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Ecological Succession and Plant Choice

By Wes Griffith, BSLA Student, and Chris Sass, Assistant Professor, University of Kentucky

While participating in LAF’s 2015 Case Study Investigation (CSI) program, many themes came to the surface, but one stood out to us as an area directly addressable by landscape architects. That theme is the issue of ecological succession and plant choice. Ecological succession describes how ecosystems change over time, sometimes in a predicable manner, but not always. So how do we as landscape architects begin to address ecological succession through our sustainable designs and planting plans?

One of the first goals to help landscape architects think about ecological succession should be to set a long-term management plan that dictates how a landscape will be managed, including removal of invasive plants, the addition of native seed or plants, and the social dynamic of the site. Such goals were addressed in one of the projects we studied, the Lower Howard’s Creek Corridor Management Plan, which considers ecological, social and economic integrity.

A long-term management plan is necessary because succession occurs over a long time period. How long is long-term? Well for example, the second growth forest at Lower Howard’s Creek has been re-establishing since the late 1800s and we are just now starting to see some mid-successional species as early successional species are beginning to be replaced. Species such as Eastern Red Cedar (Juniperus virginiana), Honey Locust (Gleditsia triacanthos) and foxtail (Seteria spp) are being replaced by oaks (Quercus spp), Shagbark Hickory (Carya ovata) and Riparian Wild Rye (Elymus riparius). So how long is long-term? Definitely longer than our current 25-year project lifespan. This reminds me of the Iroquois maxim stating we need to plan for the seventh generation if we are to truly achieve sustainability.

The Coefficient of Conservatism (CoC) is a tool we can use to plan for ecological succession. CoC numbers range from 1 to 10, where lower numbers indicate a wider range of plant tolerance and higher numbers indicate a much lower range of tolerance. The later successional species mentioned above exhibit a higher CoC number, meaning they require a more specific habitat and exhibit a lower tolerance range. While it may seem like the right thing to do, using higher CoC plants in our initial planting plans is probably not the best idea. Unless we are certain — or make certain through costly amendments — that the specific habitat requirements are there, the higher CoC plants will not make it very long, and we will have wasted the plants and the opportunity. We see this mistake often in our profession. For example, a planting plan may call for Shooting Star (Dodecatheon meadia), which in many areas is endangered or threatened and has a high CoC. It is tempting to plant, but will this plant not only survive, but thrive and reproduce in a new planting area? Probably not unless the habitat is within its tolerance range.

Using the CoC, we can plan plantings by assessing the stage of succession we are designing. Higher CoC numbers will require very specific tolerance ranges and habitat types, while lower CoC numbers will be much less fussy in the landscape. Looking through some of the project planting schedules for the sites we studied, we noticed that the CoC values of plant species ranged from 1 to 10, the minimum and maximum numbers. The question becomes: What have we designed for? A highly established landscape that is fairly stable? Or one that is just beginning to establish itself at the early seral stages?

Maintenance plays an important role in how we begin to plan for successional landscape designs. We have found maintenance to be an issue at two of the sites we studied. Both college campus projects, Northern Kentucky University’s Norse Commons and the University of Kentucky’s College of Agriculture Alumni Plaza, used native plants, and unfortunately some of the planted species have been outcompeted.

In all, as a profession concerned with sustainable approaches, we should think beyond the 25-year mark and aim more for the century mark and beyond. Let’s be more like the Iroquois and plan for seven generations.

Research Assistant Wes Griffith and Research Fellow Chris Sass are participating in LAF’s 2015 Case Study Investigation (CSI) program and working to evaluate the environmental, economic and social performance of three sustainable landscape projects in Kentucky.

New LAF Development Manager

csanders-175wWe are delighted to announce that Christina Sanders had joined the Landscape Architecture Foundation (LAF) as Development Manager. In addition to her commitment to sustainable development, Christina has a notable corporate sector background in management, marketing, and sales.

Prior to joining LAF, Christina spent four years with Apple, working between Washington, D.C. and San Francisco. She held a role in business-to-business sales before joining the Apple Store Leader Program (ASLP), a competitive 24-month management training program. Upon completion of the program, she went on to excel as a manager dedicated to achieving company metrics and financial growth while simultaneously upholding Apple’s credo and ensuring employee development.

Most recently, Christina took a year to travel abroad with a philosophy to “travel slow” through countries like Laos, Vietnam, Myanmar, Morocco, and South Africa. Along with enjoying the thrill of each new place, Christina traveled intentionally in order to observe the impact of development on societies and cultures.

We are thrilled to have Christina on board!

Landscape Innovation Paving the Way... But Not Without Some Roadblocks

By Neive Tierney, MLA Candidate, University of Texas at Austin

The three projects I researched as part of LAF’s Case Study Investigation (CSI) program all share a common story: They are progressive landscapes featuring innovative components, which caused the projects to run into barriers during construction. These obstructions arose because each project was the first of its kind in its surroundings.

Houston’s Bagby Street Reconstruction is an example of a landscape architecture project that became a catalyst for political change. The project’s extensive use of rain gardens and the designers’ decision to reduce the street width and increase pedestrian area diverged from the traditional stormwater management systems accepted in Houston. Making such a radical change to something as institutional as street design did not happen without some serious push-back from various stakeholders.

In order to move the project along, the Mayor of Houston and her staff became involved and played a large role in the completion of the project. At the Bagby ribbon cutting ceremony in 2013, the Mayor released a Complete Street Executive Order which called for changing the way streets are designed in all of Houston. The Bagby Street Reconstruction is a compelling example of landscape architecture’s influence on environmental progress. Both the client and design team were willing to take the difficult path to execute the design intent. Although this meant that the project took longer to implement than planned, its ultimate success resulted in widespread acceptance of this kind of stormwater management throughout the whole city. The design team is currently working on a similar project on the neighboring Brazos Street.

bagby-raingardenBagby Street rain garden (Image: Design Workshop)

The park at the George W. Bush Presidential Library (GWBPL) is a true example of designing with nature in mind. The design intent was to set up the perfect conditions where native ecologies could effectively “work” on their own. The first task was to establish a vital and living soil. Finding a sufficient amount of healthy soil for a project of this size was impossible, so the design team had to construct their own. With the assistance of a team of soil consultants, 65,000 cubic yards of soil were repurposed for the site. Each specific ecosystem and plant community required its own soil type. Constructed soil had to be treated like the brown gold that it is. Every precaution was taken to protect soil from overheating and becoming compacted before it was used on the site.

Another crucial component of the GWBPL landscape is the native plant material. The project is composed of large swaths of vegetation types native to the Dallas area, such as blackland prairie. Ironically, local plant vendors generally did not sell these types of native plants and as such, sourcing plant material for the 15-acre park was no easy task. Plants were sourced from vendors in neighboring states, and many of the grasses were planted from seed. The outcome of this initial obstacle is that the demand from the GWBPL was so great that it changed the kinds of plant material now available in the region, with vendors now selling more native plants.

belo-recycled-waterIllustration of Belo Center water system (Image: Ten Eyck Landscape Architecture)

The Belo Center for New Media is a facility on the University of Texas at Austin campus. Most of the campus is composed of more traditional plantings with turf lawns and many historic oak trees. Irrigation techniques are different depending on the section of campus, but the majority of campus is irrigated with potable water from the City of Austin. The courtyard landscape at the Belo Center uses a highly innovative water system. Air conditioning condensate is collected and run through a planted fountain that cleans water and circulates it back to the site for irrigation. In addition, all rainwater from the roof of the Belo Center is harvested and stored in on-site cisterns.

The sophisticated water system was difficult to implement and, in fact, did not work as planned until recently — years after the project’s completion. So many parties were involved in constructing this system that the design team had to make educational diagrams illustrating which group was responsible for each part of the system. These diagrams were posted at important locations around the site during construction. The delay in getting the system operational resulted in a much larger potable water demand than the design intended. However, starting this year, with all the problems corrected, the landscape will only be irrigated with recycled water, making it the first landscape on campus to not use any potable water for irrigation.

The innovative qualities of these projects required additional work from their design teams, but this extra effort led to projects with significantly higher environmental performance . By researching and documenting these projects through CSI, I have a clear example of the power behind innovative design. The inventive qualities of landscape architecture can not only result in a successful project; they can catalyze environmental improvements throughout entire systems.

Research Assistant Neive Tierney and Research Fellow Allan W. Shearer, PhD are participating in LAF’s 2015 Case Study Investigation (CSI) program and working to evaluate the environmental, economic and social performance of three innovative landscape projects in Texas.

Bumps in the Performance Evaluation Road

By Erika Roeber, Bachelor of Science in Agriculture Candidate, South Dakota State University

dashboard-600wUS Highway 16-West between Rapid City, South Dakota and Mount Rushmore

Driving across South Dakota’s never ending interstate, you are likely to hit a few bumps. Evaluating the performance of the three projects we are studying as part of the Landscape Architecture Foundation’s Case Study Investigation (CSI) program was no different: smooth sailing at first with the planning of our economic and environmental benefits. The social benefits brought our first bump when our research team decided to conduct user surveys for each of the sites.

All survey research involving human subjects requires approval from a university’s Institution Review Board. To get IRB approval at South Dakota State, each researcher needs to have a Collaborative Institutional Training Initiative (CITI) certificate. The faculty Research Fellow was already certified, but I had to complete a course with multiple readings and quizzes — in all it took about ten hours to complete. After that, the process of submitting our proposal and getting approval on our surveys only took 1.5 days. Our expert tip: use exempt status and only have adults as survey participants; this makes IRB approval a smoother process.

Being native to South Dakota, I know there is more than just one bump along the highway. The Mount Rushmore Visitor Center Redevelopment presented a huge obstacle when it came to doing user surveys. In order to do research on any federal land, including all national parks and memorials, researchers must first obtain a National Park Service (NPS) research permit. This process takes anywhere from one to six months. Once approved, the researcher can use scientific equipment to gather data (i.e. thermometers, water samples, etc.), and they can distribute up to nine surveys on-site.

If the researcher wants to disperse more than nine surveys, they must complete an additional application through the Paperwork Reduction Act (PRA) and PRA Clearance, a term used for the process of obtaining approval from the Office of Management and Budget (OMB) for federally sponsored data collections as required by the PRA. This rule was put into effect due to increasing complaints from the public about duplicate and lengthy federal government data collections. The PRA clearance process can take anywhere from six to nine months to be approved. Upon learning this, it was evident that on-site user surveys would not be feasible within the CSI timeframe.

Instead, we decided to post our surveys online through social media. A member of the Mount Rushmore staff indicated that we would not have any regulatory difficulties doing our surverys this way. However, upon further research and after the survey had been posted, I discovered that online surveys do require PRA clearance if specific questions are asked. So we should have gone through the PRA process after all. This approval is not necessary for very general invitations for public comments and suggestions.

Through all the bumps in the road, we were still able to gather valuable data and information about the Mount Rushmore Visitor Center Redevelopment. Alternative approaches had to be taken, but they were doable given the variety of information that had been collected from past research. Despite the challenges, federal land represents an exciting opportunity for landscape performance research.

Research Assistant Erika Roeber and Research Fellow Matthew James, Ed.D are participating in LAF’s 2015 Case Study Investigation (CSI) program and working to evaluate the environmental, economic and social performance of three public projects in South Dakota.

Rainwater Capturing Strategies: Your Input Needed

Tum Suppakittpaisarn, a Doctoral student at the University of Illinois at Urbana-Champaign, is conducting a visual preference survey of urban stormwater management strategies. He is working under the supervision of Dr. William Sullivan in the Department of Landscape Architecture.

Landscape Architecture professionals, professors, and students (18 or older) are invited to complete a short survey to rate images of landscapes from seven cities across the United States. The images depict different ways of dealing with flooding and rain water. The survey takes less than 10 minutes to complete.

Take the survey

We appreciate your participation, supporting important research for the profession!