Plant Tab

Select Your Layer

Start by selecting the layer that you wish to use for the projections from the drop down menu.

Select Goal

There are two options for Goals. The first is to set a Target Percentage. Using this option will allow you to set a canopy percentage goal for all features within your layer. For example, if you selected Neighborhoods as the analysis layer and picked a goal of 30, this will model how many trees you need to plant to reach 30% within each neighborhood. If a neighborhood is already above our Target Percentage, then it is not included in the model analysis. 

The second option is Increase By. Using this option, you will increase the canopy percentage by a select amount in all neighborhoods regardless of the current canopy percentage. This will affect all features in the layer as opposed to the Target Percentage option that only picks neighborhoods that are below the Target Percentage goal. 

When you have picked a layer and canopy goal, you will see that the map will change to the shading of green to represent the new modeled canopy percentage. In the example below, you can see the color changes when setting a goal of 10% and 35%.

Set Crown Sizes, Distribution, and Mortality Rate

After the goal is set, we now need to determine a few other parameters for the model to complete the projection. These inputs will have profound effects on the outcome of the model so we will discuss each parameter separately. 

Tree Planting Cost: The total cost of planting a tree that can include the tree stock, labor, and contract maintenance for the first few years (i.e. watering). This is per tree. 

Maintenance Cost: Not required, but this is an option to add maintenance costs over the life of a tree. This would be local information but may not be known. This is per tree. 

Distribution of Size Class (%): The model depends on a size class distribution percentage in order to calculate how much square footage is being added by planting a tree. This range for each size class will tell the model that of our planted trees, we plan to plant “X” percentage of small trees, “Y” percentage of medium trees, and “Z” percentage of large trees. 

Small Tree Crown (ft): Mature crown diameter of small statured trees at maturity. As an example, a normal small statured tree may have a mature crown diameter of 20 ft. This will vary depending on your region of the country. Use the sliders to adjust for local preferences. 

Medium Tree Crown (ft): Mature crown diameter of medium statured trees at maturity. As an example, a normal small statured tree may have a mature crown diameter of 30 ft. This will vary depending on your region of the country. Use the sliders to adjust for local preferences.

Large Tree Crown (ft): Mature crown diameter of large statured trees at maturity. As an example, a normal small statured tree may have a mature crown diameter of 40 ft. This will vary depending on your region of the country. Use the sliders to adjust for local preferences.

Canopy Stability (%): If a change assessment has been conducted, this will be set to the average gain/loss per year (Set to Default Growth). This variable is the overall trajectory of the urban forest as a whole. If no change assessment is available, this will default to 0, but can still be used to model canopy projections by moving the slider positive (gains) or negative (losses). 

Annual Mortality Rate of Planted Trees (%): This is the annual mortality rate of planted trees and is used to model young tree mortality. This gets applied each year to the remaining trees in the planting cohort. If you are not sure of this parameter, use 3% as a default.

Determine Goal/Planting Years

This step focuses on the number of years to reach our goal. Since trees do not grow quickly, it can take 10 to 15 years before they start making a sizable contribution to the overall canopy. Setting goals with a shorter timeframe will involve planting many more trees. As an example, a goal of 5 years may require to plant 100 trees whereas a goal of 15 years may only require 40 trees. 

The model inherently depends on the number of acres needed to reach your goal so reaching that goal will take considerably more resources if there is a shorter timeframe because the trees being planted won’t have time to grow and mature to fill out enough acreage. Conversely, planting 100 trees and 40 trees and both setting a timeframe of 15 years, you would see a higher canopy percentage if you plant 100 trees. To assist with modeling additional growth, the Target Year slider, allows you to model additional growth without planting new trees. 

For example, setting a goal of 10 years will include planting enough trees to reach your set goal, but you can add extra years of growth to see what the percentage would be without planting. The target year will add the specified number of additional growth years; keep in mind that this also includes mortality in the projection so your numbers could decrease still given current trends of canopy stability and planted tree mortality.