高寒草地土壤酶活性和微量元素含量对植被特征的影响

Effects of soil enzyme activities and trace elements on vegetation characteristics in different alpine grasslands

摘要:

【目的】探寻祁连山不同高寒草地土壤酶活性和微量元素与植被特征之间的相互关系，并找出影响植被特征的主要因素，为祁连山生态系统的保护提供科学依据。【方法】分析高寒草甸、高寒草原和高寒荒漠的植被特征，及其土壤酶活性和微量元素的变化规律，探讨酶活性和微量元素与植被特征的关系，运用冗余分析和蒙特卡洛检验，确定影响植被特征的主要因素。【结果】1）不同类型高寒草地的植被总盖度，草层高度依次为高寒草甸＞高寒草原＞高寒荒漠，地上生物量、香农威纳指数和丰富度依次为高寒草原＞高寒草甸＞高寒荒漠，均匀度依次为高寒荒漠＞高寒草甸＞高寒草原，优势度依次为高寒荒漠＞高寒草原＞高寒草甸；不同类型高寒草地脲酶活性依次为高寒草原＞高寒草甸＞高寒荒漠。过氧化氢酶、碱性磷酸酶和蔗糖酶活性依次为高寒荒漠＞高寒草原＞高寒草甸。Mg、Mn、Zn 含量依次为高寒荒漠＞高寒草甸＞高寒草原，Fe、Cu 含量依次为高寒荒漠＞高寒草原＞高寒草甸，Mo 含量为高寒草甸＞高寒荒漠＞高寒草原。2）随土层深度的增加，除高寒草原脲酶、蔗糖酶和高寒荒漠碱性磷酸酶活性呈先升后降的趋势外，其他草地类型脲酶、碱性磷酸酶和蔗糖酶活性呈下降趋势，不同类高寒草地过氧化氢酶活性随土层深度的增加均呈上升趋势，且增幅不大。Mg、Mn、Fe、Cu 的含量随着土层深度的增加在不同高寒草地无较大变幅，Mo 与 Zn 的含量在高寒草甸中随土层深度的增加而降低，高寒荒漠 Mo 含量的变化趋势与之相反，在高寒草原中，Mo 含量随土层增加而降低，Zn 含量则呈先升后降的趋势。3）碱性磷酸酶、蔗糖酶活性、Cu、Fe 含量与植被特征有着密切关联，影响草地植被特征的重要性排序依次为 Cu 含量＞蔗糖酶活性＞Fe 含量＞碱性磷酸酶活性。【结论】高寒草地不同类型土壤酶活性和微量元素含量因草地类型而异，且植被特征一定程度上受某些微量元素和土壤酶活性的影响，应结合二者演变规律合理利用祁连山高寒草地。

Abstract:

【Objective】 The study is performed to explore the interrelationship between soil enzyme activity and trace elements and vegetation characteristics in different alpine meadows in Qilian Mountains，and to find out the main factors affecting vegetation characteristics，so as to provide some scientific basis for the conservation of Qilian Moun- tain ecosystem.【Method】 In this paper，we analyzed the vegetation characteristics of alpine meadows，alpine grass- lands and alpine deserts，and the change patterns of their soil enzyme activities and trace elements，explored the rela- tionship between enzyme activities and trace elements and vegetation characteristics，and used redundancy analysis and Monte Carlo test to determine the main factors affecting vegetation characteristics.【Result】 The results of the study showed that：1） The total vegetation cover of different types of alpine grassland，the grass layer height was in the order of alpine meadow ＞ alpine grassland ＞ alpine desert. Aboveground biomass，Shannon-Weiner index and richness were in the order of alpine grassland ＞ alpine meadow ＞ alpine desert. The order of uniformity was alpine desert ＞ alpine meadow ＞ alpine grassland，and the order of dominance was alpine desert ＞ alpine grassland ＞ al- pine meadow. In terms of mean values，urease activity was in the order of alpine grassland ＞ alpine meadow ＞ al- pine desert. Peroxidase，alkaline phosphatase and sucrase activities were in the order of alpine desert ＞ alpine grass- land ＞ alpine meadow. Mg，Mn and Zn contents were in the order of alpine desert ＞ alpine meadow ＞ alpine grass- land，Fe and Cu contents were in the order of alpine desert ＞ alpine grassland ＞ alpine meadow. Mo contents were in the order of alpine meadow ＞ alpine desert ＞ alpine grassland. 2） With the increase of soil depth，the activities of urease，alkaline phosphatase and alkaline phosphatase in alpine grassland increased first and then decreased， while in other meadow types the activities of urease，alkaline phosphatase and sucrase showed a decreasing trend. In different types of alpine meadow，peroxidase activities showed an increasing trend with the increase of soil depth，but the in- crease was small. The contents of Mg，Mn，Fe and Cu in different alpine grasslands did not change greatly with the in- crease of soil depth. The content of Mo and Zn decreased with the increase of soil depth in alpine meadows，and the trend of Mo content in alpine deserts was the opposite. In the alpine grassland，Mo content decreased with the in- crease of soil layer，while Zn content increased first and then decreased. 3） Alkaline phosphatase，sucrase，Cu and Fe content were closely related to vegetation characteristics. The order of importance affecting vegetation characteristics of grassland was Cu content ＞sucrase activity＞ Fe content＞ alkaline phosphatase activiey.【Conclusion】 In conclu- sion，soil enzyme activities and trace element contents of different types of alpine grasslands varied according to grass- land types，and vegetation characteristics were influenced by some trace elements and soil enzyme activities to some extent，so the alpine grasslands in Qilian Mountains should be used reasonably in combination with the evolution of the two.