Urban Forest

Livingston Tree Inventory Analysis Using I-tree Software

Results include:

• Livingston has approximately 4,172 trees on public property.
• Ash species accounts for 47% of Livingston’s tree canopy, Maple 11%, and Spruce 10%.
• Livingston has an old to over-mature aged urban forest.
• Over 27% of Livingston trees could use some type of pruning.
• The trees of Livingston are worth almost 18 million dollars.
• Each citizen in Livingston receives $85.93 each year in environmental benefits from trees.

Recommendations include:

• Diversify species - Continue planting trees other than Ash, Maple, Spruce and Cottonwood around Livingston.
• Improve overall tree condition - Immediately address the 165 trees identified as poor, dead, or removed.  Then begin tackling the remaining trees that were recorded as in fair condition.
• Create an annual work plan - Develop a rotation for tree maintenance and planting where a certain number of trees are pruned or planted each year.
• Education & Outreach - Continue expanding your Arbor Day celebration each year, while using other opportunities to educate and inform the public about their urban forest.
• Training - Send tree board members and city staff to tree maintenance training.
• Funding - Begin to develop a yearly budget for Livingston’s tree program. 

Species Diversity

It is important to diversify tree species “to not put all your eggs in one basket”.  In the event that a disease, bug, or natural event comes along that wipes out one tree species, there would be others to fill the void.  American elm is a prime example.  Elms were planted in rows along many streets across the United States for their beauty and crown symmetry.  Dutch Elm Disease, a fungal disease, wiped out what were once mature, shade-providing boulevard trees in communities throughout the country.  A good goal is to not have any one species make up more than 10% of the total population or 20% of the same genus. In Livingston, Ash species account for 47% of the tree species while Maple species makes up 11 %, Figure 1. 

Figure 1: City of Livingston Tree Species 

Tree Size 

By looking at the size distribution of the urban forest, a correlation can roughly link to guessing the age of the overall stand.  Diameter Breast Height (DBH) was measured on each tree inventoried.  A reverse “J” shaped curve is a good goal to work toward.  As the trees become older, they either die or are removed.  As Figure 2 shows, Livingston has an old to over-mature aged stand of trees.

Figure 2: Diameter of Livingston Trees

Tree Condition

Tree failure is one of the most critical concerns in municipal management. Determining a tree’s condition is done by assessing how much deadwood is present in the tree.

Figure 3: Condition of Wood of Livingston's Trees

Figure 3 illustrates Livingston’s overall tree condition.  Of the trees inventoried, 3,788 trees had less than 15% deadwood.  While 220 trees were in fair condition, 165 trees were poor, dead, or removed. 

Maintenance

Only 56% of the trees were identified as needing no kind of maintenance, while 27 % were identified as needing to be pruned.  142 trees were identified as needing to be removed.  518 were noted as needing watered. 1,139 trees were identified as needing to be pruned. (Figure 4)

Figure 4: Tree Maintenance Needs

Public safety, tree health, and long term cost are all reasons to keep trees maintained.  If trees are properly established from a young age, they will require less need for major pruning later.  Trees that are kept pruned produce less damage during wet snows and wind storms saving the community tax dollars.  A pruning cycle, for example a fifteen year pruning cycle, is where a certain amount of trees are pruned in a year and those same trees are pruned in fifteen years. 

Tree Values

There are several ways to calculate a tree’s value.  The table below uses a formula (The Trunk Method) which takes into account regional data, replacement cost, location, condition, and species rating for the region. According to this calculation, The City of Livingston’s urban forest is valued at almost eighteen million dollars.

Another way to look at the value of Livingston’s trees is to look at the environmental benefits that the citizens of Livingston receive each year from trees.  I-tree is a module that uses the species, diameter and regional cost to assign a dollar amount to the energy, C02, air quality, storm water, and aesthetic benefits that the trees provide.

In one year the trees of Livingston provide $625,532.00 in environmental values.  The community saves $80,895.00 in energy each year from their trees.  Trees also reduce the need to collect storm water, a savings of $95,856.00 each year for Livingston. The table below breaks out these benefits in terms of dollar values.