Testing a New Approach to Quantify Growth Responses to Pruning Among Three TemperateTree Species

摘要

In settled areas, electrical line safety is maintained by pruning encroaching trees. Identifying key predictors of branch elongation growth rate following pruning would assist in developing predictive models and optimizing pruning cycles. However, measuring branches in trees near electrical lines is complex and challenging. This paper describes an innovative approach using a handheld laser rangefinder to safely and accurately estimate growth from the ground. In-tree and ground-based laser measurements were highly correlated. This was followed by testing for correlations between branch growth response over a number of years after pruning and many biotic and abiotic factors for Fraxinus pennsylvanica, Acer platanoides, and Acer saccharinum, in the city of Montréal, Canada. In a sample of 59 trees, A. saccharinum had the greatest branch growth, followed by F. pennsylvanica, and finally A. platanoides. Branch growth increased following pruning and subsequently strongly declined, with A. platanoides declining the fastest. Branch inclination angle was positively correlated with growth rate for two species, but not for A. saccharinum. Among the types of pruning used, directional pruning techniques resulted in the least branch regrowth rate. Tree diameter was weakly related to branch growth rates. These results suggest that while growth conditions for street trees may be perceived as homogenous, there is substantial variation in branch growth response. This variation may be related to pruning history, or unmeasured abiotic or biotic variables. Estimating pruning cycle duration is a complex task and further work is needed to develop a predictive model for more accurate estimation of return times.