Introduction to STRATUM Model
and Application
What makes STRATUM different?
 Street trees, not entire urban forest
 Costs, not only benefits
 Management tool, not only for advocacy
 Tree inventory-based, not GIS
 Answers the question: do the accrued
benefits of street trees outweigh the cost of
their management?
Structure
Management
Needs
Function
Value
The Foundation: Reference City
Research
 Regional Tree Guide studies
to develop growth models of
representative street trees
and their dimensions as a
basis for Benefit-Cost
Analysis.
Reference City Research
 Collected local street tree
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


data
Analyzed growth rates and
dimensions
Estimated magnitude of
annual benefits
Priced benefits
Priced tree care costs
Calculated net annual
benefits, benefit-cost ratios
Tree Size, Growth, and Functionality
Sweetgum in three climate zones at age 40
Inland Empire
Coastal S. CA
Central Valley
Research Process— Benefits
 Heating & Cooling Energy - Regional

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market prices ($0.095/ kWh,
$0.97/therm)
Carbon trading credits - CO2
($15/ton)
Air Pollutants - Transaction costs,
damage value and control cost of
emissions ($1-15,000/ton)
Stormwater Runoff Retention/detention costs
($0.005/gal)
Residential Property Increase Average resale price (median sales
price = $254,000)
Research Process—Costs
 Planting
 Pruning
 Removal and disposal
 Pest and disease control
 Irrigation
 Infrastructure
 Leaf litter cleanup
 Liability
 Administration
The STRATUM Application
 Define City
Define Costs 
Define Benefit
Prices
Structure
Management
Needs
Function
Value