Sunday, February 6, 2011

Native Plants for Green Roofs - Exploring Potential Ecosystem Types

Native Plants can be used on Green Roofs.

Green roofs and sustainability go hand in hand and good green roof design will reflect the stewardship and incorporation of native ecosystems.

One interesting ecosystem that will hold potential for Green Roof Botanists and Enthusiasts alike is the 'Upland Glades' ecosystem.  Not unlike the everglades, an Upland Glades ecosystem is typically found near limestone outcroppings - for an interesting discussion of the everglades geology-ecosystem click here (opens in a new window).

Upland Glades can be found across the Southeastern United States - and typically have shallow soils over limstone rock.  The hydrology is usually rain water supplied and during the wet months the soils are saturated while months with little precipitation create hot, dry soils.  These conditions are similar to those on roofs.

For an excellent Florida Natural Areas discussion of Upland Glades found in Florida click here (PDF paper download).  This paper discusses the site conditions and plant species found in Florida Upland Glades.

Another excellent website discussion of Upland Glade ecosystems is 'Starkly Beautiful Cedar Glades' article on the Wildlife Garden website.  This article contains many photos of a limestone glades area, including mentioning of plant species and observations of wildlife utilization.  Click here for the website link.

Some of the similarities between Florida Green Roofs and  Upland Glades include;
  • potential for lengthy innundation and quickly thereafter long periods of drought
  • shallow soil depths
  • lack of organic matter in the soil
  • open areas subject to harsh winds
  • intense sunlight exposure
  • high heat retention and thermal radiation from surrounding solid mass
  • and more

There are also many inadvertent Urban habitat recreations of Upland Glades within your surrounding Urban Core area.

Buildings made from concrete block and brick simulate the native rock out-croppings.  Gutters that collect organic debris carried by winds will eventually see thin layers of a soil-like material form as the leaves decay.  Seed source also carried by wind or by birds will sprout and over time, unless the gutters or cracks and crevices in the buildings are cleaned, will sprout and grow in the gutter or out of a crack in the building - much like the way plant species do in an Upland Glade.

Driving around town, always watch for plants growing on the walls of buildings, on church steeples or out of non-maintained gutters.  The plants you see growing are those species that also may do well on a green roof.  They are proven survivors of nature-based irrigation, infertile soil, harsh environmental conditions and other factors similar to the ecological traits of an Upland Glade or a Florida Green Roof.

Urban Core Green Roof Potential or Exotic Invasive? - Glade Ecosystem Type Plant

Unfortunately, some of the most resilient plant species you may see in the humankind-made Urban Core Glade ecosystems could be exotic invasive species (such as some of the ferns you will often encounter).

Florida has a native fern called Wild Boston Fern, Nephrolepis exaltata, and then Florida also possesses non-native similar species such as Tuberous sword fern, Nephrolepis cordifolia.  

A good reference site about the Boston Fern in Florida from the University of Florida's IFAS can be viewed by clicking here.

Yet studying natural systems with similar characteristics to those encountered on a roof can shed light on  new opportunities, both with plant species and hydrology.

We will be trying many of the species mentioned in the FNAI article on trial roofs and will post results.

As always - stick with native species and email us with your questions!  Happy green roofing!


1 comment:

five boros mold removal said...

Sometimes the plants and ivy that lead up on the wall of a home cause mold beneath through damp i the walls.They have to be cleaned and maintained and looked after.