水土流失是人工林植被恢复过程中生态效益评价的重要指标。2002—2006年，在广西南宁市郊丘陵 地带的杉木林采伐迹地上，建立厚荚相思人工林和尾巨桉人工林以及灌草坡自然恢复植被3个径流小区，分 别对水土及其养分流失量进行连续观测研究。结果表明：(1)3种植被的年平均地表径流量由小至大依次为 厚荚相思林(39.60 t/hm2)、尾巨桉林(45.03 t/hm2)、灌草坡(64.30 t/hm2)；(2)年平均土壤侵蚀量由小 至大依次为厚荚相思林(0.26 t/hm2)、尾巨桉林(0.29 t/hm2)、灌草坡(0.32 t/hm2)；(3)年平均水土养分 (N、P、K)流失量由小至大依次为厚荚相思林(0.036 kg/hm2)、尾巨桉林(0.039 kg/hm2)、灌草坡(0.054 kg/hm2)；(4)水土及其养分流失量在各植被类型之间的差异不显著，而在不同年份之间的差异极显著。根 据5 a各植被恢复过程中水土流失量的大小，可划分为流失高峰期(造林当年)、流失减缓期(造林后2~3 a) 和流失稳定期(造林后4~5 a)3个阶段；(5)水土流失量的季节变化程度由大至小依次为夏季(48.6 %~72.5 %)、春季(20.8 %~48.2 %)、秋季(2.5 %~3.9 %)、冬季(0.7 %~2.8 %)，分别与同期降雨量的季节分配相吻 合；(6)在广西营造短周期工业用材林，对于保持水土、减少养分流失、维护生态安全具有重要作用。

Soil erosion is an important indicator of ecoefficiency evaluation for the process of artificial vegetation restoration. Form 2002 to 2006, in the fir forest cutover land of Guangxi Nanning’ outskirts hilly country, three runoff plots were set as Acasia crassicarpa plantation in Eucalyptus urophylla×E.grandis plantation and shrubgrass natural vegetation. Based on continuous observation on the loss of soil and nutrient, the results showed that: (1)The annual mean surface runoff amount were Acasia crassicarpa forest (39.60 t/hm2), Eucalyptus urophylla×E.grandis forest (45.03 t/hm2), shrubgrass (64.30 t/hm2); (2)The annual average soil erosion amount were Acasia crassicarpa forest (0.26 t/hm2), E.urophylla×E.grandis forest (0.29 t/hm2), shrubgrass (0.32 t/hm2); (3)The average annual water and soil nutrients (N, P, K) loss amount were Acasia crassicarpa forest (0.036 kg/hm2), E.urophylla×E.grandis forest (0.039 kg/hm2), shrubgrass (0.054 kg/hm2); (4)The volume of soil and nutrient loss between the various vegetation types had no significant difference, while they were significant difference among years. According to the amount of the soil erosion of vegetation restoration in the five years period, they can be divided into three stages as follows: the peak period (planting year), loss mitigation period (2—3 years after planting), and the loss stability period (4—5 years after planting); (5)The amount of water and soil erosion for seasonal variation were summer (48.6 %—72.5 %)>spring (20.8 %—48.2 %) >autumn (2.5 %—3.9 %)>winter (0.7 %—2.8 %), which was consistent with the seasonal rainfall distribution in the same period; (6)The results demonstrated that establish short rotation cycle industrial forest play an important role for conserving soil and water, reducing nutrient loss, and maintaining the ecological security in Guangxi.