The relationship between carbon dioxide uptake and canopy colour from two camera systems in a deciduous forest in southern England
The relationship between carbon dioxide uptake and canopy colour from two camera systems in a deciduous forest in southern England
复制标题
DOI：
10.1111/1365-2435.12026
复制
发表时间：
2012-12
影响因子：
5.2
通讯作者：
Toshie Mizunuma;M. Wilkinson;E. L. Eaton;Maurizio Mencuccini;J. Morison;J. Grace
中科院分区：
文献类型：
--
作者：
Toshie Mizunuma;M. Wilkinson;E. L. Eaton;Maurizio Mencuccini;J. Morison;J. Grace
摘要1.使用涡度相关（EC）方法测量二氧化碳通量有助于研究人员开发生态系统碳平衡模型。然而，由于物候变化和可能的非生物/生物胁迫深刻影响树木的功能，使可靠的预测碳通量是不简单的。2.为了评估冠层物候状态对CO2通量的影响，我们安装了两个不同的数码相机系统在不同的视角（一个室外网络摄像头与近水平的视图和一个商业的“鱼眼”数码相机与向下的视图）在英格兰南部的通量测量塔，并跟踪冠层的视觉变化，在这个橡树为主（栎属）。两个生长季节的森林。3.摄像机白色平衡设置的变化大大影响了网络摄像头图像的质量。然而，在这两年，个别树木和整体树冠开始变绿和衰老的时间是可以检测到的。从半球形透镜的向下图像评估的绿化日期比从水平视图的图像早20.5天，因为地面植被的发展（在水平视图中不可见）。4.在2010年后期的空气霜冻的影响是显而易见的，在冠层的绿色，这些导致每日总初级生产力（GPP）的减少。摄像机记录了各个树冠之间的差异，显示了它们对晚霜的不同反应。5.这项工作的一个主要新发现是GPP和色调之间的密切关系，这比GPP和NDVI之间的关系更强。
Summary 1. Carbon dioxide flux measurements using the eddy covariance (EC) methodology have helped researchers to develop models of ecosystem carbon balance. However, making reliable predictions of carbon fluxes is not straightforward due to phenological changes and possible abiotic/biotic stresses that profoundly influence tree functioning. 2. To assess the influence of canopy phenological state on CO2 flux, we installed two different digital camera systems at different viewing angles (an outdoor webcam with a near-horizontal view and a commercial ‘fisheye’ digital camera with a downward view) on a flux measurement tower in southern England and tracked the visual change of the canopy in this oak-dominated (Quercus robur L.) forest over two growing seasons. 3. Changes in the setting of the camera’s white balance substantially affected the quality of the webcam images. However, the timing of the onset of greening and senescence was, nevertheless, detectable for the individual trees as well as the overall canopy for both years. The greening-up date assessed from the downward images from a hemispherical lens was ∼5 days earlier than from the horizontal-view images, because of ground vegetation development (not visible in the horizontal view). 4. The effects of a late air frost in 2010 were evident in the canopy greenness, and these led to reductions in daily gross primary productivity (GPP). The cameras recorded differences between individual tree crowns, showing their different responses to the late frost. 5. A major new finding from this work is the strong relationship between GPP and Hue, which was stronger than the relationship between GPP and NDVI.