鄱阳湖湿地碟形湖泊沿高程梯度土壤养分及化学计量研究

在鄱阳湖南矶山湿地自然保护区的碟形湖区,沿高程梯度采集岗地、高滩、低滩和泥沼土壤,对碳、氮、磷及其化学计量特征进行了研究。结果表明,表层土壤(0~10 cm)有机碳含量在岗地土壤最低;总氮和总磷含量均表现为岗地高滩低滩泥沼,且总氮和总磷含量呈显著正相关。土壤有机碳和总氮含量均表现出随土层加深而减少的趋势。表层土壤C/N、C/P和N/P的平均值分别为11.17、52.74和5.03,且随着高程梯度和湖泊的变化,C/N保持相对稳定,而C/P和N/P的变化较大。铵态氮含量表现出岗地高滩低滩泥沼,硝态氮含量表现出高滩低滩岗地泥沼。有效磷与总磷含量呈极显著正相关。总之,受到鄱阳湖季节周期性水文变化的影响,研究区湿地土壤养分有较大差异,其中氮是N/P比的主要控制因子。

Soil Nutrients and Stoichiometry Along Elevation Gradients in Shallow-lakes of Poyang Lake Wetland

The soil nutrients and stoichiometry along the elevation gradients of different Shallow - lakes in Nanjishan wetland nature reserve of Poyang Lake were studied here. In particular, four types of wetland habitat, i.e. downland, high beach, low beach and swamp were chosen for the elevation gradients and soil C, N and P contents were then determined. The results showed that SOC content in the 0-10 cm soil layer was lowest in the downland. The TN and TP contents were ranked as downland >high beach > low beach > swamp, and TN was positively correlated with TP content. SOC and TN contents were decreased with the depth of soil layer. The mean ratios of C/N, C/P and N/P were 11.17 ± 5.06 (ranging from 4.08 to 25.40), 52.74 ± 35.13 (ranging from 1.35 to 7.40) and 5.03 ± 2.89 (ranging from 2.21 to 14.15), respectively. In the study area, soil C/N was relatively stable, while C/P and N/P varied substantially either along the elevation gradients or among Shallow-lakes. NH4+-N content was ranked as downland < high beach < low beach < swamp, while NO3--N content was ranked as high beach < low beach < downland < swamp. Furthermore, AP and TP contents were positively correlated. In short, soil nutrients in the research area exhibited large variations due to the seasonal dynamics of hydrology in Poyang Lake and TN was the primary limiting factor of N/P ratio.