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，区域整体处于树荫遮蔽之下。当日天气晴朗，伴有微风，气温约为22摄氏度。

研究人员共随机选取10株高度≥12英尺的成年枫树，以及10株高度＜12英尺的枫树苗，采用样带（transect）法开展测量。所有原始测量单位均为英尺，后在本数据集中转换为米。本次实验旨在开展植物野外实践训练，同时借助数据集4专门探究冠层密度对枫树苗生长的影响。

研究人员测量了随机选取的成年枫树与最近的枫树苗之间的距离：将样带卷尺的一端贴合至成年枫树的树干表面，随后将样带延伸至最近枫树苗的树干表面，全程确保样带与地面保持平行。测量结果通过目视读取并记录。

为保证测量一致性，每组重复测量均由同一名实验人员完成成年树与枫树苗的胸径（Diameter at Breast Height）测量：将样带水平固定于1.5米的胸高位置，由实验人员通过目视估算树干沿样带的长度。

冠层覆盖率的估算方式如下：站在目标成年样树的正下方，双手在天空中搭建一个中空的方形观测框：双手的食指与拇指分别构成“L”形，一手的拇指需与另一手的食指相贴合。通过观察天空中双手搭建的中空方形框内可见的冠层占比，即可估算冠层覆盖率。