西藏色季拉山天然林分土壤呼吸组分量化分离及季节变化特征

Seasonal variation of soil respiration and its components partition in the typical forests in Sygara Mountain in Tibet, China

为阐明西藏色季拉山典型森林生态系统土壤呼吸速率与其组分的分离量化及其对水热因子的响应规律,采用挖沟断根法进行了土壤呼吸组分分离试验,并观测了同期地表下5 cm土壤温度和土壤湿度。统计分析结果表明:土壤呼吸及其组分的呼吸速率在夏季(7—9月)较高,冬季较低,在整个观测期内呈现单峰型曲线变化趋势。林芝云杉土壤呼吸最大值出现时间比急尖长苞冷杉滞后1个月。两种林分土壤呼吸及其各组分和土壤温湿度之间的关系可以用指数回归模型一元线性回归方程来描述,但是急尖长苞冷杉枯枝落叶呼吸速率和土壤含水量没有明显的相关关系。两种林分的微生物呼吸占总呼吸量的比例最高,其次为枯枝落叶呼吸和根系呼吸。两种林分的微生物呼吸在夏秋季所占比例较高,根系呼吸在春夏季所占比例较高,枯枝落叶呼吸则在春末夏初所占比例较高。

In order to understand the soil respiration and its components to changing soil temperature and water content in the typical forests in Sygara Mountains, the root-excluded quadrates by trenching were set up to partition soil respiration components, and the soil temperature and water content were simultaneously measured. The results indicated that the respiration rate of the total soil respiration and its different components were higher in summer than in winter, and the changes of SRR of these two forests presented as unimodal curve in the whole year. The time of the most value of SRR of Picea likiangensis var. linzhiensis was one month later than that of Abies georgei var. smithii. The relationships between SRR and soil temperature and water contents can be described by exponential equation and linear equation. But there was no significant relationship between SRR and soil water content of Abies georgei var. smithii. The Rh had the highest percentage of Rt of these two forests, followed by the Rl and the Rr. Rh had higher percentage in summer and autumn; Rr had higher percentage in spring and summer; Rl had higher percentage in late spring and early summer.