JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2022, Vol. 46 ›› Issue (2): 19-26.doi: 10.12302/j.issn.1000-2006.202012047

Special Issue: “双碳”视域下的生态系统固碳增汇

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Monthly scale variation characteristics of net ecosystem exchange (NEE) in poplar plantations at the confluence of Hongze Lake and Huai River

CUI Hao1(), HAN Jiangang1,2,3, GUO Yanhui1, JI Huai1, ZHU Yongli1,2,*(), LI Pingping1,2,3   

  1. 1. College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
    2. Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
    3. National Positioning Observation Station of Hongze Lake Wetland Ecosystem in Jiangsu Province, Hongze 223100, China
  • Received:2020-12-29 Accepted:2021-09-01 Online:2022-03-30 Published:2022-04-08
  • Contact: ZHU Yongli E-mail:c524628044@163.com;lyly1262011@126.com

Abstract:

【Objective】The aim of this study was to reveal the impact of the unique hydrological characteristics of Hongze Lake, which has a low water level in summer and a high water level in winter, on the net ecosystem exchange carbon flux (NEE) of poplar plantations at the confluence of Hongze Lake and Huai River. 【Method】In this study, eddy covariance and soil moisture monitoring systems were used to observe the NEE and environmental factors of typical poplar plantations in the river-lake intersection area for three consecutive years(2016-2018) to analyze the variations in NEE and its relationship with environmental factors on a monthly basis. 【Result】(1) The NEE values of the poplar plantations in this area displayed an obvious V-shaped curve, showing carbon absorption during the daytime and carbon release at night, with an average daily carbon sink time of 10 h. (2) The highest value of NEE during the annual 10 days study was 7.117 g/m2 in early February 2018, and the lowest NEE was -212.256 g/m2 in mid-July 2017. The average annual NEE value in the three years was -1 413.403 g/m2. (3) The water level of Hongze Lake was low during the sluice-opening period (from May to August), and soil moisture content and wind speed were the main factors affecting NEE, whereas the water level was high during the sluice-closing period (September to April of the next year), and NEE was mainly affected by air temperature and saturated vapor pressure differences. 【Conclusion】Opening the sluices and releasing water in summer were advantageous for the growth of poplar trees and increased the carbon sink. In winter, the groundwater level increased, and the adverse effects on the poplar growth could be eliminated by the ditching and ridge construction, which would be beneficial for improving the annual carbon sink function of poplar plantations in this region.

Key words: poplar (Populus×euramericana‘Nanlin 95’) plantation, net ecosystem exchange (NEE), eddy covariance, environmental factor, Hongze Lake

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