实验室模拟滨海盐沼潮滩高程对互花米草生长的影响

Laboratory simulation of the effects of tidal flat elevation on the growth of Spartina alterniflora in coastal salt marsh

为探究滨海盐沼湿地潮滩高程对互花米草生长的影响,设置六组不同高度的土柱,通过移栽互花米草进行模拟实验,研究不同高程带来的土壤水盐差异及植株生长响应情况。结果表明:(1)土壤含水率随高程的增加呈现出明显降低趋势,30 cm高程含水率最高,为46.4%,180 cm高程含水率最低,为34.1%,土壤孔隙水盐度随高程变化的趋势不明显,180 cm高程孔隙水盐度最高,为47.2 ppt,150 cm高程孔隙水盐度最低,为28.3 ppt;(2)不同高程下,互花米草的株高、生物量和根冠比呈现出显著性差异(p=0.01,p=0.03,p=0.02,均小于0.05),株高、生物量随潮滩高程增加不断降低,其中株高最大值较最小值多34.6%,生物量最大值较最小值多49.5%,植株根冠比与高程呈负相关关系,根冠比最大值较最小值增加72.4%;(3)互花米草株高与土壤含水率呈二次抛物线关系(R2=0.79),植株整体生物量与土壤含水率之间呈线性关系(R2=0.87),而株高、生物量与土壤孔隙水盐度无明显的相关性。基于实验得出,湿地高程带来淹水频率和地下水位差异,使土壤水盐随高程产生变化,进而造成潮滩较高处的互花米草株高、生物量高于潮滩较低处。

In order to explore the effects of tidal flat elevation on the growth of Spartina alterniflora in coastal salt marsh wetlands,we conducted six sets of soil pillars with different heights and transplanted Spartina alterniflora for simulation experiment to study the differences in soil moisture and salinity conditions and plant growth response brought by different elevations.The experimental results showed:(1)The soil moisture content revealed a negative correlation with elevation,with the highest soil moisture content at 30 cm(46.4%)and the lowest at 180 cm(34.1%).There was no correlation between soil pore water salinity and elevation,with the highest salinity at 180 cm(47.2 ppt)and the lowest at 150 cm(28.3 ppt).(2)The plant height,biomass and root-shoot ratio showed significant differences with different elevations(p=0.01,p=0.03,p=0.02,all less than 0.05).Plant height and biomass decreased continuously with the increase of tidal flat height.The maximum plant height was 34.6%larger than the minimum,and the maximum biomass was 49.5%larger than the minimum.There was a negative correlation between plant root-shoot ratio and height,and the maximum value increased by 72.4%compared with the minimum.(3)The plant height displayed a quadratic parabolic relationship with soil moisture(R2=0.79),and the biomass had a linear relationship with it(R2=0.87),while the plant height,biomass and showed no obvious correlation with soil pore water salinity.Therefore,it can be concluded that wetland elevation affects soil moisture and salinity conditions by altering flooding frequency and groundwater level,which in turn causes the plant height and biomass of Spartina alterniflora in the upper part of the tidal flat to be higher than the lower part.