黄土高原植被恢复对不同粒径土壤团聚体中酶活性的影响

目的]研究不同植被恢复方式下土壤酶活性以及在不同团聚体中的分布特征,为黄土高原植被恢复和管理提供理论依据。方法]通过野外调查与室内实验相结合的方法研究不同植被恢复方式对土壤团聚体酶活性的影响。结果]天然草地、15年和25年柠条林地土壤酶活性较高,而坡耕地土壤酶活性较低。土壤酶活性在不同粒径土壤团聚体中,随着团聚体粒径的增大而增大,在1~2,2~3和3~5mm粒径土壤团聚体中逐渐达到最大,之后又随土壤团聚体粒径的增大而减小。土壤酶活性主要分布在粒径1~2,2~3和3~5mm团聚体中,而小团聚体(<0.25,0.25~1mm)和大团聚体(>5mm)中土壤酶活性较低。在0—20cm土层中,土壤酶活性表现出随恢复年限的增大而增加,在20—40cm土层则表现出随恢复年限的增大而维持稳定。结论]随着人工林种植年限的增加,土壤酶活性逐渐加强,而坡耕地不利于土壤酶活性的提高。因此,未来该区的植被建设中应该加强对天然草地与柠条林地的保护,这有利于土壤酶活性的改善。

Effects of Different Revegetation Types on Soil Enzyme Activities in Different Aggregates Fractions in Loess Plateau

Objective] To investigate the distributions of soil enzyme activities in different aggregates fractions for the different revegetation types in the Loess Plateau in order to provide basic data for vegetation restoration project.Results] The field investigation and the laboratory experiments were used to explore the effects of vegetation restoration on soil enzyme activities.Results] The soil enzyme activities in the natural grassland and Caragana korshinskii lands with the 15 and 25 year ages were higher than that in crop land. The activities of soil enzyme activities increased with the increase of the aggregate sizes in small and moderate sized aggregates(1~2 mm, 2~3 mm and 3~5 mm), but decreased in the big sized aggregates. Soil enzyme activities were mainly distributed in the moderate aggregates (1~2 mm, 2~3 mm and 3~5 mm). The small(<0.25 mm, 0.25~1 mm) and large(>5 mm) soil aggregates showed less soil enzyme activities. In the 0-20 cm soil layer, soil enzyme activities increased with the age of C. korshinskii, while it was stable in the 20-40 cm soil layer.Conclusion] The activity of soil enzyme is gradually strengthened with the increase of plantation years, and the slope farmland is not conducive to the improvement of soil enzyme activity. Natural grassland and the C. korshinskii lands improved the accumulations of soil enzyme activity and should be protected in the future.