Why Living and Green Roofs are Critically Important as Urban Open Space Disappears

Habitat and green space are disappearing at alarming and exponential rates and living roofs along with rooftop permaculture are the answer to the dilemma.

Fact: The earth is not producing any additional new lands and open space.

Fact: The earth's population is increasing exponentially.

Fact: Open and green space is disappearing rapidly.

Fact: As buildings are built, hundreds of thousands of acres of rooftop are made available for reforestation and replanting of habitat and for food.

The Convention on Biological Diversity offers excellent information on just how fast habitat is disappearing and pressures endangered species face.

As Development Increases Habitat Decreases

Wildlife and plants need humankind to restore the habitat taken with development.  People need wildlife and plants for food, medicine, pollution and erosion control and especially for oxygen to breathe.

Without plants, our oxygen supplies dwindle and air pollution increases, creating potentially serious respiratory issues.

Smog is a term derived from the combination of two other words, ‘smoke’ and ‘fog’, reportedly coined by the Dr. Henry Antoine Des Voeux in 1905 referring to London’s fog.

Smog today can be attributed to automobile exhaust, coal burning and other industrial or combustion activities.  Carbon Dioxide (CO2) and other greenhouse gasses make up a large part of smog.

Smog issues are important to green roofs and vice-versa.  Smog may hurt green roof plants or possibly may help green roof plants.  Some, like the David Bellamy suggest plants grow quicker in the presence of increased CO2 levels, thereby absorbing more CO2 and serving as a balance to increasing CO2 levels.  Some studies show smog damages plants.  Regardless, Urban plants are vital to life in the city.

A great resource aid for further understanding atmospheric CO2 is available from Purdue University.  Dr. Kevin Gurney spearheaded an effort to develop a Google Earth map showing CO2 levels across the globe.  The data and Google Earth map are useful, not only in developing large scale urban and regional carbon budgets, but in verifying green roof design data also.

Ultimately, living roofs and rooftop permaculture can serve as a starting point for the restoration of volumetric green in the Urban Core.

But there is much to learn.

Growing plants on roofs has many advantages, including;

• freedom from many soil diseases
• good exposure to sunlight
• plenty of CO2
• freedom from pedestrian and vehicular traffic
• direct exposure to rainwater, and more

However rooftop gardens and living roofs also present many new challenges.  Living roofs are subject to increased winds, higher temperatures and other potentially harsh conditions.  Choosing the right soil mixture and formulation can be a challenge.  Yet since Urban rooftops provide a new frontier for food growing, habitat, permaculture and biodiversity, green roof science should become a priority.

As time moves forward and development continues, available rooftop acreage will only increase.

Lets look to the roofs as the next frontier.  Lets perfect the art of rooftop permaculture, providing food for the cities, planting native species alongside food, providing habitat and strengthening biodiversity.