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What makes a designed plant community different (and why it matters)

by Timber Press on October 7, 2015

in Design

Plants have evolved to grow among other plants, not as lone specimens. Typha latifolia, several species of Scirpus and Carex, and Eupatorium perfoliatum mingle on the edge of this pond.

Plants have evolved to grow among other plants, not as lone specimens. Typha latifolia, several species of Scirpus and Carex, and Eupatorium perfoliatum mingle on the edge of this pond. Image: Tom Potterfield

To create resilient landscapes, write Planting in a Post-Wild World authors Thomas Rainer and Claudia West, focus on a plant’s ecological performance rather than its country of origin.

A designed plant community is a translation of a wild plant community into a cultural language. Why do plant communities need translating? Practicality, for one thing—urban and suburban landscapes are so drastically altered from the historic ecosystems that once existed. Think of your home and then think of the landscape that existed there a thousand years earlier. The process of urbanization has entirely altered the environmental conditions. So a designed plant community may reflect these changes by incorporating a narrower selection of the most adaptive species. Or it may include species from different habitats to supplement a native palette, particularly when an all-native selection is not commercially available.

The second reason we create designed interpretations is to increase the pleasure and meaning of the plantings for people. This could involve increasing the number of flowering species to make the community more colorful. Or simplifying the palette of plants and exaggerating the natural patterns to make the plantings more ordered and legible. A grassland-inspired design may place accent perennials tighter together to make drifts even more noticeable. Or a single species of understory tree might be repeated in a woodland planting to create a more dramatic effect in spring. Amplifying the signature patterns of a plant community helps to make them more readable and enjoyable.

Designed plant communities represent a hybrid of horticulture and ecology. Because of this, we want to distinguish the creation of designed plant communities from ecological restoration. While designed communities may indeed provide many ecological services, they are not necessarily true ecosystems. We are optimistic about the ecological potential of designed communities, but some humility is still needed. Naturally occurring plant communities are the result of millions of years of natural selection and succession. It is doubtful that any designed planting plan could replicate all the dynamics of a real ecosystem. We still have much to learn. So until the research is more advanced, we consider designed plant communities to still reside more in the realm of horticulture than ecology.

Tight drifts of Persicaria bistorta and Iris sibirica seem to float in a matrix of Molinia caerulea at the Trentham Estate, a stylized representation of the patterns of a meadow.

Tight drifts of Persicaria bistorta and Iris sibirica seem to float in a matrix of Molinia caerulea at the Trentham Estate, a stylized representation of the patterns of a meadow. Image: Adam Woodruff

The concept of a designed plant community is entirely agnostic about where the plants come from. The group can be composed of an international mix of species or an entirely native palette. In fact, a plant community may be composed of all exotic species and still engage in ecological processes similar to a naturally occurring community. This viewpoint differs from a small but vocal faction of the native plant movement that characterizes all non-native species outside the realm of ecology. This is simply not true. All species—native and exotic—have specific ecological niches and interact with their environments and other plants. The notion of the innate superiority of native plants is problematic in that it ignores the reality that our towns and cities are increasingly surrounded by non-native vegetation. While there may indeed be ecological benefits specific to certain native species, exotics can play important roles in the formation of plant communities. The obvious exception is when the plant possesses the potential to spread beyond the site and displace or disrupt local native plant communities.

Our focus is on plants naturally adapted to their specific sites. It is the relationship of plant to place we want to elevate. For this precise reason, native species can and perhaps should be the starting point for developing high-quality designed communities. In many ways, starting with a native plant community as a reference point can simplify the design process.

In order for a designed planting to become a community, two conditions must be met. First, all plants chosen should be able to survive in similar environmental conditions. A desert agave and wetland iris, for example, obviously would not work together to form a self-sustaining community. Compatible species should be able to grow and thrive within the same environmental stresses and disturbance regimes. The second precondition of a plant community is that the plants must be compatible in terms of their competitive strategies. Understanding these different competitive strategies is the key to plantings that last.

The show garden of Lianne Pot in the Netherlands features prairie-inspired perennial meadows. The modular approach repeats a mix of dominant theme plants with companion plants. Unlike their wild counterparts, they do not evolve, but are assembled and tended by people.

The show garden of Lianne Pot in the Netherlands features prairie-inspired perennial meadows. The modular approach repeats a mix of dominant theme plants with companion plants. Unlike their wild counterparts, they do not evolve, but are assembled and tended by people. Image: Adam Woodruff

Native plant communities offer an inherent advantage with regard to both these conditions. Simply put, plants that grow together in the wild will likely go together in a similar landscape setting. While it is indeed possible to substitute an exotic plant that may also be adapted to the same conditions, choosing plants beyond the range of an existing plant community increases the burden on the designer to understand how the plant will perform in a novel community. Combinations that already exist in nature are somewhat battle-tested. Many such associations have endured for thousands of years. The more our combinations differ from natural combinations, the greater the risk.

Perhaps the most compelling reason for starting with native plant communities is to give the site a sense of authenticity. The long, organic adaptation of plant to place produces a harmonic relationship that is almost impossible for a designer to fully replicate. Consider the beauty of even the smallest moments in the wild: how the bright colors of lichens and mosses balance the more neutral colors of rock outcrops and dried grasses that surround it; how the contrasting textures of ferns against a craggy shrub heath create a playful rhythm in a wet meadow; and how the silhouettes of dried seed heads pierce  through the misty inflorescences of grasses. It is the accumulation of all these details that conveys a spirit of place. Of course, a well-designed exotic ensemble can also tickle our memory of nature, but this almost entirely depends on the skill of the designer. Starting with a palette of plants that naturally evolved together just simplifies the task. Native plant communities often have all the various components—a complete ingredient list—necessary to execute a recipe for resilient and stable design.

Designed plant communities place the emphasis on a plant’s ecological performance, not its country of origin. We are interested in practical solutions, not ideological dogma. The combination of adapted exotics and regionally native species can expand the designer’s options and even expand ecological function. This gives the designer great flexibility to blend a variety of species to create likenesses of natural plant communities, including combinations that may not actually grow together in nature.

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rainer_tThomas Rainer is a landscape architect, teacher, and writer who lives in Arlington, Virginia. He has designed landscapes for the United States Capitol grounds, the Martin Luther King, Jr. Memorial, and the New York Botanical Garden. He has been featured in a range of publications including the New York Times, Landscape Architecture Magazine, and Home & Design.

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west_cClaudia West has an extensive background in horticulture, ecology, and environmental restoration. She is a consultant for North Creek Nurseries and has also worked for landscape architects Wolfgang Oehme and Carol Oppenheimer and for Sylva Native Nursery.

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Click the image below for a look inside this book.

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“A real-world guide for creating beautiful, ecologically connected landscapes. There is not a designer or property owner that would not benefit from their approach.”—Larry Weaner, APLD, founder of New Directions in the American Landscape

{ 3 comments… read them below or add one }

1 Jenn Lasko October 13, 2015 at 9:45 am

I think that the effect a plant community would have on other elements such as local wildlife-including birds and insect populations, waterways, and erosion/soil movement should be stressed though. Even if we don’t have an advanced enough body of research in that area, and want to view plant communities as more horticultural than ecology, doesn’t mean these things shouldn’t at least be considered as much as is possible in planning. The ULTRA project ( http://www.fsl.orst.edu/eco-p/ultra/index.html ), a slew of local research projects such as PSU’s Sustainability research ( https://www.pdx.edu/sustainability/caesp/research-and-education ), and Forest Service/USGS research such as the Andrews Forest ( http://andrewsforest.oregonstate.edu/ ) actually have a TON of data in this area. It’s not so much, in fact, that there isn’t advanced enough research, as that there hasn’t been any one willing to read through it all and present it for public consumption.

2 Asesh Lahiri October 14, 2015 at 4:48 am

Very interesting paper providing information on hybrid of ecology and horticulture.In this regard i cite an example of forestry where an artificial plantation of teak raised in grassy blank,gradually turned into teak with the natural vegetation in the middle and understory of the area with time when we studied after 35 years.

3 Evgeniya October 16, 2015 at 2:39 am

It`s really interesting information!Human & natura – best harmonacal style!

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