Greater Victoria lost the equivalent of 12 Beacon Hill Parks in tree cover over six years, according to a study by the non-profit society Habitat Acquisition Trust.
“We all have a sense we’re losing trees but the sheer mass of tree cover lost was surprising,” said executive director Adam Taylor.
The amount of tree cover loss and the rate at which it happens in developing regions is cause for alarm, Taylor said.
“How are these municipalities going to manage stormwater when they’re losing trees at this rate?” Taylor asked.
“Trees literally suck up water, prevent it from cascading in those big floods with costly messes. They retain water during the dry periods. They also absorb air pollution and clean the air. As we lose trees, taxpayers will pay for that.”
The study compared aerial photos of the capital region taken in 2005 and 2011. Using Geographic Information Systems software, tree loss and development in the 13 municipalities were mapped, charted and analyzed. The report was funded in part by the Capital Regional District and the Real Estate Foundation of B.C.
The study showed Saanich lost the most treed land over the six-year period: 378 hectares, equivalent to 146 of the University of Victoria’s Finnerty Gardens.
“The cause wasn’t anything specific — which was interesting and a bit shocking,” Taylor said.
The disappearance of trees in Saanich appears to be the result of urbanization and a multitude of small, changing land-use projects, rather than major building developments.
Langford lost the second-most land — 118 hectares — with the loss driven by development in areas such as Bear Mountain and Westhills, Taylor said.
Victoria lost the greatest percentage of treed land. While 42 hectares might not seem like a lot, it is 8.8 per cent of the city’s little remaining tree cover, Taylor said.
Similarly, Sidney lost only seven hectares of tree cover, but it accounted for 7.5 per cent of its treed land.
Highlands and Metchosin lost less than two per cent of their tree cover. Highlands also has the highest level of tree cover in the region, 84 per cent, while Sidney is the least treed, with only 18.3 per cent of the town having tree cover.
“One bit of good news in the study is that we didn’t lose tree cover adjacent to streams” in all the regions, Taylor said.
Several municipalities have already organized to address the issue of tree cover loss and plan for sustainable urban forest development. In recent years, both Victoria and Saanich have developed urban forest strategies.
In June, Saanich proposed amendments to its tree preservation bylaw, which already protects arbutus, Garry oak, Pacific yew, dogwood and other large trees.
“We’re introducing tree-planting initiatives on public and private property,” said Cory Manton, Saanich manager of urban forestry, horticulture and natural areas. He worked with the Habitat Acquisition Trust on the tree cover map study and a previous one conducted by the city.
“We’re looking at incentive programs to encourage homeowners to do things like plant boulevard trees.”
Manton said one important part of the study showed the areas where trees could be planted — “which is concerning because it’s limited.”
Saanich has set a new goal of no net tree-canopy loss in the coming years, which Manton said will need residents’ participation.
“Almost 75 per cent of the land mass in Saanich is private property. Citizens are a huge part of the goal,” he said.
Jeremy Gye, a local arborist and urban forestry consultant in the public and private sector, said the tree-cover loss map is the first step in understanding a rate of loss of urban trees per capita, and developing a benchmark for sustainability.
“We need to know how different municipalities rate against that benchmark,” said Gye, who has worked with the Habitat Acquisition Trust and Colwood consultant and councillor Judith Cullington on an urban forest initiative.
One of the next steps in urban forestry planning is to look at what kinds of trees are appropriate to plant for cover in densely populated areas, Gye said.
For example, a second-growth Douglas fir might not be the best choice in a residential area in Colwood, Gye said, noting a strong wind could knock the tree onto homes.
“We need a safer kind of canopy,” he said. “And it comes down to our values. We can still treasure the natural areas by how we design, conserve and acquire.”
To read the full Land Cover Mapping report report, go to hat.bc.ca.