Ecological stoichiometry of carbon, nitrogen, and phosphorus in estuarine wetland soils: influences of vegetation coverage, plant communities, geomorphology, and seawalls

Little is known about carbon, nitrogen, and phosphorus stoichiometrical characteristics and influencing factors in estuary wetland soils. The purpose of this work is to study ecological stoichiometric characteristics of carbon, nitrogen, and phosphorus (R (CN), R (CP), and R (NP)) in estuarine wetland soils of Shuangtaizi, northeast China and the potential affecting factors like vegetation coverage, plant communities, geomorphology, and seawall. During 2008-2010, soil samples in estuarine wetland were collected for soil organic carbon, total nitrogen and phosphorus, and other elements determination. Mole ratios of R (CN), R (CP), and R (NP) were calculated. As a whole, R (CN) was in the range of 8.26 similar to 52.97 (mean, 16.15), R (CP) was in the range of 23.21 similar to 862.53 (mean, 90.66), and R (NP) was in the 0.93 similar to 29.52 (mean, 5.07). R (CN), R (CP), and R (NP) distribution were all with high spatial heterogeneities and significantly affected by vegetation coverage, plant communities, geomorphology, and seawalls. During the typical plant succession sequence of the halophytes-the mesophyte-the hydrophyte in estuarine wetland, P might be the primary limiting elements for nutrients stoichiometrical characteristics. R (CN), R (CP), and R (NP) in soils of low-lying areas were all higher than that in highlands. Plant coverage and communities formation would help to reduce restriction from nitrogen, but to increase restrictions from phosphorus meanwhile. C, N, and P ecological stoichiometry had high complexities. R (CN) in estuarine wetland soils were generally high, whereas R (CP) and R (NP) were comparatively low, indicating that ecosystems in the estuary were limited by nutrients such as N and P, with the latter being the primary factor. Vegetation covers, plant communities, geomorphology, and seawall all affected nutrient stoichiometry in soils.