A comparison of multiple phenology data sources for estimating seasonal transitions in deciduous forest carbon exchange
A comparison of multiple phenology data sources for estimating seasonal transitions in deciduous forest carbon exchange
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DOI：
10.1016/j.agrformet.2011.07.008
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发表时间：
2011-12-15
影响因子：
6.2
通讯作者：
Curtis, Peter S.
中科院分区：
文献类型：
--
作者：
Garrity, Steven R.;Bohrer, Gil;Curtis, Peter S.
目前有许多数据源可用于估计植物物候周期性转变的时间。我们比较了几个物候数据源的测量结果，以了解从这些数据源获得的物候指标与净生态系统交换（NEE）季节性转换的时间之间的关系。我们使用密歇根大学生物站（UMBS）11年的NEE数据确定了碳吸收季节的开始、峰值、结束和持续时间，以及从汇到源和从源到汇的过渡时间。使用拟合的逻辑斯蒂函数，我们确定了代理指标的物候转换从时间序列的反照率，吸收光合有效辐射（fPAR），植物面积指数（派），和MODIS归一化差异植被指数（NDVI），增强植被指数（EVI），叶面积指数（LAI）产品的各种空间表示。我们发现，没有一个单一的物候数据源能够准确地描述通量物候的年度模式。然而，对于NEE中的每一个过渡（例如，季节开始，过渡到净汇），来自一个或多个数据源的度量与这些复发事件的时间显著相关（P < 0.05）。任何指标都没有检测到11年以上NEE碳吸收期较长的轻微显著趋势，主要是因为没有任何指标可用于NEE数据的整个持续时间，并且NEE在代理数据可用的时间子集期间没有显示出显著和一致的趋势。我们的研究结果突出了每个物候数据源的相对优势和劣势，直接估计季节转换和年际变化趋势的落叶林碳通量物候。(C)2011 Elsevier B.V.保留所有权利。
There are currently numerous data sources available for estimating the timing of recurrent plant phenology transitions. We compared measurements from several phenology data sources to understand the relationship between phenology metrics derived from these data sources and the timing of seasonal transitions in net ecosystem exchange (NEE). We identified the timing of start, peak, end and the duration of the carbon uptake season, as well as the timing of the transitions from sink to source and source to sink using 11 years of NEE data from the University of Michigan Biological Station (UMBS). Using fitted logistic functions we identified proxy metrics for phenological transitions from the time series of Albedo, fraction of absorbed photosynthetically active radiation (fPAR), Plant Area Index (PAI), and MODIS normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and leaf area index (LAI) products of various spatial representations. We found that no single source of phenological data was able to accurately describe annual patterns of flux phenology. However, for each transition in NEE (e.g., start of season, transition to net sink), the metrics from one or more data sources were significantly (p < 0.05) correlated with the timing of these recurring events. A marginally significant trend toward a longer NEE carbon uptake period over 11 years was not detected by any of the metrics, primarily because none of the metrics were available for the full duration of the NEE data, and NEE did not show significant and consistent trends during the sub-sets of the time when proxy data were available. The results of our study highlight the relative strengths and weaknesses of each phenology data source for directly estimating seasonal transitions and interannual trends in carbon flux phenology of a deciduous forest. (C) 2011 Elsevier B.V. All rights reserved.