Study of the Effect of Distance to Urbanization and Tree Age on Canopy Size of Tree

<p>The data presented displays the correlation and effect that age and distance from urbanization (explanatory variables) has on the canopy size of Julgans nigra, more commonly known as eastern black walnut, in a forest habitat (response variable). The data was collected over two days, the first being October 19th 2015. The study was performed in the Saywell Woodlot on the York University Campus between 2:30 and 4:30; the temperature was 15 degrees Celsius with strong winds up to 29km/h and primarily sunny conditions. The second day of data collection was October 26th 2015. This also occurred in the Saywell Woodlot on the York University Campus between 2:30 and 4:00; the temperature was 10 degrees Celsius with weak winds up to 8km/h and sunny conditions.</p> <p>Upon initial inspection of the woodlot, the lab group decided to change the target spices, which was originally maple trees, simply due to their low abundance. Eastern black walnut was chosen as a replacement for its high abundance in woodlot as well as being a species of tree which was very easy to distinguish. Although the 55 sampled trees within the woodlot were randomly selected, the lab group split up into pairs of two, which not only increased the speed of sampling, but ensured that over the two lab days, trees from the varying conditions of the woodlot would be sampled.</p> <p>Using a 30 metre transect the distance, in metres, of a selected tree from the edge of the woodlot was measured. If the distance was longer than 30 metres, multiple measurements were taken, with the sum of the measurements representing the distance for that given tree. This measurement was used to represent the distance of an individual to urbanization when related to the experimental design. Using the 30 metre transect, the diameter at breast height (DBH) of each of the tree trunks was measured; breast height was defined as 1.50 metres above the ground. This measurement was used to represent age of an individual when related to the experimental design. The measurement of canopy coverage did not use a tool, and was simply a qualitative, observation. It was measured by standing directly beside the trunk of the tree, looking upwards, and observing how much sky was visible between the tree's leaves and branches. If the tree had already lost the majority of its leaves, canopy size was estimated by the number of branches on the tree and leaves surrounding the base of the tree. Michael Chu, Diana Pik, and Aisha Choudhry helped with obtaining the field data.