Effects of alternate flooding–drought conditions on degenerated Phragmites australis salt marsh in Northeast China

Abstract

The hydrological regime is the dominant factor associated with the degradation and restoration of inland salt marshes in Northeast China. This study investigates whether alternate flooding–drought conditions could be used to actively restore degraded inland salt marshes with the native plant Phragmites australis. Pot experiments were designed to examine changes in the growth and physiology of P. australis, as well as the saline–alkaline soil characteristics, in response to different hydrological regimes, alternate flooding–drought treatments, and single treatments of moisture, flooding, and drought. After 4 months of treatments, the P. australis population that grew in alternate flooding–drought conditions exhibited substantially more biomass accumulation and less Na+ absorption compared with the single treatments of moisture, flooding, and drought. Photosynthesis physiology served as regulating and adaptive responses to different water regimes, with increased values after the short‐term flooding, long‐term drought, and flooding–drought cycles. In addition, the saline–alkaline soil properties changed in response to the flooding–drought cycles. The flooding–drought cycles increased organic matter and total nitrogen contents, but decreased pH, electrical conductivity, and saline ion levels. Plant growth and saline–alkaline soil were improved by flooding–drought cycles (not drought–flooding cycles), which suggests that this may be an effective approach for restoration inland salt marshes.

Comparison of the Photosynthetic Capacity of Phragmites australis in Five Habitats in Saline‒Alkaline Wetlands

“…It is moderately saline‒alkaline, with an area of around 33 km 2 . The main source of water supply is Taoer River [ 38 ]. P. australis saline‒alkaline marshes are distributed in the study region, and it is characterized by a typical semiarid and moderate monsoon climate with distinctive seasons; the total annual sunlight is 5259 MJ/m 2 , the frost-free period is 137 d of the year [ 39 ], and it is one of the typical distribution areas of reeds in inland China.…”

Soil Carbon, Nitrogen and Phosphorus Concentrations and Stoichiometries Across a Chronosequence of Restored Inland Soda Saline- Alkali Wetlands, Western Songnen Plain, Northeast China

“…The soil types in the region are dominated by NaHCO 3 saline marsh soil and alkaline soil, which are characterized by high bulk densities and poor permeabilities. The soil pH ranges between 8.0 and 10.5, and the salinity varies from 0.1% to 1.6% (Li et al, 2017). Modern swamp plant cover on is dominated by Phragmites australis accompanied by Leymus chinensis, Stargrass, Cattail, Suaeda salsa, and other sedges.…”

“…They are important sources, sinks, and converters of nutrient elements (Mitsch et al, 2013). The globally rare inland soda alkaline wetland ecosystem is distributed mainly in the soda saline soil distribution area, where it maintains the ecological balance of the area (Li et al, 2017). China is one of three soda alkaline land distribution areas in the world (Sumner and Naidu, 1998).…”

How to Choose a Hydrological Recovery Mode for Degraded Semiarid Wetland in China? A Case Study on Restoration of Phragmites australis Saline-Alkaline Wetland

“…Hypoxia is enhanced by increasing the flooding duration and it is the main factor that influences the survival and growth of wetland plants [13]. Alternating flooding and drought can promote the accumulation of biomass in Phragmites australis [14]. However, hydrological recovery mode such as those with different flooding depths, durations, and frequencies have rarely been compared.…”