滨海盐沼水文特征对盐地碱蓬定植过程的影响

为了揭示盐沼水文特征对植物定植的影响,选择黄河三角洲滨海盐沼无植被、具有一定水文梯度的区域,通过定点监测和野外控制实验展开研究。结果表明：（1）潮沟作为盐沼潮水的主要源汇通道,高程和水文特征在垂直潮沟方向上发生显著变化;在时间上,盐沼表面潮汐过程存在干湿季特点;在空间上,淹水频率和淹水时长随高程增加而降低。（2）土壤水盐特征与水文特征相关性不高,但趋势显著：盐度随着距潮沟距离的增加呈上升趋势,含水率则相反。（3）盐地碱蓬（Suaeda salsa）种子捕捉量、萌发率和幼苗存活率随距潮沟距离增加而下降,远离潮沟区域由于种子到达概率较低、萌发和生长条件较差,降低了植物成功定植的概率。

Effect of hydrological characteristics on the recruitment of Suaeda salsa in coastal salt marshes

Salt marshes are increasingly valued for their function of coastal protection. Affected by periodic tidal events, salt marshes are highly dynamic ecosystems, especially for the hydrological characteristics. The dynamic hydrological characteristics have significantly affected the recruitment of plant, resulting in a profound influence on the distribution of salt marsh plants. To reveal the effect of hydrological characteristics on plant recruitment in salt marshes, this study conducted a field experiment on a bare patch of Yellow River Delta coastal salt marshes. A typical tidal inundation gradient was set, by choosing six transects from a main tidal creek to high areas on a bare patch in mid to high salt marshes. And the measurement of hydrological and soil characteristics, seed emergence and seedling survival experiments were conducted on the tidal gradient. Our results showed that: (1) Elevation, tidal hydrodynamics, and the inundation gradient had significant effects along the gradient from the creek to the salt marsh: The elevation of sampling points increased with the distance from the creek; on the temporal scale, there were wet and dry periods of hydrological process, the inundation frequency, water table and cumulative inundation period were lower during November to April, and they started to increase since May; on the spatial scale, the inundation frequency and cumulative inundation period decreased with the increase of elevation, and became stable after the average high water level; the relationship between the maximum water depth and elevation was revealed as a quadratic curve, and the maximum water depth reached the highest values in the elevation of 0.9 to 1.1 m. (2) Soil salinity and moisture content were not correlated with the hydrological gradient, but their changing trends were significant: with the increase of the distance to the tidal creek, soil salinity was increasing, while soil moisture content was decreasing. (3) The captured Suaeda salsa seeds (by seed traps), seed emergence rate and survival rate decreased with the increase of the distance to the tidal creek, which revealed that the recruitment of Suaeda salsa was significantly affected by hydrological characteristics. At the dry end of hydrological gradient (the higher area), the lower inundation frequency went against the dispersal of Suaeda salsa seeds, seeds emergence and seedling growth, which reduced the recruitment success of Suaeda salsa.