Trade-off between reproduction and growth in American Buckthorn species in woodlots on York University campus

The study site chosen for this experiment was the woodlots on the eastern end of York University campus near Chimneystack Road. Data was collected from 3:00-4:45p.m on Friday, October 17, 2014 (mild wind, cloudy and at about 15˚C) and Friday, October 24, 2014 (sunny, not windy and at about 15˚C). The sampling method used was block sampling – measured the distance between the base of one sample to the base of the other sample using a transect tape. To maintain consistency only trees with diameter at breast height of 13cm and greater (to avoid measuring saplings) were measured and recorded. The dbh was measured using a transect tape. To further maintain consistency all branches that were sampled on each tree were approximately 50cm in length (measured using a measuring tape).

The purpose of this investigation was to see if there is a trade-off between reproduction and growth in the American Buckthorn plant species. In order to observe any correlations we sampled 50 trees, and on each tree three branches were sampled. The total amount of fruits on each branch were counted and recorded. The average number of fruits per branch was then calculated ((branch1 + branch2 + branch3) /3). On each branch three leaves near the terminal end were picked and the diagonal dimensions were measured and recorded using a measuring tape. These dimensions were used to calculate the approximate surface area of the rhombus shaped leaves (SA= ((diagonal x diagonal)/2). The average surface area was then calculated and recorded ((SA1 + SA2…+SA9)/9). A fruit was picked near each leaf on each branch and the diameter was measured and recorded using a measuring tape. The average fruit diameter was then calculated and recorded ((d1+ d2…+ d9)/9). In order to observe growth in the species the height of each tree was approximated into one of three categories: less than 10ft, 10-20ft, or greater than 20ft.

The results from this dataset generally showed: taller trees had larger leaves and had less and smaller fruits whereas, smaller trees had smaller leaves but bared more and larger fruits. This study also provided as a way to gain experience in field sampling techniques with plants and experimental design.

Study members were Lilach Dahoah-Halevi, Cait Carew, and Sija Srikanthan.