Lab 4 Data - Tree Growth

Authors: Kamil Adamczewski, Joelle Brooker, Brittney Jorisch, and Karin Yosefi

On Thursday, October 15th, 2015, at 3:00 pm and on Thursday, October 22nd, 2015, at 3:10 pm, 50 different individuals of Maple trees in the Danby Woodlots at the north-east side of York University were randomly selected and observed for 3 different variables. 

The first was the diameter at breast height (dbh) of the Maple tree as an indication of tree growth. This was determined by using a transect and measuring the diameter of the trunk of the Maple tree starting at the zero mark and at a constant breast height of approximately 1.6 metres. This was recorded in centimeters. 

The second was the percentage of canopy coverage surrounding the randomly selected Maple tree being observed as an indication if the amount of light the Maple tree is receiving. This was approximated by creating a square with the thumb and forefinger of each hand and raising the square up towards the canopy directly surrounding the Maple tree. It was then determined how much of the total square was being covered by the canopy. It was measured as a percentage out of 100. 0 being no coverage at all and 100 being complete coverage of the square. Canopy of all tree species in the vicinity was included in this measurement. 

The third variable was abundance of other plant organisms surrounding the Maple tree found within a 3 by 3 metre quadrat as an indication of the density of life around the Maple tree. This was approximated by using 2 transects measured at 3 metres and placing them to create one corner of the quadrat, the other corner was estimated by using the end points of the laid out transects. The Maple tree being oberved was roughly in the centre of the quadrat. Observation was done by walking within the quadrat and noting the quantity of any other plant organisms within the quadrat. This quantity did not include any dead organisms, but did include grasses and small shoots found.

The purpose of these observations was to determine if there is a relationship between tree growth, light and density.

 The data was collected in the Danby Woodlot, at the north-east side of York University, Keele campus. The Danby Woodlot is a fairly dense area of various species of trees including Maple and Oak trees. There is a slight amount of dead or broken trees and branches littering the ground. On the first date, October 15th 2015, the temperature was 11 degrees Celcius, and it was very windy and cloudy with mild percipitation. On the second date, October22nd 2015, the temperature was 13 degrees Celcius, and it was sunny with a few clouds and slightly windy. The sample size was 50 Maple trees.