黄河三角洲湿地不同植被类型下土壤营养元素空间分布及其生态化学计量学特征

选取黄河三角洲芦苇湿地、柽柳湿地、盐地碱蓬湿地和光滩这4种典型自然湿地及农垦地棉花田作为研究对象，阐明不同植被类型自然湿地土壤营养元素分布特征和生态化学计量学特征，并进行农垦地同自然湿地的对比研究.结果表明，自然湿地内土壤总有机碳（TOC）和总氮（TN）含量总体表现为：芦苇湿地、柽柳湿地>盐地碱蓬湿地>光滩，TOC和TN含量同土壤电导率值（EC）和pH值呈显著负相关（P<0.05）;棉花田TOC、 TN和全磷（TP）含量显著高于自然湿地（P<0.05）,其中硝态氮（NO^-₃-N）含量为自然湿地的9.4～11.4倍，但棉花田碳、氮和磷含量同EC值和pH值无显著相关性（P>0.05）.相关分析表明，自然湿地土壤碳氮比（C/N）主要受控于TN含量（P<0.05）,棉花田土壤C/N显著低于自然湿地（P<0.05）.自然湿地及棉花田土壤碳磷比（C/P）和氮磷比（N/P）均值较低，且与土壤TOC和TN含量变化趋势一致.对比分析发现，整体上棉花田土壤营养元素含量、 C/N、 C/P和N/P差异显著（P<0.0...

Spatial Distribution and Eco-stoichiometric Characteristics of Soil Nutrient Elements Under Different Vegetation Types in the Yellow River Delta Wetland

To clarify the distribution characteristics and the ecological stoichiometric characteristics of nutrient elements in soils under different vegetation types, four typical natural wetlands, i.e., Phragmites australis wetland, Tamarix chinensis wetland, Suaeda salsa wetland, and Tidal flat wetland, as well as Gossypium spp. fields that were reclaimed from natural wetlands, were selected as study sites in the Yellow River Delta, and comparisons between the agricultural reclamation land and natural wetlands were conducted. The results showed that the soil total organic carbon (TOC) and total nitrogen (TN) contents in the natural wetlands were as follows:P. australis wetland and T. chinensis wetland>S. salsa wetland>Tidal flat, and the contents of TOC and TN were significantly negatively related to electrical conductivity (EC) and pH values (P<0.05). The contents of TOC, TN, and total phosphorus (TP) in Gossypium spp. fields were significantly higher than those in natural wetlands (P<0.05), especially the contents of nitrate nitrogen (NO₃^--N) in Gossypium spp. fields, which were 9.4-11.4 times that of natural wetlands. However, no significant correlations between TOC, TN, and TP and EC and pH values (P>0.05) were observed in Gossypium spp. fields. The results of correlation analysis showed that the C/N of natural wetlands were mainly controlled by the contents of TN (P<0.05), and the C/N of the Gossypium spp. fields were significantly lower than those of natural wetlands (P<0.05). The soil C/P and N/P of natural wetlands and Gossypium spp. fields in the Yellow River Delta were low, and the variation trends were consistent with those of soil TOC and TN. Comparative analysis revealed, on the whole, that there were significantly different soil nutrient element contents, C/N, C/P, and N/P in Gossypium spp. fields compared to those of natural wetlands (P<0.05). The process of reclamation could significantly change the spatial distribution of nutrient elements in wetlands. Our results should be of importance in revealing the biogeochemical process of soil nutrient elements in coastal wetland and the influence of agricultural reclamation activities on the differentiation of soil nutrient elements.