青藏高原东缘不同林龄云杉林冬季土壤呼吸特征

采用动态密闭气室红外CO_2 分析法(IRGA),连续定位测定青藏高原东部4种不同恢复阶段的人工云杉林和原始云杉林在冬季(2007.11.01～2008.03.31)的土壤呼吸.用挖壕沟法同步区分土壤自养呼吸和异养呼吸,并同步测定土壤5 cm温度和水分结果表明,土壤5 cm温度与冬季土壤呼吸速率具有显著的正指数相关关系,土壤含水量与冬季土壤呼吸的相关性不明显.亚高山针叶林冬季土壤呼吸温度系数Q_(10) 值为3.180 3～6.546 9,不同年龄阶段针叶林的Q_(10)值大小依次为:35 a人工云杉林>47 a人工云杉林>65 a人工云杉林>22 a人工云杉林>原始云杉林.22 a、35 a、47 a、65 aA工云杉林和原始云杉林冬季土壤总呼吸碳释放通量别为200.16、196.23、166.71、228.47、261.75 g(C)m~2,随着森林恢复更新,冬季土壤呼吸通量呈现出先下降后升高的趋势,这种变化趋势的拐点出现在47 a人工林附近.温度是影响土壤自养呼吸贡献率和异养呼吸贡献率的主要因子,温度与异养呼吸贡献率成负相关.22 a、35 a、47 a、65a人工云杉林和原始云杉林冬季土壤的自养呼吸和异养呼吸碳释放通量平均值分别为133.44、134.04、115.97、166.05、199.07 g(C)m~(-2)和66.71、62.20、50.73、62.43、62.68 g(C)m~(-2).图7表3参34

Soil Respiration of Subalpine Coniferous Forest in Winter in the East of the Qinghai-Tibet Plateau, China

During November 2007 ～ March 2008, soil respiration was measured by a closed dynamic chamber system in four Picea asperata plantations and its primary forest in the east of the Qinghai-Tibet Plateau in China. The heterotrophic and autotrophic components of soil respiration in winter were partitioned by entrenchment. The temperature and moisture in soil of 5 cm deep were observed by geothermometer and TDR system. The results showed that soil temperature had significant positive exponential correlation with soil respiration rate, but the correlation between soil water content and soil respiration rate at that depth was not significant. The temperature coefficients (Q_(10)) was between 3.180 3～6.546 9, the order of forests by Q_(10) was as follows: 35 a P. Asperata plantation>47 a plantation>65 a plantation>22 a plantation>primary forest. The carbon fluxes of soil total respiration in winter (01-11-07 ～ 31-03-08) in 22 a, 35 a, 47 a, 65 a plantations and primary forest were 200.16, 196.23, 166.71, 228.47 and 261.75 g (C) m~(-2), respectively. As the age of the plantations increasing from 22 a to 47 a, the carbon fluxes of soil respiration in winter decreased, but from 47 a to 65 a, the fluxs increased. A turning point in the changing trend for these fluxes occurred near the 47 a plantation. The proportions of heterotrophic and autotrophic components of soil respiration in different months had significant difference in winter. The proportions of heterotrophic components of soil respiration had significant negative correlation with soil temperature. The carbon fluxes of soil heterotrophic and autotrophic respiration in winter (01-11-07 ～ 31-03-08) in 22 a, 35 a, 47 a, 65 a plantations and primary forest were 133.44, 134.04, 115.97, 166.05, 199.07 g (C) m~(-2) and 66.71,62.20, 50.73,62.43, 62.68 g (C) m~(-2), respectively. Fig 7, Tab 3, Ref 34