Linze Inland River Basin Research Station, Key Laboratory of Inland River Basin Ecohydrology, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, Gansu, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2020 May;27(14):17085-17092. doi: 10.1007/s11356-020-08283-5. Epub 2020 Mar 7.
The wetland plants are very sensitive to hydrological regimes. In this study, the individual sizes of a widely distributed species (i.e., Deyeuxia angustifolia) at three typical marshes with different water table depths (i.e., wet meadow (WM) marsh; seasonal inundated (SI) marsh; perennial inundated (PI) marsh) were investigated in the Sanjiang Plain of Northeast China. Concurrently, three primary point pattern processes (homogeneous Poisson (HP) process, homogeneous Thomas (HT) process, and inhomogeneous Thomas (IT) process) were used to model spatial patterns in the distribution at 0-50 cm scale for this tillering-cloning species. The plant height, diameter at breast height (d.b.h), internode number, branches number, and individual aboveground biomass of D. angustifolia decreased sharply with rising water level; however, its density and coverage increased first and then decreased as water level increases. The distribution of D. angustifolia totally diverged from the complete spatial randomness (CSR) model (i.e., HP process) suggesting strong aggregation at 0-50 cm scale in all marshes, and aggregated intensity enhanced with increasing water level. Interestingly, the spatial distribution of D. angustifolia fits better with the nested double-cluster model (i.e., IT process) at all scales in WM and SI marshes, indicating that there is a series of clustered patterns under the slight flood stress. However, the spatial pattern fits well with the Poisson cluster model (i.e., HT process) at all scales in PI marsh, implying the small-scale clustering disappeared with the intensification of flooding stress. Our results highlight that the D. angustifolia population could adapt to flooding stress in a certain degree via individual miniaturization strategies and multi-aggregation mechanisms in the freshwater wetlands.
湿地植物对水文状况非常敏感。本研究以三江平原广泛分布的狭叶甜茅（Deyeuxia angustifolia）为研究对象，在三种不同水位深度的典型湿地（即湿草甸（WM）湿地、季节性淹没（SI）湿地和常年淹没（PI）湿地）中，调查了其个体大小。同时，在 0-50cm 尺度上，采用三种主要的点格局过程（均匀泊松（HP）过程、均匀托马斯（HT）过程和非均匀托马斯（IT）过程）对该分株克隆植物的分布格局进行了模拟。狭叶甜茅的株高、胸径（d.b.h）、节间数、分枝数和地上生物量个体随着水位的升高而急剧下降，但其密度和盖度随着水位的升高先增加后减少。在所有湿地中，狭叶甜茅的分布完全偏离完全空间随机性（CSR）模型（即 HP 过程），表明在 0-50cm 尺度上存在强烈的聚集现象，且聚集强度随水位升高而增强。有趣的是，在 WM 和 SI 湿地的所有尺度上，狭叶甜茅的空间分布与嵌套双簇模型（即 IT 过程）更为吻合，表明在轻度洪水胁迫下存在一系列聚集模式。然而，在 PI 湿地的所有尺度上，空间格局均与泊松聚类模型（即 HT 过程）吻合较好，表明随着洪水胁迫的加剧，小尺度聚类现象消失。研究结果表明，在淡水湿地中，狭叶甜茅种群能够通过个体小型化策略和多聚集机制在一定程度上适应洪水胁迫。
