桉树纯林和桉-珍混交林水土流失规律的分析

Analysis on the Regularities of Soil and Water Erosion in Eucalyptus gradis Pure Plantation and Eucalyptus gradis-Precious Hardwood Mixed Plantation

为了比较桉树纯林和桉-珍混交林的水土流失规律,在广西南宁市郊的马尾松林采伐迹地同一坡面上,分别营造桉树纯林（EP）和桉-珍混交林（EM）两种人工林模式,各建造径流场3个,进行水土及其养分流失量的监测研究。结果表明：EP、EM年平均地表径流量分别为181.7、182.6 m^3/hm^2;年平均泥沙流失量分别为995、1 004 kg/hm^2;年平均侵蚀模数分别为99.5、100.4 t/km^2;年平均养分（N、P、K）流失量分别为0.109、0.110 kg/hm^2。EP、EM水土及养分流失量的季节变化较一致,为夏季（77.2%-80.0%）〉秋季（18.8%-19.6%）〉春季（1.2%-3.2%）〉冬季（0.0%）。1-3年生桉树纯林和桉-珍混交林两种人工林模式各项水土流失特征量比较接近,两者的水土及养分流失量比较小,而且无显著差异（t〈0.05）。

To compare the regularities of soil and water erosion of Eucalyptus gradis pure stand （EP） and Eucalyptus gradis -precious hardwood mixed stand （EM）, we constructed these two plantations in the same slope direction of the Pinus massoniana cutting blank in the south of Nanning, Guangxi. Basing on the 3 runoff plots of each plantation, we monitored the soil erosion and nutrient loss of these two plan- tations. The results showed that there was 181.7 m^3/hm^2 and 182.6 m^3/hm- of average annual surface runoff, 995 kg/hm^2 and 1 004 kg/hm^2 of average annual soil loss, 99.5 t/km^2 and 100. 4 t/km^2 of an-nual erosion modulus, 0. 109 kg/hm^2 and 0. 110 kg/hm^2 of average annual N, P, and K nutrients loss in EP and EM, respectively. The amount of soil erosion and nutrient loss had a similar change in seasons both in EP and EM, the amount of soil erosion and nutrient loss follows the order of summer （77.2% - 80.0%） 〉autumn （18.8% -19.6%） 〉 spring （1.2% -3.2%） 〉 winter （0.0%） . Thecharacteristics of soil and water conservation from 1 to 3 years old Eucalyptus gradis pure stand were closed to Eucalyptus gradis- precious hardwood mixed stand, the amount of soil erosion and nutrient loss was small and there was no significant difference （ t 〈 0. 05） .