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洪泽湖湿地杨树林生长季碳通量变化特征及其影响因子

徐勇峰1,2,季淮2,韩建刚1,2,薛同良2,朱咏莉1,2*,李萍萍2,3   

  1. (1南京林业大学生物与环境学院, 南京 210037; 2江苏洪泽湖湿地生态系统国家定位观测研究站, 南京 210037; 3南京林业大学江苏省南方现代林业协同创新中心, 南京 210037)
  • 出版日期:2018-02-10 发布日期:2018-02-10

Variation of  net ecosystem carbon flux in growing season and its driving factors in a poplar plantation from Hung-tse Lake wetland.

XU Yong-feng1,2, JI Huai2, HAN Jian-gang1,2, XUE Tong-liang2, ZHU Yong-li1,2*, LI Ping-ping2,3   

  1. (1College of Biology and the Environment,Nanjing Forestry University, Nanjing 210037, China; 2National Positioning Observation Station of Hungtse Lake Wetland Ecosystem in Jiangsu Province, Nanjing 210037, China; 3Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing 210037, China).
  • Online:2018-02-10 Published:2018-02-10

摘要: 洪泽湖调蓄灌溉与南水北调常态化调水影响下,湖区水位显著波动对湿地土壤水分及植被生长产生深刻影响。以洪泽湖湿地典型杨树林为对象,借助涡度相关系统,研究杨树生长季(4—9月)CO2通量的动态变化特征,解析气象因子的影响。结果表明:杨树生长季净生态系统CO2交换量(NEE)与环境因子均具有明显的日、月变化特征。NEE的月平均日变化总体表现为“U”型曲线,累计达-1758.10 g CO2·m-2,在生长季表现为明显的碳“汇”。光合有效辐射(PAR)与日间净生态系统CO2交换量(NEEd)的变化符合双曲线关系,PAR能解释34.3%~75.5%生长季的NEEd的变化。5 cm土壤温度(Ts)与夜间净生态系统CO2交换量(NEEn)之间符合极显著的指数函数关系,Ts能解释38.9%~55.2%生长季的NEEn的变化。不同时间尺度碳通量与环境因子的分析发现,NEE的日变化主要受土壤含水量(SWC)、净辐射(Rn)和水汽压亏缺(VPD)的影响,而月变化主要受降雨量(P)和土壤含水量(SWC)的影响。因此,洪泽湖水位变化对湿地土壤水分的影响可能显著改变湿地碳汇功能。

关键词: 土壤微生物群落, Biolog-Eco, 多样性, 近自然经营

Abstract:

Fluctuations of water level in Hung-tse Lake are induced by the regional increasingirrigation demands and normalized water transfer with the operation of the SouthtoNorth water diversion project, with consequences on soil moisture and wetland vegetation. A poplar plantation in Hung-tse Lake wetland was selected to investigate the dynamics of CO2 flux and its influencing factors during the growing season (April to September) using the system of eddy covariance in 2016. The results showed that a typical daily and monthly variation characterized the changes of net ecosystem CO2 exchange (NEE) and environmental factors across the whole growing season. The monthly meanNEE showed a general “U” type curve with1758.10 g CO2·m-2 of accumulatedNEE, implying that the plantation was a carbon sink in the growing season. There was ahyperbolic relationship between the photosynthetically active radiation (PAR) and daytime netecosystem CO2 exchange (NEEd).PAR accounted for 34.3%-75.5% of the variation ofNEEd in the growing season. A significant exponential function relationship between soil temperature (Ts) at 5 cm depth and nighttime net ecosystem CO2 exchange (NEEn) was found, andTs explained38.9%-55.2% of the variation inNEEn. Soil water content, net radiation (Rn) and vaporpressure deficit mainly dominated the daily variation of CO2 flux, while the monthly variation of CO2 flux was mainly affected by rainfall and soil moisture. Therefore, changes of soil moisture in the wetlands, affected by the fluctuations of water level in Hung-tse Lake, would potentiallyaffect ecosystem carbon sequestration.
 

Key words: soil microbial community, Biolog-Eco, diversity, close-to-nature management