泥质海岸盐碱地刺槐-杨树混交林改土效果研究

在北方泥质海岸盐碱地采用工程整地措施修筑台田,于台田上布置刺槐纯林、杨树纯林、刺槐—杨树混交林3种树种配置模式,对混交林及纯林的降盐改土效果进行研究。结果表明,11a后3种林分类型基本郁闭,保存率为63%～72%,郁闭度为0.6～0.7。混交林的树高、胸径优于纯林。3种模式脱盐作用范围在0—70cm土层;在50—70cm这一土层形成了养分亏缺层。混交林可提高林地土壤有机质含量;0—100cm全氮含量的土壤剖面分布规律与有机质相似,3种模式土壤全磷含量变幅不大,总体表现为磷素总量不足,有效性低。因子分析表明刺槐—杨树混交林降盐改土效果好于杨树纯林,也好于刺槐纯林,能够改善泥质海岸盐碱地土壤肥力状况,可作为一项成功的造林模式进行推广应用。

Soil Amelioration Effects of Mixed Plantations of Robinia Pseudoacacia and Populus Liaoningensis in Saline-alkali Soils Along Muddy Seacoast

Soil amelioration effects resulted from salt reduction by the three plantations of pure Robinia pseudoacacia,pure Populus liaoningensis,and mixed P.liaoningensis and R.pseudoacacia were studied in raised fields established by soil preparation engineering measures in saline-alkali soils along muddy seacoast of Northern China.Results showed that the three plantations were almost closed after 11 years.The reservation rates were 63%~72% and shade densities were 0.6~0.7.The height and DBH of the mixed plantation were higher than those of the two pure plantations.The desalination effects of the three planting patterns were observed within 70 cm of soil surface and soil nutrient deficiency was formed between 50 and 70 cm below soil surface.The mixed plantation increased soil organic matter content on the forest land.Within 100 cm of soil surface,the distribution rhythms of total N in soil profiles were similar to those of organic matter.The variation of the contents of total P in the three plantations was not significant.On the whole,the total amount of phosphorus was deficient and its efficiency was low.Factor analysis indicated that soil amelioration effects for the mixed plantations of P.liaoningensis and R.pseudoacacia were better than those of pure plantations,which could enhance the fertility status of saline-alkali soils along the muddy seacoast and might be applied in practice as a promising afforestation model.