| 引用本文: | 纪小芳，龚元，郑翔，姜姜，鲁建兵，刘胜龙，王丹，方万里，
何雪凯.2020.凤阳山森林生态系统碳交换及其物候特征[J].地球环境学报,11(4):376-389 |
| JI Xiaofang, GONG Yuan, ZHENG Xiang, JIANG Jiang, LU Jianbing, LIU Shenglong, WANG Dan,
FANG Wanli, HE Xuekai.2020.Local-scale carbon exchange and phenological characteristics of forest ecosystem in Fengyang Mountain of Zhejiang, China using tower-based eddy covariance technique[J].Journal of Earth Environment,11(4):376-389 |
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| 摘要: |
| 凤阳山位于浙江省龙泉市南部，为亚热带典型森林生态系统保护区，受海洋性气候和季风的影响，是研究森林生态系统碳预算及其物候特征的理想之地。采用位于浙江凤阳山的涡动相关通量观测系统（EC）观测的2017年（除去9月）CO2通量数据、气象数据并结合物候模型来分析本地尺度亚热带森林生态系统总初级生产力（GPP）、生态系统呼吸（Re）动态特征、不同时间尺度下的影响因子及其物候特征，结果表明：该生态系统全年扮演着碳汇的角色，净生态系统碳交换量（NEE）（除去9月）为−89 g∙m−2∙a−1（以碳计），GPP总量为1377.75 g∙m−2∙a−1，Re总量为1288 g∙m−2∙a−1，GPP和Re的日变化和季节变化均呈单峰型，先增加后降低。GPP在不同的物候时期均为倒“U”型的变化趋势，而Re在夜间的生态系统呼吸略高于白天，且在日夜交替时刻会出现陡降现象。整个生态系统在174 d GPP增长率达到峰值0.25 μmol∙m−2∙s−1，达到最大恢复率；202 d的GPP增长率为0 μmol∙m−2∙s−1；228 d的GPP增长率最低，为−0.21 μmol∙m−2∙s−1，达到最大衰退率。不论是日尺度还是月尺度上，GPP和Re变化的主要驱动因素为空气温度，日尺度上Re较GPP对环境因子的变化更加敏感；反之，在月尺度上GPP对环境因子变化的响应比Re更加敏感。总体而言，凤阳山森林生态系统全年表现为碳汇，能够调节当地的二氧化碳浓度；生长季森林生态系统生长旺盛，稳定阶段的GPP与Re达到峰值；在不同的时间跨度上生态系统对环境因子的响应存在差异。 |
| 关键词: 森林生态系统 碳循环 涡动协方差 环境因子 物候模型 |
| DOI：10.7515/JEE192052 |
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| 基金项目:国家重点研发计划（2017YFC0505502）；国家自然科学基金（41701225）；江苏省自然科学基金（BK20170920） |
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| Local-scale carbon exchange and phenological characteristics of forest ecosystem in Fengyang Mountain of Zhejiang, China using tower-based eddy covariance technique |
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JI Xiaofang, GONG Yuan, ZHENG Xiang, JIANG Jiang, LU Jianbing, LIU Shenglong, WANG Dan,
FANG Wanli, HE Xuekai
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1. College of Forestry, Nanjing Forestry University, Nanjing 210037, China
2. College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
3. Fengyang Mountain Administration of Zhejiang Fengyang Mountain-Baishanzu National Nature Reserve, Longquan 323700, China
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| Abstract: |
| Background, aim, and scope Forest ecosystems are important carbon sinks for terrestrial ecosystems, the analysis of the dynamics and phenological characteristics of carbon exchange of forest ecosystems has important practical and theoretical significance for evaluating the carbon balance in terrestrial ecosystem. Since the 1990s, the research on CO2 flux in forest ecosystems has become a hot spot with the development of eddy covariance (EC) systems. Thus, this study used EC systems and phenological models to analyze the carbon dynamic characteristics of a subtropical forest ecosystem in Zhejiang, China for better understanding the carbon cycle of terrestrial ecosystems. Materials and methods This study used the CO2 flux data, meteorological data measured by the tower-based eddy covariance (EC) system in Fengyang Mountain of Zhejiang, China to analyze the dynamic characteristics of gross primary productivity (GPP), ecosystem respiration (Re), its environmental control factors and its phenological characteristics using the phenology model of a subtropical forest ecosystem among different time series at local scale. Results (1) The yearly net ecosystem carbon exchange (NEE), GPP, Re of this ecosystem in 2017 (excluding September) was −89 g·m−2∙a−1, 1377.75 g·m−2∙a−1, 1288 g·m−2∙a−1 respectively. This forest ecosystem played the role of carbon sink in 2017. (2) The growth rate of GPP in the forest ecosystem reached a peak recovery rate of 0.25 μmol·m−2·s−1 on 174 d of 2017, the growth rate of GPP reached a peak senescence rate of −0.21 μmol·m−2·s−1 on 228 d of 2017. The GPP showed a tendency of inverted “U” shape in different phenological periods, while Re at nighttime was slightly higher than the daytime and there was a steep drop during the alternation of day and night. (3) The main environmental control factors of GPP and Re was the air temperature (Ta, ℃) on daily or monthly scale, but Re was more sensitive to the change of other environmental control factors than GPP at the daily scale. Conversely, the response of GPP to the change of environmental control factors was more sensitive than Re at the monthly scale. Discussion Due to the lack of data for September in this study, the study may underestimate the annual carbon sink value. There should be a combination of analysis in several aspects, such as anthropogenic forest management, to propose some guiding forest management measures. It is generally accepted that forest ecosystems act as carbon sinks, but it is more important to explore how forests achieve these functions and how they are regulated by environmental factors. Although this paper got the different environmental factor and the GPP, Re, but its real regulation mechanism still needs to continue to explore. At the same time, different calculation methods may cause differences in research results. For example, the single-point method used in this paper may underestimate the carbon sink capacity of the forest in the study area, because the carbon storage term of the forest canopy is ignored. Conclusions The Fengyang Mountain forest ecosystem is characterized by carbon sinks throughout the year, which can regulate the local carbon dioxide concentration; the forest ecosystem grows vigorously during the growing season, and the GPP and Re peak in the stable stage; There are differences in the response of ecosystems to environmental factors over different time horizons. Recommendations and perspectives As the global CO2 concentration increases year by year, people are paying more attention to the carbon sequestration function of forests. As one of the most important ecosystems of the earth, estimating the carbon sink value and carbon exchange characteristics of forest ecosystems will make important contributions to the future research of the global carbon cycle. |
| Key words: forest ecosystem carbon cycle eddy covariance environmental control factors phenology model |
