globalchange  > 影响、适应和脆弱性
DOI: 10.1111/gcb.13547
论文题名:
The case for increasing the statistical power of eddy covariance ecosystem studies: why, where and how?
作者: Hill T.; Chocholek M.; Clement R.
刊名: Global Change Biology
ISSN: 13541013
出版年: 2017
卷: 23, 期:6
起始页码: 2154
结束页码: 2165
语种: 英语
英文关键词: carbon ; carbon dioxide ; CO2 ; eddy covariance ; effect size ; flux ; latent ; replication ; sensible ; significant
Scopus关键词: carbon dioxide ; ecological footprint ; ecoregion ; eddy covariance ; latent heat flux ; sensible heat flux ; size effect ; turbulence ; Africa ; Australia ; South America
英文摘要: Eddy covariance (EC) continues to provide invaluable insights into the dynamics of Earth's surface processes. However, despite its many strengths, spatial replication of EC at the ecosystem scale is rare. High equipment costs are likely to be partially responsible. This contributes to the low sampling, and even lower replication, of ecoregions in Africa, Oceania (excluding Australia) and South America. The level of replication matters as it directly affects statistical power. While the ergodicity of turbulence and temporal replication allow an EC tower to provide statistically robust flux estimates for its footprint, these principles do not extend to larger ecosystem scales. Despite the challenge of spatially replicating EC, it is clearly of interest to be able to use EC to provide statistically robust flux estimates for larger areas. We ask: How much spatial replication of EC is required for statistical confidence in our flux estimates of an ecosystem? We provide the reader with tools to estimate the number of EC towers needed to achieve a given statistical power. We show that for a typical ecosystem, around four EC towers are needed to have 95% statistical confidence that the annual flux of an ecosystem is nonzero. Furthermore, if the true flux is small relative to instrument noise and spatial variability, the number of towers needed can rise dramatically. We discuss approaches for improving statistical power and describe one solution: an inexpensive EC system that could help by making spatial replication more affordable. However, we note that diverting limited resources from other key measurements in order to allow spatial replication may not be optimal, and a balance needs to be struck. While individual EC towers are well suited to providing fluxes from the flux footprint, we emphasize that spatial replication is essential for statistically robust fluxes if a wider ecosystem is being studied. © 2016 The Authors Global Change Biology Published by John Wiley & Sons Ltd.
资助项目: We thank the reviewers, whose comments helped focus this manuscript, the Holker estate and Dr Robert Baxter for the loan of equipment. We acknowledge the support of the Natural Environment Research Council funded projects: CBESS (Coastal Biodiversity and Ecosystem Service Sustainability: NE/J015644/1) and GREENHOUSE (Generating Regional Emissions Estimates with a Novel Hierarchy of Observations and Upscaled Simulation Experiments: NE/K002619/1).
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/60926
Appears in Collections:影响、适应和脆弱性

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作者单位: Department of Geography, Exeter University, Rennes Drive, Exeter, United Kingdom; Department of Earth and Environmental Science, University of St Andrews, Irvine Building, North Street, St Andrews, United Kingdom; School of GeoSciences, The University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh, United Kingdom

Recommended Citation:
Hill T.,Chocholek M.,Clement R.. The case for increasing the statistical power of eddy covariance ecosystem studies: why, where and how?[J]. Global Change Biology,2017-01-01,23(6)
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