祁连山西段草地表层土壤养分和酶活性对海拔的响应特征

Response of soil nutrients and enzyme activities toaltitude in the grassland in the centralQilian Mountains

摘要:

【目的】 研究不同海拔下草地表层土壤养分和酶活性的变化特征。【方法】 以祁连山西段的天然草地为研究对象，分析了不同海拔（2 995、3 170、3 403、3 620、3 817、4 068 m）表层土壤养分含量、生态化学计量比和酶活性的变化特征。【结果】 海拔对草地表层土壤养分和酶活性具有显著影响；随着海拔的升高，土壤pH 值、Cu 含量呈上升趋势，土壤有机碳、全氮、全磷、N/P 比、脲酶活性、碱性磷酸酶活性、过氧化氢酶活性、Zn 含量、Mg 含量呈先升高后降低，土壤C/N 比、C/P 比、Fe 含量呈先下降后上升，但各指标最小值和最大值出现的海拔梯度各异；不同海拔N/P 比处于3. 58~5. 86，均小于10；基于冗余分析（RDA）发现土壤有机碳和全磷是影响土壤酶活性的关键养分因子。【结论】 草地表层土壤养分和酶活性随不同海拔高度呈规律性分布，且生产力主要受氮素的限制。建议依据海拔差异制定合理的管理措施，促进草地生态的健康发展。

Abstract:

【Objective】 The aim of the study is to investigate the characteristics changes of soil nutrients and enzymeactivities in surface layer soil of grassland at different altitudes.【Method】 In this research，the natural grasslandin the middle of Qilian Mountains was used as the research object ，and characteristics changes of soil nutrient content，ecological stoichiometry ratio and enzyme activity at different altitudes（ 2 995 m，31 70 m，3 403 m，3 620 m，3 817 mand 4 068 m） were analyzed.【Result】 The research showed that altitude had significant effects on the nutrient and enzymeactivities of the grassland surface soil. With the increase of altitude，soil pH and Cu content showed an increasingtrend，while soil organic carbon，total N，total P，N/P ratio，urease activity，alkaline phosphatase activity，peroxidaseactivity，Zn content and Mg content first increased and then decreased. Soil C/N ratio，C/P ratio and Fe contentdecreased first and then increased. However，the minimum and maximum values of each index occurred in different altitudegradients. Meanwhile，the N/P ratios in different altitude were 3. 58~5. 86，and were all less than 10，whichmeant that grassland productivity was limited by nitrogen. Based on RDA analysis it could be found that soil organiccarbon and total phosphorus were the key nutrient factors affecting soil enzyme activity.【Conclusion】 The soil nutrientsand enzyme activities in the surface layer of grassland showed regular distribution with altitude，and the productivitywas mainly limited by nitrogen. It is suggested that reasonable management measures should be formulated accordingto altitude differences to promote the healthy development of grassland ecology.