Effects of waterlogging and increased salinity on microbial communities and extracellular enzyme activity in native and exotic marsh vegetation soils

Abstract

Coastal ecosystems are vulnerable to plant invasion and expected sea level rise in China. This study explored the responses of microbial communities and extracellular enzyme activity in the marsh soils of native Phragmites australis and exotic Spartina alterniflora to waterlogging and increasing salinity (to mimic prolonged inundation and saltwater intrusion) based on the determination of phospholipid fatty acids and analysis of enzyme kinetics. The results showed that waterlogging and increased salinity treatments decreased the soil microbial biomass in both P. australis and S. alterniflora soils, with waterlogging exacerbating the negative effects of salinity. Fungi/bacteria ratios decreased under both waterlogging and salinity treatments, whereas actinomycetes/bacteria ratios increased with increasing salinity. The degree of the adverse effects of salinity on plant growth of S. alterniflora and soil microbial biomass was lower than that on P. australis. Generally, waterlogging treatment increased the activity of sucrase, cellulase, urease, and dehydrogenase in S. alterniflora soil. Increased salinity decreased all the assayed extracellular enzyme activity in both P. australis and S. alterniflora soils. The synergistic effects of waterlogging and increased salinity treatments on the enzyme activities in P. australis soil were significant, whereas only the effect on the cellulase activity was significant in S. alterniflora soil. This study indicated a greater ability of the microbial community and extracellular enzyme activity of S. alterniflora soil to adapt to waterlogging and increased salinity compared with those of P. australis soil due to the lower sensitivity of S. alterniflora growth and soil nutrients to stress.

Differential Responses of Soil Extracellular Enzyme Activities to Salinization: Implications for Soil Carbon Cycling in Tidal Wetlands

“…However, these responses were not always consistent for individual studies, indicating that other unknown factors (e.g., hydrologic context) also affect Hy‐C and Ox‐C EEAs. We tried to collect information, such as tidal range, tidal inundation frequency, mean inundation level, or intertidal flat zone, from the published papers, but very few studies provided this information (Chambers et al., 2016; Liu et al., 2021; Xie et al., 2020). The results from published studies showed that increasing flooding did not significantly alter the response of Hy‐C EEAs to salinization (Chambers et al., 2016; Xie et al., 2020), but flooding sometimes reduced the stimulation of Ox‐C EEAs with salinization in tidal wetland systems (Liu et al., 2021).…”

“…We tried to collect information, such as tidal range, tidal inundation frequency, mean inundation level, or intertidal flat zone, from the published papers, but very few studies provided this information (Chambers et al., 2016; Liu et al., 2021; Xie et al., 2020). The results from published studies showed that increasing flooding did not significantly alter the response of Hy‐C EEAs to salinization (Chambers et al., 2016; Xie et al., 2020), but flooding sometimes reduced the stimulation of Ox‐C EEAs with salinization in tidal wetland systems (Liu et al., 2021). This might be because the Ox‐C EEAs require oxygen (Freeman et al., 2001; Wang et al., 2017), and increasing inundation will reduce the oxygen availability in wetland soils (Kostka et al., 2002).…”

The competitive strategies of poisonous weeds Elsholtzia densa Benth. on the Qinghai Tibet Plateau: Allelopathy and improving soil environment

“…The determination method was slightly modified by referring to Xie et al (Chen et al, 2020;Xie et al, 2020). The urease activity was determined by the sodium phenolate colorimetric method, and the invertase and cellulase activities were determined by the 3,5dinitrosalicylic acid colorimetric method.…”

Allelochemicals-based expansion of Elsholtzia densa Benth. hindering plants’defense function: case study of Hordeum vulgare L.

“…References determination of soil enzyme activity (Xie et al 2020, Chen et al 2020). The urease activity is determined by the sodium phenolate colorimetric method, and the invertase and cellulase activities are determined by the 3,5-dinitrosalicylic acid colorimetric method.…”