Sustainable Horticulture

Wasted Yards to Mini-Farms

Posted by sustainable_hort on February 2, 2011  |  No Comments

Urban gardening continues to be an expanding trend. We are seeing more and more turf areas being replaced by some type of landscape, often food oriented. This does not break my heart. I feel most small yards (turf) are useless and a waste of space. Now, I have no problem with a larger yard, one that is used by children, pets and families for outdoor activities. Play on!

But many urban yards are just small patches of grass that need to be mowed, watered and fertilized. Some homeowners have moved to “more natural” landscapes that often incorporate native shrubs and trees to draw the local birds and insects, while many also save water. These choices are a vast improvement over un-used turf space.

Meanwhile, vegetable gardening remains hot trend, one that is seeing increasing sales. All part of the “urban homesteading movement.” The more dedicated homesteaders have also added a “perennial food system” with fruit trees, berries, grapes, and herbs. Why? Mainly because people are becoming more aware of what real food is, and this is one way to change what they eat. More and more families are realizing that food gardens don’t take much more water and fertilizer than a yard, and can be good exercise, and might even be close to fun. Good way to teach biology too!

But, the first challenge with many of today’s suburban lots is space. The empty lots and surrounding open areas of my childhood have disappeared. Today’s homes (many McMansions) have very limited outdoor space available to grow foods. So, intensive, raised-bed plantings, and careful use of sun exposed walls, fences, etc., still allow families to raise a significant amount of food. It just takes careful planning and consistent care. Add container gardening to the mix, and almost any popular vegetable can be grown successfully.

So, how? Let’s start with classic Square Food Gardening, by Mel Bartholomew, written 30 years ago (his revised book is readily available). Then, I will follow up with several other-related books that cover similar territory. They are all aimed at helping get you started changing your yard into a small farm.

In the original Square Food Gardening, Bartholomew produced a basic gardening book that also happened to cover his engineer-based, grid-growing system. The recent book explains the system well. But, according to several review comments on Google, much of the earlier basic gardening information has disappeared. I guess most of that information is available in many forms, from many sources, so the current edition is based on more photographs and less text to cover the same ground (no pun intended). The basic idea is still very useful.

One Magic Square by Lolo Houbein is, in some ways, almost a direct copy of Bartholomew’s work, except that the author bases her plans on 3-foot squares. She comes from Australia, so she may not even be aware of his history in small space gardening in the U.S. Still, the idea is the same. Still, it definitely serves the same propose as the earlier work, and she supplies 30 different designs for squares that meet different crop desires. These are very helpful to those getting started with gardening, who’s limited horticultural knowledge make planning difficult, especially in the first few years.

Sugar Snaps and Strawberries (Timber Press) by Andrea Bellamy does not instruct gardeners to plant in grids, but to use the smaller spaces around any home to grow food. Her food production is a community gardening plot and her third story balcony. Bellamy runs the blog, www.heavypetal.com., which supports organic gardening, and her experience with limited space makes her information particularly useful to those urban/suburban homes with vey limited space. She manages to cover most of the basic growing information efficiently, with useful suggestions on the best varieties and planting schedules for nearly year-around growing. She also includes details on container gardening, which is “gardening” to more and more people. Bellamy’s work creates integrated, food landscapes that blend in more naturally while maximizing growing space.

If you are looking at gardening more from the chef viewpoint, check out another Timber Press book, The Kitchen Gardener’s Handbook, by Jennifer R. Bartley. This book provides similar growing information and designs, but the real focus is the end products…the many recipes that use seasonal vegetables and fruits. As more cooks learn to use new vegetables and desire fresh ingredients, a home kitchen garden will probably be the focus of any landscape that replaces turf.

Finally, books with ambitious plans and growing information are useful to those getting started. But, does it really work? Can our neighbor’s yards become small farms? Edible Estates…Attack on the Front Lawn (Metropolis Books) edited by Fritz Haeg, with essays by food writers such as Michael Polland and Rosalind Creasy, take the issue head on. This is not a gardening guide, but an inspirational showcase of actual front lawns that have made the transition to “farm” successfully. Eight yards are examined, with design plans and step-by-step photos of the actual landscaping process.

Once you start this process, my advice is to take it slow and have a sense of humor. To keep you going, read Manny Howard’s My Empire of Dirt (Scribner), subtitled “A Cautionary Tale,” He seemed to run into an inordinate set of problems (it would discourage many beginners), but takes it all with a slightly dark sense of humor. There are a number of these autobiographical records of “becoming a farmer or urban homesteader” on the market today, but few work at this level of humor.

This whole trend is morphing, especially for young adults and young families, into a new homesteading movement…a reclaiming of the urban environment. It moves well beyond just having a small, kitchen garden to creating landscapes that more mimic the natural surroundings. It includes shrubs and trees that provide food, added diversity to draw beneficial insects and birds, trap and re-use rain water, adding chickens, rabbits and other small animals, composting, etc., etc. A visually strong introduction to this concept comes from the wonderful DK Press. Titled Self Sufficiency for the 21st Century, this larger format book runs through all the main activities that fall under this general heading. Written by Dick and James Strawbridge (co-hosts of UK television series It’s Not Easy Being Green), it is packed with how-to sections on building a home, energy and waste, growing food, animal husbandry, and many traditional home kitchen, natural medicine and craft skills, all aimed at living as far off the grid as a family might get in the urban environment. Most readers will probably only start with a few of the book’s actions, but it will give anyone a solid, visual introduction to this topic. I just love DK’s approach to making their books so visual and clear. When I travel, I use their city books because they, again, are visual. So, if you are dreaming of urban homesteading, study this book and read Howard’s view of the reality, and you might be ready to start.

COMING NEXT: The New Lawn, Part II: But, not all homeowners are interested or willing to make their lawn into a farm. No problem. There are many other options to the traditional lawns. The high maintenance turf can be replaced by more natural landscape spaces that mirror the surrounding environment. The post will cover some more recent releases that look at alternative landscapes.

Trees for CO2 Sequestration?

Posted by sustainable_hort on April 14, 2010  |  No Comments

(This is the first part of a two-part post on trees and CO2 sequestration, which looks at whether trees actually play a positive role. The second part will discuss the actual trees we should be using for this perceived benefit)

Trees can play an important, positive role in helping control the amount of carbon dioxide (CO2) in the atmosphere by absorbing that key greenhouse gas. The process, called “sequestration,” uses a tree’s photosynthesis to convert the problematic greenhouse gas to cellulose and oxygen.

As this concept has become more widely accepted and, as researchers continue to document trees’ benefits, it may expand market for some nursery crops. But, is all this excitement warranted, or do some recent questions contradict the enthusiasm?

What We Need to Know
The crucial questions at this stage become “does sequestration really work,” and if so, “which trees are most efficient at sequestration?” Research continues to delve into varietal and climate issues that affect how well a specific tree will capture CO2.

“We can certainly argue that trees, when they absorb CO2, buy us a period of sequestration,” said David Nowak, researcher at SUNY-CESF, Syracuse, New York.

But, Nowak, who has lead several major sequestration studies, points out there are many variables that need to be studied, including climate effects, tree species and age, and even the general maintenance issues.

“These all can impact the effectiveness of a tree to sequester CO2,” he said.

Other research has pointed out some distinct differences based on climate. In fact, recent computer models are even speculating that non-tropical trees might even increase planet temperatures.

But, planting trees in [any] climate is better than not. So, how does it work and what does research indicate as the best options for using trees to reduce atmospheric CO2?

What is Sequestration?…Removal of Air Pollutants
Air pollution can be reduced dramatically when plants take up CO2 and many airborne particles through their leaf stomata. Some other gases are removed by the plant leaf and stem surfaces. Gases absorbed by the plant stomata later diffuse into intercellular spaces. They then are absorbed and react with water films to form acids, or they react with inner-leaf surfaces. Some particles can be absorbed into the tree, though most particles that are intercepted are retained on the plant surface.

Some polluting particles may return to the air during transpiration or be washed off by rain. Later, the leaf and twigs may drop off the to the ground and start to decompose. This also releases some of the CO2 back, which offsets some of the early gains. Consequently, vegetation remains only a temporary site for retaining many atmospheric particles.

Benefits of Trees
Plant-It 2020 uses a ‘scientific estimate’ to develop the following statistics based upon the tree species, soil conditions and tree-planting methodology,

Their research indicated that 600 trees in the tropics would fill one acre, which could sequester up to 15 tons of CO2 annually. Other statistics include 40 trees (common varieties) will sequester one ton of CO2 each year; and that one million trees covering 1,667 acres could capture 25,000 tons of CO2 annually.

Research in major metropolitan areas showed the urban forests could have an impact. It was reported by David J. Nowak in “The Effects of Urban Trees on Air Quality” showed that in 1994, trees in New York City removed an estimated 1,821 metric tons (t) of air pollution at an estimated value to society of $9.5 million.

His research showed that while New York’s urban forests removed pollution more than Atlanta’s (1,196 t; $6.5 million) and Baltimore (499 t; $2.7 million), but pollution removal per square meter of canopy cover was similar among these cities (New York: 13.7g/m2/yr; Baltimore: 12.2 g/m2/yr; Atlanta: 10.6 g/m2/yr). These standardized pollution removal rates differ among cities according to the amount of air pollution, length of in-leaf season, precipitation, and other meteorological variables. Nowak’s work noted that large healthy trees (greater than 77 cm) annually remove about 70 times more air pollution (1.4 kg/yr) than small healthy trees (less than 8 cm in diameter) at 0.02 kg/yr.

His 2002 work matched earlier research regarding total CO2 sequestered within the US. Total carbon storage by urban trees in the coterminous United States is estimated at 700 million tons. These data correspond with previous analyses that estimated national carbon storage by urban trees as between 350 and 750 million tons and between 600 and 900 million tons. Carbon storage by urban trees nationally is only 4.4% of the estimated 15,900 million tons stored in trees in USA non-urban forest ecosystems. The estimated carbon storage by urban trees in USA is equivalent to the amount of carbon emitted from USA population in about 5.5 months based on average per capita emission rates.

The research reported that “urban forests in the north central, northeast, south central and southeast regions of the USA store and sequester the most carbon, with average carbon storage per hectare greatest in southeast, north central, northeast and Pacific northwest regions, respectively. The national average urban forest carbon storage density is 25.1 t/ha, compared with 53.5 t/ha in forest stands.”

He felt this data could be used to help assess the actual and potential role of urban forests in reducing atmospheric carbon dioxide, a dominant greenhouse gas.

Nowak’s research report stated the following:
“Air quality improvement in New York City due to pollution removal by trees during daytime of the in-leaf season averaged 0.47% for particulate matter, 0.45% for ozone, 0.43% for sulfur dioxide, 0.30% for nitrogen dioxide, and 0.002% for carbon monoxide. Air quality improves with 2 increased percent tree cover and decreased mixing-layer heights. In urban areas with 100% tree cover (i.e., contiguous forest stands), short-term improvements in air quality (one hour) from pollution removal by trees were as high as 15% for ozone, 14% for sulfur dioxide, 13% for particulate matter, 8% for nitrogen dioxide, and 0.05% for carbon monoxide.”

Meanwhile, www.plantit2020.org, has summarized recent forestry science studies in carbon sequestration related to trees, including the following:

The U.S. Forest Service estimates that all the forests in the United States combined sequestered a net of approximately 309 million tons of carbon per year from 1952 to 1992, offsetting approximately 25% of U.S. human-caused emissions of carbon during that period.

The US Forest Service also feels that large diameter; long-lived, leafy trees are more beneficial in regards to carbon sequestration. For example, they point to the fact that Atlanta’s 9 million-plus (mostly mature, broad-leafed) trees absorb about twice as much as Calgary, Canada nearly 12 million trees (many conifers).

They also noted that tree species is a strong determining factor regarding carbon sequestration, which vary by species in their rate of storing carbon, though research is still needed.
But, as a counter action, trees also vary in how many and how much harmful volatile organic compounds (VOC’s) they emit. One common example is isoprene, which produces the greenhouse gas ozone.

So, the best tree species is one that rapidly sequesters carbon but does not register high outputs of VOC’s. Long-lived trees (those living more than 50 years) are preferred by the Forest Service for carbon sequestration as dead trees rot – releasing all of the carbon that has been stored. US Forest Service recommends the following species for the United States…American basswood, dogwood, Eastern white pine, Eastern red cedar, gray birch, red maple and river birch.

Nowak does point out that the placement of trees actually has more impact that sequestration.
“The bigger impact comes from planting a tree in the proper location where it can provide cooling for buildings,” he said. “Just by preventing the added CO2 being emitted during air conditioning, trees can have four times the impact they have in sequestration.”

So, there are many functions to consider to maximize a tree’s impact on the environment, he cautioned.

Tropical Versus Temperate Zones
Another study, lead by Lawrence Livermore National Lab, indicated that trees planted closer to the equator sequester more carbon than those planted far to the North. Why this might have happened is still unclear. Some expert speculated that Southern tree species are often larger, long-lived, leafy trees compared to northern species.

Their computer models seem to confirm this observation. They built a model to determine the impact on temperatures forests have in different parts of the planet.

They focused on three key factors in their analysis:
• Forests can cool the planet by absorbing the greenhouse gas carbon dioxide during photosynthesis.
• They can also cool the planet by evaporating water to the atmosphere and increasing cloudiness; a deck of white clouds reflects incoming solar radiation straight back out into space.
• But, trees might also have a warming effect. They are dark colored, absorb sunlight and hold heat near ground level

“Our study shows that tropical forests are very beneficial to the climate because they take up carbon and increase cloudiness, which in turn helps cool the planet,” explained Dr. Bala, an author on the Livermore study.

So, the further you move from the equator, the more these gains are eroded she stated. The team’s modeling predicts trees planted in mid- and high-latitude locations could cause a net warming of a few degrees within a hundred years.

“The darkening of the surface by new forest canopies in the high-latitude boreal regions allows absorption of more sunlight that warm the surface,” Dr Baal said.

Counter Views
But, despite the general excitement over planting trees, no, literally planting forests as a solution to global warming, has hit some speed bumps recently.

In addition to the Livermore computer model concerns, two other recent papers in the scientific literature raised questions about the benefits of terrestrial carbon sinks. One paper, by Frank Keppler, Max Planck Institute, discovered that plants emit significant amounts of methane, which is a potent greenhouse gas, which traps heat much more efficiently than CO2.

Another study, by Robert Jackson, Duke University, found that plantations could reduce stream flow and increase salinization of soils to a greater extent than previously recognized. It looked at existing conversions and showed that the growing trees had larger water demands than crops or pastures “dramatically decreased stream flow within a few years of planting,” the authors wrote.

They also found that water use within existing tree plantations of all ages resulted in average stream flow reductions of 38 percent. Losses increased as the trees age, and “13 percent of streams dried up completely for at least one year,” the study said.

Overall, the tree farming used about 20 percent more rainwater, the study estimated. So, additional tree planting for carbon mitigation could have large impacts on nation’s water resources. This is ore of an issue in nations that net less than 30 percent of their total annual supplies of fresh water from rain, the authors predicted.

This has lead to experts some questioning the overall tree planting strategy, but others view this speculation as overblown.
Nowak also cautioned that urban tree management practices could diminish the net effects of urban trees on atmospheric C02. Activities used to maintain vegetation structure and health (e.g. from chain saws, trucks, chippers, etc.) emit carbon via fossil fuel combustion. Thus, too much maintenance could cause urban forest ecosystems to become net emitters of carbon unless secondary carbon reductions (e.g. energy conservation) or limiting of decomposition via long term carbon storage (e.g. wood products, landfills) can be accomplished to offset the maintenance carbon emissions

“Carbon released through tree management activities needs to be accounted for to calculate the net effect of urban forestry on atmospheric carbon dioxide,” he said.

He argues that unless there are secondary carbon reductions (e.g., energy conservation) or limiting of decomposition via long-term carbon storage (e.g., wood products, landfills), urban forests lose much of the sequestration gains. This, in turn, affects the species composition and tree maintenance activities chosen for an urban forest.

Some Conclusions
So, where does all this leave with trees and their effects on CO2 sequestration?

To maximize the net benefits of urban forestry on atmospheric carbon dioxide, Nowak wrote that urban forest managers should focus on the following:
• Planting long-lived, low-maintenance, moderate to fast-growing species that are large at maturity and matched to site conditions;
• Using maintenance activities that increase tree survival and longevity;
• Minimizing fossil-fuel use related to management and maintenance activities;
• Using wood from removed trees to delay decomposition or decrease the need for energy from fossil-fuel-based power plants (e.g., develop long term wood products; burn wood to heat residences); and
• Planting trees in energy-conserving locations.

This was summarized clearly by Greg McPherson in a Arbor Age article “Urban Tree Planting and Greenhouse Gas Reductions.”

He wrote that…”The climate benefits of trees in mid-latitude cities are not an illusion, although they certainly feel good. Reductions in atmospheric carbon dioxide are achieved directly through sequestration and indirectly through emission reductions. Still, planting trees in cities should not be touted as a panacea to global warming. It is one of many complementary bridging strategies, and it is one that can be implemented immediately. Moreover, tree planting projects provide myriad other social, environmental, and economic benefits that make communities better places to live.”

Thus, while CO2 absorption can be positive, putting the right tree in the right place remains critical to optimizing its benefits and minimizing conflicts with other aspects of the urban infrastructure.

Next part…coming soon. We will look at where trees work best, which trees might be the best, and include a long list of references on this topic. See you soon.

Plant Lists for Bioswales and Rain Gardens

Posted by sustainable_hort on March 18, 2010  |  No Comments

This post, as promised, presents a quick overview of the various plants used in bioswale and rain garden environments. It is not as simple as just throwing a few water tolerant plants in the ground. Careful plant choice and placement play key roles in successful “wet” landscapes.

Plant selection for these projects is driven by several key factors including the following:

Obviously, the basic site conditions play a huge role. Factors like sun exposure, soil depth, physical and chemical properties and moisture holding capacity can vary, so need to be understood for successful plantings.

What is the intended function of the project? For many projects, the landscape’s performance, including infiltration, pollutant removal and evapotranspiration rate will determine its success.
But, there can also be safety issues, which may require added protection such as surrounding hedges. Finally, aesthetics play a role since many working landscapes sit in neighborhoods and other public areas. While visible, they can seen as an amenity, and even provide some recreational opportunities.

No landscape is going to be maintenance free; so long term needs should be studied. This is one area where the plant material choice can have dramatically different cost impacts.
Finally, recognize each site’s natural water regime. Check the depth, frequency and duration of soil saturation, which will vary daily, seasonally or annually. For instance, Portland, Oregon, is considered a “wet” climate, but the summer is extremely dry. Plants in these urban, constructed wetland must survive extreme variations. A similar garden in Atlanta, Georgia, or Columbus, Ohio, would get significant summer rain.

Actually every rain garden or bioswale has its own “zones” that have different requirements, according to the Virginia Department of Forestry’s Rain Gardens Technical Guide. The guide points out that the center, and deepest, part of the garden best grows the very wet to wet-loving plants. Meanwhile, the middle of the garden’s side takes wet to dry plants, while the upper rim takes drier types of vegetation.

The guide lists other factors affecting the choice of the plants for rain gardens:
• Decide on objectives, such which wildlife you want to attract, then decide on the varieties you would plant to attract those species. [Refer to reference list below]
• The rain garden’s location affects use of fruit-bearing plants and trees, since if it is near the driveway or walkway, it could create messes and maintenance issues. Trees next to a power line or too close to a house are not good choices.
• If the bioswale are near enough to receive runoff from a road that gets chemical treatments for ice in winter, choose plants that tolerant salt.
And then there is actual selection of species and varieties…and a common question, should we plant natives compared to introduced, commercial varieties?

Why Native Plants?
The majority of the web sites that deal with bioswales or rain gardens are also now recommending using natives. So, why is this the accepted trend?

As Withrow-Robison and Johnson point out in the OSU publication Selecting Native Plant Materials for Restoration Projects, “selecting appropriate plant materials for restoration projects helps make any of these projects more successful. They state that, “‘appropriate’ means choosing species that are suitable for the site, are grown from locally adapted sources, and have a solid genetic composition.” In many cases, this leads to using native species.

So, what is a “native plant?” Most definitions say a “native plant” occurs naturally or has existed for many years in an area, and they can be trees, flowers, grasses or any other plants. “Local adapted sources” can mean those plants have adapted to a very limited range, living in unusual environments, under very harsh climates, or growing in unique soil conditions. Yet, while some had a very limited range, many others live in diverse areas or easily adapt to different surroundings.

So, to summarize the strengths of using natives in bioswales and rain gardens.
• First, native plants are better adapted to the local climate. Once planted and established, do tend not to need extra water or fertilizer.
• Secondly, many are deep rooted, allowing them to survive droughts. This is especially important in the Northwest, where the normal wet weather can disappear for several months during the summer months.
• Third, native plants provide habitat and food for native wildlife and, are thus very attractive to the diverse native bees, butterflies, beetles and birds, all important pollinators.

These plants, which include many wildflowers, sedges, rushes, ferns, shrubs and small trees, grow on the edges of natural wetland, also have root systems that enhance infiltration, moisture redistribution, and diverse microbial populations involved in biofiltration.

A key point to remember is that rain gardens, unlike a water garden, will be dry most of the time. Plant selection should include those that tolerate short periods of inundation, but not require constant standing water. In areas that will have moist, well-drained soil, select plants with moderate moisture requirements. For drier sites like the edge of your rain garden, plant species with low or moderate moisture requirements.
Meanwhile, any perennial plants need to be hardy in your growing zone.

Each region has growers of appropriate native and related plants for rain gardens and bioswales.

In fact, some successful growers will collect seed their own seed from the local area. For example, one Oregon native plant producer has collected seed for plants such as snowberry (Symphoricarpos albus), salmonberry (Rubus spectabilis) and twinberry (Lonicera involucrate) in the immediate area, using on a couple of mother plants for each. Another grower collects all her Pacific dogwood (Cornus nuttallii) from two trees growing at a nearby park.
See references below for several recommendation lists.

These three urban plant technologies are just part of a wider set of alternative Best Management Practices (BMPs). Many are simple, practical designs, but provide effective storm water management. Some even add aesthetic enhancements to the urban, suburban, and rural landscapes. They can be cost effective to build while providing long-term sustainability for city infrastructure and conservation of a city’s water resources. These include filter strips, grassed swale, green roof, and infiltration basin, planters and trenches.

So, as the cost savings are identified, the demand for specific plant materials should increase. At this point, the trend seems to be moving toward regionalized, native plant materials. Since there are a number of operations already propagating this niche, they may have the best opportunity to benefit from this particular green movement.

References:

The following references are available online and have been updated relatively recently, so they contain more current research and data regarding various plant choices.

• Rain Gardens Technical Guide Virginia Department of Forestry
www.dof.virginia.gov/mgt/resources/pub-Rain-Garden-Tech-Guide_2008-05.pdf

• Selecting Native Plant Materials for Restoration Projects by B. Withrow-Robinson and R. Johnson, OSU publication EM 8885-E, November 2006.
extension.oregonstate.edu/catalog/pdf/em/em8885-e.pdf

• Plants for Stormwater Design
www.wildflower2.org
Native plant database and suppliers directory for North America.

• Rain Gardens Technical Guide – Virginia Department of Forestry
Central Office
900 Natural Resources Drive, Suite 800, Charlottesville, Virginia 22903
www.dof.virginia.gov
Phone: (434) 977-6555 – Fax: (434) 296-2369
VDOF P00127; 05/2008

• Brooklyn Botanic Gardens, Rain Garden Plants.
This web site offers regionalized lists of suggested plants for rain gardens. Not as extensive as other sites, its easy to use breakdown is a good starting place in identifying plants for an effective design palette. www.bbg.org/gar2/topics/design/2004sp_raingardens.html

• 10,000 Rain Gardens (www.rainkc.com) has an extensive site that features a diverse list of plants for rain garden situations. It also has a search feature that allows criteria selection from five categories, so a nursery could focus first on what it is already growing, expand to closely related varieties, and then look for new opportunities that would fit within existing production systems.

• Bluestem Services: (www.bluestemservices.com) Has numerous plants lists, but two feature nearly 100 plants for rain gardens and wetlands.

Green Streets/Bioswales/Rain Gardens

Posted by sustainable_hort on March 16, 2010  |  No Comments

After at least a century of hard engineering solutions for urban rain/storm water run-off, communities are turning more and more to using a plant-based technology that mimics nature’s wetlands and ponds.

Portland, Oregon, has played a leading role in supporting and developing this concept, with successful demonstration projects now helping control negative storm water events that included flooding and the overflow of sewage into local rivers.

Just holding back the flow of a major rain event is enough justification for continuing the development of green streets, or rain gardens. When the cost of “hard” infrastructure is considered, these plant-based technologies may be the perfect “green” technology to receive early installation.

All these variations…green streets and rain gardens…are built on the concept of bioswales. So, much of the information is based on bioswale research and the success of earlier projects.

A Decade of Development
One of the first scientifically designed, large-scale bioswales was built in 1996 for Willamette River Park in Portland, Oregon. This bioswale, at a total of 2330 lineal feet, was designed to capture pollutant runoff and prevent it from entering the Willamette River. Silt capture was improved by adding intermittent check dams. The dams reduced suspended solids entering the river system by 50 per cent.

Another example of a large, designed bioswale is at the Carneros Business Park, in Sonoma County, California. In 1997 the California Department of Fish and Game and County of Sonoma, working with an environmental design team, created a detailed design that took the surface runoff from the park’s large parking area. The runoff came from the building’s roof and parking lots. There was also an overland flow from properties located north of the project site. A two-mile bioswale was built to reduce runoff contaminants from entering Sonoma Creek. The grass-lined bioswale channel has an almost linear construction, with a down slope gradient of four percent and six percent cross-slope gradient.

Another early project, completed in 2001, is Seattle’s pilot Street Edge Alternatives Project (SEA Streets). Its drainage designs closely mimics the natural landscape compared to traditional piped systems. Impervious surfaces were reduced, now with 11 percent less than a traditional street while providing improved surface detention in swales. SEA also added over 100 evergreen trees and 1100 shrubs. Two years of monitoring show that SEA Street reduced the total volume of storm water leaving the street by 99 percent.

Meanwhile, back in Portland, the Bureau of Environmental Services has created a “green streets” program. In one project, the city retrofitted SW 12th Avenue, near Portland State University, to collect runoff from 8,000 sq ft and running it into a series of four planters. Up to 6 inches of water can be collected in each planter, then the water overflows down the street to the next planter. In 2006, the project won a General Design Award of Honor from the American Society of Landscape Architects.

There are even companies now that focus on the design, construction and promotion of rain gardens and related products, such as rain barrels. This is another great example of how the low-tech use of plants can solve serious environmental problems, instead of billion dollar “hard” solutions such as Portland’s two massive pipe system projects now under construction.

Definitions
But, despite many similarities, there are some differences between the bioswale variations.

A swale is a low tract of land, that usually exists in a moist or marshy situation and can be a natural landscape feature or one specifically built for environmental reasons. The later is often an open drain system is that manages water runoff.

Bioswales are landscape elements designed and built to remove silt and pollution from surface runoff water. These “swaled” drainage courses are, in a sense, gently sloped ditches that contain plants, compost and/or riprap. The sloped sides are usually less than six percent slope.

As water flows though the typically wide and shallow ditch, so the water spends enough time in the swale, to help trap of silt and pollutants, a bioswale can have a meandering or almost straight channel alignment, based on the lie of the land where it is built.

Bioswales are often built around parking lots due to auto pollution. Potential harmful compound end up being collected on the paving and then flushed by rain. The bioswale, acts as a biofilter, and surrounds the parking lot. As the runoff enters the bioswale, it is cleaned before entering a watershed or storm sewer.
The bioswales can also contain biological factors also contribute to the breakdown of certain pollutants.
Bio-retention ponds, commonly called “rain gardens,” are landscape features that help control rainwater runoff. The runoff comes from roofs, driveways, walkways, compacted lawn areas and other impervious urban surfaces, and cause problems, especially during the large storm events. Structures, low-lying depressions and other landscape constructions that slow and deter running water allow heavy rains to be absorbed into the soil. This prevents the urban situation where the rains flow into storm drains and cause secondary environmental problems. Or it becomes surface water that causes erosion, water pollution, flooding, and diminished groundwater. Some studies claim this can reduce the pollution reaching creeks and streams by up to 30 percent.

Rain garden plants also return water vapor into the atmosphere through the transpiration.

Thus, rain gardens are essentially all landscape features that capture, channel, and divert natural rain and snow that falls on a property. This diverted water may also find other uses, such as stored water returned as irrigation. If designed correctly, an entire landscape or garden can become a rain garden. Individual elements act as components or small-scale rain gardens.

Meanwhile, green streets use small-scale, vegetated bioswales, built along streets that again help control storm water events. These constructed elements create on-site infiltration, while providing attractive streetscapes. They also improve a neighborhood’s livability by adding park-like elements that serve as urban greenways. As mentioned earlier, the City of Portland has officially incorporated green street facilities into all its development, redevelopment or enhancement projects. Besides treating and infiltrating storm water, these projects can also increase tree shade canopy and support native habitat all in the parkways and medians.

It is important to note that these man-made water-control landscapes’ success depends on an adequate “infiltration rate.” This measures, in inches or millimeters per hour, the rate a particular soil absorbs rainfall or irrigation. As the soil becomes saturated, the infiltration rate decreases. When the precipitation rate exceeds the infiltration rate leads to “runoff.” So, the correct soils are also crucial to the overall functioning of all these bioswale variations.

In addition, most of these bioswale-based, water control landscapes are using at least some, if not all, native or related plant choices. This leads to both environmental and cost advantages.

Why Bioswales…Benefits of Water Control Landscapes
These wetland variations, working like their natural versions, have several key benefits that will increase their use as bioswale technology becomes adopted as an effective construction element in urban settings.

• Reduced expense for storm water management facilities
In many locations, natural landscaping, like bioswales or rain gardens, can handle and control storm and flood waters. This, in turn, can reduce the need for expensive, “highly engineered” pipes systems and detention facilities. More and more real world projects are showing that drainage swales can cost much less to install than storm sewers.

“Sustainable innovations can actually reduce costs,” explained landscape architect Paul Morris, speaking at an annual meeting of Oregon Landscape Contractor Association. Morris works on planning and sustainable issues for Cherokee Investment Services, Inc., an international development firm that has long recognized the many benefits of incorporating sustainable technologies into their projects.

He said these include storm water run-off (largest environmental problem in US) control using bioswales, rain gardens, green roofs, and capturing the water on site can be less expensive to construct than traditional solutions.

When curbs and gutters are eliminated and curbs are slotted, there can be substantial construction savings. When natural drainage measures increase infiltration of storm water into the local soil, runoff volume is reduced while the need for downstream conveyance and detention structures is reduced.

Other projects found that detention basins, designed with natural landscaping to resemble wetlands or natural lake systems, also reduce costs over conventional basins. These “natural” landscapes eliminate the need for expensive riprap stabilization and low flow channels paved with concrete. Natural vegetation in detention basin bottoms and on side slopes is less costly to maintain than conventional turf landscaping (see next section), and is a more reliable soil stabilizer.

• Removing Contaminants
As was indicated in the definition of a bioswale, one reason to slow water down is so it can react with the nearby plants, roots and soil. This has documented several benefits.

First, these plant-based technologies can help control several classes of water pollutants, including silt, inorganic contaminants, organic chemicals and pathogens. This falls under the definition (according to Wikipedia) of “biofiltration.” It is defined as “a pollution control technique using living material to capture and biologically degrade process pollutants.” These process include cleaning waste water, capture chemicals that are potentially harmful, micro biotic oxidation of contaminants in air, or collecting silt from surface water runoff.

This is similar to “bioremediation,” which is defined as “any process that uses microorganisms, fungi, green plants or their enzymes to return the natural environment altered by contaminants to its original condition.” Bioremediation may be employed to attack specific soil contaminants, such as degradation of chlorinated hydrocarbons by bacteria. An example of a more general approach is the cleanup of oil spills by the addition of nitrate and/or sulfate fertilizers to facilitate the decomposition of crude oil by indigenous or exogenous bacteria. (Wikipedia)

With silt, the bioswale or rain garden’s effect is to slow the moving water, reducing turbidity, and allowing the small soil particles to drop out of the water. Thus, the soil is returned to a place where it is beneficial instead of traveling downstream to become a problem.

Meanwhile, inorganic compounds, such as metallic compounds like lead, chromium, cadmium and other heavy metals, are common pollutants, especially in areas of heavy auto use. Lead, from automotive residue (e.g. surface spillage of leaded gasoline) is the most common example.

Other common inorganic polluting compounds include phosphates and nitrates, whose main source is excess fertilization. This often causes “eutrophication,” defined as “an increase in chemical nutrients — compounds containing nitrogen or phosphorus — in an ecosystem from the release of sewage effluent, urban storm water run-off, and run-off carrying excess fertilizers into natural waters. It may occur on land or in water.

However, the term is often used to describe the resultant increase, and thus excessive, plant growth and decay in aquatic environments. This results in a lack of oxygen and results in severe reductions in water quality, fish, and other animal populations, disrupting normal functioning of the ecosystem, In aquatic environments, this enhanced growth creates choking aquatic vegetation or phytoplankton, often known as “algal blooms.”

Meanwhile, common pesticides, frequently over-used in agricultural and urban landscaping, are also seriously detrimental organic chemicals. They can actually poison some organisms and often seriously disturb aquatic ecosystems.

Finally, there are human pathogens that usually come from animal waste in surface runoff water. In just the past few years, it has lead to a several serious diseases in humans, with outbreaks coming from spinach and peanut butter.

Less recognized, but still serious, are comparable diseases that have affected aquatic organisms.

• Reduced costs of landscape installation and maintenance
Studies have shown that these “bioremediation” technologies are less expensive than the some other landscaping options. For instance, conventional rolled-sod, turf lawns can have installation costs exceeding $12,000 per acre, while planting grass seeds may cost $4,000 to $8,000 per acre. But, seeding native prairie grasses and forbs costs only $2,000 to $4,000 per acre.
Several publications noted that planting native plants plugs increases installation costs significantly but does give plants a “head start” if desired.

Another plus is that sponsors and volunteers can help control native plant installation costs. Sponsors can even sometimes be a public or private entity with plant propagating capabilities. Volunteers can be recruited to install and maintain native landscapes.

And, natural landscaping just cost less to maintain. Over the first ten years, the combined costs of installation and maintenance for natural landscape can be as little as one fifth of the costs for conventional landscape maintenance. Many projects use a range of native plants already adapted to the region’s soil conditions and climate, including summer heat and drought. Natural landscaping lowers many normal costs including labor, water, fertilizer, herbicides, insecticides, and fungicides, replanting annual flowers, and mowing. In drier climates, natural landscaping lowers the high irrigation costs.

The reduced use of lawn maintenance equipment lowers gas use, an additional benefit. Natural landscapes require simple maintenance, usually just annual mowing or burning, and some weed removal (mostly in the few years after installation)

This, like green roofs and green walls, is becoming a new market for both growers and landscape contractors. With Portland leading the way in this area, it will be one more topic this blog will continue to follow. If you are interested in more details, go to www.portlandonline.com/BES/, click on “Stormwater Solutions” under Library.

Watch for the upcoming post that discusses and provides references on the plant material being used in this newest version of sustainable horticulture.

Trees Prove Valuable in Several Ways

Posted by sustainable_hort on February 21, 2010  |  No Comments

Several posts ago I mentioned several confirmed environmental benefits of planting trees. The good news keeps coming.

First, a study from the east coast indicates that trees are growing faster, probably due to the increase in CO2. The study, published in The Proceedings of the National Academy of Sciences, concentrated on hardwood stands in Maryland that were representative of east coast tree populations. The work showed trees were growing an additional two tons of plant material per acre annually as the CO2 levels have increased 12% in the last 22 years. This is another indication that plants may yet save the planet. Gaia in action.

Then, a recent article in the Oregonian (Portland, Oregon) cited a recent research study that estimated the added value of having full size trees in a yard was $7000! Of course, as the article points out, there are a lot of added costs. And, your neighbor that shares that shade tree also gains value from it presence…without the costs. I tended to focus more on the fact that trees improve land values, and not the article’s concern that the “neighbor” was not sharing the upkeep costs…only getting the value. This is definitely a positive study for those supporting more trees in our urban/suburban settings. Make them fruit trees and they are even more valuable.

Finally, another book to recommend…Between Earth and Sky by Nalini M. Nadkarni. Not another descriptive collection of trees for yards, this one specifically discusses trees and their “intimate connection” to us. It goes beyond economic value into a more spiritual connection that is demonstrated by our long relationship with trees.

Yards Become Part of the Urban Farm Movement

Posted by sustainable_hort on February 19, 2010  |  No Comments

If anyone should know how consumers are changing their relation to food and gardening, it should be the garden writers.
They are avid gardeners themselves, always looking for the next trend, and ready to study today’s food gardening activities. So, when their latest trends research was released, most of us were not that surprised…the American family plans to garden more, for several reasons, all positive.
The Garden Writers Association Foundation (GWAF) recently released a 2010 trends survey that showed “more than one-third of the households surveyed reported plans to increase their edible gardens, while 29 percent said they would plant about the same as 2009.” The same survey indicated that only 1 percent are planting less than in 2009. One trend that remains strong. If you are interested in the entire survey, contact GWAF at www.gardenwriters.org.
Why?…Cost, interest in fresh, local food sources, concern with food safety, environmental issues, and even a return to food as a social connection. More and more, raised beds are replacing those neat, sterile lawns and mixed borders with vegetables, as food take over the summer landscape. This trend was confirmed in a recent AP story…while the general wholesale nursery industry is headed for the dumps, the story states “not all is gloom. Nurseries that specialized in edibles — vegetables, fruit trees and berries — didn’t fall as far thanks to the interest in grow-your-own food.”
As e mentioned, multiple forces drive this changing food market. But, much of it started with what is affectionately called the “foodies movement.” It comes from several waves of new ideas in food, entertainingly and succinctly covered in the United States of Arugula, by David Kamp. An equally entertaining, but more directly useful book is Marion Nestlé’s What to Eat. Her earlier works, Safe Food and Food Politics, are also worth your time and cover the topics in depth. Another recent book, Grub, by Anna Lappe (daughter of Diet for a Small Planet author Frances Moore Lappe), is a shorter, lively introduction to the “urban organic kitchen.”

Bottom line…growing at least some of your food is a growing trend, no pun intended. Urban farming, now being defined, will become an important part of sustainable living. People involved get fresher, healthier food, some extra exercise, and might even save a buck or two.
So, if you are interested in the process, you can follow our seasonal work on our organic produce farm. Just visit and bookmark the 19th Street Farms blog at www.19thstreetfarms.com/blog. That site will cover the food and food growing information, articles and opinion, while this site will continue to look at landscaping, nursery industry, environmental and sustainability topics. Hope you visit both sites.

A Landscaper Looks at Sustainability

Posted by sustainable_hort on February 4, 2010  |  No Comments

In my recent post , New Opportunities in Sustainable Landscapes, the discussion centered on new landscape directions for the industry. This post looks at how one landscape firm looks at creating a different landscape, one focused on sounder environmental principles.

“Sustainability does mean change and that’s the reason we are hearing about it all the time,” said David Sandrock, owner of Sustainable Landscapes for the Pacific Northwest, Corvallis, Oregon.
“But, it is an opportunity,” he said during his presentation at last November’s OLCA Expo. “People are looking to us for solutions.”
Sandrock said that “sustainability” is based on several key concepts.
The former Oregon State University professor said the first concept is often used as a definition of sustainability.
“Sustainable action is development that meets the needs of the present without compromising the ability of future generations to meet their needs,” he offered.
This, in turn, takes intelligent resource planning, he said, and added that this movement emerged in response to human misbehavior.
“These actions move toward landscapes that we can depend on, not landscapes that depend on us,” he concluded. “It will require a return to the art and science of horticulture.”

Trees Saving the Planet?

Posted by sustainable_hort on February 1, 2010  |  No Comments

The New York Times is reporting that a new research report, being published in today’s issue of The Proceedings of the National Academy of Sciences, indicates that trees are growing faster, perhaps in response to the atmosphere’s added carbon dioxide. (http://www.nytimes.com/2010/02/02/science/earth/02trees.html)
This relates to my last three posts that discussed the increasing role plants will play in solving climate change issues. This plant and planetary reaction seems to confirm some of the Gaia theories of James Lovelock, see site: (http://en.wikipedia.org/wiki/Gaia_hypothesis).
So, does this mean that the cooler temperate regions might actually see increased growth of not only the natural vegetation, but agricultural crops as well? There are already early olive ventures in the Willamette Valley of Oregon, moving up from California. Will Oregon start growing oranges next? Or maybe avocados!
Follow this site as we investigate, synthesize and report on the new “plant technologies,” including green roofs, green walls, bioswales, higher respirating plant varieties, plant site placement, etc.

New Opportunities in Sustainable Landscapes

Posted by sustainable_hort on January 30, 2010  |  1 Comment

This article appeared in the Oregon Landscape Contractor’s magazine. It is related to my last post that discussed how growers, retailers and landscapers might take advantage of new “green” trends and technologies. This focuses on how “Sustainable Development Offers New Opportunities for Landscape Contractors.”
And…thanks for your many positive comments on my content. Much more to come.

Many major developers are ‘going green,’ not just for good public relations, but also as an economically beneficial strategy. Innovative landscape firms have a tremendous opportunity to join this effort, position themselves as “green,” and dramatically increase their business.
“These are not little changes, but this is a sea change,” explained landscape architect Paul Morris, speaking at the annual meeting of Oregon Landscape Contractor Association in December. By 2010, industry studies predict a $19 to 38 billion in the residential green building market, he said.
Morris works on planning and sustainable issues for Cherokee Investment Services, Inc., an international development firm. He said that his company has long recognized the many benefits of incorporating sustainable technologies into their projects.
“These are no longer just warm-fuzzy things we’d like to do,” said Morris. “There are calculable benefit costs that can now be identified.”
In fact, his company, with $2 billion in assets, is the leading private investment firm in “brown field” development, working on abandoned and idle industrial and commercial urban sites often with environmental degradation and contamination, distinguished from “green fields,” undeveloped land outside urban areas. It plans to spend $250,000,000 on remediation projects, he said.

Going Green – Point Tipped

Posted by sustainable_hort on January 29, 2010  |  4 Comments

This is an article I wrote several years ago, but with a few minor changes, it still applies to the nursery and landscape industries…maybe even more with the downturn in sales. The green industry needs to market its “greenness!”

Point Tipped…Going Green
By Miles McCoy

Even that wild-eyed, business-entertainer Jim Cramer has gone green.
It was a big turning point for the popular investment show host. He had long discouraged any investment in “green” companies because they did not have a sound financial underpinning.
That changed with recent Supreme Court decision…a true tipping point. (more on that later) The Supreme Court’s decision essentially changed the pollution playing field by declaring that carbon dioxide is a “pollutant.” It thus falls under the Clean Air Act and can be regulated by both the EPA and states. A Business Week’s article stated, “The door is now open for new lawsuits against companies that emit carbon dioxide.”
Strong stuff, but seemingly not unanticipated within the US or world business communities.
In fact, a former chief economist at the World Bank, Sir Nicholas Stern, recently wrote in a Business Week column (4/16/07 – p. 90), “reducing carbon emissions is a pro-growth strategy, not an economic burden.” There is more evidence as companies as diverse as Goldman Sacs and Wal-Mart have announced major “green” efforts within their structure.
This change continues to be driven more by consumers and popular media. Vanity Fair just presented it second annual “green” issue, while a recent Newsweek cover features California’s green governor Arnold Schwarzenegger. A week earlier, the magazine’s “Tip Sheet” gave readers advice on creating a “greener garden,” with facts on native plants (another topic!), saving water, composting, mulching, and organic pest/weed control. A recent New York Times article on organic lawn care asked “are bugs the pests, or humans?!” Consumers are speaking at the cash register, demanding safe, natural products to care for their landscapes. More on that in a minute.
Meanwhile, green buildings are all the rage, with the Leadership in Energy and Environmental Design (LEED) certification now crucial, and even mandated, for new construction. While much of the green technology has little to do with our industry, we are seeing a greening of our roofs. These roofs are sold as offering environmental solutions. They may only develop a minor, niche for growers, but their concept of marketing may give the overall green industry some viable advertising themes.
For instance, should we encourage homeowners to include landscapes that handle the run-off from their home and driveways? Green roof activity is often driven by storm-water runoff control, using the roof’s plants and soil to hold back large rain events. Portland has gained a national reputation for creating what an Oregonian editorial recently described as our “greener, gentler streets,” where run-off swales are actually built into the streets. So, maybe the industry can promote ponds and swales with their water-loving plants; or pervious driveways that use tough, low-growing plant choices. New environmental options will often require our plants.