“Green” Infrastructure

Nature is our most valuable infrastructure asset

“Green” infrastructure (or natural infrastructure) can be as, or more, effective than engineered or “grey” infrastructure. Natural infrastructure requires less investment up front, is less expensive to operate and maintain, and if managed properly is more resilient to weather damage. This natural infrastructure can provide us with several types of “free” ecosystem services:

  • Habitat services provide for the essential survival needs of a range of species, including safe havens, and the support of genetic diversity.
  • Provisioning services are the products obtained from natural capital, such as food, fresh water, wood, fibre, and energy (hydropower, wind power solar power, biomass fuels).
  • Regulatory services include carbon sequestration, climate and natural hazard regulation, waste decomposition and detoxification, air and water purification, pest and disease control, plant pollination, and erosion prevention.

At a time when concern is mounting regarding our carbon footprint, natural infrastructure can provide carbon neutral, or even carbon positive, alternatives. Supplementing or replacing “grey” infrastructure with “green” infrastructure can generate significant savings as well as support biodiversity. However, many of us are not used to thinking of aquifers, ditches, forested areas, foreshores, and creek beds – to name the most obvious natural assets – as part of any formal infrastructure, just as we are not used to thinking of the Earth itself as an intelligent, living biosphere, and so we may not take the types of precautions that maintain our natural infrastructure in good working order.Here are some examples of ecosystem services that we receive from natural infrastructure and how we can preserve them:

  • Aquifers provide potable water of excellent quality (if not polluted), as well as water purification and water storage services. Their protective aquitard needs to be kept intact to prevent the inflow of salt water and other contaminants, their watershed recharge areas need to be free of contaminants, and the watershed recharge area’s conductivity needs to be maximized through tree roots and other plantings.
  • Open ditches (rather than closed pipes or concrete culverts) that contain grass or other plantings slows down the movement of water runoff from roads, driveways, and roofs and gradually cleans it as silt and other contaminants settle out. Some of the water can also be recycled into the natural water balance by evaporation and infiltration back into the ground, thus preventing flooding.
  • Creek beds provide supplemental groundwater for aquifer recharge, and riparian vegetation stabilizes the creek banks and also filters and cleans the groundwater.
  • In addition to providing habitats for diverse species, forested areas can provide slope stabilization and aquifer recharge.
  • Experience with storm surge has shown that engineered works along a marine foreshore are much more vulnerable to storm damage than a natural foreshore. A natural foreshore, if properly maintained can protect the built environment from damage by absorbing wave energy and preventing inundation. It can also protect aquifers from saltwater intrusion.
  • Eel grass (Zostera marina) beds, or meadows, act as buffers that slow swift ocean currents as they approach shore and thus also create ideal habitat for fish, migratory water fowl, and countless invertebrates. They provide habitat ecosystem services by functioning as wildlife corridors for birds and invertebrates, salmon highways, shelter for a wide range of aquatic life, and nutrient-rich nurseries for a range of species including salmonid stocks. They also provide provisional ecosystem services by being a food source for various species, thus providing the basis for commercial and recreational fishing. They are known as “ecosystem engineers” because they also provide regulatory ecosystem services such as:
    • Carbon sequestration and “blue carbon”
    • Oxygen production
    • Wave and shoreline erosion protection
    • Water filtration by trapping sediment, sewage effluent, and other pollutants
    • Stabilization of the ocean bed

Eelgrass beds depend on photosynthesis (sunlight) for their nutrition; therefore, any regular shadowing of the beds from dock or anchored or moored vessels/floats also creates problems.