STRATUM: Overview & Process

Session Purpose i-Tree STRATUM Savvy Community forest management

What’s In Store for You? Background Process Data Collection Field Practice STRATUM Create a project Inputs Reports

Background Center for Urban Forest Research USDA Forest Service PSW Research Station Davis, CA To demonstrate new ways that trees add value - quality of life - to communities.

Structure Function Value Management Needs

What We Need? Value of trees to human health and well- being Increased investment in management Planning integrated up-front, not as after-thought Green and gray infrastructure working together Increased return on investment and customer satisfaction Tools to quantify the value of trees

Tree Value Trees are assets, management adds value by increasing return on investment

Heart of Sustainable Funding Sufficient local budget appropriation Engage in outreach, public relations, special events Regularly educate and lobby community leaders Develop clear argument to justify budget: Resource assessment Resource value

STRATUM Helps You Justify and leverage funds Highlight benefits to public Plan, prioritize, and budget Benchmark progress

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.

Tree Size, Growth, and Functionality

Sweetgum in three climate zones at age 40 Inland Empire Coastal S. CA Central Valley

STRATUM was designed to extend Reference City data to all communities within a climate zone

Reference City Research Collected local street tree data Analyzed growth rates and dimensions Estimated magnitude of annual benefits Priced benefits Priced tree care costs Calculated net annual benefits, benefit-cost ratios

Sample Design Reference city data collection is used to develop growth models of representative street trees and calculate benefits. Predominant species 18 – 25 species representing >65% of forest Random sample of 35 – 70 trees per species Stratified, minimum 40 year age range

Measurements 25 field measurements for each tree, including: Diameter-at-breast-height Tree height Crown (bole) height Crown diameter Leaf area Crown shape Tree orientation and setback Condition and location Pruning level Grow space type and size Hardscape damage

Research Process—Structural Analysis Data collection – 900 trees, 20 predominant species age, species, dbh, ht., crown dia., condition, digital photos, foliar biomass samples, etc. Calculate leaf area and foliar biomass Regression models predict growth.

Research Process—Functional Analysis Models use structural data – (size at various ages). To determine magnitude of annual benefits: Energy saved Atmospheric CO 2 reduction Air pollutants removed Rainfall intercepted Aesthetics & other

Research Process—Value Analysis (Benefits) Heating & Cooling Energy - Regional market prices ($0.095/ kWh, $0.97/therm) Carbon trading credits - CO 2 ($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—Value Analysis (Costs) Planting Pruning Removal and disposal Pest and disease control Irrigation Infrastructure Leaf litter cleanup Liability Administration

Research Process—Value Analysis (Net Benefits) Convert resource units (kWh, lbs) to $ Annual Benefits: B = Energy + CO 2 + AQ + Hydrology + property value Annual Costs: C = Plant + Trim + Removal + IPM + Irrigation + Clean-Up + Sidewalk + Liability + Admin + Other Net Benefits = B – C Benefits/Costs ratio = B/C

Computer application Allows managers to evaluate current benefits, costs, and management needs. Input: - Sample inventory (3-5%) - Or existing inventory - Price adjustments, mgmt. costs Output: - Graphs, charts, tables Benefit: - Baseline data to more effectively manage the street tree resource STRATUM: Information for Better Tree Management

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?