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细根在植物的养分获取和生态系统物质循环中有重要的作用,日益增加的氮沉降改变了土壤pH值和养分可利用性,潜在地影响着细根特性。为揭示氮沉降增加对木本植物细根寿命和形态的影响,于2013年5月至2015年9月在亚热带次生常绿阔叶林中开展每月一次的氮添加试验,共设对照(CK,0 g·m~(-2)·a~(-1))、低氮(LN,5 g·m~(-2)·a~(-1))、高氮(HN,15 g·m~(-2)·a~(-1))3个水平。以该林分建群种扁刺栲(Castanopsis platyacantha)为研究对象,于2014年4月至2015年9月,每月采用微根管技术获取根系影像,室内分析后得到各样地的扁刺栲细根生物量、寿命和形态指标。2014年11月取0-10 cm土壤分析土壤pH值、铵态氮和硝态氮含量。结果表明:扁刺栲0-45 cm土层细根生物量为128.30 g·m~(-3),细根平均寿命范围为113-186天;氮添加处理未显著影响扁刺栲0-45 cm土层细根寿命和生物量;低氮处理显著降低了0-15 cm土层细根根段表面积;高氮处理显著降低了表层土壤pH值。研究表明短期氮添加通过影响该次生林土壤无机氮含量,导致表层土壤酸化,对表层土壤扁刺栲细根的形态特征造成一定的影响;短期氮添加对扁刺栲细根生物量、寿命和深层细根的形态未产生显著影响。
Fine roots play an important role in plant nutrient acquisition and ecosystem material recycling. Increasing nitrogen deposition alters soil pH and nutrient availability, potentially affecting fine root characteristics. To reveal the effects of increased nitrogen deposition on the fine root life and morphology of woody plants, a monthly nitrogen addition experiment was conducted in subtropical evergreen broad-leaved forests from May 2013 to September 2015. A total of CK, 0 g · m -2 · a -1, low nitrogen (LN 5 g · m -2 · a -1), high nitrogen (HN 15 g · m -1) ~ (-2) · a ~ (-1)) three levels. Taking the Castanopsis platyacantha as the research object, the root images were obtained monthly using the micro-root canal technique from April 2014 to September 2015, and the flattened specimens were obtained after laboratory analysis栲 fine root biomass, life expectancy and morphological indicators. In November 2014, the soil pH, ammonium nitrogen and nitrate nitrogen content in 0-10 cm soil were analyzed. The results showed that the fine root biomass of 0-45 cm soil layer was 128.30 g · m -3 and the average length of fine roots was 113-186 days. The nitrogen addition did not affect the population of 0-45 cm soil layer. The root area of fine root in 0-15 cm soil layer was significantly reduced by low N treatment, and the surface soil pH was significantly decreased by high N treatment. The results showed that short-term nitrogen addition affected the inorganic nitrogen content of the secondary forest, resulting in the acidification of the surface soil and affecting the fineness of the fine roots of the flat fescue. The effects of short-term nitrogen addition on fine root biomass, life span and depth Fine root morphology did not have a significant effect.