艾比湖地区棉花与芦苇群落光合和土壤呼吸特性对比整合初探

Preliminary Study of Contrast Integration of Photosynthesis and Soil Respiration Properties of Gossypium and Phragmites australis Community in Ebinur Lake Area

【目的】分别从拟合方程和CO2通量差值计算两个方面对棉花与芦苇的光合速率和土壤呼吸速率进行整合分析研究,旨在分别从光合速率和土壤呼吸速率的定量分析中寻找定性分析途径,探讨干旱区两大碳循环过程之间的异同,揭示干旱区棉花群落与芦苇群落植物光合和土壤呼吸对生态系统CO2源/汇效应的贡献特征。【方法】利用LI-6400便携式光合作用测定系统和LI-8100自动土壤呼吸测量系统,于2009年6月、9月同步测定艾比湖地区棉花(Gossypium)和芦苇(Phragmites australis)群落光合与土壤呼吸速率时间动态及主要环境影响因子,在对二者日变化动态及水热因子对比分析的基础上,分别从拟合方程和CO2通量差值计算两个方面进行整合研究。【结果】棉花和芦苇的光合与土壤呼吸速率在午前(约07:00～11:00)与午后(约15:00～17:00)具有相同变化规律,正午(约11:00～15:00)植物通过自身调控使光合和土壤呼吸丧失同步性;棉花和芦苇群落白天具有不同的净光合日总量和土壤呼吸日总量特征,棉花为1.207×103和0.613×103mmol/(m2.d),芦苇为0.346×103和0.612×103 mmol/(m2.d)。【结论】共同作用于棉花与芦苇光合和土壤呼吸速率的影响因子,彼此之间表现出的相关性和差异性,可在一定程度上解释两者同步变化时各自的特征;从芦苇群落到棉花群落不仅改变了植物光合和土壤呼吸的强度,在某种程度上也改变了土壤碳库、植物碳库和大气碳库比重,对干旱区碳循环过程产生不可忽视的作用。

[ Objective ] The plant photosynthesis and soil respiration are accompanied by output and input of carbon all the way, and those two aspects can be said to be the most concrete and vital content in the cur- rent research of terrestrial carbon cycle. Our study aims to explore the similarities and differences between the two primary carbon dynamics. In this article, the photosynthesis and soft respiration of Gossypium and Phrag- mites australis communities are analyzed through methods of fitted equation and CO2 flux difference calculation in order to seek for qualitative analysis method in quantitative analysis of photosynthetic rate and soil respiration rate, probe into the similarities and differences between those two carbon cycling in arid area, and reveal the contribution features of photosynthesis and respiration of Gossypium and Phragmites australis communities to ecosystem CO2 source/sink effects in arid area, thus providing a basis to conduct depth research on the inte- gration of plant photosynthesis and respiration. [ Method ] Two plant communities, Gossypium and Phragmites australis communities in Ebinur Lake Area were selected to conduct integration analysis of their photosynthesis and soil respiration through the fitted equation and calculating the CO2 flux, respectively. Photosynthesis and soil respiration of Gossypium and Phragmites australis communities in Ebinur Lake Area were measured during June and September in 2009 by using LI -6400 portable photosynthesis system and the automated CO2 efflux system （ LI - 8100）, respectively. Leaves room temperature （Tair）, soil surface temperature （ Tsoil）, leaves room relative humidity（Rh）and air relative humidity on top of the ground about 10 cm （Rh10） were moni- tored at each time point using auxiliary detector attached to the instrument, and leaf area index （LAI） was measured by using fresh weight method, and then comparative analysis was conducted about diurnal variations of photosynthesis and soil respiration and hydrothermic factor. [ Result]The results indicated that： plant photo- synthesis and soil respiration rate had the same variation properties before （about 07：00 - 11：00） and after （about 07：00- 11：00） the noon, while the plant photosynthesis and soil respiration lost the synchronization through their own regulation at noon; Gossypium and Phragmites australis communities had different character- istics of total volume on net photosynthesis and soil respiration in the daytime, Gossypium was 1. 207×103 and 0. 613×103 mmol/（m2· d）, and Phragmites australis was 0.346×103 and 0.612×103 mmol/（m2·d）, re- spectively. [ Conclusion ] Our results suggested that combined impact factors of photosynthesis and soil respira- tion rate of Gossypium and Phragmites australis communities revealed the correlation and differences between each other, to a certain extent, which can explain their own characteristics when they changed synchronously, and the change from Phragmites australis community to Gossypium community, which not only altered the in- tensity of photosynthesis and soil respiration, but also the proportion of soil carbon pool, plant carbon pool and the atmospheric carbon pool to some extent. This played a significant role in global climate change.