Effects of sediment burial disturbance on seedling survival and growth of Suaeda salsa in the tidal wetland of the Yellow River estuary

Abstract

A greenhouse experiment was conducted to determine the effects of sediment burial on survival, growth and dry mass allocation of seedlings of Suaeda salsa (L.) Pall. (Chenopodiaceae), an important pioneer species of tidal wetland near the Yellow River estuary. From April to June 2009, seeds were buried at 0.5 cm depth in plastic pots filled with sediment. Two weeks after emergence, seedlings were buried to depths of 0 (H0), 33% (H33), 67% (H67), 100% (H100) and 133% (H133) of their mean height. Results showed that seedling survivorship, height, absolute height growth rate, relative height growth rate, stem diameter, number and length of branches, dry mass and relative growth rate were significantly affected by burial depth (P 0.05). No seedlings died in the partial burial treatment, approximately 18.06 ± 5.32% seedlings survived when they were completely buried, and no seedling survived when the burial depth reached 133% of the seedling height. Seedling height, absolute height growth rate, relative height growth rate, stem diameter, number and length of branch, dry mass and relative growth rate in the partial burial treatments were much higher than those of the unburied and completely buried treatments. With increasing burial depth, there was a tendency that both allocation to root and allocation to leaf increased, while allocation to stem decreased. The stem of S. salsa formed adventitious roots after being buried for less than 4 weeks, which was favorable for the survival and growth of seedlings, reflecting the fact that the S. salsa seedlings indeed exhibit a special adaptive strategy against rapid sediment burial in tidal wetland. The burial experiment also indicated that moderate burial disturbance (H33 and H67) increased seedling vigor, while strong burial disturbance (H100) reduced seedling vigor. The use of thin-layer sediment burial to promote the vigor of plants in degraded wetland is very feasible, and our results provide valuable practical information applicable to the restoration of degraded S. salsa wetland.