White spruce (Picea glauca) densities at Brooks Range treelines, Alaska (2019-2022)

Measurements of treeline white (Picea glauca) and black (P. mariana) spruce abundance during 2019, 2020, 2021 and 2022 as sampled within n = 695 5-meter (m) radius plots (area = 78.5 square meters), each centered on a selected white spruce adult called "Focal Tree". Measurements included height of stems between 0.5 and 1.4 m tall and diameter at 1.4 m for individuals taller than 1.4 m. Those individuals taller than 1.4 m tall were also stem mapped in polar coordinates with r = distance and theta as magnetic direction from a focal center white spruce tree. The purpose of this dataset was to examine spatial variation in treeline white spruce densities and basal area across the Brooks Range and in relation to local microclimates. It also provides a baseline for future stem mapping to determine changes in abundance.

本数据集记录了2019至2022年间林线白云杉（Picea glauca）与黑云杉（P. mariana）的种群丰度。采样覆盖695个半径5米、面积78.5平方米的圆形样地，每个样地均以一株选定的成年白云杉作为中心目标树（"Focal Tree"）。本次测量包含两类指标：一是高度介于0.5至1.4米之间的茎干高度；二是高度超过1.4米的个体在1.4米处的茎干直径。对于高度超过1.4米的个体，研究人员还通过极坐标对其茎干进行定位绘图，其中r代表至中心目标树的直线距离，θ代表磁方位角。本数据集旨在探究布鲁克斯山脉（Brooks Range）林线白云杉的种群密度与断面积的空间变异特征，及其与局地微气候的关联；同时也可为未来通过茎干定位绘图评估种群丰度变化提供基准参照。