作者简介:徐 佳 (1984-),女,陕西韩城人,博士研究生,主要从事水土保持效益和土壤侵蚀研究。E-mail: xvjia0124@126.com
收稿日期: 2011-11-20
要求修回日期: 2012-02-11
网络出版日期: 2012-11-20
基金资助
国家科技支撑计划课题(2011BAD31B01)资助
Runoff and Sediment Reductions in the Different Stages of Vegetation Restoration on a Loess Slope
Received date: 2011-11-20
Request revised date: 2012-02-11
Online published: 2012-11-20
Copyright
徐佳 , 刘普灵 , 邓瑞芬 , 刘栋 . 黄土坡面不同植被恢复阶段的减流减沙效益研究[J]. 地理科学, 2012 , 32(11) : 6901391 -6901396 . DOI: 10.13249/j.cnki.sgs.2012.011.1391
Vegetation coverage can effectively protect soils from erosion by intercepting raindrop impact and retaining runoff. In the loess hilly region of China, vegetation status has been improved since the “Grain for Green” project was launched and as a result, grassland, shrub land, and forestland get greatly increased. Study of the effects of the different restoration stages on runoff and sediment reductions may provide a sound basis for evaluating the environmental effects of vegetation restoration. Natural rainfall is difficult to manipulate and consequently, and soil erosion patterns on slope with different ways of vegetation coverage under natural rainfall condition have not been examined well. Runoff plots integrating different stages of vegetation restoration, including farmland, grassland, shrub land, and forestland were set up on the loess slope of Yangou catchment in Yan’an where the “Grain for Green” project was practiced to examine the runoff and sediment reductions in the different stages of vegetation restoration under natural rainfall condition. The investigation of the accumulative runoff and sediment yields from 2004 to 2008 showed that the runoff and sediment reductions ranked in the order of forestland>shrub land>grassland>farmland. Runoff reduction for forestland was the highest, being only about 10% of runoff from farmland. This implies that farmland was the major sources of soil erosion and sediment. The spatial structure and ground litters on forestland were capable of retaining runoff and thus promoting rainfall infiltration into soil. Sediment yields on grassland, shrub land, and forestland decreased by more than 90% compared with that on farmland in all the years but 2006, in which rainfall was lower. Thus, all the three stages of vegetation restoration had significant sediment reducing effects. On grassland and shrub land, sediment reductions were higher than runoff reductions. Comparison of the runoff and sediment yields on grassland and shrub land before and after vegetation cutting showed that more than 80% of the runoff reductions on grassland and shrub land were attributed to retaining by ground litters on and roots in them. Vegetation removed shrub land had stronger soil anti-erodibility than vegetation removed grassland and sediment yields on the lands increased slightly after vegetation cutting. After vegetation cutting on grassland and shrub land, the remaining roots and ground litters still had considerable soil conserving effects. However, the sediment yields on grassland and shrub land after vegetation cutting increasing indicated that during the initial vegetation succession, the layer near ground surface was still weak in ecological function and needed protecting by closed tendering.
Fig. 1 Location of the study area图1 研究区域 |
Table 1 Runoff yields on the slope lands in the different years表1 不同年份坡面小区径流量比较 |
年份 (年) | 降雨量(mm) | 耕地 | 草地 | 灌木地 | 林地 | |||
---|---|---|---|---|---|---|---|---|
径流量(mm) | 径流量 (mm) | 较坡耕地变化 (%) | 径流量(mm) | 较坡耕地变化 (%) | 径流量(mm) | 较坡耕地变化 (%) | ||
2004 | 199.8 | 71.5 | 49.3 | -31.1 | 26.4 | -63.1 | - | - |
2005 | 131.6 | 47.4 | 20.0 | -57.8 | 10.0 | -78.9 | - | - |
2006 | 42.5 | 26.1 | 20.0 | -23.5 | 17.9 | -37.4 | - | - |
2007 | 72.4 | 45.2 | 22.1 | -51.1 | 12.5 | -72.4 | 4.3 | -90.5 |
2008 | 47.9 | 19.6 | 18.4 | -6.0 | 11.5 | -41.4 | 2.6 | -86.6 |
Table 2 Sediment yields on the slope lands in the different years表2 不同年份坡面小区产沙量比较 |
年份 | 耕地 | 草地 | 灌木地 | 林地 | |||
---|---|---|---|---|---|---|---|
产沙量 (kg) | 产沙量 (kg) | 较坡耕地变化 (%) | 产沙量 (kg) | 较坡耕地变化 (%) | 产沙量 (kg) | 较坡耕地变化 (%) | |
2004 | 184.3 | 13.6 | -92.6 | 4.8 | -97.4 | - | - |
2005 | 93.4 | 1.6 | -98.3 | 1.6 | -98.3 | - | - |
2006 | 2.5 | 1.1 | -57.4 | 1.0 | -61.4 | - | - |
2007 | 197.8 | 0.9 | -99.5 | 1.3 | -99.3 | 0.7 | -99.6 |
2008 | 12.3 | 0.8 | -93.6 | 0.7 | -94.5 | 0.9 | -92.9 |
Table 3 Runoff and sediment yields in the different raining events in 2007表3 2007年次降雨过程中的径流量和产沙量 |
降雨日期 (年-月-日) | 径流量(mm) | 产沙量(kg) | ||||||
---|---|---|---|---|---|---|---|---|
耕地 | 草地 | 灌木地 | 林地 | 耕地 | 草地 | 灌木地 | 林地 | |
2007-7-26 | 18.2 | 11.1 | 6.1 | 1.5 | 166.7 | 0.5 | 1.0 | 0.3 |
2007-7-29 | 12.5 | 5.1 | 1.7 | 1.2 | 20.2 | 0.2 | 0.1 | 0 |
2007-8-30 | 7.8 | 3.9 | 3.0 | 0.9 | 5.3 | 0.1 | 0.2 | 0.2 |
2007-9-1 | 6.7 | 2.0 | 1.7 | 0.7 | 5.6 | 0.1 | 0.1 | 0.2 |
Fig. 2 Runoff yields and coefficients on the different lands in 2007图2 2007年各小区径流量和径流系数 |
Fig. 3 Sediment yield on different lands in 2007图3 2007年雨季各径流小区产沙量(b图为a图中部分小区产沙量情况) |
Table 4 Runoff and sediment yields on vegetation cutting practiced grassland and shrub land before and after vegetation cutting表4 刈割处理前后草灌小区产流产沙量比较 |
年份 (年) | 径流量 (mm) | 产沙量 (kg) | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
草地 | 灌木地 | 草地 | 灌木地 | |||||||||
刈割处理 | 变化 | 刈割处理 | 变化 | 刈割处理 | 变化 | 刈割处理 | 变化 | |||||
前 | 后 | 前 | 后 | 前 | 后 | 前 | 后 | |||||
2007 | 22.1 | 26.5 | +19.9% | 12.5 | 8.9 | -28.8% | 0.9 | 24.9 | +2667% | 1.3 | 2.4 | +84% |
2008 | - | - | - | 11.5 | 5.4 | -53.0% | - | - | - | 0.7 | 2.3 | +229% |
The authors have declared that no competing interests exist.
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