What You Need For a Successful Urban Treepit Design:
The benefits that healthy urban trees provide to the environment are significant, but the environmental conditions in urban spaces can often be challenging for their establishment and long-term survival.
In order to provide urban trees with the best chance of survival, it is important to consider the conditions of soil, climate, and water availability that trees face when they are planted in towns and cities. The correct design and installation of tree pits will mitigate the negative effects of the urban environment.
There are several key factors to consider, including root volume availability. The following soil volumes at a minimum are recommended for healthy tree growth:
Small tree 5-15 m³
Medium tree 20-40 m³
Large tree 50+ m³
If in case this amount of space is not available, tree establishment can still happen provided that great care is taken with regard to species selection and root management. In all cases, the deployment of structural root cells can help to prevent soil compaction and ensure that the available rooting volume is fully utilized.
This is very important if the tree is to be located next to a road or another engineered structure, as the soil structure requirements for hard surfaces capable of sustaining large weights are diametrically opposed to those of a healthy tree root network.
Aside from providing sufficient volume for growth for tree roots, it needs to be appropriately directed to ensure that they do not damage surrounding surfaces or underground structures. Paved surfaces and utilities are particularly vulnerable to tree root damage and various types of root management products can be specified depending upon the item that requires protection.
For example, if a tree pit is to be located amidst a continually paved surface then the tree roots will need to be managed downwards by at least 300mm or the depth of the pavement structure to remove the possibility of paving heave.
Next, we’ll discuss more about proper irrigation, drainage and aeration to raise a strong tree network.