Effect of dikes on the distribution and characteristics of Phragmites australis in temperate intertidal wetlands located in the South Sea of Korea

Abstract

 We investigated the Korean Phragmites australis (haplotype P) distribution patterns and their association with environmental factors in estuaries with (Goseong) and without (Guman) a dike. The intertidal wetland of the Guman River Estuary has a flooding duration of 25% to 68% (average 40%), a range common to Phragmites habitats around the world. Porewater salinity in the Phragmites habitat of the Guman varied with the tides. Salinity of the overlying water influenced the salinity of pore-water only if flooding was above a certain height (overlying water depth of about 30 cm). High salinity was frequently observed in overlying water and pore-water of the Guman but the Phragmites may be able to survive with periodic exposure to freshwater, which relieves high salinity stresses. However, Phragmites experienced limited growth in some regions where flooding frequency was high but freshwater influence was low. Continuous measurement (two weeks) of pore-water salinity suggests that the salinity near the Phragmites rhizosphere is determined by the balance between the tidal and freshwater influences. Phragmites in the Goseong River Estuary was found at elevations about 100 cm lower than in the Guman and Phragmites growth was larger in the Goseong than in the Guman. We hypothesized that lower flooding duration and pore-water salinity, resulting from dike construction, allowed Phragmites to expand into lower elevation areas in the Goseong. The current study demonstrates the effects of coastal developments involving salinity structure and flooding duration changes on Phragmites distribution.

Climate Dynamics, Invader Fitness, and Ecosystem Resistance in an Invasion-Factor Framework

“…Seed production in nonnative common reed may be promoted by periodic reductions in water levels, providing opportunities for germination of seeds on temporarily exposed substrates (Carlson-Mazur et al 2014;Lee and An 2015;TougasTellier et al 2015;Table 4). Extreme flooding could also increase the invasiveness of nonnative common reed by disrupting existing vegetation and depth profiles and by directly spreading its propagules .…”

“…Likely, the most important response to evaluate in nonnative common reed in light of climate dynamics is its response to wider fluctuations in water levels that are predicted under climate change (Table 4). Seed production in nonnative common reed may be promoted by periodic reductions in water levels, providing opportunities for germination of seeds on temporarily exposed substrates (Carlson-Mazur et al 2014; Lee and An 2015; Tougas-Tellier et al 2015; Table 4). Extreme flooding could also increase the invasiveness of nonnative common reed by disrupting existing vegetation and depth profiles and by directly spreading its propagules (Kim et al 2015).…”

Characteristics of Nutrient Distribution by the Natural and Artificial Controlling Factors in Small Stream Estuary

“…또한 염분이 높을수록 퇴적물에 흡착되어 있던 암모늄이 탈착되어 질산화 박테리아 활동을 억제시키고, 염분이 높을수록 황화물 농도가 증가하여 DNRA(Dissimilatory nitrate reduction to ammonium, 질산염→암모늄)를 촉진시키고 질산화과정이 억제되므로 상류에 비해 탈질소화가 낮은 것으로 판단된다 (Seitzinger, 1988;Giblin et al, 2010). (Cooper and Cooke, 1984;Herbert, 1999;Lee and An, 2015).…”

Spatiotemporal variation of Van der Burgh's coefficient in a salt plug estuary

“…In addition, salt water intrusion can be aggravated by decreasing river discharges that result from barrages being built upstream to provide water for drinking and irrigation (Shaha and Cho, 2016). Changes in river discharge levels alter estuarine circulation, stratification, flushing times, salt water intrusion, as well as the transport of biota and dissolved and particulate materials such as salt, pollutants, nutrients, and organic matter (Azevedo et al, 2010;Lee and An, 2015;Savenije, 2012;Shaha and Cho, 2016;Valle-Levinson, 2010). Therefore, it is particularly important to understand the responses of estuarine salt transport mechanisms to temporal changes in river discharge levels be-cause salt water intrusion may lead to shortages of drinking and irrigation water (Khan et al, 2011), decreased rice production (Mirza, 2004), reduced freshwater fish habitat (Dasgupta et al, 2014), and inadequate industrial freshwater supplies (Mirza, 1998).…”