A Study on the Relative Distance Between Adult Trees and Their Diameter at Breast Height.

Metadata: Distance to Next Tree: To measure the distance between adult tees (in metres), a transect measuring tape was used and the center of one tree trunk was measured to the center of another tree’s tree trunk. (Numerical variable) The distances between trees varied from 2.1 to 7.2m.Diameter at Breast Height: A measuring tape was used and the diameter was measured against the tree trunk at approximately my chest height around 158 cm. (Numerical Variable) The diameters of the trees at breast height varied from 0.13m to 0.42m. Condition of Tree: This was determined based on a scale; 0=dead, 1=living, and 2=huge green canopy. (Response variable, Categorical)Methods: A 30m transect measuring tape was used to measure the distance (in metres) between two adult trees that were encountered and the data was recorded onto a table. Adult trees were selected if they lied on a straight line from the edge of the forest towards the centre. To meet the conditions of an adult tree, the tree had to be at least 0.1m in diameter and at least double my height (188cm). Furthermore, to measure the diameter of the trees at breast height, each tree was measured at approximately my chest height of 158cm using a measuring tape. To measure the distance between each tree, we measured from the centre of the first tree to the centre of the next tree. The condition of the tree was determined by the lab group’s observations; each person in the group determined what condition the tree was in on a scale of 0-2. 0 represented the tree being dead and 2 meant the tree was healthy with a lush green canopy. In total, 10 trees were observed to compile the data from this woodlot. Study Site Description: A field study was conducted at the Danby Woodlot located on York University’s campus near Keele Street and York Boulevard in Toronto, Ontario on September 22nd 2016, around 2:30 pm. The temperature was around 27 degrees Celsius, with sun and cloud, and a few hours into the study, a few raindrops began to fall. The woodlot was covered with lots of broken branches, leaves, soil, and was shady because of the large canopy trees. Hypothesis: The distance between the adult trees and the diameter at breast height will both have an effect on the tree’s growth conditions. The greater the distance between the trees, lack of competition results in greater nutrition and resources such as sunlight and space. Trees that are able to grow big, that have big trunks and have a large lush green canopy will be able to better, capture sunlight and resources compared to smaller trees. Prediction 1: The greater the diameter of the tree at breast height, the worse the condition will be of the nearby tree. Prediction 2: Trees that are farther apart from another will have healthier growing conditions. Prediction 3: The thicker the trunk of the tree, the tree will be healthier (example: lush canopy). Group Members: Keerthana Balachandran, Matthew Chiang, Andrew Nguyen, and Kobina Vijayakumar

元数据：
1. 相邻树木间距：为测量成年树木间距（单位：米），采用样带卷尺进行测量，测量起点为一棵树干的中心，终点为另一棵树干的中心。该指标为数值变量，树木间距范围为2.1~7.2米。
2. 胸径（Diameter at Breast Height）：采用卷尺在约测量者胸高（约158厘米）处环绕树干测量直径。该指标为数值变量，树木胸径范围为0.13~0.42米。
3. 树木健康状况：基于分级标准判定：0代表枯树，1代表存活树木，2代表冠层茂密的健壮树木。该指标为分类响应变量。

研究方法：采用30米样带卷尺对沿途偶遇的成年树木间距（单位：米）进行测量，并将数据记录至表格中。成年树木的选取需满足两个条件：其一，树木位于从森林边缘向林内延伸的直线样带上；其二，胸径至少0.1米，且树高至少为测量者身高（188厘米）的两倍。胸径测量统一在约158厘米的胸高位置，使用卷尺环绕树干完成。树木间距测量为从第一棵树的树干中心至下一棵树的树干中心。树木健康状况由实验小组共同观测判定：小组成员按照0~2的分级标准分别评估树木状况，0表示树木枯亡，2代表冠层茂密、生长健壮的健康个体。本次林分调查共观测记录10棵树木的数据。

研究样地概况：本野外研究于2016年9月22日下午约2:30，在加拿大多伦多安大略省基尔街与约克大道附近的约克大学校园内Danby林分开展。当日气温约27摄氏度，天气为晴间多云，研究开展数小时后开始零星降雨。该林分内散落大量断枝、落叶与土壤，高大的冠层树木使得林内光照较弱，整体较为荫蔽。

研究假设：成年树木间距与胸径均会对树木生长状况产生影响。树木间距越大，种间竞争程度越低，树木可获取的营养、光照与空间等资源越多。相较于小型树木，树干粗壮、冠层茂密的健壮树木能够更高效地捕获光照与生长资源。

预测1：树木胸径越大，其邻近树木的生长状况越差。
预测2：树木间距越远，其生长健康状况越好。
预测3：树干越粗壮，树木的健康状况越好（例如冠层茂密）。

小组成员：Keerthana Balachandran、Matthew Chiang、Andrew Nguyen、Kobina Vijayakumar