Influences of anthropogenic cultivation on C, N and P stoichiometry of reed-dominated coastal wetlands in the Yellow River Delta

Abstract

Motivated by the previous studies that indicated well-constrained carbon:nitrogen:phosphorus (C:N:P) ratios in planktonic biomass, and their importance to improve our understanding on the biological processes and nutrient cycling in marine ecosystems, ecologists have endeavored to search for similar patterns and relationship in terrestrial ecosystems. Recent analyses indicated that "Redfield-like" ratios existed in plants; such data might provide insight into the nature of nutrient limitation in terrestrial ecosystems. We attempted to determine if analogous C:N:P stoichiometrical ratios exist in the soil and plant in the reed-dominated coastal wetlands of the Yellow River Delta (YRD). Under the influences of anthropogenic cultivation in the YRD, the reeddominated wetlands could be classified into three categories, new-born wetland (NW), farmland converted into wetland (FW) and cotton wetland (CW). In these three wetland categories, our results showed that atomic C:N:P ratios (R CNP ) in both the soil (42.6:1.6:1, 71.2:2.0:1 and 63.2:1.9:1, respectively) and the plant (1753:22.4:1, 1539:23.0:1 and 1196:23.8:1, respectively) were not well-constrained. Though C:N ratios (R CN ) and C:P ratios (R CP ) were of relatively large variation among different wetland soils and plants, average atomic N:P ratios (R CN ) in both the soil (~1.9:1) and the plant (~23:1) were well-constrained in the reed-dominated wetlands at the YRD scale, suggesting that the N limitation and P limitation were found in the soils and the plants, respectively. The results potentially provide a useful reference for ongoing wetland conservation and restoration in the YRD.

Distribution of carbon, nitrogen and phosphorus in coastal wetland soil related land use in the Modern Yellow River Delta

“…The present results of soil TOC content (0.69–20.23 g kg −1 ) in the YRD (Table 1) were similar to the most of coastal wetlands of China18193132333435 and Sundarban mangrove wetland36 and the Mai Po Marshes coastal wetland37, but much lower than that in Louisiana coastal wetlands38. Compared to the reported results of coastal wetlands, the soil N contents in present study were much lower than those in Yangtze Estuary (southern China)333940 and coastal wetlands of southern India41.…”

“…It is believed that this should be mainly from materials by tide because many large algae, the bodies and excretion of marine animals were observed in tidal flat18. The previous study results about the distribution and accumulation of phosphorus and organic matter of the sediment in the estuary1939 can well explain why the soil TP content was relative stable and the significant relation of TP and land formation age was not observed in present study (Fig. 5).…”

“…Previous studies in YRD have reported the soil organic carbon (SOC) budget13, the distribution characteristics of SOC and nutrients stoichiometry in new-born coastal wetlands1819, the nutrients exchange between land and atmosphere202122. However, whole ecosystem scale nutrients information regarding the biogeochemical processes of C, N and P responsible for regulating the spatial distribution related land use and salinity studies in the YRD coastal systems is still lacking.…”

Grazing enhances soil nutrient effects: Trade‐offs between aboveground and belowground biomass in alpine grasslands of the Tibetan Plateau

“…Samples from the <2 mm fraction were weighed and used for analyses. SOC and SoilN contents were determined using a vario MACRO cube elemental analyzer (Elementar Analysensysteme GmbH, Germany; Qu et al, ). To remove inorganic carbon, all samples used for SOC analysis were treated with hydrochloric acid (10% HCl) prior to analysis.…”

Short-term grazing exclusion has no impact on soil properties and nutrients of degraded alpine grassland in Tibet, China

“…Soil organic carbon (SOC) and soil total nitrogen (TN) contents were determined by using a vario MACRO cube elemental analyzer (Elementar Analysensysteme GmbH, Ger-X. Lu et al: Short-term grazing exclusion many) (Qu et al, 2014). To remove inorganic carbon, all samples for SOC analysis were acid-treated with hydrochloric acid (10 % HCl) prior to analysis.…”