Percent canopy coverage, diameter at breast height and distance between maple trees in Danby woodlot, York University

On Wednesday September 23rd, 2015, lab 2 of BIOL2050 was performed in Danby Woodlot, located at York University's Keele campus. Dataset 4 was compiled from 4:30 PM to 5:30 PM. The woodlot had a desnse concentration of trees, shading the area. Weather was comprised of clear skies, a light breeze and a temperature of roughly 22 degrees celsius. In total, 10 adult maple trees (having a height of 12 feet or greater) and 10 maple tree saplings (height is less than 12 feet) were randomly sampled and measurements were made using a transect. All measurements were initially made in feet but were converted to meters in the data set.The purpose of the lab was to practice field training with plants but was also able to explore the effects of canopy density on tree sapling growth specificaly with dataset 4. Distance from randomly selected adult maple trees to the nearest maple tree sapling were measured by placing the end of a transect to the surface of the adult tree then extending the transect to the surface of the nearest sapling (ensuring that the transect tape was parallel to the ground). Measurements were observed visually and recorded. Diameter at breast height of adult and saplings were measured by the same group member (breast height of 1.5m) during each replicate to ensure consistency. Transect tape was held horizontally at breast height and a group member estimated the length of the tree along the transect tape by observation. Percent canopy coverage was estimated by standing directly below the adult samples of interest and holding up hands to make a hollow square in the sky. Specifically, on each hand, the index and thumb created an "L" shape. The thumb of one hand needed to touch the index of the other hand. The percentage of canopy coverage was estimated by observing how much canopy was contained in the the hollow square of your hands against the sky.

2015年9月23日周三，约克大学基尔校区丹比林地（Danby Woodlot）内开展了BIOL2050课程的第2次实验。数据集4的采集时段为当日16:30至17:30。该林地树木分布密集，区域被林木遮阴。当日天气晴朗，伴随微风，气温约22摄氏度。研究团队随机选取10株高度≥12英尺的成年枫树，以及10株高度＜12英尺的枫树幼树，采用样带法（transect）开展野外测量。所有初始测量单位均为英尺，后续在数据集中统一转换为米。本次实验的核心目标为开展植物学野外实践训练，同时借助数据集4专门探究林冠密度对枫树幼树生长的影响。具体测量细节如下：其一，株间距离测量：以随机选取的成年枫树树干表面为样带起点，将样带沿与地面平行的方向延伸至最近的枫树幼树树干表面，测量二者之间的直线距离，所有测量均通过目视完成并记录。其二，胸径（diameter at breast height）测量：由同一名小组成员在各重复测量中，于1.5米胸高位置测量成年树与幼树的胸径，以保证测量一致性；测量时将样带卷尺水平固定于胸高位置，由组员通过目视估算树木沿样带的延伸长度。其三，林冠覆盖率估算：在待测成年枫树正下方站立，双手在天空中摆出中空方形框：双手的食指与拇指分别构成"L"形，一手拇指与另一手食指相接触，通过观察该中空方形框内可见的林冠占比，估算样地的林冠覆盖率。