Abstract:

Soils in salt marsh ecosystems have been undergoing certain changes including those related to sediment types and burial depths due to tidal activity and a variety of biotic factors. The changes in sediment type affect water-retaining properties, permeability and organic content while those in burial depth alter soil humidity, nutrition content, oxygen content, light intensity and temperature. Although many previous studies have focused on the effects of soil properties on plant growth and reproduction, few have explicitly tested the impacts of sediment type and burial depth on plants in salt marsh ecosystems. The exotic species Spartina anglica found in coastal China has been experiencing increased mortality over the past decade, however the mechanism of this mortality remains unclear. This study mainly focused on the effects of sediment type and burial depth on growth traits and biomass accumulation of S. anglica and was conducted under greenhouse conditions. The experiment included two types of sediments with clay and clay-sand mixtures (the volume of 1:1). Furthermore, four treatments were established with burial depths from 0 cm to one quarter of the plant height, one half of the plant height and three quarters of the plant height. Results indicated that clay increased leaf area, number of leaves, number of rhizomes, total length of rhizomes, rhizome mass and aboveground mass, while the clay-sand mixture led to an increase in the number of ramets, total mass, underground mass and root mass. All of the measures, except for leaf area, peaked at one half of the plant height burial treatment among all treatments. Overall, burial depth at one half of the plant height in clay was the most suitable combination for S. anglica. The results indicate that changes in sediment properties and subsequent changes in burial depth for S. anglica may assist with management of its populations over the species range.

Key words: salt marsh, Spartina anglica, population invasion and decline, biomass accumulation