川西北高寒沙地不同恢复年限对土壤机械组成的影响

Effect of Different Vegetation Restoration Years on Soil Mechanical Composition in the Alpine Sandy Land of Northwest Sichuan

采用时空替代法,即在立地条件一致或相近的条件下,在一定的空间尺度内,选择不同地点上不同治理年限的流动沙地来代替同一生长地点上的不同恢复年限的流动沙地。以若尔盖县高寒沙地示范区内未治理流动沙地、生态恢复年限分别为3年、5年、10年的高寒沙地作为研究对象。结果表明,高寒流动沙地与草地土壤颗粒含量差异明显,随着治理时间的递增,流动沙地土壤黏粒、粉砂等细颗粒物质含量逐渐增加,不同深度的土壤颗粒逐渐演变为表层较下层细,可能是受植被恢复地表植被影响所致,通过10年的沙化治理,流动沙地的土壤得到一定的改善,但从本试验看出土过程在川西北高寒地区是一个缓慢的过程,防大于治。因此,应继续加强对脆弱区生态系统的保护和管理,避免荒漠化导致土壤生态环境的难以恢复。

The space-for-time substitution method was used in this study,i.e.under identical or similar site conditions within a certain spatial scale,the mobile sands with different treatment years in different locations were selected to substitute for the mobile sands with different restoration years in the same growth location.In oder to clarify the effects of different vegetation restoration years on soil mechanical composition,four types of treatment were selected in the demonstration area of Ruoergai county,i.e.non-controlled alpine mobile sand dunes,the controlled sand dunes with three-,five-and ten-years of ecological restoration.The results showed that there was a significant difference in the content of soil particles between the sand dunes and the grassland soils.With the increase of treatment time,the content of fine particles such as clay and silt in the sand dunes gradually increased.And soil particles at different depths gradually improved to be finer in the surface layer than in the lower layer,which might be caused by the restoration of surface vegetation.After 10 years of sand desertification,the soil in the sand dunes had been improved to a certain extent.However,from this study,it could be seen that the soil formation process was a very slow process and the prevention was more important than vegetation restoration in the alpine regions.Therefore,we should continue to strengthen the protection and management of ecosystems in the fragile area,so as to avoid the difficult restoration of soil ecological environment caused by soil desertification.