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Creating Biodiversity Through Rooftop Farming?

Green Team at Green Roof Technology, - Tuesday, June 19, 2012

By Kat Harrold

 

Photo By ~ Kat Harrold

Rooftop farming has the allure of self-reliance in a world of food uncertainties.

It is well known that urban agriculture on rooftops has recreational and educational value. However when it comes to economy and ecology these little pieces of intensive used land in polluted cities are more than questionable.

Depending on crop selection rooftop farms can provide habitat for several pollinators. At the same time they also provide food and shelter for insects, birds, and small mammals that might not be wanted. On ground remote locations it is very difficult and labor intensive creating a natural balance among wanted and unwanted organisms. Finally it depends on your goal, the time you like to invest, how much additional weight your roof can carry and last but not least your experience and knowledge in farming on impervious areas. Potentially urban agriculture on roofs or rooftop farms can be a diverse environment or – most likely - a monoculture stage for chemical warfare between man and nature.


Join us next week as we cover bio-diversity on semi-intensive green roofs!

Biodiversity on Intensive Green Roofs

Green Team at Green Roof Technology, - Tuesday, June 12, 2012

By Kat Harrold


Photo By ~ Jorg Breuning

Intensive green roofs with great media depth and plant selection offer ample opportunities for biodiversity.  Ramps or tiered levels offer roof access to non-aerial fauna setting the stage for the introduction and interaction of the surrounding ecology.  Just because a large animal such as a bear or moose may inhabit the local area does not mean that the intensive green roof must attract it to make the biodiversity effort a success.  Creating an environment which supports a variety of plants and fauna on the lower levels of the food chain benefit the entire food web for the surrounding area.  

Visit us again next week as we discuss biodiversity and rooftop farming!




Creating Biodiversity on a Green Roof

Green Team at Green Roof Technology, - Monday, June 04, 2012

By Kat Harrold

 

Photo by ~ Jorg Breuning

Creating biodiversity on a green roof or green wall is significantly different than restoring it on ground level.  On a rooftop there is no preexisting ecology to enhance; everything is from scratch.  In most cases the growing media is drastically different from the soil down below which in turn dictates what ecology can be supported.  Accessibility, high winds, and proximity to the sun can also be challenging issues for organisms.

Studies show that plant selection and depth of growing media have a greater influence on the biodiversity of a green roof than height.  In the translation of research covering the biodiversity of green roofs, “Where the Beetles are Crawling and the Honeybees are Humming,” the biodiversity found on green roofs as tall as 400 feet were comparable to that of lower green roofs.

Tray or modular green roof systems create the visual impression of a green roof by placing a series of planters close together.   The history of German trays, introduced in 1978, show that in most cases the performance of pre-planted boxes fail to meet performance and maintenance expectations.  The composition of a modular system simply does not provide the right set-up to reliably enjoy the 30 to 50 year lifespan expected from a built up equivalent system.  Additionally there tends to be incredible amounts of species die back during the first 5 years creating a sparsely vegetated monoculture setting.  These factors create a very poor and unreliable environment for biodiversity to take place.

Visit us next week for more information on bio-diverse intensive green roofs!

 

 


Engaging the Senses

Green Team at Green Roof Technology, - Thursday, May 31, 2012
By Kat Harrold

   

Photos by ~ Green Roof Technology

When designing green roofs which encourage human interaction it is important to keep in mind the 5 senses, taste, touch, smell, sight, and sound.  

Taste – While the a green roof may be a tough environment for some vegetation to grow, there are still several edible herbs that can provide delicious accents to a meal or tea.  Mint, chives, parsley, cilantro, thyme, oregano and rosemary are just a few edible herbs that thrive on extensive to semi-intensive green roofs. 

 

 

 

 

 

 

Touch – Flowing grasses with prickly seed heads and the fuzzy leaves of Hieracium create a dynamic contrast to the lush springy texture of succulents and sedum.  Small berms can be used to integrate ornamental grass areas into extensive green roofs while keeping weight restrictions in check.

 

 

 

 

 

 

 

Smell – Closely related to taste, many culinary herbs can also employ a richly scented environment.  Other fragrant options for green roofs are lavender, polyantha rose “the Fairy”, sage, and Echinacea Daydream.

 

 

 

 

 

 

Sight – One of the many beautiful things about a green roof is there are a multitude of drought tolerant plants which provide year round interest.  Late winter and spring welcome a blast of color from crocus, Sedum hybridum “Czar’s Gold,” Dianthus, and Allium.  Summer brings forth a variety of extended bloomers including Sedum kamtschaticum, Hieracium, and Telinum.  Fall offers a variety of color from Aster Purple Dome, Snowcap Shasta Daisy as well as a red and gold glow from the foliage of several sedums.  Winter blankets the roof in festive greens and reds.  Sedums kamtschaticum, ‘Czar’s Gold,’ ‘Blue Spruce,’ and spurium ‘John Creech’ maintain their green foliage while Sedum spurium ‘Fuldaglut,’ moranense, album ‘Coral Carpet,’ and rupestre ‘Angelina’ brighten the season with displays of red and gold.

 

 

Sound – Green roofs have the to power to not only clean rain and air pollution but sound pollution as well.  When designing a green roof to function as a patio space, consider using plants which rustle in the wind such as grasses.  The tall reeds create white noise which helps mask the sound of a busy street.   

 

 

 

 

 

 

 

Biodiversity

Green Team at Green Roof Technology, - Tuesday, May 29, 2012

By Kat Harrold

The American Heritage Scientific dictionary describes biodiversity as, “the number, variety, and variation of different organisms found within a specific geographic region.”  

A biodiverse environment can have both native and introduced species.  A mono-culture of a native species can be just as detrimental as having a monoculture of an invasive species.  The key word in a biodiverse environment is diversity.  For an environment to thrive there must be competition and prey predator relationships to strengthen the key players within that ecology.  

On ground level, efforts to promote biodiversity are typically geared toward enhancing or restoring the surrounding to preexisting environment.  Preexisting elements such as soil and accessibility play a critical role in what species can thrive there.

As a result of development, there exists a lot of fragmented habitat creating connectivity and migration challenges.  Some creative ways that connections can be made between severed environments are wildlife bridges, tunnels, and green corridors.  Wildlife bridges and tunnels serve not only as key instruments allowing safe passage from one environment to the next, they also cut down on traffic accidents.  Green corridors are often an area around a stream left wooded in a heavily developed area.  This area serves as a haven for bird and mammal migration.

While green roofs can provide habitat for biodiversity to exist they often have a similar challenge of disconnect for non-aerial fauna.  To create access to a green roof one option would be to design the building so that it is built into a hill or create a ramp which wraps up the side of the building to the roof.  Terraced landings or steps can also be used to promote access to the roof.  Species and size of fauna depending, green walls consisting of vines can also be a method of access.  

 

 

 

 

A Feast for Fauna - Creating Biodiversity for Pollinators

Green Team at Green Roof Technology, - Friday, May 11, 2012

By Kat Harrold

 

Photo - By Kat Harrold

Green roofs are more than just a lush tool for stormwater management.  Green roofs have other benefits such as the potential to bring forth a bountiful feast to pollinators.  Pollinators are critical to our survival making it possible for grow the crops that feed our hungry nation and aiding in the replication of vegetation which purify our air and bodies of water.  Pollinators include a variety of areal insects as well as a few birds and bats.  

A shining example of this style of green roof we have worked on is the Hamerschlag Hall at Carnegie Mellon.  Hamerschlag Hall features extensive and semi-intensive green roof areas with a variety of ground covers and tall grasses.  Herbaceous plants and sedums provide food while an array of evergreens creates opportunities for shelter.

On the rooftop of the Resource Conservation Technology Ice House we created a garden specifically for honey bees.  Fragrant drought tolerant herbs and bulbs bloom from February to November creating both seasonal interest and a consistent food source.  

Click here find out more about the specific plants used in the garden.

 

 

Signs of Spring

Green Team at Green Roof Technology, - Friday, March 02, 2012

By Kat Harrold


Photos by ~ Kat Harrold

 

Sedums may be great for the hot dry climate of the green roof there are more colorful accent plants to consider such as bulbs.

 

Early spring when sedum album is just starting to wake from its winter’s nap Snow drops (Galanthus nivalis) spring forth with their deep green foliage and delicate white flowers.    

Other excellent spring bulb choices are dwarf iris, crocus, daffodils, tulips, and chionodaxa.    As the seasons progress, splashes of color  can be added to the roof with bulbs such as allium and cyclamen in summer and early autumn.  

Many of these bulbs are native to the harsh environments of the middle east and western Asia making them perfect candidates for the green roof environment.

The general rule of thumb when planting bulbs on a green roof is to cover the bulb with 3 times with the amount of growing media as its height with the crown facing upwards.  In other words if you have a 1 inch tall bulb you want to cover it with 3 inches of growing media.  Therefore, larger bulbs will have greater success in deeper green roofs with a 4 inch or greater growing media depth.       
 

Green Roofs and Facades: A Habitat Template Approach

Green Team at Green Roof Technology, - Friday, September 30, 2011

by Jeremy T. Ludholm

 

Review by Kat Harrold GRP

Great article on using the potential our built environment presents for plant life rather than trying to turn it into an environment it simply is not.  This article explores how we can use plants adapted to rocky surfaces and windy areas to green our cities and our green roofs.   

Are there any rocky areas in a park near where you are?  What kind of plants do your find growing there and how might you be able to create a habitat for them in your built area?



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