人工植被恢复是干旱、半干旱区荒漠化防治的重要措施之一,为阐明人工植被恢复对干旱沙区土壤物理性质的影响,以腾格里沙漠东北缘1984—2018年不同恢复年限的飞播植被群落为研究对象,分析人工植被恢复过程中土壤粒径组成、容重、含水量、饱和入渗率等物理性质的变化。结果表明：（1） 随着植被恢复年限的增长,群落内土壤质地得到了有效改善,与对照组相比,飞播37 a后1 m深度内黏粒、粉粒和极细砂粒分别增加了0.2%、2.6%和7.6%;细砂粒减少了27.1%,粗砂粒和极粗砂粒分别增加了15.0%和0.5%。（2） 随着植被恢复年限的增长,土壤质量含水量呈先减少后增加的趋势,且不同深度的变化存在垂向分异,37 a后深层土壤含水量减少0.7%,浅层土壤含水量增加0.6%;土壤干容重增加,饱和含水量和饱和入渗率下降。（3） 土壤质量含水量、饱和含水量与干容重呈显著负相关,与饱和入渗率无显著关系,干容重与饱和入渗率呈显著负相关;除土壤质量含水量外,饱和含水量、干容重和饱和入渗率变化受土壤粒径组成变化的影响。综上所述,干旱沙区人工植被恢复对土壤物理改良具有积极作用,促进了土壤颗粒细化,增强了土壤的保水能力,提高了土壤水分的有效性。

Dryland covering 41% of the Earth’s terrestrial land surface involves regions where land degradation and desertification are the most prominent global environmental problems. For restoring the degraded ecosystem, artificial afforestation of native or exotic species has been widely implemented, of which aerial-seeding afforestation was one of the effective measures owing to its penetration capability in inaccessible areas and labor- and cost-saving characteristics. Thus, this measure is crucial for understanding the change in soil physicochemical property with the aerial-seeding community succession in arid regions. To identify the effect of aerial-seeding afforestation on soil physical properties, the study selected one migratory dune (CK) and six aerial-seeding communities of successional sequence from 1984 to 2018 in the Alxa Desert to analyze the change in soil physical properties and their relationship. Compared with CK, the results show that slit and very fine sand increased by 2.6% and 7.6%, respectively, fine sand decreased by 27.1%, and sand and very coarse sand increased by 15.0% and 0.5% after 37 a, respectively. Compared with the other areas and afforesting means, the aerial-seeding afforestation has minimal effect on soil texture improvement, suggesting that the transition of soil texture from sand to loam is difficult in the short term. Otherwise, the saturated moisture content decreased while dry bulk density increased, which may induce an increase in sand and very coarse sand. The mass moisture content was significantly positive with very fine sand content, that is, the former increased with aerial-seeding ages; however, this content demonstrated differentiation patterns among soil layers, as indicated by a 0.7% reduction in deep layers and a 0.6% increase in shallow layers. Soil mass and saturated water contents were significantly negatively correlated with dry bulk density and uncorrelated with saturated infiltration rate, while the latter two were negatively relevant. Except for the mass water content, the other aforementioned contents were correlated with soil particle size content. Overall, the aerial-seeding afforestation also has positive but limited effects on the improvement of soil texture in the short term and enhanced the soil water-holding capacity and soil water availability. The differentiation of mass moisture content among soil top and deep layers induced community succession from shrub to grass.