摘要
依托江西水土保持生态科技园,2015年3月―8月期间,对裸地、草地、果园和湿地松人工林四种类型径流小区自然降雨条件下侵蚀过程中径流泥沙和土壤有机碳的流失特征进行了原位监测。结果表明,监测期间24场降雨下,径流系数和侵蚀模数基本上均随雨型的增大而增加。随着土地利用类型由裸地向果园、草地和林地的转换,减流效益和减沙效益依次增大。径流量和泥沙流失量最主要的影响因素分别是降雨量和径流量。裸地、草地、果园和林地四种类型坡面上,自然降雨下土壤有机碳随泥沙迁移的比例分别为64.67%、47.38%、53.94%和36.03%,碳流失强度分别达到560.3、1.98、122.5和2.66 mg m-2。径流有机碳含量与径流量之间、泥沙含碳量与泥沙量之间均呈负相关关系。裸地、果园、草地和林地四种径流小区泥沙有机碳富集比分别为1.27、1.10、0.80和0.58,即随着土壤侵蚀模数的降低,有机碳富集比也减小。泥沙有机碳富集比均随雨强的增大而减小,有机碳的选择性迁移在低强度降雨条件下表现更为明显。
[Objective] The red soil hilly region in South China is one of the areas of the country suffering serious soil erosion. Currently, the researches on loss of soil organic carbon with soil erosion in this region were executed mainly via simulated rainfall tests, without much in-situ field quantitative monitoring under natural rainfalls or comparison between fields different in land use. This study was intended to explore relationships of surface runoff and sediment loss with organic carbon carried in runoff and sediment under natural rainfall, so as to characterize responses of soil organic carbon transfer and loss to changes in rainfall, soil erosion and land use, and to deepen the scientific knowledge about relationship between soil erosion and carbon recycling. [Method] Tracts of bare land, grassland, citrus orchard, and secondary splash pine forest were selected for the experiment as runoff plots Science Park. Surface runoff, sediment loss and soil in the Jiangxi Soil and Water Conservation Ecological organic carbon carried therein were monitored under 24 typical rainfalls between March to August, 2015 in order to illustrate selective transfer of soil organic carbon. [Result] Results show as follow: ( 1 ) Runoff coefficients and the soil erosion modulus increased with increasing rainfall intensity during all the 24 rainfall events. With the conversion of land use in type from bare land to orchard, grassland and forest, the effects of land use reducing runoff and sediment increased. Rainfall intensity was the major factor affecting runoff volume, while the latter was the one affecting sediment loss, with correlation coefficient being 0.89 - 0.92 (p 〈 0.001 ) and 0.95 - 0.98 (p 〈 0.05 ) , respectively. ( 2 ) Under natural rainfalls, the concentration of organic carbon was 5.00, 7.68, 6.11 and 10.02 mg L-1 in runoff and 7.69, 8.58, 8.08 and 8.93 g kg-1 in sediment on the bare land, grassland, orchard and forest, respectively. The concentration of organic carbon in runoff was significantly and negatively related to volume of the runoff and so was the concentration in sediment with the volume of sediment loss. The sediment-associated loss of soil organic carbon in the four plots accounted for 64.67%, 47.38%, 53.94% and 36.03% of the total lost with the erosion, and reached 560.3 mg m^-2, 1.98 mg m^-2, 122.5 mg m^-2 and 2.66 mg m^-2 in intensity, respectively. ( 3 ) The organic carbon enrichment ratio of the sediment in the bare land, orchard, grassland and forest was 1.27, 1.10, 0.80 and 0.58, respectively, and decreased gradually with increasing rainfall intensity. Selective transfer of organic carbon was more evident in weak rainfalls. [Conclusion] Under natural rainfalls, soil erosion has very important impacts on migration of soil organic carbon in slope fields in the red soil region. Selective migration of soil organic carbon with surface runoff or sediment is determined mainly by rainfall characteristics (especially rainfall intensity ) and land use pattern. In all the lands, regardless of land use, intensified soil erosion makes it easier for soil organic carbon to migrate with sediment, and organic carbon enrichment ratio of the sediments also increases with intensifying soil erosion. However, organic carbon enrichment ratio of the sediment decreases with rising rainfall intensity.
出处
《土壤学报》
CAS
CSCD
北大核心
2017年第4期874-884,共11页
Acta Pedologica Sinica
基金
国家自然科学基金项目(41303064)
公益性行业(水利)科研专项(201501047)
江西省水利科技重大研究项目(KT201417)共同资助~~
关键词
自然降雨
水力侵蚀
土壤有机碳
红壤坡面
富集比
Natural rainfall
Water erosion
Soil organic carbon
Red soil slope
Enrichment ratio