七里海湿地芦苇群落和碱蓬群落分布格局的形成机理

Qilihai wetland provides very important ecological services and functions, thus it is designated as one of the National Nature Reserves in China. Although much attention has been paid to the protection and recovery of Qilihai wetland, the distribution patterns of plant communities in Qilihai wetland have rarely been studied. We surveyed the plant communities in Qilihai wetland and found that overall Phragmites australis is the main vegetation in the wetland, while at some area with relatively higher elevation, better drainage and higher soil salinity, Suaeda glauca is distributed. Based on previous studies, we hypothesize that P. australis cannot grow in S. glauca zone probably because it cannot tolerate the higher soil salinity; and S. glauca cannot grow in P. australis zone probably because P. australis has stronger competition ability which eliminates S. glauca from P. australis zone. To test these hypotheses, we propose to conduct a field transplant experiment and a full factorial greenhouse experiment. In this study, we will explore whether the distribution patterns of P. australis and S. glauca communities in Qilihai wetland are determined by environmental factors or interspecific interactions, or the influences from both. We will also disentangle the relative roles of soil salinity, flooding and interspecific interactions in determining the distribution patterns of P. australis and S. glauca communities in Qilihai wetland. This study will examine the factors mediating the distribution patterns of plant communities in Qilihai wetland, thereby will provide the scientific baseline for more effective management of these factors, which is crucial for successful conservation of biodiversity and ecosystem functions in the valuable Qilihai wetland.

七里海湿地为国家级自然保护区，具有极为重要的生态价值。虽然对七里海湿地的保护恢复得到了各方面的重视，但对其植物群落分布格局的研究却仍非常缺乏。调查发现，七里海湿地植被以芦苇为主体，其间在一些地势略高，排水稍好且盐度较高区域毗邻分布着碱蓬。我们假设：这种分布格局的形成是由于芦苇不能耐受环境胁迫（如较高土壤盐度）故不能生长在碱蓬分布区，而碱蓬竞争能力不敌芦苇而被排挤出芦苇分布区。我们拟开展野外移栽实验和温室多因子控制实验来检验上述假设，探究七里海湿地芦苇群落和碱蓬群落分布格局的形成是由环境因素，还是生物因素，或两者共同决定；并具体解析土壤盐度、淹水胁迫和种间相互作用对芦苇和碱蓬生长的影响，及它们在芦苇群落和碱蓬群落分布格局形成中的相对重要性。本研究能深入了解影响七里海湿地植物群落分布格局的因素，为科学选择适宜措施管控这些因素，有效保护七里海湿地生物多样性和恢复七里海湿地生态功能提供理论依据。

七里海湿地为国家级自然保护区，具有极为重要的生态价值，但对其植物群落分布格局的研究却仍非常缺乏。我们通过温室控制实验和野外移栽实验探究了土壤盐度、淹水深度和种间相互作用对七里海优势植物芦苇和碱蓬生长和分布的影响。我们的研究结果表明：（1）随着土壤盐度的升高，芦苇的生长受到抑制；较深的淹水使芦苇地上生物量、株高、总叶面积、分株数、果实重、表观量子效率和光饱和点显著增加。（2）较高盐度使碱蓬地上生物量显著增加，果实生物量和叶绿素含量显著降低，但叶生物量显著增加；较深的淹水抑制了碱蓬的生长。（3）种间相对相互作用强度指数（RII）分析表明：在较低盐度下，随着淹水深度的增加，芦苇所受到的来自碱蓬的竞争作用显著减弱，在较深淹水条件下，芦苇对碱蓬的竞争作用较强，芦苇在与碱蓬的竞争中占优势；而在较高盐度下，芦苇受到来自碱蓬的竞争作用较强；在较高盐度且排水的生境中，碱蓬受到来自芦苇的相互作用趋于中性，而芦苇受到来自碱蓬的竞争作用最强，碱蓬在与芦苇的竞争中占优势。本研究使我们更加深入地了解影响七里海优势植物芦苇和碱蓬生长和分布的因素，为科学制定措施管控这些因素，有效维护七里海湿地植物群落的稳定和发展，进而更好保护和恢复整体湿地的生物多样性和生态功能提供理论依据。