Envisioning a Biophilic Province
- SARAH VALENTINE DESIGN
- 1 day ago
- 7 min read
Visionary writer, ecologist and Nobelist, E O Wilson defined Biophilia in his book also of the same title that it meant human’s 'urge to affiliate with other forms of life’
Mass urbanization is now more localized than ever, and we, now more than ever, require guidelines for a landscape in line with a need, rather than urge, to cohabitate with other ‘forms of life’
Located at the conjuncture of three major ecozones, the Pacific Maritime wet coastal mountains, the freezing arctic of the Boreal Cordillera and the Montane Cordillera inland drylands, BC consists of multitudes of ecosystems found between the ocean, the tundra and the vast grassland ranges and home to a wide range of animal, fungi and plant species, as edges often are
Canada's tallest trees, the most rainfall, and the longest and deepest fiords are located in BC, as well as it's driest, wettest, coldest and hottest conditions. Towering rain-catching mountains and the ever-changing Pacific maritime climate gives BC its distinctive character
As of 2020 more than 2,000 species of animals and plants endemic to BC are at risk of disappearing - to reverse the fate of the most critically endangered species, supporting sharing space with wildlife to restore their habitats and ecosystems is crucial
The sterile trees and lawn landscapes of cultivated parks do not provide food, shelter nor breeding places for wildlife - it is reported that the number of threatened extinctions of higher animals in Sweden is directly attributable to urbanisation and the tendency to manicured parks
The past decade has seen the four most severe wildfire seasons on record in BC (2017, 2018, 2021 and 2023). Extreme flooding events following extreme heat domes have forced BC’s residents to flee their homes or seek the shelter of community services to cool down if not equipped with air cooling systems. Solutions to cool our streets and to keep them from flooding is imperative
The following are suggestions to achieve a holistic transformation of BC's increasingly urban areas by adapting more green spaces into our landscapes
5 Methods of Water Catchment and Water Conservation
Fully functional green streets require minor design modifications and an evaluation of how to maximize the benefits of environmental systems by improving onsite stormwater management and water quality
When building a new street, the layout and street network must be planned to match road function with environmental performance as well as understanding the existing hydrologic functions of the land (preserve wetlands, buffers, high-permeability soils, etc.) combined with minimal impervious areas
Minimizing street width by including alternative street parking configurations, vehicle pullout space, connected street networks, prohibiting parking near intersections, and smaller block lengths would increase the sense of community and provide less impervious pavement for runoff to sewer systems
1. Bioretention Cells & Retention Ponds
Bioretention cells are shallow, vegetated non-structural depressions cut out of the sides of streets (2) that are filled with a structural soil and amended with mulch (3) and organic matter (OM), often with a flexible underdrain discharge pipe (1)
Benefits include:
Collection, absorption, retention and storage of overflow of rainwater from storm events
Reduces runoff volumes and peak flows
Stormwater is filtered through vegetation and soil with the biological and chemical reactions which occur in the mulch, soil matrix and root zone
Filters either before discharge or infiltrates it into planting and soil components
Native planting can provide habitat for wildlife, including important pollinator species, increasing overall biodiversity, as well as the general sense of community with the possibility for environmental education
If planted with nuts trees, perennials, herbs and other useful and/or native plants, would help keep the planting sufficiently moistened
Nut trees would increase food security as well as foster a greater sense of community
Nut trees do not accumulate toxins as other food plants do
Sales from the nut trees could be donated to the food bank or children’ centres
2. Permeable Paving of Sidewalks, Driveways and Paths (not Streets)
Permeable paving has an aggregate base which provides structural support, runoff storage and pollutant removal through filtering and adsorption
Four forms of permeable pavement are:
i. permeable concrete
ii. permeable asphalt
iii. permeable interlocking concrete pavers
iv. grid pavers
Additional benefits of a well-designed permeable pavement structure includes:
Replenishment of groundwater supply
Cooler ambient temperatures by absorption of rainwater leads to more desirable neighbourhoods and greater community
Minimized vehicle hydroplaning and road noise
Air voids provide space for moisture to freeze and ice crystals to expand
Rapid drainage eliminating freezing puddles and black ice
A cost analysis of permeable pavement in Washington State found that both the construction and maintenance cost for pervious pavement was lower than traditional pavement once the cost of the management of the stormwater pond was considered
A cold climate such as BC's will need to adjust snow plowing and de-icing programs for permeable pavement areas
3. Side Street Swales, Vegetated Infiltration Basins & Raingardens
Bioswales are vegetated depressions with sloped sides, an in- and out-put and a centre that is deeper than the edges designed to slow down rainwater through a curving or linear path; most efficient when combined with amended soil materials, organic material and thick, diverse vegetation
Raingardens are designed to capture, retain and infiltrate rainwater in a bowl shape with a level bottom.
Benefits include:
Used to sink, spread and store runoff
Reduction of stormwater volume through increased capacity for infiltration
Improved water quality through vegetative and organic matter filtration
Reduced flow velocity of runoff by increasing channel roughness
Absorbing moisture which sustains vegetation
Charging groundwater reserves by percolating into soil
Sustain stream base flows
Attracting pollinators and birds, increasing overall biodiversity
More complex forms of swales options:
i. Bioretention cells
ii. Gravel storage areas
iii. Underdrains
iv. Weirs
v. Dry wells
If unable to preserve the naturally occurring soil and vegetation, thick layers of mulch are applied on the disturbed soil where there is the possibility of runoff
4. Curb Cuts, Water-harvesting Chicanes & Vegetated Curb Extensions
Including curb cuts into the streetscape focuses stormwater runoff into side street swales and water-harvesting chicanes, especially if positioned upstream of the storm drain
Benefits include:
Slowing down of traffic with narrower streets, making walking and biking safer
Beautifying neighbourhoods increases desirability and a sense of community
Naturally bioremediating contaminants
Freely irrigating plantings, encouraging food security if planted with fruit and nut trees and easy-maintenance perennial food crops
Shading and cooling neighbourhoods in the heat of the summer
Reducing heat-island effect (the above-normal temperatures caused by exposed pavement that absorbs and reradiates the heat of the sun)
Saving money and increasing financial resources for the Municipalities
If stormwater of 11 inches (280mm) - or equal 3 million litres of runoff of kilometre stretch of residential neighbourhood street – was directed to street-side plantings, rather than the storm drain, there would be enough water to freely irrigate over 400 native, food-bearing shade trees per 1.6 km
This would additionally reduce downstream flooding as well as cost of requiring an underground storm drain
In a simulated 25-year storm event flow test, the curb extensions captured 85% of the runoff volume that would end up in the combined sewer system and reduced peak flow by 88%
5. Street Tree Planters & Sidewalk Planter
Street tree and curbside containers are placed below grade, filled with structural soils and planted with trees and layered companion planting
Ideally, design street tree planters to be large enough to provide appropriate space for tree roots to grow to their preferred size with a healthy soil volume and able to accept the runoff from storm events
Allowing ultimate growing capacity in the tree’s root system allows for:
The benefits of a mature-sized tree in terms of shade, air-quality and carbon-sequestering
Increases the health of the tree
Numerous studies have shown that street trees increase the sense of community in a neighbourhood as well as increase the value of homes
Increases growth of the tree compared with a tree in a confined root space
Benefits of sunken street side tree planters are:
Street trees are irrigated by the street, and thus grow larger and healthier since they receive more water and nutrients
Creates a greater sense of community due to the shade, beauty, oxygen, carbon sinking actions of trees
Possible location of food plants, including nut and fruit trees, herbs and berry bushes creating greater food security
Studies of inner-city neighbourhoods show that vegetation increases residents’ use of local outdoor spaces, leading to more ‘eyes on the street’
Treed outdoor spaces have shown to be consistently more used by youth, adults and mixed-age ground than treeless spaces in a series of studies
Allows for sidewalks to be constructed near trees while still leaving void space for tree roots
Least expensive option to obtain the volume needed for tree roots unhindered by utilities, etc
Police crime reports that ‘greener surroundings associated with lower levels of fear, fewer incivilities and less aggressive and violent behaviour’ leading to greater sense of community (if planted with widely-spaced, high-canopy trees, flowers and other highly visible plantings)
Types of street tree plantings:
i. Root paths are a tunnel-like system which extends from the tree underneath a sidewalk and connects to an open space on the other side
ii. Silva cells are another option for supporting sidewalks near trees while still providing enough space for roots to grow. These plastic milk crate-like frames fit together and act as a supporting structure for a sidewalk while leaving room for uncompacted soil and roots inside the frame
iii. Structural soils means avoiding low quality soil and sod as such landscaped areas create polluted runoff because they quickly become compacted, instead having a calculated amount of a specific composition that provides structure to the sideway allowing the tree’s roots to grow unhithered
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