ABoVE: White Spruce Photosynthetic and Leaf Traits, Alaska and New York, 2017

This dataset provides measurements of gas exchange (light response curves, Kok curves and ACi curves), leaf traits (carbon, nitrogen, and specific leaf area), leaf pigments (Chlorophyll a, Chlorophyll b and Carotenoids), the photochemical reflectance index (PRI), and average photosynthetic photon flux density as collected from hemispherical photographs. Data were collected on white spruce trees (Picea glauca (Moench) Voss) growing at the northern edge of the species' distribution in Alaska and at the southern edge of the species' distribution in Black Rock Forest (BRF), New York. Measurements were taken at high and low canopy positions on each tree at both sites during the 2017 growing season (2017-06-19 to 2017-07-20). Gas exchange, leaf trait, pigment and spectral measurements were obtained using a portable photosynthesis system (LI-6800, LI-COR, Lincoln, NE). Photochemical reflectance index was determined using a spectroradiometer, and hemispherical photographs were taken with a digital camera. These data were collected to better understand how vertical canopy gradients in photosynthetic physiology change from the southernmost to the northernmost range extremes of white spruce. The data are provided in comma-separated value (CSV) format.

本数据集提供了气体交换（光响应曲线、Kok曲线和ACi曲线）、叶片性状（碳、氮及比叶面积）、叶片色素（叶绿素a、叶绿素b及类胡萝卜素）、光化学反射率指数（PRI）以及平均光合光通量密度的测量值，这些数据均来源于半球形摄影。数据收集于阿拉斯加物种分布北缘的雪松（Picea glauca (Moench) Voss）和纽约布莱克洛克森林（BRF）物种分布南缘的树木。在2017年生长季节（2017年6月19日至2017年7月20日）期间，对每个地点的树木高、低冠层位置进行了测量。气体交换、叶片性状、色素和光谱测量使用便携式光合作用系统（LI-6800，LI-COR，林肯，内布拉斯加州）进行。光化学反射率指数通过光谱辐射计测定，半球形摄影则使用数码相机完成。收集这些数据的目的是为了深入理解白松从最南端至最北端的分布极限处，其光合生理学垂直冠层梯度的变化。数据以逗号分隔值（CSV）格式提供。