Editorial

by Jake Fisher, Roy-Fisher Associates

Weinstein, Neil & Kloss, Christopher. The Implications of Section 438 for the Green Technology. Stormwater, March/April, pg 8.

In a recent editorial in Stormwater, experts Neil Weinstein and Christopher Kloss discussed the likely impact of Section 438 of the Energy Independence and Security Act. Weinstein and Kloss declare Section 438 requires federal facilities to meet predevelopment hydrology for new building construction over 5,000 square feet using planning and nonstructural and structural best management practices (BMPs) to the maximum extent technically feasible. The underlying goal is to protect and restore watersheds using technologies that make sense for the site and the targeted management goal thereby promoting the use and development of the most efficient technologies. Currently being produced (via an EPA Subcontract) is a guidance document which will create the framework for innovation and research needed to develop this high-performance approach.

Furthermore Weinstein and Kloss maintain Section 438’s representation of an “important next step toward improving the health of the nation’s waters and signifies Congress’ recognition of the work of the EPA and its partners advocating for greener stormwater controls.” Section 438 will bring increased green infrastructure at federal facilities. For example, vegetation will be used to intercept rainfall and evapotranspirate moisture back into the atmosphere, undisturbed or enhanced soils will allow natural infiltration, and water harvesting systems will collect and reuse rainfall on site. Green infrastructure, effective at reducing the volume, peak flow, and pollutant load of stormwater will be used to reduce the burden on existing infrastructure and to protect receiving streams. The new law allows the federal government to become the earliest innovators within the realm of sustainable infrastructure which can be used to provide numerous positive outcomes for the environment (and in so doing develop the federal government’s “economic and environmental sustainability”.

Weinstein and Kloss additionally assert the interconnectivity of water and energy stating “the transport, use, and disposal of water are energy intensive” and “integrated water management that recognizes the resource value of water will lead to improved energy efficiencies and conservation”.

“The federal government is the largest landholder in the US; the passage of the EISA, coupled with a renewed commitment to infrastructure investment, presents a unique opportunity to establish an improved infrastructure network”.

Glenn Acomb & UF Green Roof

Although your test plots are useful for general observations, I would caution you that they do not replicate green roof conditions very well.

Testing with container as small as these will yield results from which you cannot easily base conclusions.  The ambient temperature of a roof is a combination of the heat generated by direct and indirect means as well as the insulation provided by the plants and media.  The typical high temperature range for a Florida conventional roof is approximately 140+ degrees F, versus the high for a green roof at approximately 80 degrees F (UCF, Dr. Marty Wanielista, 6" planting media + 2" drainage media).  We have found our temperatures to be similar.

Your test plots will generate heat that is greater than normal and this will cause plants greater stress and lead you to believe that these conditions are typical of a green roof.  the heat will also distort the water balance by excessive drought and cause you to believe that you should irrigate more than you would in a green roof of a larger area.  The mortality you experienced is likely due to the heat and perhaps, drought. 

As I talk to many professionals that want to know my experience with the UF Green Roof, I find myself explaining that a green roof should not be seen too simplistically.  It is not as many believe, a mere planting of plants on a roof.  There is much more to consider.  It is an environment hotter and drier than a terrestrial landscape.  The media performs differently.  One must know much more about plants (growth rate, root depth, capacity to retain water, and more) as well as the water cycle/delivery and irrigation system for plant processing.

Your blog comments about plants and their appropriateness for certain media depths.  Please be careful with conclusions based from limited tests.  For example, I would NOT recommend Muhly Grass for even a 6" media depth.  It has not done well on the UF green roof, which is a 5" depth.  I would suggest at least 8" or 10" for a healthy plant.  If one wants to know for sure, pull up mature plants (from a similar soil and environmental condition) and measure their root system.  A depth of 4"-6" is not very much for most plants.  Further, with depths that shallow, the choices do not include many ornamental-like natives. 

In addition to the characteristic of media depth is another important issue of the media itself.  Most green roof product mixes are very well-drained shale-based (or similar type of well-drained soil) and the infiltration rates are much greater than soils in which we are accustomed for use in conventional terrestrial landscapes.  Infiltration is rapid and residual saturation is brief. 

I would recommend that you increase the plot size as large as you can to correctly base conclusions.  I am working on a paper that summarizes my experiences of the past year with the UF Perry Construction Yard Green Roof and it will summarize this and the plant material responses in a North Central Florida environment.  Many, but not all of the plants will easily adapt to a South Florida application. 

Glenn A. Acomb, ASLA

University of Florida
Department of Landscape Architecture and
The Program for Resource Efficient Communities

Attracting Wildlife

We are going to start a series of monthly green tip posts. These tips will reflect on a new way to help infuse your garden and life with green living!

Green Tip #1:

Attract Wildlife to your Garden

                                      Photo: Award winning Jacqueline Fiske Healing Garden                Photo Credit: Michiko Kurisu

Florida has a diverse wildlife population, but rapid growth throughout Florida is destroying native wildlife habitat. But, make some basic changes to your landscaping and you can create a yard that will provide habitat for a variety of birds, butterflies and beneficial insects.

• Increasing the variety of plants in your landscape design.
• Creating natural corridors with bordering properties to allow wildlife to move through the larger neighborhood.
• The easiest way to attract birds, butterflies and beneficial insects is to select and plant flowers, shrubs and trees that bear fruit, seeds or flowers that birds and other wildlife depend on for food.
• A birdbath, fountain or pond is an important source of fresh water that will attract birds. Constructed ponds provide important water resources for a variety of wildlife.
• Avoid using pesticides and other chemicals on a regular basis without reason. When necessary, choose the least toxic controls to minimize harm to birds, butterflies and beneficial insects in your landscape.

Source: www.Floridayards.org