不同植被类型对沙区土壤持水性的影响

Effect on Soil Moisture Capacity under Different Vegetations in Desert Area

为研究东部湿润沙区植被持水特性，对青龙湾沙区7种类型植被下土壤的物理性质进行了分析。结果表明：农田、毛白杨林和混交林表层土壤（0-20cm）容重较小；植被中层土壤（20～60cm）容重差异不明显，下层土壤（60～100cm）容重与中层相比有所减小。随着土层深度的增加榆树林、刺槐林、果树林、小叶杨林、毛白杨林下土壤总孔隙度总体呈上升趋势，混交林和农田土壤总孔隙度则先降后升，土壤的毛管孔隙度与总孔隙度变化类似，非毛管孔隙度变化无规律。混交林和毛白杨林下土壤持水性较好，农田、果树林和小叶杨林次之，榆树林和刺槐林相对较差。从土壤水分亏缺状况看，只有农田和榆树林下40～60cm土层土壤水分不亏缺，其余林下土壤水分均不同程度的亏缺，特别是小叶杨林下土壤水分亏缺极为严重。总体来看，植被下层土壤（60～100cm）水分亏缺比上层（0～40cm）轻些，果树林和农田土壤水分亏缺比人工林轻些。相关分析表明，土壤孔隙状况与土壤持水量之间相关性较好。研究显示青龙湾沙区植被下土壤状况欠佳，需要注重植被的更新、种草植灌和加强植被日常管理等。

To study soil water capacity, soil physical properties of 7 vegetation types were analyzed in desert area of Qing- longwan. Results showed the bulk density with surface soil of 0-20 cm of farmland, mixed forest and Populus tomentosa was smaller, bulk density with middle layer soil of 20-60 cm had no sufficient difference and that of subsoil of 60-100 cm was lower. Total porosity of Ulmus pumila, Robinila pseudacacia, Populussimonii, Populus tomentosa and orchard was decreased with increase of soil depth, and that of farmland and mixed forest was first decreased and then increased. Trend of capillary porosity was similar to total porosity, but non-capillary porosity changed irregularity. Soil moisture capacity of inixed forest and Populus tomentosa was largest, followed by that of orchard, farmland, Populussimonii and Ulmus purnila, and that of Robinila pseudacacia was poor. Soil water of 40-60 cm of farmland and Ulrnus pumila was not deficient and the others of forest soil had different degree deficits, especially Populussimonii. Water deficit in the upper layer soil of 0-40 cm was more serious than that of subsoil of 60-100 cm, and that of plantation was also more serious. Both soil porosity condition and soil water capacity had a good relativity. It was obvious that soil condition was seriously poor and more attention should be paid to renewal of vegetation, growing grass and daily management. Key words：