陕北水蚀风蚀交错区生物结皮对土壤酶活性及养分含量的影响

论文以陕北水蚀风蚀交错区六道沟小流域的生物结皮为对象,研究分析了其对土壤酶活性和土壤养分特征的影响。结果表明:生物结皮对土壤酶活性和土壤养分的影响主要体现在结皮层。结皮层的土壤脲酶和过氧化氢酶活性分别为下层(0～2 cm)土壤的1.56和1.31倍,碱性磷酸酶活性提高幅度最大,为结皮下层的3.72倍;生物结皮能显著提高结皮层土壤有机质、全氮及速效氮含量(P0.05),研究中结皮层土壤有机质、全氮、速效氮含量分别为15.67 g.kg-1、0.65 g.kg-1和22.51 mg.kg-1,而其下0～2 cm层土壤则分别为5.54 g.kg-1、0.30 g.kg-1和14.6 mg.kg-1;生物结皮对土壤速效磷和速效钾的影响不明显(P0.05);生物结皮层土壤pH值为8.08,低于其下0～2 cm层土壤(pH值为8.32,P0.05)。总之,生物结皮的形成和发育可以改善表层土壤的生物化学性质,对该区植被的恢复与重建具有积极意义。

Effects of Biological Soil Crust on Soil Enzyme Activities and Nutrients Content in Wind-water Erosion Crisscross Region, Northern Shaanxi Province, China

Biological soil crust (BSC) exerts important ecological functions in the arid and semi-arid ecosystems. In this paper, the effects of BSC on soil enzyme (urease, catalase and alkaline phosphatase) activities and nutrients (soil organic matter, total N, available N, P and K) content were studied in the revegetated lands in the water-wind erosion crisscross region on the Loess Plateau, northern Shaanxi Province of China. The results indicated that compared to no crust, BSC could significantly improve soil enzyme activities in crust,but had no significant increase effect on soil enzyme activities in subsoil. The activities of soil urease and catalase in crust layer were 1.56 and 1.31 times as high as that in 0-2 cm topsoil under crust, respectively. The increasing extent of soil alkaline phosphatase activity in crust was the biggest, which was 3.72 times of that in 0-2 cm topsoil under crust. Soil nutrients accumulation effects of BSC were obvious mainly in crust soil. In this study, BSC significantly increased the content of soil organic matter, total N and available N in crust (P<0.05),but the increase effects of available P and K were not significant (P>0.05). The contents of soil organic matter, total N and available N were 15.67 g·kg^-1, 0.65 g·kg^-1 and 22.51 mg·kg^-1 in crust, and were 5.54 g·kg^-1, 0.30 g·kg^-1 and 14.6 mg·kg^-1 in 0-2 cm topsoil under crust, respectively. The soil pH was 8.08 in crust, which was lower than that in 0-2 cm topsoil under crust (pH=8.32, P<0.05). The decrease effect of BSC on soil pH was helpful to improve the soil nutrients bioavailability. Therefore, it can be concluded that the formation and development of BSC would be beneficial to bettering surface soil biochemical properties, which can promote vegetation restoration and reconstruction in such arid and semiarid regions. There were many factors which influenced the formation and development of BSC. Therefore, effects of BSC on soil enzyme activities and nutrients under different environmental conditions and various vegetation types should be paid more attention in the further studies.