College of Resources and Environment, Shandong Agricultural University, Tai'an, 271018, China.
Shandong Provincial Engineering and Technology Research Center for Phyto-Microremediation in Saline-Alkali Land, Shandong, China.
Sci Rep. 2021 Feb 3;11(1):2911. doi: 10.1038/s41598-021-82376-0.
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 CO m s, 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 CO efflux were 375, 513 and 944 g CO·m 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.
滨海湿地土壤碳（C）被称为“蓝碳”，由于气候变化和土地开垦，其碳储量已大量减少。由于土壤呼吸（RS）是全球范围内土壤碳释放到大气中的主要机制，因此研究开垦滨海湿地的土壤呼吸速率动态特征对于了解其在维持全球碳循环中的重要作用是必要的。本研究监测了黄河三角洲一个裸湿地（CK）和两个开垦湿地（CT，棉花单作模式和 WM，小麦-玉米连作模式）的土壤呼吸季节性和昼夜变化。在昼夜尺度上，三个研究点的 RS 呈单峰曲线，最低值出现在午夜（00:00 a.m.），最高值出现在中午（12:00 a.m.）。在季节尺度上，CK、CT 和 WM 四月的平均昼夜 RS 分别为 0.24、0.26 和 0.79 μmol CO m s，这些地区的 RS 在八月份达到峰值。将裸湿地转化为耕地显著增加了土壤有机碳（SOC）库。三个地点的 RS 幅度有显著差异，CK、CT 和 WM 的年 CO 排放量分别为 375、513 和 944 g CO·m。在三个研究点，土壤表层温度与昼夜和季节尺度的 RS 呈显著正相关，其占日间 RS 季节变化的 20-52%。土壤含水量仅在 CK 点对昼夜尺度的 RS 有显著但负相关，而在所有研究点的季节尺度上，土壤含水量均随 RS 显著增加。尽管 RS 与土壤温度和水分含量的组合具有明显的关系，但这两个环境因素的协同效应并不比各自的效应高很多。此外，相关分析表明，RS 还受到土壤理化性质的影响，土壤全氮与 RS 的关系比其他养分更密切，表明土壤氮含量在促进碳损失方面起着更重要的作用。
