苏北淤泥质海岸土壤盐分特征及其对杨树生长的影响

【目的】掌握江苏北部滨海盐碱地土壤盐分特征及其与杨树生长的关系。【方法】分析江苏盐城市大丰区林场的35杨(Populus deltoides ‘I-35’)林地、农耕地以及未开垦的盐碱地土壤盐分状况,并对杨树胸径、树高和成活率进行了调查。【结果】不同类型的土壤含盐量差异较大,农耕地土壤含盐量(质量分数)普遍低于0.1%;杨树林地土壤含盐量多数低于0.2%;未开垦的盐碱地土壤含盐量明显较高;含盐量较高的土壤盐分具有明显的表聚特征;土壤pH普遍为8~9,平均为8.23,属于碱性土壤;土壤含盐量、电导率和pH三者之间存在显著的正相关关系,其中土壤含盐量与电导率之间用二次多项式方程拟合的效果最好;土壤含盐量与pH之间、土壤电导率与pH之间均是指数方程的拟合效果最好;土壤含盐量与杨树的成活率、胸径、树高之间均呈显著的负相关,相互之间的关系可以用指数方程或乘幂方程拟合。【结论】不同利用类型的土壤含盐量及其盐分特征存在较大差异;土壤含盐量对杨树的生长和成活率影响较大,当土壤含盐量高于0.3%时,杨树的胸径和树高生长以及成活率均明显较低;当土壤含盐量低于0.2%时,杨树的胸径和树高生长以及成活率均比较正常。

Characteristics of soil salinity and its effects on poplar growth in a silting coastal area of Northern Jiangsu Province

【Objective】This study was performed to understand the characteristics of soil salinity and its relationship with poplar growth in a coastal saline-alkali land of Northern Jiangsu Province. 【Method】We analyzed the soil salinity of poplar plantation (Populus deltoides ‘I-35’), farmland and uncultivated saline-alkali land, and determined the diameter at breast height (DBH), height and survival rate of poplar trees in Dafeng Forestry Farm, Yancheng City, China. 【Result】The salt content of different soil types varied considerably; soil salinity (mass fraction) of farmland was generally less than 0.1%, soil salinity of poplar plantation was mostly less than 0.2%, and soil salinity of uncultivated saline-alkali land was evidently the highest. Soil with high salinity had marked characteristics of salt accumulation in the topsoil layer. In this study, the pH value of soil generally ranged from 8 to 9, with an average value of 8.23, which depicts alkaline soil. There were significant positive correlations among soil salinity, electrical conductivity and pH values. The fitting effect of the quadratic polynomial equation between soil salinity and electrical conductivity was the best. Additionally, the fitting effects of the exponential equation between soil salinity and pH values, and soil electrical conductivity and pH values were the best. There were significantly negative correlations between the soil salt content and survival rate, DBH and poplar height, which could be fitted by exponential equation or power equation. 【Conclusion】There were considerable differences in the soil salt content and salt characteristics among different utilization types of soil. Soil salinity had a remarkable effect on the growth and survival rate of poplar 35 (Populus deltoides ‘I-35’). When soil salinity was more than 0.3%, DBH, height growth and survival rate of poplar were significantly lower. When soil salinity was less than 0.2%, DBH, height growth and survival rate of poplar were normal.