• 研究简报 •

### 各径级马尾松树干CO2释放速率及其温度敏感性

1. 南昌工程学院生态与环境科学研究所 江西省退化生态系统修复与流域生态水文重点实验室 南昌 330099
• 收稿日期:2016-05-22 修回日期:2017-08-28 出版日期:2017-10-25 发布日期:2017-11-29
• 基金资助:
国家自然科学基金项目（31260172）。

### Stem CO2 Efflux Ratio of Pinus massoniana of Various DBH Classes and Its Sensitivity to Temperature

Tu Jie, Fan Houbao, Wang Yonggang, Li Zhipeng

1. Research Institute of Ecology & Environmental Sciences, Nanchang Institute of Technology Jiangxi Provincial Key Laboratory for Restoration of Degraded Ecosystems & Watershed Ecohydrology Nanchang 330099
• Received:2016-05-22 Revised:2017-08-28 Online:2017-10-25 Published:2017-11-29

Abstract: [Objective] Stem CO2 efflux rates of various DBH classes and its sensitivity to temperature were investigated of the important pioneer tree species Pinus massoniana in the degraded red soil region. The aims of this study were to providefundamental data for evaluating the carbon sink contribution of stem respiration from Pinus massoniana plantation to the ecosystem.[Method] We conducted year-round in situ chamber measurements of FCO2 on twelve stems of Pinus massoniana using an automated, portable gas-exchange system (LC PRO-SD, ADC BioScientific Ltd., Hoddesdon, UK), which was equipped with an infrared gas analyzer and a transparent plexiglas cuvette. The sample trees were selected from four DBH classes (15.9-17.9, 18.9-20.5, 22.8-24.8, and 27.1-29.8 cm) with three replicates. At least 24 h prior to measurements, loose bark was removed from the surface of measurement and then collars were mounted horizontally on the north-facing stems at about 135 cm above-ground with 100% silicone sealant. During the process of measurements, the chamber was wrapped with aluminum foil to avoid excess heating by direct sun exposure. Stem temperature at 1 cm depth (Ts) were recorded synchronously. The measurements were conducted from 8:00 to 17:00 for the selected days each month between January and December in 2015 to ensure that the temperature range of data was collected as widely as possible. The temporal fluctuations of FCO2 and difference between various DBH classes were analyzed. And the exponential regression models were also established between FCO2 and Ts.[Result] There was clear seasonality in FCO2 for four diameter classes following similar remarkable single-peak patterns, with the maximum values occurring in July and the minimum in January. Obviously, the monthly FCO2 values were significantly higher(P<0.01)during the fast-growing season than in the slow-growing season. The values of FCO2 differed significantly(P<0.01)among various DBH classes during the growing season but not in the non-growing season. Significant exponential relationships were found between FCO2and Ts, with the correlations of determination higher in the bigger DBH classes than those in the smaller DBH classes. Furthermore, the values of temperature sensitivity (Q10) for four diameter classes varied from 1.47 to 1.64, which were within the range of values previously reported for most conifers. Additionally, FCO2were significantly correlated positively with DBH(R2=0.89), suggesting that DBH could be used as a proxy for predicting stem respiration for conifers.[Conclusion] Therefore, the temporal variations in FCO2and difference between various DBH classes should be simultaneously considered when estimating forest carbon budgets so as to improve the accuracy of evaluation.