Municipalities use tree inventories for managing the urban forests that are under their jurisdiction. Imagine the tree inventories for a city like New York City. Over a 10-year period of time, New York City plans to plant 220,000 street trees, 530,000 trees in public spaces and 250,000 trees with public partners for a total of one million new trees. The goal is not merely planting new trees — NYC plans to plant and care for these trees across its five boroughs over the decade.

In order to plant and care for these trees, someone must know the trees, the planting sites and the management of the planting and aftercare of those trees. Otherwise, the million tree goal is, at best, a shot in the dark and, at worst, a waste of a lot of effort, creating a new maintenance headache. For both large and small municipalities, trees are inventoried so they can be managed.

Tree inventories typically record information on each tree, such as specific location, species, size or age, condition and risk. Among other things, this information allows planners to pursue the holy grail of municipal arboriculture — a varied tree inventory with diversity of age and species alike. Diversity is prized because in the case of age, all the trees will not reach the end of their lifespan simultaneously, or in the case of species, all the trees will not be a specific pestilence that uniformly decimates a specific species of trees. The worst case scenario in a municipal arborist setting would be to have to remove and replace all of a city’s trees at once.

What about homeowners? Should they have a tree inventory? The answer is yes. For homeowners, having a tree inventory would increase their knowledge of their landscape, for example, it will tell them when they should expect the blooms. It would also tell them when they should expect to rake the leaves. If, for example, their ash or hemlock trees will soon die due to the Emerald Ash Borer or the Wooly Adelgid, how long until they have to budget for removal? Or, if they have landscape trees planted alongside their swimming pool, will these trees eventually steal all the sun? And is that big old tree by the house a risk to their health if it falls? These are all other questions that the tree inventory will help homeowners answer.

Homeowners would also want to know if the reason their lawn always suffers under their maple is because of a problem with the lawn or because the tree is a Norway maple and secretes substances to reduce competition from lawns. Homeowners may want to know if they have valuable timber in their woodlot or if their maples can be tapped to make homemade syrup.

Bottom line: use an inventory and get to know your trees.

Joshua Arp is an ISA-certified Municipal Specialist, a Clarks Summit Tree Commissioner and an operator of a landscape maintenance business. He can be reached at