Half Tree Ring Small - Cement: A tree ring creates a defined border around the base of a tree and can really help protect it from physical damage as well as ensure that the root ball of a new tree has access to the water and nutrients we supply it with. The way they are designed and constructed can affect the tree's health and growth.They are from cement and therefore durable and easy to maintain. Concrete cobbles can be added as it provides a simple way to enhance your outdoor space while making your mowing and trimming chores easier.