The purpose of a tree inventory is to render a complete description of the overall age and condition of a tree population. Whether those trees are owned and managed by a homeowners association, large corporation or a government agency, a tree inventory will help with long-range tree pruning and root-pruning schedules or tree removal and replacement programs. Tree inventories will also help identify problematic trees that pose a risk.
Tree inventories typically include the following data fields.
1. ID Number: Each tree is tagged with an aluminum tree tag and given an identification number in order to cross reference individual trees.
2. Species: Trees are identified by genus and species and listed by their common name.
3. Tree Location: All of the common area trees are noted according to nearest individual unit or given a general location, and noted in the Tree Location columns.
4. Size Classifications: The current trunk diameter and height of each tree is estimated and noted
5. Condition and Pruning Requirements: The current condition of each tree is recorded and a recommendation is made for its next pruning treatment. Each individual tree is factored into a long-range maintenance schedule.
6. Pruning Cycles: Each individual tree species is given a recommended prune cycle. Recommendations are based on species, growth characteristics and site conditions.
7. Hardscape Condition: Hardscape is defined as any paved area surrounding a tree or adjacent to a tree, such as a sidewalk, street, curb, gutter, driveway, planter wall, retaining wall, walkway etc. Other fixed objects such as meter boxes, vents or poles may be included this category as well. Hardscaped areas, which appear to be disrupted as a result of tree roots, are noted in the inventory. In some instances trees, which have the potential to cause hardscape disruption, are noted with a year that it could be expected.
8. Recommended for Root Prune: Trees which are damaging hardscapes but can adapt to their site conditions with root pruning are indicated in the inventory. In most cases however, trees which require root pruning should ultimately be removed and replaced.
9. Recommended for Removal: Trees which are considered unsuitable for its site, yet serve a specific purpose may be recommended for replacement at a future point in time.
10. Condition, Comments & Affected Areas: Individual trees which appear to have special circumstances or are affecting specific landscape features or a section of infrastructure were noted.
11. Budget Estimates: The projected costs shown in these columns are estimates based on industry standards and submitted for the purpose of budget only. Actual costs may vary depending on the individual contractors and the time of year the work may be performed.
DISCUSSION AND ANALYSIS OF TREE INVENTORY
A complete breakdown of the tree inventory will show the diversity of the trees owned by an HOA. Tree inventories that are made up of a few dominant species run the risk of becoming negatively affected by a species-specific insect or disease epidemic. Therefore, it is particularly important that there are never too many trees of one species in a single area or throughout the property. This information will help an HOA Board of Directors make informed decisions about future tree replacements.
Urban foresters will recommend a diverse forest where no species constitutes any more than 10% of the total tree inventory. In addition to providing optimum levels of species diversity, it is also important to vary the ages of trees within each species that is represented which can be achieved through an annual planting program. This measure will help to prevent wide spread loss of trees would that reach the end of their useful lifespan at the same time.
The inventory analysis will also show how many trees are in good condition, as well as which of the trees are unsuitable for their locations and will eventually outgrow their sites.
Good condition is defined as trees with little or no structural defects and growing vigorously. Fair condition is defined as trees with good vigor but have minor structural defects that can be corrected through pruning or other treatments.
A tree management plan will show the current trunk diameters as they exist at the time of the inventory. The report will show the total quantity of trees that have the potential to outgrow the sites in which they are growing.
A Tree Management Plan will also show the height ranges as they exist at the time of the inventory and how many will require regular pruning to control their size.
Since many species of trees are individually unique in form, structure and their pruning needs do not always fit a strict or uniform application. Therefore, all trees do not all need to be pruned the same way, or at the same time. A recommended 5-year timeline for trimming and removals based on species, growth habit, current condition and anticipated growth over a 5 year period of time helps to balance out an annual budget and would be shown in the Fiscal Impact section of a management plan.
The Plan will also show the quantity of trees that will require trimming each year over the next five years.
The graph below is an excerpt from another report to show a five-year projection of pruning requirements throughout the HOA. It is recommended that pruning requirements be re-evaluated after 5 years. The actual pruning schedule is actually an Appendix at the end of the report.
Typically, hardscape condition should be inspected annually to detect hardscape damage from tree roots. Although the chart indicates that by 2008 there will be no sites with displaced concrete, the projection is based on current observations and a proposed root-pruning schedule based on those current conditions. The blue bars in the chart below represent the number of trees that will require root pruning over the next 5 years. The red bars represent the number of sites that have displaced hardscapes and should be repaired at the same time the roots are pruned.
5 year cost projection for tree trimming.
5 year cost projection for tree pruning
SAMPLE INVENTORY WITH PRUNE SCHEDULE