黄土丘陵沟壑区退耕植被恢复地土壤水稳性团聚体的变化特征

以黄土高原典型丘陵沟壑区—吴旗县为例,研究了退耕地不同植被恢复年限、不同植被类型和不同恢复方式下的土壤水稳性团聚体含量的变化。结果表明,>0.25mm土壤水稳性团聚体含量,在0～60cm土层随着退耕地恢复年限的延长而不断增加,乔木地相对较高,草地相对较低,灌木地介于两者之间。自然恢复方式>自然 人工恢复方式>人工恢复方式,坡耕地的团粒含量最低;在0～20cm土层,恢复前期土壤水稳性团聚体含量增幅较大,后期增幅较小,而40～60cm土层的变化规律则相反。对同一种植被类型,>5mm的土壤水稳性团聚体含量从0～20cm到40～60cm土层均呈下降趋势,并且在较浅土层灌木地的降幅相对较大,在较深土层乔木地的降幅相对较大。人为干预使得土壤水稳性团聚体从大粒径向小粒径转化,这种转化在较深土层表现的较明显。可见,在退耕地植被恢复中,具有较长恢复年限的乔木地,土壤的抗蚀性较强;自然 人工的恢复方式既缩短了植被恢复时间,也提高了土壤水稳性团聚体含量,从而改善了土壤结构。

The changes of soil water-stable aggregates in abandoned lands during vegetation restoration in hilly and gully regions on the Loess Plateau

Based on the observation in the typical hilly and gully region on the Loess Plateau-Wuqi county, the changes of soil water-stable aggregates of different abandoned times? different types of vegetation and different restoration measures during vegetation restoration in abandoned lands were studied. The results showed that the content of >0.25 mm soil water-stable aggregates increases with the increasing of the abandoned time within the depth of 0~60 cm; the content of arbor lands is relatively higher and grassland is relatively lower, bush land is in the middle; For the restoration types, the content of natural restoration is bigger than that of natural restoration with artificial measures, and that of artificial restoration is lower, the cropland is the lowest. The increasing degree of the content of soil water-stable aggregates at the depth of 0~20 cm is bigger in the first stage of vegetation restoration, and lower in the later stage; the changes at the depth of 40~60 cm are on the contrary; The content of >0.25 mm soil water-stable aggregates of the same vegetation land is decline with the depth, the decreasing degree of shrub lands is relatively bigger in shallow layer, and the decreasing degree of arbour lands is relatively bigger in deep layer; soil water-stable aggregates are transformed from bigger particles to smaller ones by means of human interference, and this transformation is more obvious in deeper layer; soil anti-erodibility of arbour lands with longer restoration time is stronger;the natural with artificial restoration not only shorten the restoration time, but also increase the content of soil water-stable aggregates,so the soil structure is improved.