A reproduction and plant development trade-off in American Buckthorn species

The objective of this experiment was to determine a trade-off relationship between the reproductive and growth mechanisms of the American Buckthorn species found in the woodlot on The Chimneystack Road, East of the York University campus. This was done by examining the size and abundance of this species’ fruits, leaves, and its height.

On October 17th and 24th from 3 – 4:45pm, the sampling of the American Buckthorn trees took place. It was cloudy and windy (wind was strong enough to move small branches) on the first sampling trial on October 17th. The weather condition of the second sampling trial on October 24th was more ideal since it was mostly sunny with little wind. However, due to the weather condition of the previous week, a large portion of leaves and fruits had fallen, thus making it harder to evaluate the trees.

The sampling procedure began with an initial tree at an edge of the woodlot (distance from tree to tree was recorded as 0 meters). Three accessible branches of approximately 50 cm were used for the sampling. The total amount of fruits for each chosen branch was counted by the researchers. The average amount of fruits was calculated by taking the mean of the observed number of fruits for the branches located on the same tree. Three leaves were removed from the terminal end of each branch. The lengths and widths of the leaves were measured in centimeters using a measuring tape. The average leaf area was later determined by calculating the area of each sampled leaf through the following formula: area = (length*width)/2, and finding the mean for those scores. Similarly, three fruits were removed from each branch. The fruits closest to each sampled leaf were picked. Their diameter was measured in centimeters using a measuring tape. The average diameter was calculated by finding the mean for all the diameter values for a specific tree. The height of the tree was estimated by the researchers and the trees were categorized as either less than 3 meters tall, between 3 to 6 meters tall, or more than 6 meters tall. The DBH of each tree was measured using a measuring tape. Trees with a DBH smaller than 13 cm were not sampled to avoid using underdeveloped saplings. After a tree was sampled the next closest tree would be sampled. The distance between the previous and the following tree was measured using a transect tape.

All observations and measurements were done by a group of researchers, including Lilach Dahoah-Halevi, Nitharsija Srikathan, and Cait Carew.