川西亚高山针叶林土壤硝化作用及其影响因素

采用BarometricProcessSeparation(BaPS)技术对川西亚高山针叶林土壤总硝化作用速率的季节动态进行了研究,并分析了各影响因素与总硝化速率的关系.通过土壤温度和水分含量的控制实验,对温度和水分含量与总硝化速率之间的关系进行了一次线性和曲线模拟.结果表明,6至10月各月份之间的总硝化速率存在显著差异(P<0.01),在7月总硝化速率达到最大值;土壤温度和水分含量与总硝化速率显著正相关(P<0.05),对总硝化速率的影响存在明显的交互作用,水分含量可能对总硝化速率的影响更大,在季节变化中温度和水分含量可能对硝化过程产生直接和间接两种作用;pH值与总硝化速率之间的相关性不明显;森林凋落量与总硝化速率间没有显著相关性,但若仅考虑6至9月,森林凋落量与总硝化速率极显著相关(P<0.01).总之,土壤温度和水分含量很可能是影响总硝化速率的两个最主要的因素.图6表2参31

Nitrification and Impact Factors of Subalpine Coniferous Forest Soil in Western Sichuan, China

Gross nitrification rates were determined during growing season of plants in subalpine coniferous forest soil using the barometric process separation (BaPS) technique. The impact factors for nitrification rates were investigated. To study the direct effects of soil temperature and water content on nitrification, a controlled laboratory experiment, and the linear and quadratic equations for describing these effects were made. The results showed that there was obvious seasonal variation for gross nitrification rates in subalpine coniferous forest soil (P<0.01) and the highest value was found in July. Soil temperature and water content were positively related to the gross nitrification rates (P<0.05) and had a profound interactive effect. The controlled laboratory experiment suggested that water content might play a more important role in the variation in nitrification rates than soil temperature. The temperature and water content could both directly and indirectly affect the nitrification in different seasons. Nitrification rates were not closely related to pH value and litterfall. However, the rates were correlated with litterfall from June to September (P<0.01). It could be concluded that soil temperature and water content were the two most critical factors controlling the gross nitrification in subalpine coniferous forest soil. Fig 6, Tab 2, Ref 31