Abstract:

The seasonal characteristics of enzyme activities affected the distribution of vegetation types in the Yellow River Delta Natural Reserve. This study selected five typical vegetations including Suaeda salsa, Tamarix chinensis, Phragmites communis, Black Locust, and Sorghum to examine the seasonal characteristics of soil enzyme activities of different vegetation in the Yellow River Delta Natural Reserve. The soil urease, catalase, alkaline phosphatase, dehydrogenase, and sucrase activities of profile soil samples for four seasons were determined. Results concerning soil dehydrogenase activities showed the following order: Suaeda salsa>Tamarix chinensis>Black Locust>Sorghum>Phragmites communis. In terms of the other enzyme activities, results showed that Black Locust>Tamarix chinensis>Sorghum>Phragmites communis>Suaeda salsa. In the same season, significant differences of enzyme activities among different vegetations were found. Soil urease, alkaline phosphatase and sucrase activities of Tamarix chinensis and Black Locust forests were generally higher than those of the other communities, while Suaeda salsa was the lowest. There was a close relationship between soil enzyme activities and basic physical and chemical indexes of the soil. There were significant positive correlations among soil catalase activity, urease activity, and sucrase activity (P<0.01). Catalase, urease, and sucrase had significant positive correlations with soil organic matter or alkaline hydrolysis nitrogen (P<0.01). There was a significant positive correlation between dehydrogenase and available phosphorus (P<0.01). In the 0-40 cm soil layer, alkaline phosphatase activity increased with the increase of soil depth, but catalase, dehydrogenase, urease and sucrase decreased as the soil depth increased. Further analysis of the relationships among different soil enzyme activities showed that there were strong and significant positive correlations among catalase, urease and sucrase (P<0.01). The study provides evidence that supports vegetation management in the Yellow River Delta.

Key words: Yellow River Delta, soil physicochemical properties, soil enzyme activity, season, vegetation, soil layers

摘要：

黄河三角洲自然保护区的酶活性季节特征一定程度影响了该地植被分布类型,为研究黄河三角洲自然保护区不同植被土壤酶活性的季节特征,分别选取碱蓬（Suaeda salsa）、柽柳（Tamarix chinensis）、芦苇（Phragmites communis）、刺槐（Black Locust）和高粱（Sorghum）5种典型植被作为研究对象,分别在4个季节采集不同深度土壤,测定土壤脲酶、过氧化氢酶、碱性磷酸酶、脱氢酶、蔗糖酶活性。结果表明,土壤脱氢酶活性规律表现为碱蓬>柽柳>刺槐>高粱>芦苇,其他酶活性总体变化规律表现为刺槐>柽柳>高粱>芦苇>碱蓬;在同一季节中,不同植被间酶活性存在显著性差异,柽柳和刺槐林土壤脲酶、碱性磷酸酶和蔗糖酶活性普遍高于其他群落,碱蓬最低;土壤酶活性与土壤基础理化指标有着密切关系,土壤过氧化氢酶活性、脲酶活性和蔗糖酶活性之间存在极显著性正相关（P<0.01）,过氧化氢酶,脲酶和蔗糖酶与有机质、碱解氮呈显著性正相关（P<0.01）,脱氢酶与速效磷呈显著性正相关与pH之间呈负相关（P<0.01）;在0—40 cm土层中,碱性磷酸酶活性随着土层深度增加而增加,而过氧化氢酶,脱氢酶,脲酶和蔗糖酶随着土层深度增加而减少;进一步分析不同土壤酶活性之间的关系,过氧化氢酶、脲酶和蔗糖酶之间存在极显著性正相关（P<0.01）。该研究结果可为黄河三角洲不同植被的管理提供数据支撑。

关键词: 黄河三角洲, 土壤理化性质, 土壤酶活性, 季节, 植被, 土层