Observations from the field

Heavily suppressed trees! – This has been a common observation during our field work this year. Trees being suppressed by their neighbours resulting in poor crown form, poor leaf area, over extension in one of the cardinal directions, and excessive deadwood in the crown. Much more careful consideration must be given to SPACING when establishing new trees. If the tree species that is chosen has a broad spreading crown and a mature tree height of >25m then a minimum of 12m should be allowed for the tree to mature unobstructed. In urban sites where space is generally restricted the focus should be on establishing a few good quality trees rather than many poor-quality trees. Less is more!!! 

Tree ties – There have been many cases of trees being choked by trees ties. Tree stems being fixed to wooden cross arms with rubber ties and nails is not good practice. Who is responsible for removing the rubber band when the tree is established?? No one!!! This results in unnecessary tree loss in urban environments. Replacement will most likely not happen. New ways of supporting trees after planting must be explored. Materials that break down in sunlight over an extended period should be favored. Below is an example of good tree support practice taken from Himelick & Watson, The Practical Science of Planting Trees.