Dynamics of the soil respiration response to soil reclamation in a coastal wetland

Abstract

The soil carbon (C) pools in coastal wetlands are known as “blue C” and have been damaged extensively owing to climate change and land reclamation. Because soil respiration (RS) is the primary mechanism through which soil carbon is released into the atmosphere at a global scale, investigating the dynamic characteristics of the soil respiration rate in reclaimed coastal wetlands is necessary to understand its important role in maintaining the global C cycle. In the present study, seasonal and diurnal changes in soil respiration were monitored in one bare wetland (CK) and two reclaimed wetlands (CT, a cotton monoculture pattern, and WM, a wheat–maize continuous cropping pattern) in the Yellow River Delta. At the diurnal scale, the RS at the three study sites displayed single-peak curves, with the lowest values occurring at midnight (00:00 a.m.) and the highest values occurring at midday (12:00 a.m.). At the seasonal scale, the mean diurnal RS of the CK, CT and WM in April was 0.24, 0.26 and 0.79 μmol CO2 m−2 s−1, and it increased to a peak in August for these areas. Bare wetland conversion to croplands significantly elevated the soil organic carbon (SOC) pool. The magnitude of the RS was significantly different at the three sites, and the yearly total amounts of CO2 efflux were 375, 513 and 944 g CO2·m−2 for the CK, CT and WM, respectively. At the three study sites, the surface soil temperature had a significant and positive relationship to the RS at both the diurnal and seasonal scales, and it accounted for 20–52% of the seasonal variation in the daytime RS. The soil water content showed a significant but negative relationship to the RS on diurnal scale only at the CK site, while it significantly increased with the RS on seasonal scale at all study sites. Although the RS showed a noticeable relationship to the combination of soil temperature and water content, the synergic effects of these two environment factors were not much higher than the individual effects. In addition, the correlation analysis showed that the RS was also influenced by the soil physico-chemical properties and that the soil total nitrogen had a closer positive relationship to the RS than the other nutrients, indicating that the soil nitrogen content plays a more important role in promoting carbon loss.

Changes in microbial community and enzyme activity in soil under continuous pepper cropping in response to Trichoderma hamatum MHT1134 application

“…JSM-2 from alkaline papermaking wastewater. As the continuous cropping time increases, the soil gradually becomes salinised 37 , and the abundance levels of alkaline-tolerant fungi may also increase. In addition, the abundance of Acidobacteria increased along with the planting years.…”

Soil temperature, microbial biomass and enzyme activity are the critical factors affecting soil respiration in different soil layers in Ziwuling Mountains, China

“…For example, soil salinity and R S show a negative correlation. When in a salt-stress environment, the activities of plant roots and soil microorganisms are severely affected ( Song et al, 2021 ).…”

Soil texture and pH affect soil CO2 efflux in hardwood floodplain forests of the lower middle Elbe River

“…Soil microbial communities are often adapted to specific pH and EC levels (Chen et al, 2014; Sardinha et al, 2003). The negative relation of soil CO 2 efflux to EC (Figure 6g) could reflect a stress effect on plants and microorganisms, which usually occurs in coastal wetlands (Song et al, 2021). The negative effect of pH on microbial activity tends to occur in alkaline soils (Yang et al, 2019).…”