Missoula Urban Forest CommunityViz Cost/Benefit Model

Early in 2008, Missoula County submitted a grant proposal to the Montana Department of Natural Resources to develop a CommunityViz project with Geodata Services, Inc, analyzing the costs and benefits of the municipal trees in the Missoula urban forest.  A primary objective was to conduct analysis, prepare model results and documentation to help achieve adequate funding and staffing for the Urban Forestry Division to encourage a vibrant, diverse, mixed age urban forest and maintain the municipal trees on City of Missoula right of ways and parks. 

The CommunityViz Scenario 360 analysis was a means of dynamically experimenting with different budget scenarios and evaluating their growth pattern and benefits over a century (the assumed average maximum life of a typical Missoula maple tree). An analysis includes alternative approaches (“scenarios”), input, analysis, outcomes, and decisions. In Scenario 360, an analysis provides the overall framework for a project. It includes all of the map data, scenarios, calculations, and indicators for the various alternatives and "What if" type analysis with multiple scenarios for the maintenance of existing urban trees, and the plantings of new and replacement trees for those that die during the century. 

Some of Missoula's premiere maple tree neighborhoods are even aged and approaching the end of their lifecycle.  The areas immediately west of the University of Montana campus for instance, include many old mature trees that are approaching 100 years old, nearing the natural length of the maple life cycle.  They will not all die at once, but many will within a short period of years.  Every time the City establishes a urban forest budget, they are making a 100 year investment.  Significant change in the urban forest composition cannot occur in short periods, it requires a long term perspective.  The visualization to the left is the current tree inventory for a portion of the neighborhood near the University of Montana.  The image on the left shows the current tree inventory (2003), primarily old mature maple trees.  Given the current budget for planting and pruning, the image on the right shows what the neighborhood tree distribution may look like in 2050.

Multiple alternative scenarios can be compared head-to-head.  In this example, the current status-quo budget and pruning scenario (based on a 49 year pruning cycle) is shown in the left column, and one proposed 2009  budget scenario with a recommended 7 year pruning cycle, and 200 additional trees planted each year.

Many assumptions underlying the model can be adjusted, and the model recalculated in seconds usng the new assumption values.  Values that can be changed include staff labor and equipment costs for each category, the recommended pruning cycle, storm and insect and disease mortality, average benefits for different tree size and age classes, and others.