Trees are falling in every municipality from Sidney to Sooke. New mapping by Habitat Acquisition Trust has revealed that in the six years between 2005 and 2011 the thirteen CRD municipalities lost 1037 hectares (2564 acres) of tree cover, roughly equal to losing Mount Douglas Park every year.
Habitat Acquisition Trust completed land cover mapping of the Capital Regional District (exlcuding the Gulf Islands). As expected the mapping reveals that the 13 municipalities in the Regional District have lost significant tree in the 6 year period covered by the report.
Trees play an important role our communities. They reduce flooding, absorb air pollutants and carbon, increase property values, provide habitat for wildlife, and contribute to our physical health and sense of well-being. In addition to the environmental and wildlife impacts, as trees are lost communities can expect to pay more for the services trees provide for free, such as stormwater management and pollution control.
The mapping also looked at changes in impervious surface (e.g. buildings and roads). In many ways, impervious surfaces do the opposite of trees: they increase water runoff, trap heat, and concentrate pollution in waterways. The six years between 2005 & 2011, the region was covered by 1500 hectares of new impervious surfaces.
The land trust’s findings highlight the need for action to be taken to reduce the rate of tree loss, and to plant new trees where possible. Some local governments are taking action. In 2010, Saanich adopted an Urban Forest Strategy aimed at achieving a sustainable urban forest with no net loss of tree cover. The City of Victoria is well into the planning stages of an urban forest strategy, and several other municipalities are looking into creating strategies as well.
There is an important role for private citizens in protecting and restoring tree cover in our region. Most tree loss occurs on private property, and not just on development areas. Caring for existing trees, and planting new trees helps to conserve wildlife habitat, shade our homes in summer and protect them from winter winter.
The Mapping was made possible in part with funding from the Real Estate Foundation of BC and the Capital Regional District, as well as in-kind resources and expertise from the CRD, District of Saanich, Gye & Associates Urban Forestry Consultants, Judith Cullington & Associates, and the District of Oak Bay. Photo analysis, mapping, data layers and report were prepared by Caslys Consulting.
Download the Executive Summary (2.5mb pdf)
Download the Full Report (35mb pdf)
Highlights of the Results
Of the 13 CRD municipalities, in the 6 years between 2005 and 2011:
• The District of Saanich lost the most tree cover: 378 hectares. Langford was next losing 118 hectares of tree cover.
• The City of Victoria lost the largest percentage of its remaining tree cover - 8.8%. In absolute terms, this was only 42 hectares, but the City of Victoria has a relatively small amount of tree cover.
• The Town of Sidney lost the least amount of tree cover at 7 hectares, but that accounts for 7.5% of the small municipality’s remaining tree cover.
• Metchosin lost just 1.3% of its tree cover (66 hectares), the lowest percentage of any municipality. Highlands was next best, losing only 1.4% (46 hectares) of its tree cover.
• Highlands also has the highest level of tree cover in the region: 84% of the municipality is treed. Sidney is the least treed - only 18.3% of the Town has tree cover.
Looking at impervious surfaces between 2005 and 2011:
• Saanich gained the most impervious surface at 532.8 hectares, followed by Langford, which gained 183 hectares.
• Sidney gained the least impervious surfaces – 19.2 hectares.
• Victoria is the most “paved” municipality; 55% of the municipality is covered with impervious surfaces. Highlands is at the opposite end of the spectrum; only 3.1% of the municipality is covered by roads and buildings.
About the Mapping
The mapping used orthophotography (air photos) of the region and computer aided analysis to build land cover data sets. Every square meter of the region was classified as belonging one of 17 categories, such as treed, impervious surface, agricultural land, and exposed soil. This process was repeated using 2005 and 2011 air photos, and enabled us to compare changes between the two time periods. Results were then summarized by municipality.
Tree cover and impervious surface results were further analyzed by looking at density levels of tree cover and impervious surface in a one hectare grid. The results of the density mapping and changes can be found in the full report linked to above.