缙云山针阔混交林土壤呼吸速率对降水输入量变化的响应

为探讨亚热带季风性湿润气候地区降水对土壤呼吸的影响,于2014年选取重庆市缙云山自然保护区内针阔混交林为研究对象,通过人为拦挡和增水方式模拟不同降水输入量对土壤呼吸速率的影响,包括达到土壤含水量的70%(增水70%,70%A),100%(增水100%,100%A),130%(增水130%,130%A)及对照(CK)和零降水(Z)5种情况。结果表明:(1)不同降水处理下土壤呼吸速率日变化均呈单峰变化曲线,并在12:00—14:00之间达到最大值;其年内月变化也为单峰曲线,于8月份达到最大值,12月份达到最小值。(2)适当增水可以提高土壤呼吸速率与10cm深度土壤温度的Pearson相关性,但指数模型的拟合度以对照组最好,减水和过度增水都会减少其相关性;温度敏感性Q10值的变化情况与其相同。(3)土壤呼吸速率与10cm深度的土壤含水量的相关性总体很低,但明显受到土壤水分条件影响,除零降水处理表现为极显著正相关外,对照组几乎不相关,增水处理转为明显的负相关,尤其增水130%后呈显著负相关。(4)在研究地区的自然环境条件下,增水100%时提高了土壤呼吸速率,也扩大了其变化范围,减水明显降低了土壤呼吸速率。

The Influence of Different Water Input on Soil Respiration in Mixed Broadleaf-conifer Jinyun Mountain

To explore the various degree water input influence on soil respiration in subtropical monsoon climate region, selected mixed broadleaf-conifer forest of Chongqing Jinyun Mountain Nature Reserves as the research object in 2014. The artificial blocking and increasing water were used to simulate different precipitation input, and then to analyze the impact (including 70% of saturated soil water content (addition 70%: 70%A), 100% (addition 100%: 100%A), 130% (addition 130%: 130%A), comparison (CK) and no precipitation (Z)). The result shows that: (1)All the diurnal changes of soil respiration formed a curve under the different water inputs, and it reached the maximum value during 12:00 to 14:00; and the same as monthly variation, it reached the maximum value in August and the minimum value in December; (2)Properly increased water could improve the Pearson correlation between soil respiration rate and soil temperature of 10 cm soil depth, but the best fitting of exponential model was comparison group. Reducing water and excessive increase water would reduce its correlation; the same as the temperature-sensitivity coefficient Q10; (3)The correlation of soil respiration rate and soil water content of 10 cm soil depth was low as a whole, but the influence was obvious. In addition to no precipitation showed significantly positive correlation, it almost off the mark between comparison and water content, and it negatively correlated between water addition and water content, especially the addition 130% was marked negative correlation; (4)In General, water addition 100% improved the soil respiration rate, expanded its excursion, water reduction reduced the soil respiration rate in the study region nature environment.