DBH, Canopy Coverage, and Distance from Tree to Sapling of Silver Maple Trees at York University

Data from 20 random Acer saccharinum (Silver Maple) trees were collected from York University's woodlot, Danby Woods. Four traits were measured: diameter at breast height (dbh) of tree, canopy coverage, distance to sapling, and dbh of sapling. Dbh was measured in cm and rounded to the nearest whole cm using a 20m transect tape measure. Canopy coverage was calculated as the percentage of sky present subtracted from 100% determined by the researcher by making a square with index fingers and thumbs; holding it up above researcher's head toward canopy and looking through the square. Distance to sapling was measured from the outermost point of the tree closest to the sapling to the outermost point of the sapling closest to the tree using a 20 m transect tape measure held along the ground. Saplings were defined in this experiment as any Silver Maple tree shorter than or equal to twice the height of the researcher.

本研究从约克大学丹比林地（Danby Woods）的样地中随机采集了20株银枫（Acer saccharinum）的相关数据。共测定四项性状：林木胸径（diameter at breast height，简称dbh）、冠层覆盖度、目标林木与幼树间距以及幼树胸径。胸径以厘米为单位，采用20米样带卷尺进行测量，结果四舍五入至最接近的整厘米数值。冠层覆盖度通过如下方式计算：研究者以食指与拇指搭建正方形观测框，将其举过头顶对准冠层并透过方框观测天空占比，最终以100%减去天空占比得到冠层覆盖度百分比。目标林木与幼树间距以沿地面铺设的20米样带卷尺测量，测量起点为目标林木最靠近幼树的外边缘点，终点为幼树最靠近该林木的外边缘点。本实验中将幼树定义为高度不超过研究者身高两倍的银枫植株。