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河岸带是水陆交错地带氮素生物地球化学循环的热点区域,春季融雪时期的气温变化引起的冻融交替是影响土壤氮素转化过程和氮素流失重要因素之一。通过室内模拟,研究了河岸带珍珠梅、落叶松和农田3种植被类型土壤可溶性氮含量与净氮矿化速率对不同冻结温度和冻融频次的响应。结果表明,冻融频次对3种植被类型河岸带土壤可溶性氮影响显著(P<0.05),不同植被类型土壤可溶性氮含量变化趋势相似,在第1次冻融之后达到峰值,在第10次冻融之后稳定。3种植被类型土壤无机氮含量受冻融交替影响显著升高(P<0.05)。冻融温度对土壤净氮矿化速率影响显著(P<0.05),土壤净氮矿化速率在第1次冻融之后达到最大值,随冻融次数增加而下降。3种植被类型土壤受冻融交替影响均有一定程度的氮素流失风险,农田土壤无机氮含量本底值较高,土壤氮素随冰雪融水流失风险较大。
The riparian zone is a hotspot area of nitrogen biogeochemical cycle in the interlaced region of land and water. The freezing and thawing alternation caused by the temperature change during the spring snowmelt period is one of the important factors affecting soil nitrogen transformation process and nitrogen loss. Through indoor simulation, the responses of soil soluble nitrogen content and net nitrogen mineralization rate to different freezing temperature and freezing and thawing frequency were studied in three types of riparian pearl riparian, larch and farmland vegetation. The results showed that the frequency of freezing and thawing had a significant effect on soil soluble nitrogen (P <0.05) in three types of riparian zone. The trend of soil soluble nitrogen content in different vegetation types was similar, and reached the peak value after the first freeze-thaw cycle. After the financial stability. The content of inorganic nitrogen in the three vegetation types was significantly affected by the alternating of freezing and thawing (P <0.05). The freezing and thawing temperature had a significant effect on the net nitrogen mineralization rate (P <0.05). The net nitrogen mineralization rate reached its maximum after the first freeze-thaw and decreased with the increase in the number of freeze-thaw cycles. There was a certain degree of risk of nitrogen loss in the three types of soils affected by freezing and thawing alternations. Soil inorganic nitrogen content in farmland was high, and the risk of nitrogen loss from snowmelt was greater.