Improving the ability of the photochemical reflectance index to track canopy light use efficiency through differentiating sunlit and shaded leaves
Improving the ability of the photochemical reflectance index to track canopy light use efficiency through differentiating sunlit and shaded leaves
复制标题
通过区分阳光照射和阴影的叶子，提高光化学反射指数跟踪冠层光利用效率的能力
DOI：
10.1016/j.rse.2017.03.012
复制
发表时间：
2017-06
影响因子：
13.5
通讯作者：
Zhang Fangmin
中科院分区：
文献类型：
--
作者：
Zhang Qian;Chen Jing M.;Ju Weimin;Wang Huimin;Qiu Feng;Yang Fengting;Fan Weiliang;Huang Qing;Wang Ying-ping;Feng Yongkang;Wang Xiaojie;Zhang Fangmin
准确估计植物冠层的光利用效率（LUE）对于使用光利用效率模型计算总初级生产力（GPP）至关重要，并且对于校准区域和全球应用的基于过程的模型也很有用。利用光化学反射指数（PRI）遥感估算ue是一种很有前途的方法。然而，有内部（如颜料浓度）和外部因素（如环境条件和太阳目标视图几何）影响PRI信号。考虑到遮阳叶片和被遮阳叶片的反射率差异，用观测到的冠层反射率与叶片反射率之比来表示被遮阳叶片的观测分数，利用几何光学模型计算遮阳叶片的观测分数。因此，将一个冠层级的PRI观测值分为阳光下的PRI值和阴影下的PRI值，两叶冠层的PRI （PRIt）是这两个值分别被各自的阳光和阴影叶面积指数加权后的和。利用2013年4 - 9月在中国南方亚热带针叶林通量塔上获取的自动多角度PRI观测数据，对prtin估算冠层LUE的有效性进行了评估。在每15分钟的观测周期内，PRI在固定为（37°，47°，57°）或（42°，52°，62°）的四个视图天顶角上进行观测，并且在方位角范围内的瞬时太阳天顶角为45°至325°（从大地北开始）。在半小时和日的时间步长上，pritc都能有效地提高（>在r2中分别增加50%和35%）作为在给定时间间隔内多角度测量的算法平均值的大叶PRI上的塔通量测量所获得的LUE的代理能力。在7 ~ 9月的旱季，在日时间步长上，两叶情况下PRI与LUE的相关性明显强于大叶情况。pritt与LUE的相关性在7月份最强（R2= 0.785,p< 0.001）。PRItis对LUE在半小时时间步长上的光和中低干旱胁迫检测非常有效，而对严重的大气水和热胁迫检测无效，这可能是由于替代辐射能量汇，即光呼吸。总的来说，双叶方法很好地克服了一些干扰PRI信号的外部影响（例如太阳-目标-视野几何）。
Accurate estimation of light use efficiency (LUE) of plant canopies is essential for calculating gross primary productivity (GPP) using LUE models and is also useful for calibrating process-based models for regional and global applications. A promising method for estimating LUE is through remote sensing of the photochemical reflectance index (PRI). However, there are internal (e.g. pigment concentrations) and external factors (e.g. environmental conditions and sun-target-view geometry) that affect PRI signals. Considering the reflectance difference between sunlit and shaded leaves, the ratio of observed canopy reflectance to leaf reflectance is used to represent the observed fraction of sunlit leaves, and the observed fraction of shaded leaves is calculated with a geometrical optical model. Thus, a canopy-level PRI observation is separated into sunlit and shaded PRI values, and a two-leaf canopy PRI (PRIt) is calculated as sum of these two values weighted by their respective sunlit and shaded leaf area indices. The usefulness of PRItin assessing the canopy-level LUE is evaluated with automated multi-angle PRI observations acquired on a flux tower from April to September 2013 over a sub-tropical coniferous forest in southern China. In each 15-minute observation cycle, PRI is observed at four view zenith angles fixed at (37°, 47°, 57°) or (42°, 52°, 62°) and the instantaneous solar zenith angle in the azimuth angle range from 45° to 325° (from the geodetic north). In both the half-hourly and daily time steps, PRItcan effectively improve (> 50% and > 35% increases inR2, respectively) the ability as a proxy of LUE derived from the tower flux measurements over the big-leaf PRI taken as the arithmetic average of the multi-angle measurements in a given time interval. In the dry season from July to September, correlations of PRI with LUE at daily time steps are much stronger in the two-leaf case than in the big-leaf case. The correlation between PRItand LUE is the strongest (R2= 0.785,p< 0.001) in July. PRItis very effective in detecting the light and low-moderate drought stress on LUE at half-hourly time steps, while ineffective in detecting severe atmospheric water and heat stress, which is probably due to alternative radiative energy sink, i.e. photorespiration. Overall, the two-leaf approach well overcomes some external effects (e.g. sun-target-view geometry) that interfere with PRI signals.
登录
查看更多内容
影响因子：
6.2
作者：
X. Wen;Guirui Yu;Xiaomin Sun;Qingkang Li;Yunfen Liu;Leiming Zhang;C. Ren;Yu-ling Fu;Zheng-Quan Li
通讯作者：
X. Wen;Guirui Yu;Xiaomin Sun;Qingkang Li;Yunfen Liu;Leiming Zhang;C. Ren;Yu-ling Fu;Zheng-Quan Li
影响因子：
3.4
作者：
M. Spanner;L. Pierce;D. Peterson;S. Running
通讯作者：
M. Spanner;L. Pierce;D. Peterson;S. Running
DOI：
10.1111/nph.13251
发表时间：
2015-04
期刊：
The New phytologist
影响因子：
--
作者：
Christopher Y. S. Wong;J. Gamon
通讯作者：
Christopher Y. S. Wong;J. Gamon
DOI：
10.1111/nph.13159
发表时间：
2015-04
期刊：
The New phytologist
影响因子：
--
作者：
Christopher Y. S. Wong;J. Gamon
通讯作者：
Christopher Y. S. Wong;J. Gamon
影响因子：
56.9
作者：
Beer, Christian;Reichstein, Markus;Papale, Dario
通讯作者：
Papale, Dario