apr 7;10(4):e0124156. doi: 10.1371/journal.pone.0124156. eCollection 2015.
Climate and human-induced wetland degradation has accelerated in recent years, not only resulting in reduced ecosystem services but also greatly affecting the composition and diversity of wetland plant communities. To date, the knowledge of the differences in community parameters and their successional trends in degraded wetlands remains scarce. Here based on remote sensing images, geographic information system technology, and statistical methods, we produced a successional gradient map of the Yeyahu Wetland Nature Reserve in Beijing, which has experienced a steady decline in water level in recent decades. In addition, we analyzed community composition and diversity along with each identified gradient. The results showed that community diversity decreases while dominance increases with the progress of succession, with the highest diversity occurring during the early stage of succession. Moreover, the community demonstrates greater similarity among subareas during later successional stages, and the similarity coefficients calculated from the important value (IV) of each species are more accurate. Correlation analysis showed that the impact of soil factors on diversity was not significant at a subarea scale, although these nutrients showed an increasing trend with the community succession. Furthermore, the IVs of the dominant species had a particularly significant impact on diversity, showing a significantly negative correlation with diversity indices and a significantly positive correlation with dominance indices. Further analysis showed that the retreat of water level resulted from sustained drought and local human activities was a major extrinsic driving force resulting in observed differences in the community successional stages, which resulted in differences in community composition and diversity. On the other hand, interspecific competition was the main intrinsic mechanism, which significantly influenced the IVs of the dominant species and community diversity. The results of this study could aid in improving the understanding of community composition, diversity, and its successional trends in degraded wetlands.
近年来，气候和人为导致的湿地退化加速，不仅造成生态系统服务功能减少，还极大地影响了湿地植物群落的组成和多样性。迄今为止，关于退化湿地群落参数差异及其演替趋势的认识仍然匮乏。在此，基于遥感影像、地理信息系统技术和统计方法，我们绘制了北京野鸭湖湿地自然保护区的演替梯度图，该保护区近几十年来水位持续下降。此外，我们分析了沿每个识别梯度的群落组成和多样性。结果表明，随着演替的推进，群落多样性降低而优势度增加，多样性在演替早期最高。而且，在演替后期各子区域间群落表现出更大的相似性，由各物种重要值（IV）计算得到的相似系数更准确。相关性分析表明，在子区域尺度上土壤因子对多样性的影响不显著，尽管这些养分随群落演替呈增加趋势。此外，优势种的重要值对多样性有特别显著的影响，与多样性指数呈显著负相关，与优势度指数呈显著正相关。进一步分析表明，持续干旱和当地人类活动导致的水位下降是造成群落演替阶段出现差异的主要外部驱动力，进而导致群落组成和多样性的差异。另一方面，种间竞争是主要的内在机制，它显著影响优势种的重要值和群落多样性。本研究结果有助于增进对退化湿地群落组成、多样性及其演替趋势的理解。
