海南不同林分地表径流特征分析

目的探讨桉树林、橡胶林和次生林3种森林地表径流的月动态以及不同雨量等级发生的地表径流规律，为准确评价3种森林水源涵养效益以及人工林可持续经营提供科学依据。方法在海南黎母山不同林分建立径流场，其中桉树林中有4个（F1、F2、F3、F4），橡胶林有1个（F5）、次生林中有1个（F6），从2010年4月到2011年3月进行地表径流观测，对比分析了3种森林类型地表径流特征，并借助G（2,1）模型基本思路以及sigmoid模型预测了月地表径流系数。结果（1）F1 ~ F6径流场全年地表径流量分别为230 、49 、170.1 、84.2 、340 、396.4 mm，其中雨季地表径流量分别占全年地表径流量的90.28%、91.61%、87.89%、92.74%、91.86%、90.88%。（2）各月地表径流量大小呈现相同的顺序，即F6 > F5 > F1 > F3 > F4 > F2。（3）雨季次生林地表径流总量是桉树林的1.75 ~ 8.11倍，橡胶林是桉树林的1.49 ~ 6.89倍。（4）单次降雨超过10 mm才会发生地表径流，地表径流随降雨等级而增大，大于60 mm的降雨量占全年总雨量的57.95%，而F1 ~ F6径流场产生的地表径流分别占全年地表径流量的84.92%、89.08%、82.14%、87.75%、79.56%、83.49%。sigmoid模型对雨季地表径流系数的预测精到高于旱季，但对2010年8月各径流场的地表径流预测偏差较大。结论该地区5年生桉树、6年生橡胶人工林的地表径流并不总是比次生林大，因此在评价人工林水源涵养能力时有必要考虑林龄和地理位置。 

Characteristics analysis of surface runoff for three types of forests in Hainan Island,southern China

ObjectiveThe aim of this study was to provide a scientific basis for the accurate evaluation of water conservation benefits in three forest types and sustainable management of plantations. We discussed the monthly dynamics of surface runoff from eucalyptus plantations, rubber plantation and secondary forest and the surface runoff laws of different rainfall levels.MethodRunoff fields were established in different forests in Limu Mountain, Hainan Province, southern China, including four fields in eucalyptus plantations (F1, F2, F3, F4), one field in rubber plantation (F5), and one field in secondary forest (F6). Surface runoff observation was carried out from April 2010 to March 2011 and the surface runoff characteristics of three forest types were compared and analyzed. The monthly ground runoff coefficient was predicted by the basic idea of G(2,1) model and sigmoid model.Result(1) The annual surface runoffs of F1?F6 fields were 230, 49, 170.1, 84.2, 340, 396.4 mm, of which the rainy season accounted for 90.28%, 91.61%, 87.89%, 92.74%, 91.86%, 90.88%. (2) The monthly surface runoff was all ordered as F6 > F5 > F1 > F3 > F4 > F2. (3) The total runoff of the secondary forest in the rainy season was 1.75?8.11 times of the eucalyptus plantations, and the rubber plantation was 1.49?6.89 times of the eucalyptus plantations. Surface runoff occurred when the rainfall exceeded 10 mm, and the surface runoff increased with the rainfall level. The rainfall greater than 60 mm accounted for 57.95% of the total annual rainfall, while the surface runoff from F1 to F6 fields accounted for 84.92%, 89.08%, 82.14%, 87.75%, 79.56%, 83.49% of the annual surface runoff. (4) The sigmoid model predicted that the surface runoff coefficient of the rainy season was higher than the dry season, but the surface runoff prediction of each field in August 2010 was more biased.ConclusionOur results indicate that the surface runoff of 5-year-old eucalyptus and 6-year-old rubber plantations in the region are not always larger than that of secondary forests. It is necessary to consider the forest age and geographical location when evaluating the water conservation capacity of plantations.