Street Tree Planning and Management: Guiding Principles · Eric Wiseman Mason Patterson Sarah Gugercin Dept. of Forest Resources & Environmental Conservation Virginia Tech August

Eric Wiseman Mason Patterson Sarah Gugercin

Dept. of Forest Resources & Environmental Conservation Virginia Tech

August 15th 2012 What We Have, What We Want, & How We Get There Street Trees in Virginia ~

Street Tree Planning and Management: Guiding Principles

PRESENTATION OVERVIEW

August 15th 2012 Street Tree Planning and Management: Guiding Principles

• Urban forestry paradigm

• Street tree management model

• Principles of structure

• Principles of function & value

• Take-home messages








URBAN FORESTRY PARADIGM

Sustainable Urban Forest

Management

Structure

Function

Value


Management

Structure

Function

Value

Abundance Location Composition



Management

Structure

Function

Value


Policy

Planning Arboriculture



Management

Structure

Function

Value


Policy

Planning Arboriculture

Bio-physical Socio-economic

Benefits Costs









STREET TREE MANAGEMENT MODEL

Resource Assessment

Management Goals

Management Plans

Re-assess

What Do We Have?

What Do We Want?

How Do We Get There?

Are We There Yet?








PRINCIPLES OF POPULATION STRUCTURE

• Street Tree Abundance – Stocking

o Full Stocking 1 tree every 50’ (Wray & Prestemon 1983)

45’ | 35’ | 25’ (Various municipalities)

o Typical Stocking 46% (Ball et al. 2007)

38% (McPherson and Rowntree 1989)

9–66% (McPherson et al. 2005)

o Optimum Stocking (Miller 1997)

- Biological capacity - Economic capacity - Social capacity

• Street Tree Abundance – Stocking

o Available Planting Spaces - Remotely-sensed or field-surveyed - As part of a tree inventory - Strip/cut-out size; utilities; setbacks


• Street Tree Composition – Size Distribution

40% 30%

20% 10%

0-8" DBH

8-16" DBH

16-24" DBH

> 24" DBH

Richard's Ideal Distribution 40%

25% 15%

10% 6% 4%

0-6" DBH

6-12" DBH

12-18" DBH

18-24" DBH

24-30" DBH

> 30" DBH

McPherson's Ideal Distribution

(Soares et al. 2011) (Richards 1983)


• Street Tree Composition – Stature Distribution

(US Forest Service 2004)

10%

27%

63%

Small Stature (<25')

Mid Stature

(25'-45')

Large Stature (>45')

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• Street Tree Composition – Stature Distribution

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30%

20%

10%

Family Genus Species

Santamour's Ideal Distribution

(Santamour 1990)

• Street Tree Composition – Taxonomic Diversity

“A community forestry goal of a 10% limit on a single species could give a false indication of stability…. (t)here is probably little concern about the diversity of families used as street trees, but not enough concern on the reliance on a limited number of genera…a 10% limitation on genera may be our best measure of stability.” (Ball et al. 2007)



o Ecology (site suitability: soil, space, pests, stress) oSocial norms (citizens want fast-growing, colorful trees) oDesign and management norms (symmetry and uniformity) oNursery production (nurseries produce what consumers demand)

What is holding us back?




o Ecology (site suitability: soil, space, pests, stress) oSocial norms (citizens want fast-growing, colorful trees) oDesign and management norms (symmetry and uniformity) oNursery production (nurseries produce what consumers demand)

What is holding us back?

o Educate (share results of assessments; websites; social media) o Incentivize (tree replacement request preference for diverse spp.) oSubsidize (rebate or discount on diverse spp. sales) oRegulate (approved/prohibited spp. in policy or ordinance)

What do we do about it?









PRINCIPLES OF POPULATION FUNCTION

• Urban heat island and energy conservation

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• Urban heat island and energy conservation


• VOCs and ozone-forming potential

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PRINCIPLES OF POPULATION VALUE

• Understanding street tree benefits and costs

• Understanding street tree benefits and costs

Bene

fits

Cos

ts

PRINCIPLES OF POPULATION VALUE








TAKE-HOME MESSAGES

• The urban forestry paradigm conceptualizes the interelationships of structure, function, value, & management

• Street tree management is cyclical and is based on resource assessment

• Optimizing structure of street tree populations helps ensure resiliency, stability, and functionality

• High-value street trees are those that provide maximum benefit at minimal cost

QUESTIONS?

Documents

Street Tree Planning and Management: Guiding Principles · Eric Wiseman Mason Patterson Sarah Gugercin Dept. of Forest Resources & Environmental Conservation Virginia Tech August