天空状况对亚热带针叶林净生态系统生产力的影响从半小时到每天的时间尺度上有所不同。
Effects of sky conditions on net ecosystem productivity of a subtropical coniferous plantation vary from half-hourly to daily timescales.
机构信息
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China.
出版信息
Sci Total Environ. 2019 Feb 15;651(Pt 2):3002-3014. doi: 10.1016/j.scitotenv.2018.10.190. Epub 2018 Oct 15.
The dynamic changes of solar radiation have received wide attention in global change studies, but there are controversies about the influence of diffuse radiation on ecosystem carbon sequestration. Using eddy covariance measurements from 2010 to 2012, the effects of sky conditions extracted from adjacent sunny, cloudy, and overcast days on net ecosystem productivity (NEP) of a subtropical coniferous plantation were examined from half-hourly to daily scales. Half-hourly NEP responded to the changing radiation more efficiently on overcast days compared to sunny days, but such response did not differ obviously between cloudy and sunny days. Compared with sunny conditions, apparent quantum yield (α) under overcast (cloudy) conditions changed 282.4% (41.7%) in spring, 140.3% (-4.2%) in summer, 218.5% (38.9%) in autumn, and 146.2% (0.5%) in winter, respectively; annually, α under overcast (cloudy) conditions increased by 225.9% (19.8%) in 2010, 189.8% (6.0%) in 2011, and 159.5% (21.4%) in 2012, respectively. Moreover, the potential NEP at the light intensity of 150 and 750 W m was improved due to increased diffuse fraction. However, both daytime NEP and daily NEP were significantly lower under overcast skies than under sunny and cloudy skies. Compared with sunny days, daily NEP on overcast days decreased by 127.7% in spring, 126.4% in summer, 121.8% in autumn, and 100.6% in winter, respectively; annually, daily NEP decreased by 122.5% in 2010, 141.7% in 2011, and 109.9% in 2012, respectively. Diurnal patterns of daily NEP were quite similar between sunny and cloudy days. Both path analysis and multiple regression showed that solar radiation, especially diffuse radiation, was responsible for the variations of NEP under different skies across seasons, but this effect may be weakened by seasonal droughts. This study implies that the effects of sky conditions on NEP are timescale dependent and should be paid more attention in ecosystem carbon cycle study.
太阳辐射的动态变化在全球变化研究中受到广泛关注，但关于漫射辐射对生态系统碳固存的影响存在争议。本研究利用 2010 年至 2012 年的涡度相关测量数据，从半小时到日尺度，研究了从相邻晴天、多云和阴天中提取的天空条件对半温带针叶林净生态系统生产力（NEP）的影响。与晴天相比，阴天条件下半小时 NEP 对辐射变化的响应更有效，但阴天和晴天之间的响应没有明显差异。与晴天相比，在阴天（多云）条件下，表观量子产量（α）在春季分别变化 282.4%（41.7%）、夏季 140.3%（-4.2%）、秋季 218.5%（38.9%）和冬季 146.2%（0.5%）；年均来看，在阴天（多云）条件下，2010 年 α 增加 225.9%（19.8%），2011 年增加 189.8%（6.0%），2012 年增加 159.5%（21.4%）。此外，由于漫射分数的增加，潜在 NEP 在 150 和 750 W m 的光强下得到改善。然而，阴天条件下的日 NEP 无论是白天还是全日均显著低于晴天和多云天气。与晴天相比，阴天条件下，春季日 NEP 减少 127.7%，夏季减少 126.4%，秋季减少 121.8%，冬季减少 100.6%；年均来看，2010 年日 NEP 减少 122.5%，2011 年减少 141.7%，2012 年减少 109.9%。晴天和多云天气下，日 NEP 的日变化模式非常相似。路径分析和多元回归均表明，太阳辐射，尤其是漫射辐射，是不同季节不同天空条件下 NEP 变化的原因，但这种效应可能会因季节性干旱而减弱。本研究表明，天空条件对 NEP 的影响具有时间尺度依赖性，在生态系统碳循环研究中应予以更多关注。
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