London's Dusty Gedge and Ecoroofs for Biodiversity

Dusty Gedge on Rooftop.

One of the silver linings of my unexpected stay in London last month was meeting urban ecologist Dusty Gedge and learning about the efforts of Dusty and his collaborators- John Little and Gyongyver Kadas- to promote ecoroofs in the U.K. and beyond (thanks to Mike Houck who connected us). For five of the eight days I was in London, Dusty graciously put me up at his place in Lewisham (South London) and gave me a fine introduction to London’s ecoroofs and the state of the art in their design to promote biodiversity.

A former street performer and entertainer, Dusty is probably the leading advocate for ecoroofs in the U.K. and a pioneer in designing urban ecoroofs to support biodiversity (in addition to multiple other values: water quality, carbon sequestration, reduced urban heat island affect, and esthetics). Dusty is involved in ecoroofs at a number of levels, from policy and planning; to design, research, and installation; and to public education and outreach that encourages local citizens to install small-scale community or residential ecoroof projects. Put in taxonomic terms, Dusty is a hybrid London version of our own ubiquitous and indefatigable Mike Houck with the Urban Greenspaces Institute and our internationally known ecoroof guru Tom Lipton at Bureau of Environmental Services.

In 2004, he co-founded the Living Roofs organization that educates
and advises on green roof development, especially in the U.K.Dusty is also a professional ecologist and ornithologist, specialising in brownfield ecology.

One of Dusty’s ecoroofs at the Komodo Dragon House at the London Zoo.

The view out Dusty’s apartment window of a mini-ecoroof where he grows some common rooftop plants for seed.

On Sunday September 13th I had the opportunity to attend an Ecoroof DIY workshop held at the Kent Wildlife Trust Headquarters outside of London in Maidstone, England. Dusty led the workshop with John Little a fellow collaborator in promoting, designing and installing ecoroofs to support biodiversity in the U.K. The workshop included a general introduction to ecoroofs, the values they can support, their design, and their installation. After the presentations by Dusty and John, participants were led through a process of constructing a 1’X1’ ecoroof template illustrating basic materials and design. For participating we got a free copy of Dusty and John's DIY Green Roof Guide.

John Little led us in constructing our ecoroof templates.

My partner, Joan, had already constructed an ecoroof on her garage. She shared photos and her experiences at the workshop.

In order to illustrate how to construct an ecoroof with the proper seal and water resistance, we constructed a roof corner with one layer of waterproofing and two layers of fleece.

Gyongyver Kadas and the Komodo Dragon House ecoroof at London Zoo.

On Monday Sept. 14, I met another of Dusty’s ecoroof collaborators, Dr. Gyongyver Kadas, at the London Zoo to visit Dusty’s Komodo Dragon House ecoroof and to visit one of Dr. Kadas's (Gyongyver's)ecoroof research sites. She is a researcher at Royal Holloway University of London and did her Masters thesis on spider populations on greenroofs, relating them to populations on brownfield sites. She recently completed her PhD researching biodiversity and green roof design. Check out this 2005 paper entitled "Green Roofs and Biodiversity” by Dusty and Gyongyver.

To get to Gyongyver’s study ecoroof we had to climb a latter in a woman’s loo in a building at the London Zoo. Here is Gyongyver extending the latter to reach her rooftop research site.

Once of the rooftop, I took some photos of the study roof and learned about the research design. The study roof is made up of 45 individual roof cells roughly 1.5 meters square and arrayed 9 by 5. Within the cells Gyongyver established mini-ecoroofs with three different substrate types (different combinations of crushed brick and concrete) and with different substrate depths ranging from 3.5 to 8 cm. On another site she varied organic content). Some cells were planted and others were allowed to self-seed. She has assessed and compared conditions of the different mini-ecoroofs cells largely with two dependent variables: plant diversity and invertebrate diversity. The invertebrate diversity measurements focus on spiders, beetles, and bees.

While we were at the London Zoo we saw David Cameron the leader of the Tory party and likely the next prime minister of England. Apparently he was having some sort of meeting with dignitaries at the Zoo. I snapped this photo of him playing with this monkey/lemur type creature. Gyongyver thought we would see a photo like this would be in the newspapers the next day. Gyongyver informed me that David Cameron is relatively good environmental issues. Supposedly the Labor, Tory, and Liberal Democrat parties have all become greener with the episodic electoral success of the Green Party. (BTW, a similar dynamic played out in the recent German election where the Greens made gains with a greener center-right coalition.) Gyongyver wanted to go talk to Mr. Cameron about green roofs but we did not get a chance.

Dusty and John have promoted structural diversity in their ecoroof designs in order to foster a diversity of micro-habitats favorable to wildlife, especially invertebrates. They advocate varying substrates and topography and have incorporated dead wood and other found objects to enhance structural diversity. Below is a sample of these techniques in one of Dusty’s roofs located at refuse and recycling depot in Lewisham. The tire and old shoes were just something they found on site and threw up on the green roof... part impromptu art and part habitat enhancement.

Dusty and John have used topography to substitute for sloped drainage layers in flat roofs (which apparently can be expensive) by designing channels with courser substrate that help drain the roof. Some of these channels are actually designed to contain shallow pools, thereby adding to habitat diversity. John Little pointed out in the DIY workshop that if a roof is going to leak it is not likely to be from the fact that it is a ecoroof. Moreover, the soil and fleece layers can actually extend the life of a roof by preventing degradation from solar radiation. Dusty also emphasized that solar panels need not be in conflict with ecoroofs designed for biodiversity since elevated panels can actually add to the diversity of rooftop habitats (he had a great photo illustrating this in his slideshow).

Dusty is also involved in landscape level planning to encourage more green roofs along waterways and rail corridors important for urban wildlife in London. It was clear from talking to him that ecoroofs are considered as mitigation for the loss of the significant ecosystem services provided by brownfields and other undeveloped sites that we- in Portland Oregon- do not often consider to be "habitiat." Increasingly Londoners appear to consider even the most degraded undeveloped site as a resource that provides important ecosystem services to the community, services whose loss should be compensated for via mitigation, sometimes with ecoroofs.

Still, Dusty emphasized that ecoroofs designed for biodiversity present the opportunity to “replicate” habitats not “restore” them. He encouraged me to think about the types of thin-soiled habitats in and around the Portland-Vancouver region that ecoroofs could most likely replicate. Balds in the Coast Range or in the Columbia Gorge came to mind. It does seem that ecoroofs present the opportunity to provide many of the low-structure vegetation habitats with grasses, forbes, and herbaceous plants that are increasingly rare even in many of our parks and natural areas that tend to contain either lawn or forested areas but rarely natural meadow habitats without woody vegetation.

Unfortunately I missed the opportunity to see some of Dusty's higher-profile commercial projects like the Canary Warf greenroof located on top of the Barclays bank building and the Laban Dance Centre greenroof. I actually plan to be back in London this fall and may try to visit some these sites if possible.

While staying in Lewisham, Dusty took me out one morning to tour portions of his local urban watershed and specific reaches of the Ravensbourne River.

The Ravensbourne is considered to be one of the most engineered waterways in the London metropolitan region.

Dusty has been actively involved in improving the Ravensbourne through a number of ecological enhancement projects.

Minor enhancements ranged from the installation of small rip-rap like structures placed in an a completely cement channel to add structural diversity and hydraulic variability favorable to plants and insects.

More ambitious enhancements included removing a cement channel wall and laying back the bank.

Dusty informed me that this was not the “historic” cross-section form of streams like the Ravensbourne that had steep banks composed of a mix of clays and aggregates. Hence, these ecological enhancements are not meant to be historical restorations but aimed at providing specific ecosystem services.

One large scale enhancement meandered a side-channel of the Ravensbourne through and active recreation park for flood storage and some habitat enhancement. While impressive in scale, I thought the riparian area left much to be desired. Dusty explained that increasing flood storage capacity and human access were primary goals of this project. The mainstem channel was allowed to remain much more vegetated for wildlife.

Below are a few more shots of parks and greenspaces in London that may be of interest especially to park and greenspace advocates in the Portland region.

On the commuter rail to from downtown London to Lewisham I saw this advertisement for South London’s “Green Chain”, a “branded” network of parks and greenspaces serving the community. This looks like the type of regional coordination and branding envisioned for the Intertwine effort in the Portland-Metro region.

While in London I explore Holland Park, Hyde Park, Kennsington Garden, and Regent’s Park as well as several smaller parks squares.
Holland Park Map, Wildlife Area, and Trail:

“The Serpentine” (Lake) in Hyde Park.

George Fredric Watts’ masterpiece, Physical Energy Statute, located in the center of in Hyde Park.

Some beautiful mystery ducks in Regent’s Park.

Tufted Duck in Regent’s Park.

FDR memorial in Grosvenor Square.

Rose-Ringed Parakeet in Kenningston Gardens.

Londoners clearly carefully manage dogs in Parks. I saw numerous signs like these meant to control, limit or prohibit dogs in parks.

Tango at Spitalfields Market Square. I have a new appreciation for urban plazas as great places to dance tango!

I concluded my stay in London by meeting up with Portland's own Steve Reed Johnson, who was in town on a sustainability tour. We had dinner and had an engaging conversation about Portland's peculiar civic life. It was great to see and visit with Steve and think about Portland from afar.

Later posts:

Some green & gritty rooftops in Basel, Switzerland

Green Roofs of Plenty in Stuttgart, Germany