中文摘要：

为了比较林木对重盐碱地的改良效果，以沙枣、绒毛白蜡为试材，研究了不同季节沙枣林地、绒毛白蜡林地不同土层（0～20，20～50，50～80 cm ）的p H值、可溶性盐、有机质、速效钾含量及阳离子交换量的变化．结果表明：不同季节不同林木对土壤不同化学性质的改良效果不同．6月，沙枣林地各土层p H值有不同程度地降低，20～50 cm p H值降低最多；20～50 cm阳离子交换量明显地高于对照，但土壤含盐量、有机质和速效钾含量变化均不明显．绒毛白蜡林地各土层p H值也有不同程度地降低，20～50 cm p H值降低最多；各土层速效钾含量明显增加，20～50 cm阳离子交换量明显高于对照，但含盐量和有机质含量变化均不明显．10月，绒毛白蜡对p H值、有机质含量、阳离子交换量的改良效果较沙枣好，绒毛白蜡林地50 cm土层的pH值降低明显、有机质含量增加较多，各土层阳离子交换量均高于对照，而沙枣林地20 cm土层p H值降低明显、有机质含量和阳离子交换量增加较多；两块林地含盐量均不同程度地降低，但20 cm土层的含盐量降低最多，且沙枣林地的含盐量降低的更多；两块林地0～20 cm速效钾含量明显高于对照．10月测定的两块林地各土层的p H值、含盐量均低于6月的测定值，测定的有机质含量均高于6月的测定值；对于速效钾含量，沙枣林地所有土层的速效钾含量均高于6月，绒毛白蜡林地所有土层的速效钾含量均低于6月；沙枣林地除0～20 cm阳离子交换量高于6月外，其它土层的阳离子交换量均低于6月，绒毛白蜡所有土层阳离子交换量均高于6月．总体而言，与沙枣林地相比，绒毛白蜡林地的pH值更低，有机质、速效钾含量、阳离子交换量均更高，但土壤含盐量也较高；两树种10月对土壤化学特性的改良效果优于6月．

英文摘要：

In order to compare improving effect of the forests for heavy saline-alkali soil ,the soil pH ,soil salt content ,soil organic matter ,available potassium and cation exchange capacity of different layer （0-20 cm ,20-50 cm ,50 -80 cm） in different seasons for pure forest of Elaeagnus angustifolia ＆amp; Fraxinus velutina had been studied .The results showed that different forests could provide different effects for dif-ferent chemical properties in different seasons .In June ,the soil pH of different soil layers for Elaeagnus angusti f olia forest soil decreased in different degree ,and the soil pH of 20 -50 cm in depth decreased most ,cation exchange capacity of 20-50 cm in depth was higher obviously than that of CK ,but the soil salt content ,soil organic matter and available potassium didn＇t obviously change ;the soil pH of different soil layers for Fraxinus velutina forest soil also decreased in different degree ,available potassium content of different soil layers obviously increased ,and cation exchange capacity of 20-50 cm in depth was higher obviously than that of CK ,yet the soil salt content and soil organic matter content didn＇t obviously change . In October ,effect of improvement of Fraxinus velutina about the soil pH ,soil organic matter and cation exchange capacity was better than that of Elaeagnus angustifolia ,for Fraxinus velutina forest soil ,the soil pH of 50 cm-depth obviously decreased ,soil organic matter of 50 cm-depth increased more ,cation ex-change capacity of different layers was higher obviously than that of CK ;for Elaeagnus angusti f olia for-est soil ,the soil pH of 20 cm-depth obviously decreased ,soil organic matter and cation exchange capacity of 20 cm-depth increased more;soil salt content of Elaeagnus angusti f olia forest soil decreased more than that of Fraxinus velutina forest soil ,and soil salt content of 20 cm-depth for two forests soils decreased most ;available potassium content of 20 cm-depth for two forests soils was higher than that of CK .Com-pared with Octo