【摘要】 第四纪红色粘土发育的红壤在我国南方地区分布较广 ,不合理的开发和利用导致植被覆盖破坏严重 ,致使该地区长期以来遭受强烈的土壤侵蚀作用。1 37Cs作为一种有效的示踪剂 ,在国内外越来越多地用于中长期 ( 4 0余年 )以来的土壤侵蚀模数的估算。采用 1 37Cs技术 ,研究第四纪红色粘土发育的红壤典型小流域的土壤侵蚀作用。结果表明 ,该流域的1 37Cs基准值为 2 10 7Bq/m2 ;对于表土质地较为粘重的非耕作红壤而言 ,1 37Cs在土壤剖面中呈指数型分布 ;该流域内山坡和山顶非耕作土的 1 37Cs分布深度通常在 15 cm以内 ,而耕作土中则达 3 0 cm ;对于坡度相对较大 ( 5 .5～ 11°) ,植被条件较差的迎风坡非耕作红壤而言 ,其土壤侵蚀模数达 11.2～ 14 .5 t/hm2 · a;对于坡度较小 ( 1.5～ 4 .5°) ,植被条件较好的背风坡非耕作红壤而言 ,土壤侵蚀模数为 0 .3～ 10 .8t/hm2·a;坡上部水作梯田的侵蚀作用比坡下部的水作梯田小 ,且水作梯田比旱作梯田更有利于水土保持。更多还原

【Abstract】 Haplic red soil developed from quaternary red clay was widely distributed in southern China. Severe soil erosion, occurred in the region dominated by haplic red soil, was mainly caused by the destruction of vegetational cover. 137 Cs technique was employed to investigate soil erosion over a medium term or long term time scale (more than 40 years), because it is well documented that 137 Cs is a useful tracer to study the soil particle movement. Using 137 Cs measurements, a study was carried out to investigate soil erosion occurred within a small catchment in southern China dominated by haplic red soil. The 137 Cs reference inventory was determinated to be 2 107 Bq/m 2. 137 Cs exhibits exponential vertical distribution in uncultivated red soils, characterized by relatively high content of clay in the surface soil. Generally, the maximum distribution depth of 137 Cs in soil profile is 15 cm for uncultivated soils, while 30 cm for cultivated soils. On uncultivated soils with relatively large slope angle in the range from 5.5 ~11°, characterized by relatively poor vegetational cover, the soil erosion rates ranges from 11.2~14.5 t/hm 2·a. However, on uncultivated soils with relatively small slope angle in the range from 1.5~4.5°, characterized by relatively good vegetational cover, the rate of soil loss ranges from 0.3~10.8 t/hm 2·a. The soil erosion rate, associated with paddy terrace field on the higher part of the slope,was lower than that on the lower part of the slope.Moreover,in view of soil conservation, the paddy terrace field is better than the dry terrace field.更多还原