Burrard Inlet Environmental Indicators Report - the BIEAP and ...

Burrard Inlet Environmental Indicators Report February 2008
1. Tree Canopy Cover
Why look at tree canopy cover?
Natural vegetation, measured as tree canopy, provides
many ecosystem and economic benefits. Tree canopy is
particularly valuable in an urban environment, where
development tends to replace natural vegetation with paved
surfaces. Land use in the Burrard Inlet watershed includes
urban and residential areas at lower elevations and forested
mountain terrain at higher elevations.
Measuring tree canopy over time in the developable area
will track how well the region balances population growth
and development with ecosystem health. A decrease in tree
cover could be a trigger for policy makers to increase
Benefits of trees
Treed areas and a healthy tree canopy
provide many benefits to urban, residential
and undeveloped areas, such as:
• removing air pollutants
• providing shade
• providing natural rainwater
management
• taking up carbon dioxide
• evapotranspiration of up to 1/3 of
rainfall
• recharging groundwater and increasing
summer stream flows
• providing wildlife habitat and
maintaining biodiversity
When tree cover is reduced during
development, these functions can be
reduced. Communities replace lost natural
services with infrastructure, such as
stormwater conveyance and treatment
systems, and pay for long-term health and
economic issues related to air quality and
other contaminants.
Lions Gate Bridge and North Shore
Mountains
protection of tree canopy in the approval processes for land development.
Current status: Tree canopy cover is currently 42% of the entire developable watershed, and ranges
from approximately 26% in English Bay and Inner Harbour catchments to 84% in Indian Arm catchment.
Using tree canopy an indicator
The amount of tree canopy provides an indicator of
how land is used today and can be used to monitor
changes in the future. To describe the indicator, the
Burrard Inlet watershed has been divided into two
categories (undeveloped and developable land) and
four catchments (English Bay, Indian Arm, Inner
Harbour and Port Moody Arm) as shown in Map 3.
Undeveloped land is defined as higher elevation areas
that will remain mostly forested. Developable land
includes lower elevation land that contains or has the
potential to become urban and residential areas. 3
The Burrard Inlet watershed has a total area of
98,235 ha, with 76% of land in the undeveloped area
and 24% in the developable area. The undeveloped
area will remain forested, given the mountain terrain
and political boundaries; however, development will
continue in the lower elevation developable area.
Monitoring tree canopy cover in the developable
area keeps the focus on lands most likely to change.
The indicator was calculated by combining satellite
and Geographic Information Systems (GIS) data for
Burrard Inlet with a software model called CITYgreen to assess the quality and amount of forest in
the Inlet. Map 2 (the aerial photograph in Section 1) provides an overview of land use in Burrard
Inlet. Information on conditions such as rainfall, soil type, land use, zoning and elevation is
included. The model gives a measurement of tree canopy cover over the entire inlet, and allows a
breakdown of land cover type in the developable area.
3 The boundary between developable and undeveloped land is shown in Map 3 – 320 m elevation to the west of
Lynn Creek (in North Vancouver) and 200 m to the east of Lynn Creek, consistent with Official Community Plans.
This line places drinking water reservoirs and protected areas within the undeveloped area.
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