Over the past three years we have been ravaged by one of the severest droughts on record for this region. Yet during that same period, the City of Calgary -- using our money -- has planted and has caused to be planted more new trees than during any previous three year period in our history. And drought or no drought, the plan, for the moment at least, is to continue doing the same next year and the year after.
That's the bad news. The good news is that Urban Forest Manger Bashir Jamal and the folks in the City's Urban Forest section are learning; they are adapting to the new realities of a warmer climateThe really good news is that they are open to suggestions that maybe they shouldn't plant quite as many trees next year as they are planning to plant should the drought show signs of moving into a fourth scorching quarter.
This is important. The estimated value of Calgary's urban forest currently sits at about a third of a billion dollars. That's $335,000,000 according to the folks down at City Hall. In an average year we can expect an average tree mortality of about three percent. That's about $10 million dollars worth of trees lost to old age, disease, winter kill, construction and car accidents every year.
When drought hits, as it has for the past three consecutive years, the mortality rate climbs. How high does it climb? Nobody can say exactly. Mature trees do better during periods of drought than old trees well past their prime and better than young trees not yet in their prime. Healthy trees also do better during droughts than sick trees. So while one might expect to see mortality rates double or triple during extended dry periods, it ain't necessarily so.
Taking the baseline mortality rate of $10 million annually though, one can estimate that when all is said and done, when all of the additional trees killed by the drought have been replaced and when all of the additional trees weakened by the drought have finally succumbed to the inevitable,
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the past three years will have cost us somewhere between $35 million and $80 million in existing trees and replanting labour. This is between $5 million and $50 million more than we would probably have spent otherwise.
Now to be fair, I don't recall very many people predicting three years ago that we were about to enter the first of three consecutive years of drought. Therefore I don't expect that the Urban Forest section put any kind of drought preparedness plan into effect at the first sign of dry weather in the spring of 2001. Like every taxpayer in the city, though, I do expect them to be ready if we enter a fourth consecutive year of drought in 2004 because if next year is as dry as the last three have been, I don't think anyone should be surprised.
So while it may be fair to characterize the city's tree planting policy of the past few years as irrationally defiant -- we will see 20,000 new trees planted this year drought or no drought -- the fact is that common sense is gradually taking root. The Urban Forest section, for example, has nearly stopped planting trees immediately adjacent to major roadways where salt drift poisons the soil and kills expensive trees. They have also greatly reduced the number of trees planted on medians where compacted soil conditions combined with salt drift can shorten the life expectancy of a tree from over 100 years to less than 10.
A primary drought-year strategy now is to plant trees in places like Birthplace forests where a proximity to water, a shared bed and layers of mulch combine to stretch the lives of trees (and the value of our tax dollars spent on trees) ten times further than roadside plantings. A similar strategy has city workers planting more trees on the boulevards of local community roads where conscientious homeowners can reach them with their garden hoses.
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So while the drought has been bad news for city trees and the wallets that support them, the time has never been better for residents in new communities dreaming about tree lined streets and avenues. With a fourth straight year of drought looming, the chances are very good that the Urban Forest section will decide next spring that planting trees within reach of suburban garden hoses is a better bet than planting them in places only watering trucks can reach.
It is also a good time for groups who want to increase the canopy cover over their parks, community centres and playgrounds because while they would normally have to compete with the need for roadside trees during non-drought years, the persistence of the drought and a change in planting policy will make more trees available for water conserving mass plantings that have volunteers signed up to care for them.
In the meantime, the average citizen can once again this fall help the city save some of the hundreds of millions of tax dollars we have invested in our urban forest by watering the trees on city property around them. One good drink between now and the end of September will make the difference between living and dying this winter for many of the trees in our city.
© Brent Johner. Originally published in the Calgary Herald, September 2003. Reprint rights available.
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