SUSTAINABILITY 1 GCE

LA Course #GCE-1-1901

Sustainability Issues 1 - Climate Change Solutions

Sections Go directly to the Section by clicking on the title below

A Solution to Global Warming
Carbon-Neutral Trees
Riparian Buffers

Note: Click on green text in each section for more information and photos.

A Solution to Global Warming
By Len Phillips; edited by R W Gibney RLA - ISA

One of the best ways to deal with global warming is to plant trees. Better still, plant trees that will be tolerant of the rising temperatures, so they will survive when other trees may not. Most landscape architects and arborists are familiar with the U.S. Department of Agriculture's Plant Hardiness Zone Map. By using the map to find the zone where you work, you will be able to determine which trees will "winter over" in your city and survive for many years.

A heat zone map indicates the average number of days each year that a given region experiences "heat days" or temperatures over 86° F (30° C). That is the point at which plants begin suffering physiological damage from heat. The zones range from Zone 1 (Canada with less than one heat day) to Zone 12 (Florida and Texas with more than 210 heat days). Heat damage can first appear in many different parts of the tree: The flower may wither, or the leaves may droop, or the tree may become more attractive to insects, or chlorophyll may disappear so that leaves appear white or brown, or the roots may cease growing. Tree death from heat is slow and lingering.

As expected there are several species of trees that will tolerate heat, but there are now many new cultivars or introductions that have been selected for their heat tolerance in addition to other desirable features. Keep in mind that although these trees are heat tolerant, that does not mean that they are also resistant to disease and pest problems or other abiotic conditions. So when you are selecting a tree for planting, make sure you plant the right tree in the right spot, for the right reason.

Heat Tolerant Species
The following is a list of species that are tolerant of urban heat.

Botanical Name                Trade Name                Hardiness Zone         Heat Zone
Acer buergerianum          Trident Maple                       5 – 9                       9 - 5   Photo
Acer campestre                Hedge Maple                       5 – 8*                      8 - 4         Photo
Acer rubrum                      Red Maple                           3 – 9                       8 - 1         Photo
Catalpa speciosa              Catalpa                                4 – 8                       8 - 1         Photo
Cedrus spp. Cedar 5 – 9*                      9 - 6 Photo
Celtis occidentalis Hackberry 2 – 9                       9 - 1        Photo
Cryptomeria japonica        Japanese Cryptomeria        5 – 9                       9 - 4 Photo
Eucommia ulmoides          Hardy Rubber Tree             4 – 7                       7 - 1 Photo
Ginkgo biloba                    Ginkgo – male cultivars       3 – 9                       9 - 3 Photo
Juniperus virginiana          Eastern Redcedar               2 – 9                       9 - 1 Photo
Lagerstroemia spp.           Crape Myrtle                        7 – 9*                   12 - 9 Photo
Pinus spp.                         Pine 2 – 9*                      8 - 1 Photo
Pistacia chinensis             Chinese Pistache                 6 – 9                       9 - 6 Photo
Quercus acutissima          Sawtooth Oak                      5 – 9                       8 - 1         Photo
Quercus phellos                Willow Oak                          5 – 9                       9 - 3         Photo
Quercus rubra                   Red Oak                              4 – 8                     9 - 5         Photo
Sophora japonica              Japanese Pagodatree         4 – 8                       9 - 5         Photo
Tilia cordata                       Littleleaf Linden 3 – 7                      8 - 1         Photo
Tilia tomentosa                  Silver Linden 4 – 7 9 - 1         Photo
Ulmus parvifolia                 Lacebark Elm 4 – 9 9 - 1 Photo
Zelkova serrata                 Japanese Zelkova 5 – 8 9 - 5 Photo

* Zone range depends on the species selected, as some are more heat tolerant than others.

Heat Tolerant Cultivars
This second list contains heat tolerant cultivars selected from species that are not noted for being heat tolerant. These cultivars were selected for their excellent tolerance to heat within the climatic range of the species.

Botanical Name                                Trade Name                          Hardiness  Zone    Heat Zone
Acer ginnala 'JFS-UGA'   Red November™ Maple 2 – 8 7 – 1         Photo
Acer saccharum 'Autumn Splendor' Autumn Splendor Sugar Maple       5 – 9 8 – 1         Photo
A. s. ‘Bailsta’ Fall Fiesta® Sugar Maple               4 – 8 8 – 1         Photo
A. s. ‘Green Mountain’ Green Mountain® Sugar Maple      4 – 8 8 – 1         Photo
A. s. ‘JFS-Caddo2’ Flashfire® Sugar Maple 5 – 9 8 – 1         Photo
A. s. 'John Pair' John Pair Sugar Maple 5 – 9               8 – 1         Photo
A. s. ‘Legacy’ Legacy’® Sugar Maple                    4 – 8               8 – 1         Photo
A. s. 'Morton' Crescendo™ Sugar Maple 5 – 9               8 – 1 Photo
A. s. 'Reba' Belle Tower™ Sugar Maple             5 – 8               8 – 1         Photo
Acer x freemanii 'Jeffersred' Autumn Blaze® Maple 3 – 8               8 – 1 Photo
Acer truncatum x plat. ‘JFS-KW202’ Crimson Sunset® Maple 4 – 8               8 – 1         Photo
Betula nigra 'BNMTF' Dura-Heat River Birch 6 – 9             11 – 1         Photo
Betula platyphylla ‘Whitespire’ Whitespire White Birch 4 – 9               7 – 5         Photo
Carpinus betulus JFS-KW1CB’ Emerald Avenue® Hornbeam 4 – 7               8 – 1 Photo
Celtis 'Magnifica' Magnifica Hackberry 2 – 9 9 – 1 Photo
Fraxinus pennsylvanica 'Cimmzam' Cimmaron™ Ash ** 3 – 9 9 – 1
F.p. 'Georgia Gem™' Georgia Gem Ash® ** 3 – 9 9 – 1     Photo
F.p. 'Urbdell' Urbanite™ Ash ** 3 – 9 9 – 1 Photo
Gymnocladus dioicus ‘Espresso-JFS’ Espresso™ Kentucky Coffeetree 3 – 8              9 – 2   Photo
Koelreuteria paniculata 'JFS-Sunleaf'  Summerburst Goldenrain Tree 5 – 9              9 – 1   Photo
Ulmus propinqua 'JFS-Bieberich          Emerald Sunshine Elm 5 – 9              9 – 1        Photo

** non-EAB areas only

I hope you find this list useful, plant wisely and with the future in mind.

Sources

Appleton, Bonnie, et. al. “Trees for hot sites”, Virginia Cooperative Extension, Publication 430-024, 2015
J Frank Schmidt Reference Guide, 2014.

Carbon-Neutral Trees
Edited by Len Phillips

Trees provide us with so many benefits including controlling stormwater runoff, reducing urban temperatures, and most importantly, sequestering carbon. But, do they? There are carbon footprints involved in their production, installation, pruning, and ultimate removal. Trees play the long game because it takes decades before they provide the ecosystem services that we plant them for. The way we work with trees can increase or decrease the time before they become “carbon neutral” and lengthen the number of years they can provide vital ecosystem services to us all.

Two studies have analyzed this issue.

The U.S. Forest Service study of 2014 looked at the Million Trees Los Angeles program (MTLA). The Forest Service study found that the MTLA trees using various species, would become net carbon reducers after 40 years, assuming they remain alive for 100 years.

2. The more recent How Green Are Trees? study funded by the Horticultural Research Institute (HRI) that examined the life cycle of red maple (Acer rubrum) in the Chicago area. Both studies looked at the carbon emissions used in nursery production, delivery and installation, pruning, and removal of street trees. The HRI study was slightly more optimistic, projecting a range of 26-33 years to carbon neutrality for Red Maple in the Chicago area.

One of the main differences between the studies is that the Forest Service considered mulch and root decomposition as part of the emissions associated with tree work and the HRI study did not. The Forest Service Study also used longer transport distances and more intensive irrigation in their model as appropriate for the Los Angeles setting. It is typical in California to irrigate new trees for several years, compared to one year of irrigation in Chicago where rainy days are more common.

While the studies differ, both conclude that reducing emissions associated with tree maintenance reduces the number of years after installation before the tree attains carbon neutrality and prevents the urban forest from actually becoming a carbon emitter.

Emission Reductions
Some strategies for reducing emissions recommended by the two studies are listed below. No municipality or organization can incorporate them all, but we can certainly make improvements in some areas of our operations:

When selecting a tree, choose a species that attains a large mature size, but not larger than the space warrants.
Grow trees at a moderate rate (slow growers take longer to become carbon-neutral, fast growers may need more pruning and often have shorter lifespans)
Select trees that are climate-adapted and drought-tolerant.
Select trees from nurseries close to the installation site to reduce travel time.
Using smaller, fuel-efficient maintenance trucks or trucks that use lower-carbon fuels.
Organize the daily work schedule so the minimum amount of driving is necessary for tree maintenance on any given day.
Use equipment with the minimum horsepower required for the job and reduce idling time, or use battery-operated equipment.
Provide a very hospitable soil environment for root growth so trees can reach their maximum size as soon as possible. This may include using structural soils or soil cells on new developments and providing larger openings in the pavement for sidewalk trees.
Installation and backfilling of new trees manually rather than using mechanized methods and equipment.
Minimal or no tree staking, use root stabilization instead of staking, if needed.
Recycling tree root stabilizer materials through thoughtful installation and removal techniques.
Minimal irrigation by using an irrigation bag instead a water truck. If using a water truck, turn off the engine when loading and discharging the water.
Conduct a structural pruning cycle on 3 to 5-year old trees and minimal pruning after that.
Conduct periodic “windshield” surveys using a hybrid vehicle, setting up a system of public feedback, or merging surveying activities with other activities to reduce visits and emissions.
Utilize waste wood from tree removal and stump grinding, either by using the wood itself to make furniture or structures, or by using it as feedstock for biopower production.

After reading both studies, some additional recommendations come to mind.

Utilize the labor of community volunteers – insurance requirements and individual skill levels generally necessitate manual rather than mechanized work.
Installing smaller or bare root specimens that are easier to move and plant by hand and also require less water to establish.
Installation at the correct time of year for the region to reduce irrigation time. In California, installation in autumn at the beginning of the rainy season is preferred.
Structural pruning in the first 5 years after installation to minimize pruning and reduce the risk of failure, lengthens the useful life of the tree.
Tougher tree protection ordinances – preserving existing trees is much “greener” than removal and replacement.

It is important to be aware that everything we do has an environmental impact, even when it’s “good” work. If we are lucky, we will live long enough to stand in the shade of the trees we have installed, and breathe the clean air they provide us.

Source:

Shea, Ellen, “Shades of Green: The Hidden Carbon Cost of Tree Planting and Care”, Deeproot, August 14, 2017.

Riparian Buffers
By Richard H. Miller

A riparian buffer is the stream bank where the land, shrubs, and trees have an effect on the water and the water has an effect on the land and vegetation. It is the area where trees, shrubs, and other plants grow to the water's edge. Riparian buffer widths are important for stream diversity, quality of fish, and the protection of the stream’s ecosystem.

On a local scale, the riparian forest may regulate stream width and form, as well as seasonal water temperature and the energy base. While riparian cover has the most impact in the head water areas, it serves a purpose downstream by providing localized habitats, shade, aesthetics, and to some extent, a sound barrier.

Riparian Forest Health
In the good urban riparian areas one can forget where they are and they do not hear (or at least mentally close out) the harsh sounds of the nearby city. In most cases though, man’s physical and visual impacts, including canopy removal, may overwhelm the capacity of riparian areas to provide buffer effects for stream fauna. In fact, much of the suspended solids and pollutants in streams following storm events may arise from within the stream bed as well as from sheet erosion off the adjacent lands. Drainage system discharges due to human influences may also make natural erosive forces much worse.

Hydraulic alterations to a watershed may overwhelm most influences that local urban riparian forests have on stream life. Conversely, viewing aerial photos of a less urbanized stream such as the Stillwater River, in western Ohio’s corn-belt has its’ riparian zones virtually unbroken. The Stillwater River stream health is good and fishing can be exceptional on this shaded rural fishery.

Fish Populations
Pools and open bank areas support numerous fish species. Streams containing woody debris and associated riparian vegetation support the more desirable fish species. Relative to sport fishing success, when I go fishing along Walnut Creek in populated central Ohio, I generally do not catch the desirable sport fish in the pools along open banks with sparse underwater woody debris.

According to one researcher urban stream buffers are less important to fish diversity because:

they are often by-passed,
the impacts of watershed land use overwhelms the capacity of riparian zones to buffer a stream's ecosystem,
discontinuous riparian buffers will not settle water quality problems because transport through perennial vegetation gaps (agriculture) dominate the discharge in addition to reduced canopy, direct storm sewer discharges, and impervious urban landscapes,
hydraulic alteration overwhelms any influence of riparian forests on stream biota.

Ecologists have shown that the number of endemic and sensitive fish species found in many urban streams are best predicted by the amount of forest cover and the amount of urban-impervious surfaces within the catchment area. An abundance of sensitive species exhibit a striking response to the amount of forest in the riparian network, with virtually no sensitive species found at sites with less than 70% forest.

Riparian Health and Water Quality
Additionally, research shows that the riparian cover in the upstream network is important for maintaining sensitive fishes, while local reductions in riparian forest cover increase the population of tolerant fishes.

This is not to say that riparian vegetation in urban sites is necessary for riparian health and water quality. Overreaching influences of impervious surfaces, field drains, stormwater pipes in urban reaches, and rural catchments drastically affect aquatic systems via non-point-source water quality impairment.

Pristine Streams
Pristine streams have not been seen for hundreds of years and it may not be practical to envision a return to such a complex environment. Even at modest levels of disturbance, deforestation, and the conversion to agriculture, urbanization, and other disturbances have detrimental effects on the water quality of streams.

We have destroyed the natural systems that maintain the watershed. No pollutants appear to have had a more universal or lasting adverse effect upon aquatic life, since the first settlers in 1800, than have the original clays and silts. Plowing the land following the removal of trees increased the erosion of glacial silts and clays also causing adverse effects to the pristine streams.

In addition, stream bank erosion can be viewed as a problem only if it affects man and man's vision of what a stream should be. Stream banks have been eroding and rebuilding at least since glacial times, 10,000 years ago. Stream bank erosion only occurs within the meander pattern of the stream valley. Stream dynamics necessitate knowledge of erosive forces that define stream meander width, structure, and health. Historically, with few exceptions, the streams in Ohio usually were devoid of clayey silts, even during floods. The waters were very transparent or clear, which the pioneers referred to as “fair water,” until at least 1850, when “dirty” or turbid waters began to be mentioned increasingly. Presently we clearly view riparian vegetation as holding stream banks in place albeit in a degraded wider, shallower, and more linear condition than before European settlement.

The Future with Climate Change
Shaded streams, especially head-water areas, are kept cooler in summer by riparian vegetation and definitely have effects on head-water systems. Climatologists are concerned that many fish species will not survive to the end of this century because of climate change and its effect on aquatic environments. Climatologists indicate that as water temperatures rise, tolerant species will dominate and species diversity will decline. Head-water riparian forests will prove to be even more critical to small steam life. Local urban riparian forests are necessary but may not critically control biotic integrity in eastern urban streams. In the extreme view, man-altered linear streams such as those enclosed by concrete banks are not as pleasing, diverse, or as pristine as sinuous tree lined environs. Realistically viewed, the pristine will support a richer diversity of life and desirable fish species and instill a sense of place regardless of the challenges of catchment restoration to mimic a natural pre-disturbance hydrology and canopy to watersheds including opinions of essential widths of urban riparian areas.

Sources

Farst S., Unpublished abstract, EMH&T Engineers, Ohio Statewide Floodplain Management Conference, 2012.
Ohio EPA ,”TMDL for the Walnut Creek Watershed”, (2.3 pg. 8), 2006.
Roy, A.H., “Can riparian forests mediate Impacts of urbanization on stream fish assemblages?”, Pg. 1-80, 2004.
Trautman, M.B., “The Ohio Country From 1750 to 1977 A Naturalist’s View”, The Ohio State University, Pg. 1-9, 1977.

Richard H. Miller is with the Urban Forester for the city of Canal Winchester, Ohio



The test that follows contains 30 questions.  Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.

LA CES will award 1.0 PDH (HSW) credit for a passing grade.  North Carolina Board of LA and New Jersey Board of Architects will award 1.0 credits for a passing grade.

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