Vanwassenaer_CONSERVATION ARBORICULTURE ...

URBAN FOREST INNOVATIONS INC.

Philip van Wassenaer, B.Sc., MFC 1248 Minnewaska Trail Mississauga, Ontario web: www.urbanforestinnovations.com email: [email protected]

CONSERVATION ARBORICULTURE: MAINTAINING OLD TREES IN THE HUMAN LANDSCAPE

Society of Municipal Arborists International Urban Forestry Conference September 25-28, 2011 Milwaukee, WI

Heritage Trees

Neville Fay at

Ashton Court

Heritage Trees

Ted Greene in Great Windsor Park.

Presentation Outline

• Heritage Trees

• ‘Working Trees’ – A History of Tree Management

• Urban Forestry and the Benefits of Trees

• Conservation Arboriculture

• Tree Risk Assessment: Theory and Methods

• Management Options for Retaining Old Trees

HERITAGE TREES

Heritage Trees – A Definition

• In 2001, Dr. Paul Aird, Professor Emeritus, Faculty of Forestry, University of Toronto was asked to create a definition of heritage trees.

Heritage Trees

A Heritage Tree or Heritage Plant

• An outstanding specimen due to size, form, shape, age, colour, rarity, genetic constitution, or other distinctive features

• A distinctive community landmark

• A specimen associated with a historic person, place, event or period

• A representative of a crop grown by ancestors and their successors that is at risk of disappearing from cultivation

• A specimen recognized by members of a community as deserving heritage recognition

• Dr. Konijnendijk – defining a sense of place.

Heritage Trees

Cultural Heritage -The Dancing Linden of Sachsenbrunn, Germany H

eritage Trees

Heritage Trees

http://upload.wikimedia.org/wikipedia/commons/4/41/Tanzlinde_Sachsenbrunn.jpg

The Holy Edigna of Puch – Bavaria, Germany H

eritage Trees

H

eritage Trees

Edigna, a “Hermit nun” and the daughter of the King of France, is said to have lived in the hollow of this tree from 1075 - 1109

Alexander Muir “Maple Leaf Forever” – Toronto, ON H

eritage Trees

Text Here

Text Here

Heritage Trees

White Oak – Bronte Creek Provincial Park, ON H

eritage Trees

Giant Redwoods – California, USA H

eritage Trees

Ficus Planted by Pres. Roosevelt, Early 1900s – San Diego, CA

Courtesy: Darin Hinesly

Heritage Trees

Theodore Roosevelt:

“A people without children would face a hopeless future; a country without trees is almost as hopeless…”

Heritage Trees

Live Oak (Quercus virginiana) – Savannah, GA H

eritage Trees

‘WORKING TREES’ – A HISTORY OF TREE MANAGEMENT

Heritage Trees

Working Coppice ‘W

orkin

g Trees’

Ready for Coppice

Coppice Harvested

Coppice Regeneration

Coppice with Standards

Heritage Trees

URBAN FORESTRY AND THE BENEFITS OF TREES

wakeforest.nc.gov

Urban Forest Benefits U

rban

Forestry

The urban forest provides a wide range of services such as:

• Improved air quality

• Micro-climate effects (e.g. shading)

• Property value & aesthetics

• Storm-water attenuation

• Energy conservation

• Noise reduction

• Wildlife habitat

• Physical & psychological wellbeing

• etc.

Maximizing Leaf Area U

rban

Forestry

CONSERVATION ARBORICULTURE

What is Conservation Arboriculture? C

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Conservation arboriculture is an ecosystem approach to understanding and working with trees.

• A multidisciplinary science informing practical management of trees.

• Trees are habitat, homes for inter-dependent species.

• Trees have co-evolved with other organisms.

• To optimise their health trees require functioning, balanced natural ecosystems, above and below ground.

Veteran Trees: A UK/European Perspective C

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Introduction to Veteran Trees: A UK/European Perspective C

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• In 1993, the Ancient Tree Forum was formed in the UK to discuss management of ancient trees.

• Led to the formation of the Veteran Tree Initiative (1996), to develop a standard for identification, assessment and management of veteran trees in Europe.

Old Trees – History and Habitat C

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Old trees are important habitat for saproxylic beetles and other organisms.

living on dead wood

Jonsell (2004) found that old oaks and lindens (up to 300+ years) in Swedish parks have comparable ‘red-listed’ beetle diversity as old remnant natural areas.

By conserving old trees in cultural landscapes, we can protect history and habitat at the same time.

Old Trees – History and Habitat C

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Old Trees as Habitat C

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Redwood Rainforest

Coast Redwoods

• 115 trees/ha • 12 trees have 95% of the biodiversity • These are the old trees with broken tops, etc.

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Sillett and Van Pelt 2000. ‘A Redwood Tree Whose Crown May Be the Most Complex on Earth’

Ancient Redwoods C

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Rainforest Canopy Biodiversity C

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Urban Forest Benefits C

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Neville Fay

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Neville Fay

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TREE RISK ASSESSMENT

How Trees Fail C

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FILE

Fracture Stem / Limbs

Uprooting Stem Base / Root failure

Often result of internal damage,

which is often difficult to estimate from

the outside.

Typically caused by root decay or damage,

or failure of the root/soil interface.

Tree Risk A

ssessm

ent

Trees Fall – but they don’t always die!

Kew Gardens, UK

Tree Risk A

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Trees Fail – but they don’t always fall down!

A veteran oak between Milton and Burlington, ON

Tree Risk A

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Tree Risk Assessment - Methods Tree R

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• Visual Tree Assessments

• Hammer Test

• Drilling - fine bits or increment core

• Drilling - Penetrometer

• Sonic Tomography

• Elasto-Inclinomethod, SIA

• Others (e.g. Tree Radar)

Traditional Methods

Advanced Methods

Drilling and Residual Walls Tree R

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Decay

• Drilling only selectively detects the residual wall

• Information obtained is insufficient to describe the state of the tree...

• ... or the number of holes has to be so high that the damage is greater than the information obtained

Tree Risk A

ssessm

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Tree Radar Tree R

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Sonic Tomography Tree R

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Sonic travel paths

Receiver

Receiver

Receiver

Receiver

Impact – Start Signal

Damaged wood (decay, cavity..)

Receiver

Receiver

Receiver

Tomograph Results Tree R

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Hollow ≠ Unsafe C

OM

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FILE Tree R

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SIM – Statics Integrating Method Tree R

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Engineering-Based Tree Pulling Tests

Statics Integrated Method – Pulling Test Tree R

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• Winch creates the wind simulation force • Different positions of instruments

MANAGEMENT OF VETERAN TREES

Crown Restoration: Retrenchment Pruning C

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Neville Fay

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Neville Fay

Retrenchment Pruning Terminology C

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• Stabilisation

• Promotion of internal growth

• Redeployment of resources

• Epicormic stimulation

• Rejuvenation/reiteration

• Management of meristem tissue

• Phased according to form and vitality

Crown Restoration: Retrenchment Pruning C

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Neville Fay

2004 2006

2007

Cabling and Bracing C

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Case Study – Woodside Tulip Tree C

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CONCLUDING REMARKS

Threats and Challenges

• Abiotic and biotic influences are threatening all of our trees, and heritage trees may be especially vulnerable

• The challenge is for us to find effective ways to offer real protection to trees identified as heritage features

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Dutch Elm Disease – Winnipeg, MB C

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Courtesy: Mike Allen

Construction Blight C

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Root Loss C

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FILE C

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Conservation Arboriculture Do’s and Don’ts

• Intervene as a last resort • Manage by restoring naturally functioning systems • Don’t intervene without knowing about the soil-rooting ecosystem • Crown management should mimic natural aging process and species survival mechanisms • Manage to retain maximum biodiversity

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Conservation Arboriculture Guiding Principles

From the National Tree Safety Group (UK) 2010 draft guidance document:

1. Trees provide a wide range of benefits to society

2. Trees are living organisms which naturally lose branches or fall

3. The risk to human safety from trees is very low

4. Tree owners have a duty of care for their trees

5. Approach to tree management must be balanced and proportionate.

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Let’s not let the sun set on our heritage trees!

QUESTIONS? COMMENTS?

Philip van Wassenaer, B.Sc., MFC ISA Certified Arborist ON-0361A ASCA Member

1248 Minnewaska Trail Mississauga, Ontario, Canada L5G 3S5 (905) 274-1022

e-mail: [email protected] or [email protected] http://www.urbanforestinnovations.com

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