November 2010
An American legend in landscape design, John Charles Olmsted (1852–1920), helped plan Rock Creek Park in the heart of Washington, DC along the Potomac River to provide the public with trails for hiking and areas for other public activities. Photo: Oksana Hlodan.
Approaching landscape design in a sustainable way has implications for everyone, but especially for the landscape designer—a term used here to include engineers, landscape architects, urban and rural planners, horticulturalists, and garden designers. While these disciplines are rarely what pop to mind when discussing the front lines of the environmental sciences, they are, broadly speaking, applied sciences, and they represent a vital link in the ability of science to impact our surroundings.
Landscape designers at all scales may need to evolve their craft and thinking to address:
- Time. Time is an explicit design element, whereby landscapes change naturally. Designers are catalysts of a landscape’s ecological path—not sculptors or painters of a stagnant medium.
- Culture. Human behaviors and cultural habits must be a factor in the equation. There is no more “away” something can go to; there is no more room to live beside nature but not in it.
Complex
Sustainability in landscape design has everything to do with complexity—with the interrelationship of the parts to the whole over time. Increased complexity gives landscapes resilience by
- embedding redundancy of function;
- inhibiting the transfer of problematic pests and diseases; and
- supporting a rich trophic network that allows an intricate balance of growth and decay.
Landscape complexity is largely the intersection of biodiversity and scale. Measuring biodiversity is more than counting the variety of bird species in a given area. It actually speaks to diversity occurring on many levels: from the molecular, cellular DNA-scale to the vast landscape mosaic, and the matrix of interior and edge, patch, and corridor. Though some landscape designers have already begun to address the need for complexity in the context of natural systems and at the mosaic scale, the transformation to sustainability will not be complete if we do not address diversity at the DNA scale.
Over the past 100 years, landscapes were often split into component parts because we valued predictability and simplicity, which came at the expense of sustainable functionality and variability. As a result, residential zones are severed from agricultural districts, and wilderness is separated from infrastructure, all with the idea that we have enough space for each of these to be independent.1
With infrastructure, for example, 20th century centralization gathered power generating stations into large inter-urban clumps, which created vast webs of power lines that shed electric power during the long transit between generator and end user. This system forced the generation of excess power to meet demands hundreds of miles away. In a sustainable landscape, power generation would be reintegrated into the urbanized landscape. It would require the fracturing of generation sources into hundreds or thousands of microgenerative moments, such as microturbines and rooftop solar power collection. This more eco-mimicking web of interdependent elements would replace the hub and spoke model.
An innovative program of the Nichols Arboretum, Michigan, initiated by Professor Robert Grese of the university at Ann Arbor, interweaves the design of the arboretum with research into the impact of fire management. Photo: University of Michigan.
Sustainability must also happen at the species and DNA scales, and tree biodiversity illustrates this model.2 Already, researchers and others—who understand that tree monoculture [in which there is only one species of tree] leads to a breakdown of resilience—are planting a wide variety of tree species throughout an area. The horticultural industry, however, has the habit of favoring plant cloning over seed germination. Though cloning is economically popular in part because it produces results faster, it is largely popular because these results are predictable. Cloning ensures that these trees will all have the same basic form and appearance—characteristics that the designers value highly and that too many consumers demand. For example, the landscape architecture firm that specifies 800 blue oak [Quercus douglasii] trees to reforest a subdivision site may be only vaguely aware that the horticultural supplier will likely deliver 800 copies of the exact same genetic code. Should Sudden Oak Death [a recently recognized disease caused by a fungus-like organism (Phytophthora ramorum) that is killing oaks and other plant species in the western U.S.3] infect this landscape, there are only two likely results: all 800 trees die, or all 800 trees are able to resist and survive.
Operative
Those 800 trees are just the beginning. Landscape architecture is called perpetually to design a static site, yet stasis no more exists in nature than in Hollywood—despite massive efforts to encourage eternal youth. Not only do designers request that the trees arrive nearly full grown—a practice that vastly increases the carbon footprint of a project by magnifying the size of machinery required to move the tree between any two points—they simultaneously design a site for the tree that absolutely limits the ultimate trunk girth and canopy volume achievable. Then they expect the tree to live as long as possible within these confines. Until landscape architect, researcher, and author, James Urban, began convincing others of the terminal reality of the small soil volume allotted to city trees, this issue had largely been ignored.4
The reality is that time passes, and a sustainable landscape must be able to sustain itself. Balance must be achieved between the maturing of the individual inhabitants, and the generation of new inhabitants. A grove of trees all the same age should worry any visitor, for death will come. Here, complexity of age speaks directly to the capacity of the grove to operate as a grove continuously.
Figure 1
Julie Bargmann considered all aspects of landscape design, including cleanup and maintenance, when faced with the challenge of a dilapidated shipyard. The Philadelphia Navy Yard district is now a significant mixed-use office, research, and industrial park. Photo: NavyYard.org
Dynamic stasis represents one form of regeneration—a key component of how landscapes operate. A biome survives interruption when the pattern of interruption is in harmony with the pattern of regeneration. The term regeneration is also used by clean-up artists (for example, Julie Bargmann5; see Figure 1 above), who are revolutionary in landscape design for their process-centric emphases on actual clean up, versus tossing a “lid” over the site and pretending the site is not toxic anymore. While comparatively few designers are involved with toxic sites, all must reclaim a “maintenance regime,” and they must make it a universal design component of every site—from schoolyards to parkways, and from backyards to playgrounds.
Maintenance is a huge challenge for landscape designers. Even when the cost calculation’s timespan is expanded to include enough years of operation to offset the money required for many sustainable features, when our own behavior is asked to change, we balk. Changing our habits causes hesitation because it asks us to shift from passive to participant—to move from the sidelines to stewardship. Looking at this more broadly, clients (including the public) are resistant because to date there has not been a habit of collaboration established between
- the community of research scientists developing new materials and methodologies;
- the design and engineering communities designing and building with these findings;
- the social scientists who study effective and efficient social change.
Understanding humankind as one of several forces impacting an ecosystem requires an objective view, and we must ask if our interactions are creating a sustainable balance, or are our interactions pushing the surrounding ecosystem out of balance?
Cumulative
Ecological functions, such as fire or the flow of wind and water, accumulate change over time and scale, as do our own behaviors (including neglect). Landscapes are not only inhabited by field mice and other animals, they are inhabited by humans locked into economic and social systems. Part of how and why landscapes function as they do is because their inhabitants—e.g., beavers, ants, elephants, or humans—interfere with them, creating a landscape built of the combined cumulative impact of natural forces and millions of discrete individual behaviors. Pollution and environmental degradation are mostly errors that build up over years. Rarely does a single wrong instance decimate a landscape; more commonly, decimation occurs from the accumulation of hundreds of small bad habits.
A park in Vintondale, Pennsylvania, includes treatment of water polluted by acid mine drainage. It is an example of learning-by-doing, in which a design innovation is being tested in the field, this one by Kristen Ford of North Carolina State University. Photo: AMD&Art.;
Take, for example, the rain. In many buildings today, the rain that falls on the roof drains into the gutter, down the drainpipe, and into a conduit, which connects that drainpipe either to a local sewer line, or to a culvert or ditch at the edge of the property. Viewed in ecological terms, rain on the roof (sheet flow) is converted into rain in the gutter (channel flow) and dumped offsite without soaking into the soil. Channel flow has higher erosive ability than sheet flow and less of a chance to infiltrate. Instead, the rainwater carves ditches and streams deeper, and increases the carrying capacity for streams and rivers, which means that larger and larger debris can move to the next town downstream, eroding its channels and dykes, and damaging their bridge pilings. In the stream beds themselves, erosion moves the rocks and soil faster than aquatic life can grow, and the resulting turbidity buries stream bottoms with fine sediment and greatly reduces how far into the water sunlight can travel; this diminishes the help gained from plant roots in holding the stream banks stable. Without aquatic plants, most fish have little to eat, and the stream slowly dies, even though it is full of water.6
More subtly, the same conversion of sheet flow into channel flow that reduces the volume of water infiltrating the soil also reduces the subsurface flow. Subsurface water moves much more slowly than surface water, giving the biotic life in soil time to filter impurities from the water. While surface flow will reach the stream within hours, subsurface flow may take days or months, allowing the volume of water flowing in the stream to remain more constant, and at a cooler temperature, despite gaps between rains. Subsurface flow also has the ability to infiltrate even further, joining ground water supplies in aquifers.
If these problems occur after the construction of a single house, it may not be noticeable, but cumulatively, these issues at the scale of an entire subdivision or office park can change the creeks nearby rapidly.
Implications for designers
This means that the science of environmentally sustainable design is largely about understanding process and function over time. The functionality of landscapes must become a design element, with fresh attention paid to duration, accumulation, and erosion. If all landscape designers were required to represent the projects over the first two decades of the projects’ life visually, clients would better understand the nature of the nature they are inheriting.
This representational shift occurring broadly across the disciplines is vital: how designers convey their ideas is how they are thinking about them, and the environment is not awaiting a single savior. A sea change within the design fields will produce, in aggregate, change far larger and more powerful than any one firm can produce alone. Landscape designers are on the front lines [and thus, leaders] in the efforts of environmental scientists to lean on cultural habits; and this capacity of the aggregate ought to be leveraged through policy shifts that would induce a few pivot points to leverage vast changes in design and construction. For example, when contractors put out projects for bid, the majority of buyers seek the lowest bid; yet, few consumers require that these bids represent anything more than the anticipated costs from sitting down at the drawing board to the grand opening. If instead the designers were required to expand their proposal to include the first 7–10 years of maintenance, functionality, and worker safety (a.k.a., life-cycle service costs,), then the implications of many sustainable choices would skew into favor with great haste.
Concerted effort is required to target a goal; to make the options and benefits familiar to the decision-making public; and to make the sustainable choices accessible—both physically and economically. Known to social marketers as the four P’s (product, promotion, price, and place), coordinating these ideas is complex enough that the temptation is to organize them for a vast audience, yet this would return our thinking to the “one massive solution” habit that birthed many of today’s dilemmas. It is important to target particular regions and to seek specific, definable progress goals. These are huge implications for designers, purported purveyors of idealized perfection, asking clients to change their cultural understandings of their role in the environment, or even their economic understanding of what constitutes trash.
What we can all do
Sustainable landscape design starts at home, and there are simple ways you can begin to achieve an eco-friendly space.
Plant a variety of trees to ensure survival of species at the DNA level. Photo: Microsoft Images.
- Compost your organic waste from plants to create natural fertilizer.
- Use a rain barrel to collect and store rainwater or use a drip irrigation system to water your plants.
- Emphasize species that are native to your region because they adapt well to their environment and better resist diseases and pests.
- Replace sections of grass, which consume water and fertilizer, with wildflowers or other plants.
- Volunteer to help your local beautification organization, such as a tree planting group.
© 2010, American Institute of Biological Sciences. Educators have permission to reprint articles for classroom use; other users, please contact editor@actionbioscience.org for reprint permission. See reprint policy.
