Understanding the effect of disturbance from selective felling on the carbon dynamics of a managed woodland by combining observations with model predictions
Understanding the effect of disturbance from selective felling on the carbon dynamics of a managed woodland by combining observations with model predictions
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通过将观测结果与模型预测相结合，了解选择性砍伐干扰对管理林地碳动态的影响
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
T. Quaife
中科院分区：
文献类型：
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作者：
E. Pinnington;E. Casella;S. Dance;A. Lawless;J. Morison;N. Nichols;M. Wilkinson;T. Quaife
森林和陆地生态系统对干扰的响应是气候变化背景下全球碳循环的一个重要过程。本研究的重点是在一个管理的林场选择性砍伐（间伐）的影响。以往对研究地点涡动相关数据的统计分析发现，间伐扰动对生态系统净碳吸收量没有显著影响。为了更好地理解变薄对碳通量的影响，我们使用了四维变分数据同化的数学技术。数据同化为通量数据的更常见统计分析提供了一种令人信服的替代方法，因为它允许将许多不同来源的数据与动态模型的物理约束相结合，以找到对系统状态的改进估计。我们开发了新的观测算子，将白天和夜间的净生态系统交换观测数据与每日时间步长模型相结合，使观测数据增加了4.25倍。我们的研究结果支持了之前的分析，预测2015年未砍伐森林的净生态系统碳吸收率为426±116 g C m−2，而砍伐森林的净生态系统碳吸收率为420±78 g C m−2，尽管模型预测总初级生产力减少了337 g C m−2。我们表明，这可能是由于干扰后生态系统呼吸减少，补偿了总初级生产力的减少。这支持了森林净碳吸收率上限的理论，这是由于生态系统呼吸与总初级生产力的尺度关系。
The response of forests and terrestrial ecosystems to disturbance is an important process in the global carbon cycle in the context of a changing climate. This study focuses on the effect of selective felling (thinning) at a managed forest site. Previous statistical analyses of eddy covariance data at the study site had found that disturbance from thinning resulted in no significant change to net ecosystem carbon uptake. In order to better understand the effect of thinning on carbon fluxes, we use the mathematical technique of four‐dimensional variational data assimilation. Data assimilation provides a compelling alternative to more common statistical analyses of flux data as it allows for the combination of many different sources of data, with the physical constraints of a dynamical model, to find an improved estimate of the state of a system. We develop new observation operators to assimilate daytime and nighttime net ecosystem exchange observations with a daily time step model, increasing observations available by a factor of 4.25. Our results support previous analyses, with a predicted net ecosystem carbon uptake for the year 2015 of 426 ± 116 g C m−2 for the unthinned forest and 420 ± 78 g C m−2 for the thinned forest despite a model‐predicted reduction in gross primary productivity of 337 g C m−2. We show that this is likely due to reduced ecosystem respiration postdisturbance compensating for a reduction in gross primary productivity. This supports the theory of an upper limit of forest net carbon uptake due to the magnitude of ecosystem respiration scaling with gross primary productivity.
影响因子：
4.9
作者：
Bloom, A. A.;Williams, M.
通讯作者：
Williams, M.