兰州市城郊林草地土壤碳通量特征及其影响因素

Characteristics and Influencing Factors of Soil Carbon Flux in Suburban Forest and Grassland in Lanzhou

    摘要
  • 摘要:
      目的  探讨兰州市城郊林草地土壤碳通量变化规律，定量估算土壤碳排放量，为城市与城郊区碳排放和碳循环研究提供参考依据。
      方法  以兰州市城郊“小青山水土保持科技示范园”内刺槐、苜蓿和沙打旺为试验样地，利用LI-8150“土壤碳通量测量系统”对三种林草地土壤碳通量进行长期连续监测，分析土壤碳释放特征，阐明土壤碳通量与影响因素间的相关关系。
      结果  ①兰州市城郊三种林草地土壤碳通量最高值出现在每天下午14:00左右，最低值在凌晨6:00左右；早上10:00和晚上20:00左右的土壤碳通量值与日均值基本一致。苜蓿草地年度土壤碳排放量为2321.30 g m− 2，高于刺槐林地1.24倍、沙打旺草地1.48倍。②三种林草地之间的地表温度变化和5 cm深处土壤温度变化规律一致，均无显著差异（P > 0.05），地表温度和5 cm土壤温度都与土壤碳通量具有显著的正指数相关关系（P < 0.05），其中刺槐林地土壤碳通量对温度的敏感性最高。③三种林草地土壤碳通量与太阳辐射强度显著相关（P < 0.05），刺槐林地土壤碳通量与降雨量呈抛物线状显著相关（P < 0.05）。
      结论  兰州市城郊林草地在每天下午14:00左右土壤碳通量最高，苜蓿草地土壤二氧化碳排放量最高，温度和太阳辐射强度与土壤碳通量显著正相关（P < 0.05）。

     

    Abstract:
      Objective  The paper aimed to explore the variation of soil carbon (C) flux in suburban forest and grassland in Lanzhou, and quantitatively estimate soil C emission, so as to provide reference for the study of C emission and C cycle in urban and suburban areas.
      Method  In this study, locust, alfalfa and Sandgrass were used as experimental plots in "Xiaoqingshan Soil and Water Conservation Science and Technology Demonstration Park" in the suburbs of Lanzhou. LI-8150 "Soil carbon flux measurement system" was used to continuously monitor the soil C flux of three kinds of forests and grasslands, analyze the characteristics of soil C release, and clarify the correlation between soil C flux and influencing factors.
      Result  ①The highest value of soil C flux occurred at about 14:00 in the afternoon, and the lowest value occurred at about 6:00 in the morning. The soil C flux values at 10:00 AM and 20:00 PM were basically consistent with the daily average. The annual total soil C emission of alfalfa was 2321.30 g m-2, which was 1.24 times higher than that of robinia pseudoacacia forest and 1.48 times higher than that of astragalus pastures. ②The changes of land surface temperature and 5 cm soil temperature were consistent among the three kinds of forest and grassland, and there was no significant difference (P > 0.05). The soil C flux had a significant positive exponential relationship with surface temperature and 5 cm soil temperature (P < 0.05), and the soil C flux in robinia pseudoacacia forest had the highest sensitivity to temperature. ②Soil C flux of forests and grasslands was significantly correlated with solar radiation (P < 0.05), soil C flux of artificial Robinia perseudoscacia was significantly correlated with rainfall (P<0.05).
      Conclusion  The highest soil C flux is found in the forest and grass fields in the suburb at around 14:00 in the afternoon, and the highest soil C emission is found in the alfalfa grass fields. Temperature and solar radiation intensity are significantly correlated with soil C flux（P < 0.05）.

     

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