Assessing Maple Species in The Annex Neighbourhood from 2011 to 2022

Abstract

The Annex neighbourhood is an old neighbourhood located in downtown Toronto, Ontario. Due to its early history in land development, it started with tree planting back in the 1900s. The first tree inventory for the Annex was done from 2011 to 2014. The inventory project was conducted by volunteers and students from the University of Toronto with support from the Neighbourwoods© program. In 2022, the community started reassessing trees sampled in 2011. The objectives of this study were to understand the performance of the three most abundant maple species, Manitoba maple (Acer negundo), Norway maple (Acer platanoides), and silver maple (Acer saccharinum), in the Annex by analyzing the changes in their growth from 2011 to 2022. The other objective was to assess their health condition by analyzing three health indicators, rot/cavity on the trunk, crown defoliation, and branch poor attachment. The results show that Manitoba and silver maples have significantly faster growth rates than Norway maple in the Annex. Norway maple demonstrates a comparatively inferior performance when compared to Manitoba and silver maples. Notably, Norway maple exhibits a significantly slower diameter at breast height (DBH) growth rate than silver maple. While the defect of rot/cavity has a lesser impact on Norway maple compared to Manitoba and silver maples, crown defoliation and poor branch attachment emerge as the two pressing tree health issues that require attention. In 2022, there is an increase in the number of Norway maple trees exhibiting higher severity levels of these defects compared to the data collected in 2011, emphasizing the need for prompt resolution.