黄土丘陵沟壑区小流域植被恢复对土壤稳定入渗的影响

经过20多年的退耕还林还草和封禁措施,纸坊沟流域植被得到良好恢复,并对土壤产生正面影响。流域内11种主要植物群落下以及不同生活型下土壤稳定入渗速率均有显著差异,其中灌木和草本群落下土壤稳定入渗速率较大,乔木林下较小。土壤稳定入渗速率与其影响因子之间存在相关关系,其中土壤稳定入渗速率与土壤容重、土壤总孔隙度及土壤活性孔隙度存在极显著的相关关系;与枯枝落叶层厚度也有一定的相关关系;还与土壤水稳性团聚体重量百分含量、土壤有机质含量有一定的相关关系。结果表明,黄土丘陵沟壑区进行植被建设选择灌草群落较好,天然群落可优先选择铁杆蒿、茭蒿、长芒草和白羊草等,人工灌木群落可优先选择柠条等。由于该区属森林向草原的过渡区,尽管也能种植刺槐等乔木树种,但营造乔木林应考虑林灌草隔带混交和垂直配置,并注意微地形的影响。

The effect of vegetation restoration on soil stable infiltration rates in small watershed of loess gully region

Changes occurred in soil stable infiltration rate,soil water stable aggregate and soil organic matter by stopped grazing in loess gully region of China.Data including soil stable infiltration rate,soil water stable aggregate and soil organic matter was collected through field experiments for present ecological study.Statistical analysis revealed that the soil stable infiltration rates vary significantly among different plant communities.And among communities having different plant life forms,the stable infiltration rates under bush and grass communities are faster than those under forest communities.Results of regression analysis include:(1)the soil stable infiltration rate has significant linear correlation with soil bulk density,total porosity and valid porosity;(2)the soil stable infiltration rate has linear correlation with layer thickness of fallen leaves and humus on soil surface;and(3)the soil stable infiltration rate has linear correlation with the content of soil humus and water stable aggregate.In loess gully region,bush and grass are superior vegetations than forest for ecological restoration,and among bush and grass plants,Artemisia sacrorum,Artemisia giraldii,Caragana korshinski,Stipa bungeana and Bothriochoa ischemum are superior plants for vegetation building.Although some trees can be planted for vegetation reconstruction in this region,yet,the forestation density,vegetation structure and site choice are also critical to forestation.