May 2010


Trees are critically important in the food cycles of many insects, birds and mammals, including humans. The majority of our food crops depend on  pollinators for fertilization. And the numbers of pollinators are in serious decline.

Pollinators include Butterflies and Moths (lepidoptera family) as well as Bees, Wasps,Beetles and Flies.

Please remember that dead wood is also critical for pollinators. Approximately 30% (around 1,200 species) of Bee species in North America are wood nesters. Generally, these bees nest in abandoned beetle tunnels in logs, stumps and snags. Dead limbs, logs or snags should be preserved wherever possible (Xerces Society, Pollinator Conservation Strategy, 2009).

The information in the following table is taken from ‘Bringing Nature Home’ by Douglas W. Tallamy, and available at Guelph Public Library.

Common Name Plant Genus No. of Species Supported
Oak

Willow

Cherry, Plum

Birch

Poplar (cottonwood)

Crabapple

Maple

Elm

Pine

Hickory

Hawthorn

Spruce

Ash

Basswood (Linden)

Hazelnut

Walnut (Butternut)

Beech

Chestnut

Quercus

Salix

Prunus

Betula

Populus

Malus

Acer

Ulmus

Pinus

Carya

Cratageus

Picea

Fraxinus

Tilia

Corylus

Juglans

Fagus

Castanea

517

456

448

413

368

311

285

213

203

200

159

156

150

150

131

130

126

125

The Value of Urban Trees

Over a 50-year lifespan, the average tree will provide:

  • $31,250 worth of oxygen
  • $62,000 worth of air-pollution control
  • $37,500 worth of water recycling and humidity control
  • $31,250 worth of soil-erosion control
  • $31,250  habitat and pollinator support
  • $2500  worth of protein

This works out to almost $200,000, equivalent to $4000 per year

Values provided by The U.S. Forest Service

Your tree can also add 10-25% to your property value

Other benefits provided by urban trees include:

  • shade that reduces heat in your home and our city
  • reduced exposure to harmful UV radiation, responsible for a rapidly increasing rate of skin cancer (S. Ontario has the strongest UV radiation in Canada)
  • improved water quality and quantity
  • air purification, reduces greenhouse gas production

Please choose your tree well. Protect and maintain it. Our sustainable community depends on it.

Visit Guelph Urban Forest Friends at the Farmers’ Market on Saturday mornings under The Big Umbrella

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