增温对高寒湿地土壤呼吸动态变化的影响

Effect of Temperature Increase on Dynamic Changes of Soil Respiration in Alpine Wetlands

为研究在模拟增温状态下高寒湿地土壤呼吸的动态变化,并探究增温状态对土壤呼吸产生的影响,于2016年6月—2017年9月通过LI-8100土壤碳通量测定系统(开路式)对实验样地矮嵩草草甸(Kobresia humilis)的土壤呼吸速率及地下5、10和15 cm土壤温度、土壤体积含水量进行测定,结果表明:模拟增温有利于提高土壤呼吸速率,其与自然状态(CK)、增温状态(W)土壤呼吸速率之间有极显著性差异(P<0. 01);土壤呼吸速率与各层土壤温度和土壤体积含水量均有极显著相关性(P<0. 01),自然状态下的温度敏感性(Q10值)均比增温状态下的Q10值大,并且Q10值随着土壤深度的增加而增加;然而土壤温度与体积含水量共同影响下的土壤呼吸作用在2 a内减弱;增温状态有利于提高地上及地下生物量,并且对浅层地下生物量作用明显;与不增温比较,增温有利于提高土壤有机质含量,但差异随土壤深度的增加而依次减少。研究表明,连续2 a的增温对高寒湿地土壤呼吸产生促进作用,增温环境有利于促进土壤碳释放。

Experiment was conducted to determine the soil respiration rate, the soil temperature in 5, 10, and 15 cm layers and soil water content of Kobresia humilis in the sample plot by LI-8100 automated soil CO 2 flux system (open path) from June 2016 to September 2017, so as to study the dynamic changes of soil respiration in alpine wetlands in the simulated temperature increase state, and to investigate the effects of temperature increase on soil respiration. It can be seen from the results that simulated temperature increase is beneficial to the increase of soil respiration rate, which is significantly different from the rates both in the natural state (CK) and in the temperature increase state (W)( P <0.01);that the soil respiration rate is significantly correlated with the soil temperature and soil water content of each layer ( P <0.01). The temperature sensitivity values Q 10 in the natural state are larger than those in the temperature increase state, and the Q 10 value increases as the soil depth increases. However, soil respiration was jointly influenced by the soil temperature and soil water content and it decreased after 2 years. The temperature increase is helpful to the increase of above-ground and below-ground biomass, and has a significant effect on shallow underground biomass. When compared with no temperature increase, temperature increase is conducive to increase the soil organic matter content, and the difference decreases as the soil depth increases. The experiment results have shown that temperature increase for 2 consecutive years can promote soil respiration in alpine wetlands, and a warming environment is conducive to promoting soil carbon release.