Thursday, September 22, 2016

Flora of the Now

Peter Del Tredici, senior research scientist at Arnold Arboretum and a lecturer at the Harvard Graduate School of Design, makes an excellent case for urban ecologies. In his article, Flora of the Future, in Places journal (April 2014, available at, Del Tredici emphasizes two ecological tenets: that environmental stability is an illusion, and that an unpredictable future belongs to the best adapted. Hence, the dynamics of urban plants. Peter also points out some fun “new infrastructural taxonomies” that include:
·         The chain link fence. “They provide plants — especially vines — with a convenient trellis to spread out on and a measure of protection from the predation of maintenance crews.”
·         Vacant lots. “Their soils typically have high pH levels, and they are usually colonized by a suite of plants that I like to refer to as a “cosmopolitan urban meadow.” 
·         The road median strip. “In short, the median strip is perfect for crabgrass.”
·         Stone and masonry walls. “From the plant’s perspective, these structures are good stand-ins for a limestone cliff, and many cliff species are well adapted to growing on city walls. “
·         Pavement cracks. “We tend to think of pavement cracks as stressful habitats, but in fact, as the water sheets off the pavement, it flows right into the crack, making it a rich site in terms of its ability to accumulate moisture and nutrients”
·         Specialized microclimates. “As an example, carpetweed (Mollugo verticillata), a summer annual from Central America, subsists only on air-conditioner drip.”
·        River corridors. “They serve as important pathways for the migration of both plants and animals into and out of the city.”

These are fun to think about, what are some other spaces unique to the urban fabric that create their own micro-ecologies—drainage swales, brick walls, flat roofs, parking lots, steps, utility rights-of-way, etc. How many species can we find?

Thursday, September 1, 2016

What nature will be like?

“Because life is fueled by the energy captured from the sun by plants, it will be the plants that we use in our gardens that determine what nature will be like 10, 20, and 50 years from now.”
 -- Doug Tallamy

Thursday, August 25, 2016

Transitional Ecologies

On a recent trip to Shanghai, China, I was struck by the sheer number of urban redevelopment projects happening there. The economy is booming in China, and it seemed that as soon as a residential district aged about 50 years it was slated for demolition and “renewal.” From the stacked elevated highways, the sprawling metropolis displayed dozens of recently bulldozed neighborhoods. The city was a checkerboard of grey concrete high rises alternating with walled-off rubble piles. Growing over the concrete debris were trusty early successional plants -- sumacs, grasses, plantains, and smartweeds. As a matter of fact, the rubble piles were one of the few areas where I didn’t see managed park-like landscapes in the city; they were about the only places that wildscapes can exist. 

This led me to think about economics as a driver of early successional landscapes in cities. It’s relatively easy to take down old buildings, it’s much more expensive and time-consuming to put new ones up. So the land often sits there while the wheels of economics spin. As the land waits, seeds blow in from nearby sites or emerge from the soil bank below. Flowers open in the first season, moths and butterflies dive in, spiders follow suit. Suddenly a thriving ecosystem occurs where none, and I mean none, existed before. Of course this doesn’t last long before new construction begins. But in the meantime, a foothold for new life begins its march into new territories. An age-old, time-tested march.

There are plenty of plants that follow human disturbances. Eastern American native peoples named the European plantain (Plantago major) “white man’s footprint” because it only appeared where the Colonists settled. Humans are a busy sort, and because of this, they continually create the way for opportunistic plants, animals, and diseases to thrive. Whether we like it or not, they are our constant companions and work to heal our landscapes. Urban renewal creates transitional ecologies, which in my book, can create important early successional plant communities. Maybe one will hopscotch near you.

Friday, August 12, 2016

Allowing for Landscape Dynamism

Landscape architects take immense pride in their sketches and the crafting of shining visions of what a project could be. These are beautifully rendered and often use freehand ink and marker drawings, Photoshop jpegs, 3d Sketchup models, and photo-realistic Lumion visualization software. Sometimes, these images are so lush and colorful that the clients will end up paying for a really nice sketch-- but in actuality is a dysfunctional design. But does the landscape ever really look like the image that they imagined? Does it ever take into account the droughts, the insect infestations, the eutrophic waterbodies, the reductions in maintenance budgets, or just plain decline of the entire system? Where is landscape process and the inclusion of ecosystem services in client presentations? Simple, it is intentionally and quietly not discussed for many projects. That magically falls to the realm of the client and the landscape manager.

Designers project their visions of what the landscape will look when it is semi-mature, usually 10 to 15 years out. The trees are large, the fountain is always flowing, and there are plenty of parking spaces available. Project sketches are an ideal of the project on a good day. The sun shines and has billowy clouds, there are happy children with kites and balloons in the air, and families out enjoying a Sunday stroll. Happy drawings (think Bob Ross) make for happy clients. But does this give clients a static view of their landscape that eventually guides their long term management? To account for this, do we expect the average person to have an advanced understanding of landscape succession and management? Do clients budget the landscape funding accordingly to keep that perpetual view? Landscapes are most often looked at as temporary gardens in a throw-away culture. If the old one doesn’t suffice, let’s get the dozers in and make a new one. New owners have new ideas and new image brands for their properties. And cities are ripe with areas for “redevelopment” (code for let’s take out the old and put in the new).

How can a design represent successional process?  A 2014 article in the journal Places discusses just that. Written by Chris Reed and Nina-Marie Lister, the article traces prior world-views of static ecological systems to today’s dynamic landscape processes.  Entitled Ecology and Design: Parallel Genealogies, the authors state “There is a growing recognition that what is needed are more flexible, adaptive approaches to managing human activities and designing within the systems that sustain us. What designers make of this has much to do with how change and dynamism are understood and interpreted in the humanities and within cultural production.”

 Lawrence Halprin waterfall sketch

There are landscape architects such as Michael Van Valkenburg, Michael Hargreaves, Richard Haag, and Ian McHarg that have incorporated some ecological process into their work; and are highlighted in the article. But this will happen only when designers realize that landscape is a living process, and not just a product. You can view the full article at

Thursday, August 4, 2016

Hybrid cities

"Why can we imagine smart technologies and not smart behaviors, smart institutions, and smart societies? Why think only of technology and not of humans and their societies that co-evolve with Earth?" --Marina Alberti, from

Wednesday, June 22, 2016

Lights Out? Give us back our Dark Skies

 Moonlight Tower, Detroit, 1900

In the early 1900s there was perpetual daylight over the city of Detroit. The Motor City had erected an extensive system of early street lights called Moonlight Towers--which stood nearly 16 stories high. These towers lit 21 square miles of Detroit and effectively turned night into day. Austin, Texas still has a few of these massive towers but they are now mostly gone from the American landscape, and were replaced by the ubiquitous shorter, less expensive utility pole. But since then we found out that artificial light at night is instead blinding us with light pollution. Excessive light at night impacts our environment, safety, energy consumption, and health. The American Medical Association has released a report affirming the dangers of excessive amounts of blue LED lights, which affect the circadian rhythms of humans and urban wildlife (AMA report available online at

The U.S. at night, 2012, NASA

Recent studies have shown that night lights are impacting urban vegetation as well. A paper entitled "Ecological effects of artificial light at night on wild plants" was published in the February 2016 Journal of Ecology by Bennie, Davies, Cruse and Gaston. In it, they find that lights at night change some plant species leaf and flowering characteristics, and can have significant effects on the health, survival and reproduction of plants. Many urban designers are now selecting night and security lights that have shields to light just the ground, rather than the entire sky. An organization called the International Dark Sky Association creates public awareness and assists conservation organizations with lighting management. You can find out more at

Monday, June 13, 2016