An Ecological Approach to Landscape Architecture
What nature looks like, or is supposed to look like, appears to be our problem, a cultural matter; it has little to do with ecology. – Laurie Olin, FASLA
Ethics and aesthetics are the same thing. – Richard Haag, FASLA
We, as landscape architects practicing in the early twenty-first century, talk a lot about ecology and ecological design. A glance at the program from the 2014 ASLA Annual Meeting in Denver or the 2015 ASLA Professional Awards illustrates this point. As we hurdle ever rapidly toward greater imbalance between limited natural resources and a growing human population, this resurgence of ecological discourse could build much needed momentum toward widespread application of a truly ecological approach to built and managed environments.
Landscape architectural history is populated by ecologically-minded thinkers, from Jens Jensen and Ian McHarg to current practitioners and academics like Carol Franklin, Grant Jones, Bill Wenk, and Chris Reed. More and more landscape architecture firms are collaborating closely with ecologists, and some have added them to their rosters. It’s an exciting time to practice ecologically focused landscape architecture; we are on the leading edge of what may prove to be a philosophical sea change in design and planning.
So, what does it actually mean to practice “ecological design?” How are academic theories, lofty ideas, and benevolent leanings transmogrified onto the physical plane? It begins with science.
Ecologists build models—not 3D models like those we construct to envision built work, but mathematical and algorithmic models that predict the outcome of a given set of ecological conditions. These models provide one of the best foundations upon which we can develop our designs. Detailed quantitative and qualitative analyses and projected outcomes can inform our design process and maximize the potential for ecological uplift—the net gain in ecological function between existing and proposed conditions.
Functional assessments that measure the relative health of a specific habitat or landscape also provide valuable data for driving the design process. Rapid assessment tools like the Hydrogeomorphic Method, or HGM, and the Evaluation for Planned Wetlands, or EPW, facilitate efficient analyses of a wetland’s ecological functionality. The EPW is particularly relevant for designers because it evaluates an existing plan or design, compares it to a reference site, and assigns scores based on a range of metrics. The scores expose the weakest aspects of the design’s potential to achieve ecological uplift, and the EPW includes design guidelines for increasing that potential. Additional assessment tools, such as the Stream Visual Assessment Protocol, or SVAP, and Habitat Equivalency Analysis, or HEA, can be utilized in similar ways to evaluate riparian and upland ecosystems, respectively.
Translating the results of data analyses and functional assessments into design solutions requires interpretation and adaptation. Ideally, this stage in the process is not linear; cyclical iterations of interpretation, conceptual design, analysis, and revised conceptual design produce alternatives that balance science, art, and culture. Design adapts to meet disparate objectives, and the built work continues to adapt well past project close-out.
Of course, many projects lack the necessary budget and/or motivation to complete rigorous scientific analyses. In such situations, landscape architects can apply the core principles of the ecological approach in the most appropriate manner possible. In doing so, we set the stage for successful establishment of functional habitat. Project scales, programs, and objectives vary widely, but below are some basic practices to consider to increase ecological value.
- Preserve existing native habitat and drainage patterns through sensitive design solutions. Restore historic habitat and hydrology if applicable and appropriate. Minimize fragmentation of habitat and drainage systems.
- Incorporate ecological systems into the site plan and infrastructure design from the outset, not merely as an afterthought or topdressing.
- Design for a multitude of plant and wildlife species. Understand the implications of the project upon pollinators, small mammals, aquatic and amphibious species, birds, and a wide range of native plants. Incorporate design elements that foster a thriving natural system.
- Consider the context. Assess the impacts of the proposed intervention on the surrounding natural systems. Ecological functions do not stop at property lines. Is there a potential connection? Can the design complete a missing link in a larger system?
- Maximize on-site connectivity. Capitalize on opportunities to connect planting areas, hydrology, buffers, corridors, greenways, and open space.
- Design landforms that maximize potential for habitat diversity and capitalize on potential to improve water quality. Introduce horizontal and vertical complexity with curvilinear forms that increase ecotone edges and create microtopographical features.
- Build healthy soils, or salvage and properly manage existing soils to preserve biological integrity during construction.
- Let the site inform the palette. Choose plants and materials that will thrive and function under existing site conditions.
- Use native plants.
- Diversify the plant palette. Even if planting in drifts and layers, include a wider variety of complementary plant species.
- Add structural diversity. Include a variety of herbaceous and woody plants, including grasses, forbs, shrubs, and trees.
- Incorporate stormwater BMPs to improve water quality and reduce irrigation demands.
- Conserve water with efficient planting and irrigation design.
- Get creative. Break the rules. Often the best solutions lie outside the norm!
Landscape architects are generalists. We understand a range of concepts and processes, and how to distill and synthesize them into successful built work. We have the potential to bridge the gaps between engineering, science, planning, and design. We can communicate complex ideas and visualize anticipated outcomes through graphic, written, and verbal methods. The ephemeral nature of landscape forces us to consider the effects of natural processes through time. We choreograph connections between humans and the environment. All of this means that we are uniquely positioned to champion the ecological design approach and affect positive change in the built and managed environments. We have the tools, the creativity, and the momentum. So, as Ian McHarg put it, “…let us resolve to green the earth, to restore the earth, and to heal the earth with the greatest expression of science and art we can muster.”
This article originally appeared in the 2015 Colorado Design Journal.
by Chris Loftus, RLA, ASLA, Ecology & Restoration PPN Officer