Studying the Effect of Tree Density and Light Availability on the Leaf Length of Adult Maple Trees

Four researchers collected data by examining adult maple trees from the grassland and woodlot regions of Danby Woods at York University. Twenty adult maple trees were studied on October 15, 2014 from the grassland. It was a cloudy day with isolated showers. Twenty adult maple trees were also studied on October 22, 2014 from the woodlot. It was a windy day with clear skies. The first tree sample was obtained in a pseudorandom manner; the adult maple tree that was closest to the centre of the grassland (or woodlot) was studied. Trees around this central tree were then observed. Then, the percent of open space was determined by making a square with the thumb and index fingers of both hands and holding this square up to the adult tree whose foliage had to be measured. The researchers estimated how much of the square was covered by the canopy, as a percentage and subtracted this value from 100%. This value represents the percent of light that is allowed to pass through the foliage to the ground. Next, the researchers selected three adult trees (of any species) that were closest to the adult maple tree being studied. The distance from the tree of interest to each of the three trees was measured using a transect and was recorded in metres to the nearest hundredth. The average of the three distances was taken. The units, metres, retained. An adult tree is one that is taller than twice the height of the average researcher. The researchers obtained three leaves from the tree of interest. Each leaf was plucked from a different branch of the maple tree and was not taken from the ground. The length of each leaf was measured using a 15-cm ruler to the nearest tenth of a centimetre. The leaf was measured from its absolute tip to the beginning of its stem formation. The average leaf length was calculated and recorded in centimetres. This procedure was performed for twenty adult maple trees in the grassland and twenty adult maple trees in the woodlot. With each tree being studied, from tree one to tree twenty, the researchers moved from the centre of the woodlot (or grassland) to the outskirts of it.