不同更新方式巨尾桉人工林的水土流失规律

Regularities of Soil and Water Erosion Caused by Regeneration Modes of Eucalyptus grandis ×urophylla Planted Forest

在桂南沿海地区选择巨尾桉植苗林及其萌芽林以及采伐迹地灌草坡3种植被类型，分别建立径流小区进行连续6年水土流失量的观测，探讨不同更新方式桉树人工林的水土流失规律。结果表明：（1）年均地表径流量为植苗林（65．17mm）〈萌芽林（73．67mm）〈灌草坡（85．26mm）；年均土壤侵蚀量为萌芽林（2．79kg／hm2）〈植苗林（2．90kg／hm2）〈灌草坡（3．89kg／hm2）；3种植被类型的年均养分（N、P、K）流失量为3．72～3．76kg／hm2。（2）各植被类型的水土流失量均随着植被恢复年龄的增加以40．4％～98．5％递减率下降；当植被恢复至6年时，其水土流失量仅占造林开始2年的6．8％～8．8％。（3）水土流失量的季节变化为夏季（78．9％）〉春季（11．5％）〉秋季（9．6％）〉冬季（O），与降雨量的季节分配相吻合；一次产流过程的地表径流量与降雨量之间的关系呈多项式模型，因此，可以根据当地降雨量来预测地表径流量。

In order to prove up the regularities of soil erosion caused by regeneration modes of Eucalyptus grandis × urophylla planted forest in the southern part of Guangxi, three vegetation types, forest planting, sprout forest, and cutover land were chosen to observe the soil erosion via and set up runoff plots individually in 6 consecutive years. The result showed that. （1）The average surface runoff per year was forest planting （65.17 mm） 〈sprout forest（73.67 mm） 〈cutover land（85.26 mm）, the amount of soil erosion per year was sprout forest（2.79 kg/hm2） 〈forest planting（2.90 kg/hm2） 〈cutover land（3.89 kg/hm2）, the nutrient（N, P, K） loss of the three vegetation types per year was 3.72-3.76 kg/hm2. （2）The amount of soil and water erosion of each vegetation types decreased by 40.4-98.5%, along with increasing vegetation restoration age, when vegetations restoration increased to 6 years, soil and water erosion decreased by 6.8-8.8% in the first two years. （3）The amount of soil and water erosion in different seasons was summer（78.9%） spring（11. 5%） 〉autumn（9. 6%） 〉winter（0）, corresponding to seasonal rainfall. It showed that the relationship between surface runoff and rainfall was polynomial model. Therefore, the surface runoff could be forecast according to the local rainfall.