毛乌素沙地3种人工植被类型对土壤颗粒组成和固碳的影响

Effects of Three Artificial Vegetation Types on Soil Particle Composition and Carbon Fixation in the Mu Us Sandy Land

植被恢复会对干旱半干旱区土壤固碳过程产生重要影响,探讨植被恢复对不同土壤颗粒碳含量的影响有利于进一步揭示荒漠土壤演变过程。选择毛乌素沙地东南缘人工植被恢复区的乔木林、灌木林、草地和流沙地为样地,对0—30 cm的土壤进行了分层取样分析。结果表明:乔木、灌木和草地的恢复均会降低土壤粗颗粒(细砂粒、粗砂粒)含量,增加团聚体和粉黏粒含量;植被恢复后土壤有机碳(SOC)和无机碳(SIC)含量均显著增加,其中最大值均出现在乔木样地,分别达到流沙地的3.96倍和2.08倍;植被恢复对土壤有机碳密度(SOCD)的影响较土壤无机碳密度(SICD)更为明显;乔木有利于粗砂粒和细砂粒有机碳的累积,灌木更有利于粉黏粒和团聚体有机碳的累积;各粒级SOC含量在细砂粒中增幅最为明显;SIC含量在粉黏粒中增幅最为明显;粉黏粒有机碳对总有机碳的贡献率较为显著。总之,不同类型植被的恢复均会提高土壤有机和无机含量,从增加土壤固碳的角度出发,乔木为毛乌素沙地的最佳植被恢复类型。

Vegetation restoration has an important impact on soil carbon sequestration in arid and semi-arid regions.Exploring the effects of vegetation restoration on soil carbon content of different particles is helpful to further reveal the evolution process of desert soils.The arbor forest,shrub forest,grassland and shifting sandy land were selected in the artificial vegetation restoration area on the southeastern margin of the Mu Us Sandy Land,and top 0—30 cm soils were collected and analyzed layer by layer.The results showed that the restoration of arbors,shrubs and grassland can reduce the content of soil coarse particles(fine and coarse sand particles)and increase the content of aggregates,silt and clay;the contents of soil organic carbon(SOC)and soil inorganic carbon(SIC)significantly increased after vegetation restoration,and the highest values of soil carbon were observed in the arbor forest,which were 3.96 times and 2.08 times higher than that of shifting sandy land;the effect of vegetation restoration on SOC density was more obvious than SIC density;arbor forest was beneficial for organic carbon accumulation in coarse sand and fine sand,and shrub forest was more beneficial for organic carbon accumulation in silt and clay and aggregates;SOC contents of each particle size increased most obviously in fine sand and SIC contents of each particle size increased most obviously in silt and clay;the contribution rate of organic carbon in silt and clay to total organic carbon was more significant.In summary,the restoration of three different types of vegetation can increase the SOC and SIC,planting arbor is the best choice for vegetation restoration from the perspective of increasing soil carbon sequestration in the Mu Us Sandy Land.