氮添加对若尔盖高寒泥炭湿地土壤碳稳定性的影响

发布时间：2018-01-02 12:42

  本文关键词：氮添加对若尔盖高寒泥炭湿地土壤碳稳定性的影响　出处：《北京林业大学》2016年硕士论文　论文类型：学位论文

  更多相关文章： 湿地土壤 氮添加 有机碳 温室气体通量 微生物群落结构 酶活性

【摘要】：我国已成为全球第三大氮沉降区。土壤有机碳库在全球碳循环中具有重要作用,氮沉降增加会影响土壤中碳的稳定性。本研究通过模拟氮沉降,运用静态箱-气相色谱法分析不同施氮水平(0、10、20和80 kgN · hm-2 · a-1)对高寒湿地土壤碳输入和输出的影响,运用室内培养法研究氮添加对高寒泥炭土壤碳矿化的影响,并从微生物群落结构和功能角度,阐述和解释高寒湿地土壤有机碳稳定性对氮添加的响应机制,为湿地土壤对全球气侯变化的贡献提供参考。研究结果如下：氮添加显著促进了地上生物量和凋落物分解率。高氮、中氮和低氮处理下的地上生物量均值分别比对照高76.21%、56.67%和35.93%,凋落物分解率分别比对照高115.96%、90.64%和66.60%。在20℃培养温度下,高氮和中氮处理下的土壤碳矿化速率显著高出对照处理的165.79%和168.42%,低氮处理下的碳矿化速率高出对照68.42%,差异不显著。氮添加对土壤CO2、CH4的排放具有显著促进作用。在高氮、中氮和低氮处理中,土壤CO2平均排放通量比对照处理高34.00%、80.96%和26.72%,土壤CH4平均排放通量比对照处理高117.65%、123.53%和62.75%。氮添加对湿地土壤碳汇产生了显著促进作用。低氮、中氮和高氮处理下的土壤碳汇量显著高出对照处理的45.67%、34.73%和118.55%。氮添加明显改变了土壤细菌、古生菌丰度及微生物群落多样性。细菌丰度随施氮量的增加而显著增加；低氮处理下的土壤古生菌丰度明显比对照高34.36%,高氮处理下的古生菌丰度却显著低于对照61.35%。凋落物残留率与放线菌呈显著负相关,与硝化螺菌呈显著正相关；土壤CO2排放通量与变形菌和放线菌呈显著正相关,土壤CH4排放通量与古生菌、疣微菌和浮霉菌呈显著正相关。土壤中脲酶和硝酸还原酶活性随施氮量的增加而显著增加,土壤p-葡萄糖苷酶和多酚氧化酶活性均在中氮处理下最高,氮添加对过氧化氢酶活性的影响不显著。凋落物残留率与土壤硝酸还原酶和多酚氧化酶活性呈显著正相关；土壤CO2排放与土壤脲酶和过氧化氢酶活性呈显著正相关,土壤CH4排放与p-葡萄糖苷酶、硝酸还原酶和过氧化氢酶活性之间存在显著正相关。总之,氮添加促进了高寒湿地土壤中的碳输入和碳输出,活跃了土壤中的碳动态,整体上表现为“氮促碳汇”
[Abstract]:China has become the third largest nitrogen deposition area in the world. Soil organic carbon pool plays an important role in the global carbon cycle. The increase of nitrogen deposition will affect the stability of soil carbon. The effects of different nitrogen levels on soil carbon input and output in alpine wetland were analyzed by static box-gas chromatography. The effects of nitrogen addition on carbon mineralization in alpine peat soil were studied by means of indoor culture, and the response mechanism of soil organic carbon stability to nitrogen addition in alpine wetland was explained from the point of view of microbial community structure and function. The results are as follows: nitrogen addition significantly promoted aboveground biomass and litter decomposition rate. The mean aboveground biomass of medium and low nitrogen treatments was 76.21% and 35.93% higher than that of the control, respectively, and the litter decomposition rate was 115.96% higher than that of the control. At 20 鈩，

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