陕北黄土高原藓结皮的7种土壤酶活性及其剖面分布特征

Soil enzyme activities and vertical distribution of moss-dominated biological soil crusts on the Loess Plateau in Northern Shaanxi

【目的】研究藓结皮对土壤酶活性及其剖面分布特征的影响,为认识和理解生物结皮的生态功能提供实证,同时也为黄土高原生态修复提供参考。【方法】以陕北黄土高原的藓结皮为对象,测定了0~12cm土层藓结皮和无结皮处理土壤的7种酶(脲酶、碱性磷酸酶、蔗糖酶、蛋白酶、过氧化氢酶、过氧化物酶、多酚氧化酶)活性,分析藓结皮和无结皮处理土壤养分含量、酶活性及其剖面分布特征的变化,并分析藓结皮和无结皮条件下不同土壤酶活性的相关性。【结果】在0~12cm土层,藓结皮处理的全氮、全磷、碱解氮、速效磷以及土壤有机质含量均高于无结皮处理,藓结皮处理的5种土壤养分含量的平均值分别是无结皮处理的0.53,0.29,0.34,0.81和0.24倍。藓结皮处理极显著提高了表层(0~2cm)土壤7种酶的活性,其脲酶、碱性磷酸酶、蔗糖酶、蛋白酶、氧化氢酶、过氧化物酶和多酚氧化酶活性分别是无结皮处理的3.51,44.76,32.91,2.22,2.47,9.93和4.13倍;显著提高了2~6cm土层碱性磷酸酶、蔗糖酶以及蛋白酶的活性,3种酶活性分别是无结皮处理的9.41,9.28以及1.78倍;极显著提高了0~12cm土层过氧化物酶和多酚氧化酶活性,2种酶的活性分别是无结皮处理的18.58和8.69倍。藓结皮与无结皮条件下,土壤酶活性具有类似的剖面分布规律,均随土壤深度的增加总体呈递减趋势,但藓结皮条件下土壤酶活性的剖面表聚特征更为明显,无结皮条件下的表层(0~2cm)土壤酶活性为下层(10~12cm)土壤的1.97~12.97倍,而藓结皮条件下的表层土壤酶活性为下层土壤的0.76~6.53倍。藓结皮条件下7种土壤酶活性之间呈极显著相关性,而无结皮条件下7种土壤酶活性的相关性相对较差。【结论】藓结皮对土壤养分积累和酶活性具有促进作用,对土壤肥力提升、退化土地治理以及生态环境修复均有重要意义。

【Objective】This study determined the effects of moss-dominated biological soil crusts（hereafter moss crusts）on the activities and profile distribution of soil enzymes to help understanding the ecological functions of biological soil crusts and their roles in ecological restoration in the Loess Plateau.【Method】Moss crusts and corresponding no crust treatment at soil layers of 0-12 cm were sampled in the northern Shaanxi.The activities and vertical distribution of seven soil enzymes（urease,alkaline phospha-tase,sucrase,protease,catalase,peroxidase,and polyphenol oxidase）,as well as soil nutrient contents were analyzed.The relationships between soil enzymes activities under the conditions of with and without moss crusts were also analyzed.【Result】Moss crusts significantly increased the contents of total nitrogen,total phosphorus,alkali-hydrolyzable nitrogen,available phosphorus,and organic matter by 0.53,0.29,0.34,0.81 and 0.24 times at depth of 0-12 cm.Moss crusts also significantly increased the activities of urease,alkaline phosphatase,sucrase,protease,catalase,peroxidase,and polyphenol oxidase by 3.51,44.76,32.91,2.22,2.47,9.93 and 4.13 times at depth of 0-2cm.The activities of soil alkaline phosphatase,invertase,and protease were increased by 9.41,9.28 and 1.78 times at depth of 2-6cm and the activities of peroxidase and polyphenol oxidase were extremely significantly increased by 18.58 and 8.69 times at depth of 0-12 cm.With and without moss crusts,the vertical distribution of enzymes activities had similar decreasing trend as the increase of soil depth.The soil enzyme activities at surface（0-2cm）without crust were0.76-6.53 times of that in deep soil（10-12cm）,while those with moss crusts were 1.97-12.97 times.The soil enzyme activities with moss crusts closely correlated with each other,while the soil enzyme activities without crust were poorly correlated with each other.【Conclusion】Moss crusts had positive effects on soil enzyme activities,and they played important role in improving soil fertility,treating degraded land and restoring ecosystem.