Spatial Distribution of Soil Organic Carbon and Total Nitrogen in a Ramsar Wetland, Dafeng Milu National Nature Reserve

Xiuying Yao,Yao Liu,Siying Xie,Jingtai Li,Zhaoqing Luan,Dandan Yan,Yufeng Sheng

doi:10.3390/w14020197

Abstract

The invasion and expansion of Spartina alterniflora in coastal salt marsh wetlands have greatly affected the material cycle of the ecosystem. A total of 372 topsoil samples were collected from 124 sites representing two land-cover types by implementing an unprecedented high sampling density study in the Dafeng Milu National Nature Reserve. Classical statistics and geostatistics were used to quantify soil organic carbon (SOC) and total nitrogen (TN) spatial distribution. Redundancy analysis (RDA) was used to detect correlations between environmental factors, SOC, and TN. The results showed that SOC and TN have moderate variability. The spatial distributions of SOC and TN were similar, and the highest values were observed in the southwest of the study area. In different land cover types, the SOC and TN in the vegetation coverage areas with Spartina alterniflora as the dominant species were significantly higher than those in bare land. RDA showed that TN and aboveground biomass significantly affected the spatial distribution of SOC, while SOC and AGB dominated the spatial distribution of TN.

Highlights

Affected by the interaction of sea and land, coastal wetlands provide essential ecosystem services, including shoreline protection, biodiversity maintenance, and regional climate regulation [1,2,3]
The selected study area is the Dafeng Milu National Nature Reserve (DMNNR) located in southeastern Dafeng, Yancheng City, Jiangsu Province, which exhibits an area of 25 km2 (Figure 1)
This study found that the contents of soil organic carbon (SOC) and total nitrogen (TN) in the vegetation area dominated by S. alterniflora were significantly higher than those in the mudflat (Table 2), which is consistent with previous research [18,20]

Summary

Introduction

Affected by the interaction of sea and land, coastal wetlands provide essential ecosystem services, including shoreline protection, biodiversity maintenance, and regional climate regulation [1,2,3]. The carbon stored in plants and soil of terrestrial ecosystems through photosynthesis is often called “green carbon”. In contrast to terrestrial green carbon and marine blue carbon, the carbon stored in coastal ecosystems is defined as “coastal blue carbon”. In the “coastal blue carbon” ecosystem, soil is the largest carbon pool and provides an environment for wetland plant growth [6]. Wetland soil is an integral part of the nitrogen cycle, in which nitrogen content, migration, and transformation have an essential impact on the structure, function, and productivity of the entire wetland ecosystem [9]. Chemical, and biological processes, SOC and TN exhibit significant heterogeneity in spatial locations [10]

Methods

Results

Discussion

Conclusion