模拟氮沉降对温带森林土壤酶活性的影响

Abstract

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟氮沉降对温带森林土壤酶活性的影响 DOI: 10.5846/stxb201510232140 作者: 作者单位: 北京林业大学,北京林业大学 作者简介: 通讯作者: 中图分类号: 基金项目: 中央高校基本科研业务费专项资金（2016JX02）；国家自然科学基金（41373069） Effect of simulated nitrogen deposition on soil enzyme activities in a temperate forest Author: Affiliation: Beijing Forestry University,Beijing Forestry University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:森林土壤酶作为土壤中最活跃组分，能影响生态系统的物质循环过程，其活性能快速反映氮沉降对土壤环境的变化。以北京地带性植被辽东栎林为研究对象，利用模拟氮沉降方法，原位设计低氮（50 kg N hm-2 a-1，N50）、高氮（150 kg N hm-2 a-1，N150）两个施氮水平，每个施氮水平设置NaNO3、（NH4）2SO4、NH4NO3 3个不同的施氮类型，另设置空白对照（0 kg N hm-2 a-1，N0）。从时间格局上研究不同氮素化学形态和剂量对温带森林土壤6种酶（脲酶、酸性磷酸酶、碱性磷酸酶、β-葡萄糖苷酶、多酚氧化酶和过氧化氢酶）活性的影响。结果表明：在氮形态和水平的交互作用下，NH4NO3-N处理的脲酶活性显著高出NO3--N处理的24.20%（N50），NH4+-N处理对酸性磷酸酶活性的影响显著高出NO3--N处理的13.82%（N150）；在NH4+-N和NH4NO3-N处理中，N50水平下的脲酶活性分别高出N0处理的38.90%和24.20%，差异显著。对无氮形态和水平交互作用的酶活性分析得出，不同的施氮水平，对碱性磷酸酶和多酚氧化酶的酶活性有显著促进作用，碱性磷酸酶活性在N50和N150处理下分别比N0高20.2%和11.5%，N50和N150处理对多酚氧化酶活性的促进作用分别比N0处理高64.3%和41.8%，差异显著（P < 0.05）；NH4+-N处理对β-葡萄糖苷酶活性具有显著促进作用（P < 0.05），不同的施氮形态，对碱性磷酸酶、多酚氧化酶和过氧化氢酶的酶活性无显著影响。6种酶活性均呈现了显著的时间变化，氮添加对森林土壤酶活性的时间分异规律没有显著影响。此外，土壤微生物量碳、硝态氮和铵态氮含量与酶活性具有显著相关性（P < 0.05）。以上结果表明，氮添加通过改变森林土壤的环境因子，影响了土壤中的水解酶和氧化酶活性，进而改变了土壤有机碳库和养分循环。 Abstract:As one of the most active components of forest soil, soil enzymes contribute to the processes of soil organic matter decomposition and synthesis and influence all the biochemical reactions of soil, directly or indirectly. Human activities have dramatically increased the quantity of nitrogen fixed in terrestrial ecosystems, due to fossil fuel combustion, production and use of chemical fertilizers, and live stock ranching. Nitrogen (N) addition may rapidly influence soil carbon and nitrogen turnover during litter and soil organic matter (SOM) decomposition processes by changing the soil enzyme activities. Specifically, we hypothesized that adding N to N-limited ecosystems would increase the activity of hydrolytic enzymes and decrease that of oxidase. In the present study, we explored the effects of different forms and levels of nitrogen addition on extracellular enzyme activities in a temperate forest soil with dominant Quercus liaotungensis (light loam, mean annual temperature 11.7 ℃), in the Xi Mountain Forestry Station, China. Nitrogen loading was designed using three N forms (NO3--N, NH4+-N, and NH4NO3), each containing a low-N (50 kg N hm-2 a-1, N50) and high-N (150 kg N hm-2 a-1, N150) treatment plot; a treatment plot of 0 kg N hm-2 a-1 (N0) served as a control. Each treatment comprised three replicate plots of 10 m × 10 m on the forest floor, with each plot having similar vegetation and biological soil crust cover. Soil urease, acid phosphatase, alkaline phosphatase, β-glycosidase, polyphenol oxidase, and catalase activities were analyzed to investigate the impacts of N forms and levels on soil enzyme activities from the temporal pattern. The results showed a significant increase of NH4NO3-N treatment in soil urease activity (+24.20% upper NO3--N, N50), and NH4+-N treatment in acid phosphatase activity (+13.82% upper NO3--N, N150), and a considerable increase of N50 level in soil urease activity (+38.90% and +24.20% upper NH4+-N and NH4NO3 in N0, respectively) (P < 0.05). However, N forms and levels did not affect the activities of alkaline phosphatase, β-glycosidase, polyphenol oxidase, and catalase. Increasing N (N50 and N150) resulted in higher alkaline phosphatase activity (+20.2% and +11.5% upper N0, respectively) and polyphenol oxidase activity (+64.3% and +41.8% upper N0, respectively); and, with the increase in N addition, both the alkaline phosphatase and polyphenol oxidase activities increased at N50 addition, and decreased at N150. We observed a significant increase in β-glycosidase activity (P < 0.05) with the different forms of N addition (NH4+-N > NH4NO3-N > NO3--N), whereas N forms had no effect on alkaline phosphatase, polyphenol oxidase, and catalase activities. Furthermore, the highest activities of soil enzymes including urease, acid phosphatase, alkaline phosphatase, and polyphenol oxidase occurred in summer, but the highest β-glycosidase activity and the lowest catalase activity were found in the winter and autumn, respectively. However, N addition made little difference on temporal variation. Significant correlations of soil enzyme activities with soil microbial biomass carbon, NH4+-N, and NO3--N were established (P < 0.05). These results suggested that N deposition could affect the soil carbon and nutrient flow by influencing environmental factors and microbial enzymatic activities in temperate forest ecosystems. 参考文献 相似文献 引证文献