Provide Natural Habitat

• Green roofs provide "natural" habitat for endangered and rare species affected by humans encroaching on land. With the expansion of cities, wildlife is forced to find new habitat and search for food sources. Plentiful green roofs support a microcosm of wildlife.
  
  Paul Kephart, executive director of Rana Creek in California, says his company specializes in habitat restoration and living architecture. In National Wildlife, he says he sees "green roofs as a way to restore biodiversity to the urban environment."
  
  

Absorb Rainwater

• Green roofs absorb a substantial amount of rainfall, minimizing stress to the city's sewage system. Normally during heavy rainfall in New York City, for example, the water goes into the East River, New York Harbor and Hudson River. With the green roofs soaking up the water, the city can potentially stop millions of gallons of contaminated water from entering the waterways, therefore protecting the water, natural habitat and wildlife.
  
  

Reduce Urban Heat Island Effects

• Another benefit of green roofs is they reduce urban heat island effects by absorbing sunlight. On a hot summer day, roof temperatures can be 50 to 90 degrees hotter than the air, according to the EPA. Shaded areas maintain a cooler temperature. This creates islands of hot air within cities.
  
  The hot rooftop heats storm-water runoff. This heated water flows through the storm sewers and into ponds, streams, rivers and lakes. Changes in water temperature affect the reproduction and metabolism of many species and is not only stressful to wildlife, but at times fatal.
  
  

Reduce Heating and Cooling Costs

• According to the EPA, reducing heating and cooling costs is one of the best ways to minimize the effect of commercial buildings on the environment. Green roofs do just that. In the summer, living roofs protect the roof from solar radiation. Evapotranspiration, water evaporating or transpiring from the ground surface into the air, cools the roof, minimizing and sometimes eliminating heat absorption.
  
  The insulation added by green roofs decreases the need for heating in the wintertime. Wildlife is directly affected by the overuse of heating and cooling systems involving the release of harmful carbon emissions. Green roofs significantly reduce the need for heating and cooling systems.
  
  

Supporting Rare Species

• Green roofs support rare species.Beauti image by Thilo Kierdorf from Fotolia.com
  
  Green roofs attract and support rare species worldwide. Paul Kephart's roofs in San Francisco are re-creations of the Bay Checkerspot butterfly's habitat. This butterfly with black bands and bright red, yellow and white spots has been on the federal list of endangered and threatened species since 1987.
  
  Though one insect disappearing seems insignificant to the well-being of the planet, each plant and creature plays its role in balancing nature. In Basel, Switzerland, the law not only protects endangered species but mandates the use of green roofs on all newly constructed buildings with flat roofs. Scientists in Switzerland have observed northern lapwing and little ring plover birds breeding and nesting on green roofs. Increased numbers of beetles and rare species of spiders also live on green roofs. This diversity of species is helping to restore the delicate balance within the ecosystem.