Heat islands ... or more trees?
Our world’s increasing urbanization, reflected in Aylmer’s growth, brings equally-expanding problems: traffic congestion, crowded transit, parking shortages, noise and light pollution, declining air quality, plus soaring real estate prices and a shortage of living spaces, especially for restricted budgets. What’s counterintuitive is that, despite increased urban populations, cities are now home to bigger, healthier trees than rural areas. It’s no longer easy to find a big red oak to lean against out in the country.
Older neighbourhoods have preserved maples, oaks, basswoods, pines and spruces, which dwarf most of what we now find on the farms and forests surrounding our cities. Fence-lines have been bulldozed to create larger fields, removing old trees, while orchards and homestead trees have been removed for new construction.
However, when a neighbour had three magnificent trees removed from his yard this summer, I was surprised. This newspaper had published interviews of realtors – a few years ago – to identify the features making homes easier to sell, or yielding higher prices. A universal recommendation was: trees, the bigger the better (despite the supposed danger of branches falling on a roof). Their estimate was that each mature tree can add $3,000 to a home’s value. And that’s nothing – quality black walnut trees have been sold for as much as $30,000 per tree.
Homeowners are continually removing or severely pruning their trees which, apart from sales value, provide other services like air conditioning and shade. And, yes, these choices are individual aesthetic preferences.
But for a whole city, this dynamic changes. It has long been noted that cities create urban heat islands (UHIs), substantially warmer and drier than their surrounding countryside. With climate change now so obvious, and presenting us with increasingly severe and longer heat waves, any measures that will mitigate the heat island effect – and heat-related mortalities – are worth our attention.
City planners already recognize the benefits of urban forest, more parks and greenspaces and open water. Planners also work with building shapes and placement to increase street ventilation; they calculate the value of living roofs and light-reflecting roof surfaces, plus the need to reduce vehicle CO2 emissions. Apparently 75% of the world’s C02 emissions from energy use are generated within cities. We citizens should support even more of these heat-island mitigation strategies – for our own sakes.
Besides our municipal planning, how about encouraging individual property owners to keep and plant more trees and greenery – tree-removal permits can require replacement trees, and municipal tax credits based on tree counts. We might reconsider our waste of wood, replacing decks for example, in order to reduce deforestation. Vacant lots can be ordered replanted by the city.
Gatineau’s heat-island effect is growing with climate change, as are most cities’, but there are many modest green actions we can take now before we’re into a crisis with only radical and expensive solutions.