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通过模拟大气氮沉降,对安徽祁门查湾自然保护区亚热带常绿阔叶林大气降雨及穿透雨进行持续监测,探讨森林降雨中可溶性有机碳、氮动态对大气氮沉降的响应。本试验设置了2个处理即高氮处理和无添加对照。结果表明,降雨中水溶性有机碳(TOC)年平均含量为3.204 mg·L-1,NH4+-N为0.243 mg·L-1,NO3--N为0.408 mg·L-1,可溶性有机氮(DON)为0.754 mg·L-1。经过森林林冠淋洗后,穿透雨中TOC年平均浓度达5.623 mg·L-1,对照林分(5.923 mg·L-1)>高氮处理(5.322 mg·L-1);NH4+-N年平均浓度为0.285 mg·L-1,对照(0.273 mg·L-1)<高氮处理(0.297 mg·L-1);NO3--N年平均浓度为0.509 mg·L-1,对照(0.523 mg·L-1)>高氮处理(0.494 mg·L-1);DON年平均浓度为0.691 mg·L-1,对照(0.665 mg·L-1)<高氮处理(0.716 mg·L-1)。降雨经过林冠层后,TOC、NH4+-N、NO3--N含量均有明显提高,但DON的含量有所下降;短期的模拟氮沉降对穿透雨可溶性碳和氮没有显著影响。大气降雨中TOC、NH4+-N、NO3--N、DON含量的季节变化明显,主要受控于降雨强度、降雨量,穿透雨的变化可能和树木的生理需求程度有关。
By simulating the atmospheric nitrogen deposition, the atmospheric and pervious rains of subtropical evergreen broad - leaved forests in Qiaowan Nature Reserve in Anhui Province were continuously monitored to investigate the response of the dynamics of dissolved organic carbon and nitrogen to the deposition of atmospheric nitrogen in forest rains. In this experiment, two treatments, high nitrogen treatment and no added control, were set up. The results showed that the annual average content of TOC was 3.204 mg · L-1, NH4 + -N was 0.243 mg · L-1, and NO3 - N was 0.408 mg · L-1. The contents of soluble organic nitrogen DON) was 0.754 mg · L -1. After the forest canopy was leached, the annual average concentration of TOC in the through rain was 5.623 mg · L-1, and the control forest (5.923 mg · L-1)> high-nitrogen treatment (5.322 mg · L-1); NH4 + -N The average concentration of NO3 - N was 0.285 mg · L-1, the control was 0.273 mg · L-1, the high-nitrogen treatment was 0.297 mg · L-1, (0.416 mg · L-1), the average annual DON concentration was 0.691 mg · L-1, while the control (0.665 mg · L-1) 1). The contents of TOC, NH4 + -N and NO3 - N increased obviously after rainfall passed canopy layer, but the content of DON decreased. Short - term simulated nitrogen deposition had no significant effect on the penetration of soluble carbon and nitrogen. The seasonal changes of TOC, NH4 + -N, NO3 - N and DON in atmospheric rainfall are obvious, which are mainly controlled by rainfall intensity, rainfall, and the change of penetration rain may be related to the physiological demand of trees.