(I’ve made earlier postings on this topic, but this piece actually predates those.  I wrote this in 2013 while still working as a horticulturist for the City of Portland Parks and Recreation as a member of a Bureau committee that was working to define ‘sustainable landscapes’ so that we could begin to make our policies and practices more consistent with our ‘desire’ to create sustainable landscapes and protect the relatively intact ones that remain.  This was a difficult process.  We spent a lot of time discussing/arguing about what constitutes a sustainable landscape and ultimately the direction that Parks should be headed.

There was a large divide between those of us who saw ultimately, that the only truly sustainable landscape was one that recreated those native landscapes that preceded the massive changes that European Americans brought with them, so that our efforts should be on these, and those of us who, having spent much of our professional lives in the field doing maintenance in created/urban landscapes, arguing that these new landscapes played a necessary role in the modern world and that our designs and maintenance of them could be moved in a more ‘sustainable’ direction.  These urban/functional landscapes, whether for active sports, community gardens or even many passive uses, provide places and venues for activities that native landscapes cannot.

The organizational structure of the Bureau has been built around three primary landscape ‘types’: ‘natural landscapes’ which tend to be larger and border more densely populated sectors of the City, ‘contrived landscapes’ that are dispersed throughout the City and serve the more traditional Park functions for sports and more casual social use and the ‘enterprise landscapes’ of Golf and PIR that serve very narrow functions and depend on those uses for much of the revenue that supports them.  These are operated and maintained by discrete groups within the Bureau, have different cultures and priorities and view sustainability very differently.   Because these are all in a highly urbanized area the degree of historical disturbance and the continuous pressures that a concentrated population apply to them, they can never by truly ‘sustainable’ in that they will always require our active stewardship to counterbalance these pressures.  This is not to say that we give up on the idea of balanced/dynamic landscapes of appropriately chosen plant communities.  We just need to remember that these are urban areas and be good stewards of the land.  We can even move ‘high use’ landscapes in a more sustainable direction, both in their design and in their maintenance.  It is incumbent upon us to do this to ultimately minimize the pressures put upon them and natural areas by weeds, invasives and human use.)

The key to understanding what a sustainable landscape is, is in its definition.  A sustainable landscape can be recognized in several ways: it is stable over time; it requires minimal/ no inputs from outside of its ‘natural’ cycling of water, energy and nutrients; it is complex and diverse; its composition and structure vary across the wider landscape in accordance with the terrain, geological features and micro and macro-climate; its composition is consistent across a region, land mass/ continent and reflective of the natural history and particular species available there…and over time it can perpetuate itself while remaining in a ‘healthy’ state… without our intervention. [Italicized is added.]  They can also be characterized by what is not there: minimal to no human disturbance.

This is the crux of the problem for us[, disturbance].  For thousands of years in North America the native people lived without radically degrading their landscape.  As hunter/gatherers their survival depended upon an abundant and predictable supply of food and the various resources they required to sustain themselves and their way of life.  Even those peoples who practiced subsistence forms of agriculture were attuned to the realities and conditions of their sites.  [the italicized is added.] There is some evidence of peoples who did take too much and consequently died out, but because there was no written history these instances were mostly lost over time and consequently have been easily missed by us.  The successful native people were careful observers of the natural world and located themselves where the resources they required were more abundant such as along the coast line and where salmon runs were strong.  Successful peoples were careful not to ‘take’ too much from a place at one time, their approach, in some ways, reverential.  They learned, no doubt making mistakes, how to use fire to increase the abundance of those species they desired, that required the light a forest canopy absorbed.

Agriculture and industry ‘freed’ us from this old relationship all people once had with the Earth and its life.  We learned to manipulate the landscape to our ‘advantage’ to make it ‘more productive’ than it would be without our efforts.  At first our impact was relatively minimal.  Our population was small.  We selected seeds and animals that showed more promise than others.  We learned to prepare the ground with tillage and how with the use of irrigation we could assure ourselves a larger and more productive crop.  We did not notice, or care so much, what was lost in the process, because from the beginning we valued it less.  Our soils eroded and we ‘created’ and began to disseminate, weeds.  At first our impacts were relatively small, but our successes brought increased population and specialization which began the process of improved technology.  In themselves these are not necessarily bad things.  Taken to an extreme, we began to see our ideas, our technology, as superior to that of Nature.  The world we live in today is one we believe to be malleable to an extreme.  We believe that we can shape it with little negative consequence and can even recreate nature in our landscapes where we may desire to.  We can do this because, as a people, we have mostly ‘forgotten’ what a natural landscape is, what is essential to it.

There are two models for a sustainable landscape: wild, undisturbed nature in which we play a neutral part and the created landscape in which we as its creator play an active role.  Nature is undeniably sustainable.  The manmade, built landscape is where things get a little fuzzy and gray.  On the one hand, if we make a commitment, we can maintain the most fanciful, contrived, even ridiculous landscape, in perpetuity.  It is a given that we must be an actor in the landscape.  We live in it.  We use it.  We abuse it.  We must at minimum take on a role to offset our negative impacts.  If we do this, then our actions may be viewed as sustainable.  A landscape, routinely removed and replanted, such as an annual display bed, may by this definition be considered sustainable.  As we have experienced, however, while we may make such a commitment, budgets, expectations and priorities change over time.  What we were once committed to we may no longer be a few years down the line.  What was once viewed by the organization as a sustainable effort, is no longer.  This definition of sustainability is associated with political will, and though taken on willingly, may quickly be sacrificed as times change.  This is definitely a piece of the solution but not the entirety.  There are three other pieces to the solution: design, maintenance and use.

Design/Maintenance: A Linked Effort

Sustainable design, may appear simple to some, we duplicate the site specific landscapes that existed in undisturbed nature.  For a multitude of reasons this strategy, one taken on by various organizations and groups from Metro to BES to Parks to the Nature Conservancy and various Soil and Water Conservation Districts, has only been partially successful.  Efforts have relied almost exclusively on the use of native species.  What we have found is that these are often at a competitive disadvantage on the disturbed and compromised sites we have to work with.  Non-native, aggressive, species have self selected and often dominate any given site.  Purple Loosestrife, the misnamed Himalayan Blackberry, Reed Canary Grass and various annual Bromes, are a few examples of weedy species that can easily dominate many disturbed landscapes.  Despite thoughtful and concerted effort these can claim our most well intended projects.  Pandora is out of the box.  I would argue that plants must be included that can deny space to these disrupters.  If we do not do something to reduce/eliminate the production of seed, sooner or later they will reclaim these landscapes.  The point is, insisting on a locally native palette of plants, may insure that we won’t regain anything like a dynamic, complex and balanced landscape in our tenure here.  We have to be willing to look at the landscape without the purist’s eye.  Instead we have to make intelligent efforts to rebuild, to be patient and understand what we have put into action when ever we act.

In this sense design cannot be considered separate from maintenance.  What we do along the way is every bit as important as where we start from.  The key lies in minimal disturbance, which includes undoing, to the extent possible, the effects of past ‘wrongs’.  A sustainable design should, pre-empt, the need for disruptive maintenance practices.  In a sense, a sustainable design will be an ideal, something to strive toward rather then something to be attained simply upon completion of construction.  It will be unsuccessful to the degree that it still requires disruptive practices.

What then is ‘disruptive’?  The upending of the soil profile resulting from the never ending practice of cutting, filling and re-grading; altering the movement of water over and through the soil; the stripping of living plant material, of leaves and other organic matter and other disturbances of the soil surface, i.e., cultivation, as a routine practice, that in turn may alter drastically, the life within the soil upon which a sustainably operating landscape relies; the neglect of adjacent properties resulting in the establishment of weed populations that continuously re-infect the landscapes we are maintaining; the practice of routine irrigation in order to maintain the healthy growth of planted material shifting conditions in favor of many of the Eurasian weedy species that come from summer wet regions of the world; any use of a property that results in soil compaction which in turn limits all that may live below and above the soil surface; the addition of contaminants to a site be it waste the disposers are trying to get rid of cheaply or the use of pesticides intended to control some plant, animal, disease or fungal pest that threatens the planted landscape.

Sustainable practices will tend toward building health.  While an individual plant may be allowed to decline and die the goal should be an improvement in the overall health of the landscape.  The individual death of a plant or of a species on a site should be viewed as an example of inappropriate selection or placement, or as a signal that the conditions have changed since planting, perhaps enough to support other species. [The italicized is added.]  Such instances should serve as lessons to improve our practice.  Right plant, right place.

What we should be doing is creating place sensitive plant communities that not only work well within the particularities of the site but also work to improve the conditions for the members of the community.  Every plant has its own requirements that, provided for, will foster its healthy growth.  In turn each plant is active and effects the growing conditions of those other plants in the community.  They hold and release nutrients supporting soil micro-biota that are beneficial to their neighbors.  They are strong and thrifty taking no more than they need so as not to preclude the life of their neighbors nor are they so weak that they cannot tolerate the competition of the same.  In fact the whole landscape becomes a self-selected community, with many of the members being dependent upon the inclusion of others.

Careful studies of native plant communities have supported this view.  Fungi and bacteria that benefit one plant may be essential for the survival of another.  The addition of another species may crowd out one of the ‘keystone’ members resulting in the degrading/decline of the entire community.  It is a very complex process.

Today, in our landscapes, all of these relationships have been broken.  While we can identify with some confidence the members of these various communities, we can only very roughly compose them on the ground.  Our ignorance of their precise relationships and the non-existing supporting soil microbial life is daunting.  Life supports life.  Soil conditions cannot be created separate from the life that needs it.  We are caught in a chicken and egg story.

We have to, however, begin somewhere.  The species that once filled our landscapes before our heavy handed involvement, may no longer be the best or even viable alternatives.  Soil conditions and the inclusion now of thousands of other species here will not allow us to go back.  The natural, sustainable, landscape of the future will include some of the old members, but it will most assuredly include many of the new arrivals.  Regardless of what a sustainable landscape is composed of, it will require a degree of stability or lack of disruption on our part.  As long as we keep ‘wiping the slate’, as long as we allow vacant and under utilized properties to be major weed seed generators periodically mowed down thus preventing any stable perennial populations from establishing, as long as we continue to maintain unviable designs in a manner consistent with outdated aesthetics instead of changing them towards a more sustainable, input neutral, landscape, we will continue to fight and lose our landscapes.

With the limitations of an urban environment then what are we to do?  Designs should seek to re-establish the natural cycling of water and nutrients upon a given site.  These landscapes will inevitably be broken up by hard surfaces and the built environment.  These built upon pieces should respect these same directives to the degree possible.  The resultant landscape will be a network of landscapes that work not unlike wildlife corridors that support a wild population that would never survive on isolated islands.  Sometimes this may mean that built upon land be put back into use as landscape.

Landscapes should not have built into them expectations and maintenance practices that are ultimately unsustainable.  This calls into question the idea of formally laid out landscapes that are more concerned with an architect’s preconceived ideas than the particular demands and limitations of a given site.  Certain practices such as one species sweeps of plantings, that seem more concerned with an almost graphic designers concern for effect than they do for matching the horticultural requirement of a plant to a site, must be stopped.  These will inevitably require greater expenditure of resources to maintain than a flexible design that is sensitive to site realities.

Design should also concern itself with what is going on below the soil surface.  Upended, compacted fill soils do not exist in nature.  Building landscapes upon abandoned industrial properties with unconsolidated fill including rubble, and even organic layers that will be very slow to decompose buried away from oxygen and the organisms intended to convert it, is another model without precedence in nature.  In these instances every effort should be made to ameliorate these conditions before a landscape is installed.  Poorly draining heavily compacted soils are not conducive to deep rooting of forest trees.  If this is not kept in mind failure cannot be far behind.  Perched water tables and the rotting of root systems in the winter here must be expected.

Design should also keep in mind the use, and too often, over use of dense urban landscapes.  Heavy foot traffic can be one of the most compacting forces that can be inflicted upon a landscape.  Soil compaction destroys pore space, can stop completely percolation, greatly limits the diversity of healthy soil life possible within it and inhibits penetration by roots.  All of this works to drastically reduce what can grow on a site.  Annual Blue Grass can completely replace desirable lawn species.  Prostrate Knotweed and many of the common Eurasian weeds that have followed us around the globe occupy compacted beds.  Very few desirable plants can even survive in compacted soil conditions, yet compaction is often a fact of life in urban landscapes.  Our common practice of cleaning the ground surface even works against us in combating compaction.  Not only have we made it more difficult for soil organisms to move through the soil to aerify it, contributing to its crumb structure and tilth, but when we remove the organic debris, we remove the food sources of many of the micro and macro organisms upon whose existence good soil tilth depends.  In many cases, it is not just the removal of the debris that damages, but the relationship between the organisms and the specific components of the litter layer.  Many plants need the mulch layer that only their own litter can provide…and we rake it away to satisfy a misguided aesthetic.

When a landscape is designed plant choice is vital.  If the goal is to move closer to a sustainable standard, it is even more so.  The plants must stand on their own.  Maintenance is almost always intrusive and can be very disruptive which works counter to this ideal.  Time and energy invested into maintenance should be short term and move the whole landscape closer to its goal of sustainability.  There are choices to be made.  Most plants establish quicker and with a more healthy root system when planted out young and small.  However, a young plant may not be able to ‘fend’ off the aggressive moves of its neighbors, for example, a mature Manzanita has built up an organic layer beneath it that has allopathic qualities that will limit the incursion of other species, thus limiting their ability to take nutrients or water from the growing Manzanita.  In a stable natural landscape nature has time and numbers on its side.  Whether a particular plant lives or dies is less important as seeding is relatively broad and random, increasing the odds that enough young plants will thrive.  We don’t have that.  In addition we are working with a soil seed bank that includes a great many aggressive other species.  It therefore becomes necessary for us to take a measured, intelligent role in the growth and development of these landscapes over time.  This requires an almost intimate knowledge of the site and the goal.

Our role in this itself must become more engaged and dynamic in order to stay responsive to an ‘evolving’ landscape.  Over time choices will inevitably be made, maintenance choices, that will affect the design.  There will be a continuous evaluation of what is happening on the site and of what may need to be changed or continued concerning maintenance.  There will also be reason to periodically introduce new, or additional species to a site, but this should be done with careful consideration.  Over time, we will notice that some species are more successful than others and will begin to move around on their own.  Ultimately, a sustainable landscape will be able to perpetuate itself.  Planting a landscape full of plants that cannot reproduce is a dead-end.   Planting a landscape of plants that reproduce aggressively is as well.  The secret is in a balance.  If managers are looking for a scripted formula with a high probability of success up front, we won’t get anywhere.  Above all careful observation with some kind of peer review is necessary.  A model would be much like that used in the medical field in which the health of the patient is kept foremost in mind along with a clear understanding of the ‘patient’s’ history and regular consultation with one’s peers should the ‘response’ to an action not go as expected.

Getting back to a definition of a sustainable landscape, it is a landscape that is subjected to minimal disturbance; in which the natural cycling of water and nutrients is able to move along unhindered; is composed of species, above and below the soil, that can be best characterized as complex or diverse, vital and exist in relationship with one another, not merely a conglomeration; all of which allow it to function as a dynamic, yet stable, whole.  Such a landscape is ‘healthy’ and does not rely upon the constant addition of energy and resources that exist outside of it.  These outside inputs should be understood as necessary expenditures to maintain a landscape that is out of balance.  Having said that, it must be remembered that, most landscapes are currently out of balance and therefore unsustainable.  Because of this they will require large inputs of energy and resources to bring them back to balance.  Urban landscapes also exist with a human population that exerts considerable pressure on them in the form of both use and abuse.  They will always require offsetting inputs in the form of maintenance to keep them viable.  Lastly, because the native landscape is ‘broken’ and contaminated, we cannot merely put the plant pieces back together.  The relationships that once existed are broken.  New ones must be created.  This is a long term endeavor that will probably go on for generations.  We can begin by working to end the cycle of disturbance to the landscape and educating ourselves, our peers and community.  We cannot do it alone.

Reclaiming our landscapes and protecting them from constant invasion requires broad support and participation.  It must become a higher priority across our community.  Our efforts have thus far failed because the work hasn’t been understood and shared.  It cannot be accomplished by a handful of specialists.  Design, maintenance and use/abuse are all essential factors in this.  We all have a role to play.  We have spent many years in coordinated effort disrupting our landscapes, pursuing other priorities that have trivialized our landscape and followed an aesthetic based in habit and ignorance.  It will take a lot of thought and effort to change our course.  [Added]