Performance metrics for street and park trees
JOURNAL OF FORESTRY | 2018
Tree performance in urban forests is difficult to evaluate, because there is not a unified metric to determine the highest performers. This study set out to evaluate tree performance metrics. Size metrics included diameter at breast height and canopy projection area, and composite metrics looked at growth rate ratio (BRATIO) and a tree performance index (TPI). The BRATIO and TPI incorporated size and growth rate and were developed as quantitative metrics for evaluation of urban trees. Study results suggest that tree performance evaluated with size metrics versus the composite metrics may prioritize faster growth over sustained longer-term growth.
Volunteer- and researcher-collected urban tree inventory data
INTERNATIONAL SOCIETY OF ARBORICULTURE | 2018
To assess the potential impact of emerald ash borer on a Minnesota, U.S., community forests, communities were selected in 2009 and 2011 to complete tree surveys or inventories. Trained volunteers in each community were used to identify, measure, and assess community trees. Training methods, technical assistance, and measurement tools utilized were updated between 2009 and 2011 based on input from community volunteers and university training staff. To assess volunteer efficacy and the effect of updated training protocols on data quality, comparisons between volunteer-collected data and university-collected data were analyzed for agreement in genus and species identification, tree measurements, and condition rating for a subsample of trees in each community. The study indicates that decisions to use volunteer-collected data should incorporate appropriate levels of training and tool sophistication for the level of specificity required for a project.