Shade Tree Advocate - Winter 2010 by Minnesota Shade Tree Advisory Committee

Vol. 12, No. 1

COMMUNITY FOREST PROFILE

Let All Biomes Gather in One Community By Kathleen Preece and Jerry Stensing

his is a story about partnerships. And it’s about a lot of the details that go into making Minnesota—Minnesota. It’s about planting red and white pine trees, and maples, aspens, and oaks. And it’s about generous people like Jack Strowbridge who donated trees, and foresters like Jerry Stensing who walked the extra mile (and planted the extra tree). And it’s about the students in the J.W. Smith Elementary School of Beltrami County’s Independent School District #31 who took part in the creation of the Minnesota Biomes Project, right in their Beltrami County located school’s back yard. Okay, let’s begin with Chapter 1 of the story of the Bemidji Biome Project. The setting is J.W. Smith Elementary, a 300-body student population, and one of six public elementary schools serving the Bemidji area. J.W. Smith is located in a highly urbanized setting just north of downtown Bemidji, adjacent to residential and light commercial zoning, and a few blocks to the west of the Bemidji State University campus which—all combined— results in very limited opportunities for a child’s first‑hand contact with nature. Chapter Two (and Three and Four and Five…): Enter character Jerry Stensing. As

a forester with the Beltrami Soil and Water Conservation District (SWCD), Jerry knows trees, and really likes young people. Jerry dreamed of a project whose purpose was to provide increased environmental science opportunities to the J.W. Smith school’s students. His plan? Create an outdoor classroom—but not just any classroom. This one would be shaped as the state of Minnesota, with trails that followed major river courses and forest cover that geographically represented the vegetation of Minnesota’s biomes. The Minnesota Biomes Project would enhance environmental education by creating a representation of Minnesota’s forests and prairie lands.

Minnesota Biomes Project

Inside This Issue 2 The Year of Emerald Ash Borer 4 Measuring Canopy Cover 6 Turning Over the Umbrella 9 Mystery Tree 12 Winter Damage to Trees and Shrubs 15 Board Member Bio 16 Arbor Month

As the story unfolded, the restoration included vegetative representation of Ontario, Manitoba, Wisconsin, Iowa, Where Biomes Gather… continued on p. 10

Visit MnSTAC on the Web at www.mnstac.org

The Minnesota Shade Tree Advisory Committee’s mission is to advance Minnesota’s commitment to the health, care, and future of all community forests. ADVOCATE • Winter 2010

URBAN FOREST HEALTH

2009: The Year of Emerald Ash Borer

e knew it was coming. We just didn’t know when. Many of us in state and federal agencies were hoping that a few more years would elapse before we had to engage our emerald ash borer (EAB) response plans. Figure 1

Source: Minnesota Department of Agriculture

Figure 2

EAB was found in Minnesota when our “backs were turned.” Here’s what happened: On April 6, an EAB infestation was discovered in Victory, Wisconsin, across the Mississippi River from the corner of southeast Minnesota bluff country (Fig. 1). All attention turned to Houston County, where EAB surveys were being conducted, traps and trap trees were being set up, quarantine regulations were being planned, news releases were being created and inter-agency relationships were being forged. A few weeks later on May 13, an EAB population was found in St. Paul when a tree care worker was doing some routine tree inspections. He noticed a symptom of EAB in an ash tree: a thinning crown. When he peeled back the bark, he saw characteristic S-shaped galleries, and contacted the Minnesota Department of Agriculture (MDA) with his find. EAB was discovered when we least expected it, but not where we least expected it; according to a risk map produced by MDA in 2003, the Twin Cities area had a very high risk of EAB introduction (Fig. 2). The day after the St. Paul discovery, a quarantine was enacted in the Twin Cities’ counties of Hennepin and Ramsey (Fig. 3). In an intensive, short-duration delimiting survey of the discovery area of St. Anthony Park in St. Paul (Fig. 4), 68 ash trees were found to be infested and were Figure 3

Source: Minnesota Department of Agriculture

Source: Minnesota Department of Agriculture Winter 2010 • ADVOCATE

Figure 4

Source: Minnesota Department of Agriculture

subsequently removed and chipped by the City of St. Paul and brought to St. Paul’s District Energy for incineration. Twenty suspect trees were girdled (stripped of trunk bark) near the infestation to attract any adult EAB in the area. The suspect trees were removed in the fall; some of these trees were found to be infested as well. The Minnesota Department of Agriculture and agency partners deployed nearly 700 purple panel traps within a 4-mile radius of the discovery, which captured only four EAB adults between the end of May and October. One of the adults was found in a trap a ½-mile from the discovery site, and two were found on one trap 1 mile north of the site, on the St. Paul campus of the University of Minnesota. Results from dendrochronological studies of EAB-infested trees indicate that the St. Paul infestation dates back to 2006, making this one of the quickest discoveries of an EAB infestation. An Incident Command System was initiated to facilitate communication about EAB events, outreach, and planning, with unified command representatives from the Minnesota Department of Natural Resources (DNR), the MDA, and USDA APHIS Plant Protection and Quarantine.

forests, the economy, citizens, and natural resources. Planning and detection plans have been developed collaboratively by the MDA, DNR, and University of Minnesota. Through the foresight and collective approach of these agencies, strategies have been outlined as to the “who does what” as Minnesota deals with both the pending and realized threats of EAB across its forests. The DNR is currently developing guidelines for forest managers, for ash utilization, and black ash management. Ash makes up 50 percent of the lowland hardwood forest cover type in Minnesota, and Minnesota has the third highest volume of ash in the U.S. Based on a survey in 2006, there are over 3 million ash trees that are publicly owned in municipalities “Have you missed us? across the state. No, you are not losing your mind! You did lose two The DNR is continuing its efforts to limit introductions of exotic issues of the Advocate. forest pests onto state‑administered That emerald green bug has lands by enforcing recent firewood tripped us up and grabbed legislation. Firewood from over all of our attention. However, 900 vendors has been approved by DNR-Forestry for use in we are back on track to face Minnesota State Parks. Since EAB EAB, AND to keep the Shade was found inside Minnesota and Tree Advocate coming to three counties are now your mailboxes!” quarantined, additional firewood vendor restrictions were added in 2009: all hardwood firewood from quarantined counties or their bordering counties can only be used in those counties. Public outreach campaigns continue.

The state has developed a readiness plan to minimize the impact of emerald ash borer in the state of Minnesota and specific to urban and rural ADVOCATE • Winter 2010

URBAN FOREST HEALTH

Measuring Canopy Cover: What Should My City’s Canopy Cover Be?

any U.S. cities are turning to canopy assessments to identify areas that need more tree cover. Aerial photographs or satellite images provide the perspective needed to determine how much of the city is currently covered by tree canopy (see figure 1). The results are then used as a basis for setting an urban tree canopy goal, either for the entire city or for individual sections of the city.

Jill Johnson is Coordinator, Midwest Center for Urban and Community Forestry, U.S. Forest Service

There are many different ways to analyze tree canopy and determine realistic goals. The approach Figure 1: The tree canopy covers roughly 20% of the total area seen in this photo. described below was developed by the U.S. Forest Service, University of Vermont, The first step is for the specialist to create a land and several state forestry agencies. There are five cover map from the aerial photographs or satellite basic steps: images. At a minimum, the final map should show 1) Complete an urban tree canopy assessment to where existing tree canopy is located. But it is very determine how much canopy cover currently helpful if the pavement, grass/shrubs, and water exists and where there are opportunities for are also identified (see figure 2). more, 2) set a goal to increase canopy cover based on Once the existing canopy is mapped, the next step the assessment, is to determine where it’s possible to add canopy. 3) create a plan to achieve the goal, Because trees cannot be planted on top of build4) implement the plan; and ings, in the middle of roads, or in water, these 5) evaluate successes and challenges, adjusting areas are blocked out. What is left is a map showthe plan as necessary to meet the goal. ing where it is biophysically possible to plant trees. Most communities will need help with the first step, the assessment. But the other parts of the process can be completed internally if there is an urban forester on staff. The details of each step are outlined below.

Urban Tree Canopy Assessments The assessment determines how much canopy a community currently has, called “Existing” canopy, how much is “Possible,” and then depending on the specific interests of the community, where canopy is most “Desired.” These assessments require high resolution aerial photographs or satellite images and experts called remote sensing specialists to analyze them.

©Metropolitan Design Center, Regents of the University of Minnesota

by Jill Johnson

The final step involves integrating specific interests of the community. Social and other environmental concerns can be incorporated so increases in canopy cover address multiple issues. For example, one city wanted to plant trees in low-income neighborhoods. So the map of “Desired Canopy” highlighted those low-income neighborhoods that had the least amount of canopy.

Setting a Canopy Goal The big question is always, “How much is enough?” Unfortunately there is no clear answer. The national non-profit organization, American Forests, has developed some guidelines from their experience analyzing tree cover in U.S. cities. Winter 2010 • ADVOCATE

Canopy Grass/Shrubs Impervious (roofs and pavement) Figure 2: Land Cover These are as follows: • Average tree cover for the entire city • Suburban residential zones • Urban residential zones • Central business districts

40% 50% 25% 15%

These are just guidelines; every community should consider its own needs and set realistic and achievable goals. The canopy cover of U.S. cities completed to date ranges from 12% in Frederick, Maryland to 39% in Burlington, Vermont. So deciding on an acceptable goal depends significantly on the community’s current situation. When setting a goal, be specific about the geographic boundaries. Most communities have a city-wide goal, but many have identified separate goals for different neighborhoods or land use types. The goal should be to increase canopy cover. However, considerations for wide-scale losses due to insect or disease outbreaks should be noted. Specify the timeline for achieving the goal, and be sure that it is endorsed by local officials.

Make a Plan The plan should include activities that will both protect existing canopy as well as create new canopy by planting. It is difficult to achieve increases in canopy within a 10 to 30 year timeline by planting new trees and ignoring the existing ones. The plan needs to incorporate activities for both. This includes measures to design adequate above- and below-ground growing space for trees, protecting high quality trees already in the landscape, providing quality tree care, and managing the population with ADVOCATE • Winter 2010

practices that minimize the impacts of storms and insect or disease outbreaks. Because the greatest potential for increasing canopy often exists on private property, some parts of the plan may include initiatives to fund or assist with private tree planting and regulations for private tree protection.

Implementation of the Plan All action items in the plan should be completed in the given timeframe.

Evaluation and Revision Finally, it is advised that a subsequent canopy cover assessment be completed every 5-10 years. The follow-up assessment may only need to examine existing canopy to determine how successful the efforts have been and identify necessary changes to the plan (or goal).

Goal Setting in Minnesota The cities of Woodbury and Minneapolis have recently received grant funds to set Urban Tree Canopy goals. Both are working with the University of Minnesota‘s remote sensing specialists for the analysis.

Canopy Cover Assessments versus Tree Inventories Tree canopy assessments should not replace community tree inventories. Their purposes and value are different. A public tree inventory provides information about the species, size, condition, and maintenance needs of individual Tree Canopy Cover continued on p. 8

Turning Over the Umbrella: The Role of Trees in Storm Water Management By Loren W. Culver

eelings of foolishness flooded over me. Unpacking my umbrella, I overheard the local weather man make reference to the ongoing drought. The low flow faucet and showerhead, disposable plastic cups, and instruction card on reusing towels were all water saving measures implemented by the hotel. How could I have forgotten? Out of sight, out of mind, I suppose. I had just arrived in Atlanta for the 2008 Partners in Community Forestry National Conference. Leveraging trees as stormwater management tools increases their value, building on the “Trees Pay Us Back” program completed by the USDA Forest Service. Maximizing their value by leveraging trees to the greatest extent practicable, and with a focus on stormwater applications, was a primary topic of the concurrent (education) session that I, along with colleagues Janette Monear (Texas Trees Foundation) and Randy Neprash (Bonestroo), presented. While flying in, I studied the urban forest canopy, or the lack thereof. I recalled a Wall Street Journal article, “Loss of Trees Compounds Pollution in Cities” that claimed a temperature increase of 5 to 8 degrees in Atlanta apparently followed decades of development that had “…bulldozed wooded areas.” Could the loss of trees (and natural watersheds) be responsible, at least in part, for the drought? Given the extent of development, how could the urban tree canopy be expanded to act as, and provide the benefits of green infrastructure? The severity of the drought underscored the need for change. It highlighted the need for green infrastructure and especially for partnering trees and stormwater. Over the next three days, I would find answers to these and other questions as a broad based group gathered to identify ways to work in partnership for community forestry.

session. “Greening of our Nation’s Urban Places” was presented by Dan Burden, a nationally recognized authority on bicycle and pedestrian facilities and programs—who, incidentally, earned a B.S. in Forestry at the University of Montana. He straightforwardly walked us through what makes a livable and ‘walkable’ community and the vital role trees play. Trees contribute heartily, providing benefits ranging from economic, environmental, and social. Creating the backbone of green infrastructure, trees can, and should, be integrated with gray infrastructure. The City of Red Wing has accomplished this with its comprehensive Asset Management Plan. This innovative program is providing the city with new perspective on the value of, and a renewed commitment to its public trees. This allows it to prioritize and facilitate improvements for its trees, such as incorporating stormwater.

Turning the Umbrella Upside Down So what does it mean to integrate trees and stormwater? My otherwise useless umbrella will help illustrate. Right side up, its function is similar to traditional stormwater (gray) infrastructure. It directs water away. In this scenario water is considered a liability and efficiently removed. Let’s turn the umbrella upside down. It now captures water and directs it toward the center. A tree and stormwater BMP functions as the latter. It captures, directs, and stores rainwater above or below grade for use by trees. Through filtration and infiltration it also prevents rainwater from immediately leaving the site. Stormwater management seeks to achieve interception (rate control), evapotranspiration (quantity control), filtration (quality), and infiltration (recharge). And integrated tree and stormwater BMPs, when properly designed and installed, can achieve all four.

Trees as Green Infrastructure

Trees–and Stormwater–Pay Us Back as Existing Vertical Raingardens

The conference theme: promoting trees as green infrastructure while building healthier, livable communities, was apparent from the opening general

Trees, especially large canopy trees, transpire far more water than a traditional rain garden. Due to their unique relationship to the ground plane,

Winter 2010 • ADVOCATE

An Important Partnership–Trees and Stormwater There was an abundance of information about the important partnership between trees and stormwater at the conference. The case for “Connecting Trees to Water Quality and Stormwater Management” (also the session’s title), was made by Vincent Cotrone, an urban forester with Penn State Cooperative Extension. He discussed the role of trees and forests in healthy watersheds and how they manage stormwater, reduce flooding, and improve water quality.

Figure: Virginia Tech College of Natural Resources, Susan Day

trees can be used where rain gardens cannot (i.e., parking lots, along streets, etc.) In general, as compared to traditional rain gardens, trees live longer and costs for maintenance and replacement are less, giving them a supreme advantage. Leveraging trees as stormwater management tools is a simple concept. It increases their value, building on the “Trees Pay Us Back” program completed by the USDA Forest Service. Maximizing their value by leveraging trees to the greatest extent practicable, and with a focus on stormwater applications, was a primary topic of the concurrent (education) session that I, along with colleagues Janette Monear and Randy Neprash presented. The concept is simple. Use trees as vertical raingardens. Implementing it can be a bit more difficult. Generally, as urban density increases, so too does the design’s complexity. However, the resulting benefits increase exponentially and trees more completely pay us back and in several ways not fully realized initially. First, supplemental water can be significantly reduced or eliminated as well as the associated costs. Second, trees will have a better chance of establishment and survival. Third, and of growing significance, stormwater fees can be vastly reduced or eliminated entirely using a smartly designed system. The advantages will increase dramatically over time as water and stormwater fees reflect true costs. Eventually, equilibrium will be reached between implementing tree and stormwater BMPs and the resulting cost savings. ADVOCATE • Winter 2010

It also stands to reason that healthy watersheds contain healthy trees. In “Advanced Green Infrastructure in Compact Green Developments,” Dan Staley, an urban planner from Aurora, Colorado, discussed prioritizing code to allow/capture comprehensive sustainable benefits. We have been so successful in building what we thought to be highly efficient systems that we now need to engineer trees back into the urban fabric and our lives. Integrating trees and stormwater BMPs provide effective sustainable solutions that are mutually beneficial to trees and in meeting many stormwater requirements—done either through preserving existing trees and tree stands or innovative design solutions. Managing Stormwater for Urban Sustainability Using Trees and Structural Soils is a synthesis of research by Virginia Tech, Cornell University, and the University of California Davis. It presents a new space-saving infiltration BMP that mitigates runoff using pervious surfaces and structured soils, and one that could benefit Atlanta’s parched trees.

Combating Global Climate Change–One Tree at a Time Larger Opportunities to Use Trees In “Our Evolving Understanding of Climate Change and Weather,” Stu Ostro from The Weather Channel presented ongoing research indicating how global warming is responsible for unpredictable weather patterns. Urban forests and tree planting are a strong part of the solution to global climate change. Sustainable expansion of the urban forest canopy can assist in mitigating increasingly erratic weather conditions. Continued on next page

Turning Over the Umbrella continued from p. 7 During a media panel we also learned how Atlanta’s prolonged drought had unexpected consequences. Sudden tree drop was a current symptom and had recently claimed a victim. To prevent the resulting dendrophobia from spreading like wildfire, local foresters had to perform the combined roles of spokesperson and therapist to assuage fears. As the voice of reason, they were required to instantaneously respond and provide relevant information to prevent clear cutting of the urban forest. Lessons learned? First, always be prepared to advocate for trees! Second, sustaining trees with rainwater through integrated stormwater BMPs makes sense–small quantities of water take on increased importance during times of drought.

Community Trees–Expanding Partnerships Developing and maintaining effective partnerships are critical to expanding the reach of community forestry. Conference social events, informal breaks, and the product expo provided ideal networking opportunities to discuss and explore partnerships among diverse professionals. These partnerships are key to identifying mutually beneficial goals and possible funding opportunities among agencies along with facilitating the implementation of innovative programs. Partners in Community Forestry was an extremely well organized conference presented by The Home Depot Foundation and Arbor Day

Measuring Canopy Cover continued from p. 5

Foundation. For information about this years conference consult the Arbor Day Foundations website for updates. Useful links for additional information: • Partners In Community Forestry National Conference–Photos and Presentations 2008 http://www.arborday.org/shopping/ conferences/photos/pcf/2008/ • BeltLine: Atlanta Connected www.BeltLine.org • Trees Atlanta www.treesatlanta.org • Managing Stormwater for Urban Sustainability Using Trees and Structural Soils http://www.cnr. vt.edu/urbanforestry/stormwater/ • Dan Burden’s Walkable Communities website; For “22 Benefits of Urban Street Trees” go to www.walkable.org click on resources, then articles • Red Wing Asset Management Plan: http:// www.red-wing.org/images/content/files/ departments/planning/openspace.pdf Lorin Culver is a LEED AP and Landscape Architect licensed in MN and CA. He has worked on projects with a national scope. As the recently selected National Park Foundation Transportation Scholar, he is helping to develop an Alternative Transportation Plan for the Mississippi National River and Recreation Area within the Twin Cities. His professional profile can be viewed at: www.linkedin/in/lorinculver He can be reached at lorinculver@gmail.com

trees—information critical for managing the population.

cover in a park may be buckthorn. It is imperative that any community considering an urban tree canopy goal understand these challenges and limitations.

Challenges

Where to Get More Information

There are a few challenges associated with canopy goals. First is the cost of obtaining high-quality imagery. Second is the cost of hiring specialists to analyze the imagery. Third is that most of the opportunities for increasing canopy cover exist on private property. And finally, it is difficult to ascertain the difference between high and low quality tree canopy. For example, the widespread tree

To learn more about measuring urban tree canopy or view reports from communities who have set goals, visit the U.S. Forest Service Web site at www.nrs.fs.fed.us/urban/utc.

Or visit the American Forests’ Web site at: www. americanforests.org/resources/urbanforests/ treedeficit.php. Winter 2010 • ADVOCATE

Photo: Steven J. Baskauf

Mystery Tree... by Kathleen Preece

Bark

Photo: Steven J. Baskauf

Leaves

Kathleen Preece is a writer in natural resource communications.

Fruit

This shrub or small tree (up to 5 meters in height) has some very distinct and unique characteristics. Its leaves are opposite, compound with three leaflets with serrated/fine-toothed edges. The branches of older trees/shrubs have bark that is streaked with white. In the spring, small, pendant white flowers are produced. They mature to highly-distinctive, inflated, papery capsules containing several large seeds. At maturity, the capsules can be induced to “rattle” by shaking the fruit. The capsules themselves are relatively large, ranging from 1 to 2 inches in length. Flowers are clustered at the end of twigs and appear in April–May, with fruits maturing mid-August through September. In summary, your clues are the following: drooping clusters of cream, bell-shaped flowers; attractive, dark‑green, trifoliate leaves; greenish bark textured with white cracks; and interesting fruit. The fruit, which changes from green to yellow to brown, is a three-chambered bladder. (PS) Speak French? Here’s a real clue: Staphylier à trois folioles ADVOCATE • Winter 2010

Answer on p. 14

Where Biomes Gather from on p. 1 North and South Dakota. Handicap accessible trails are planned to follow the major river courses of Minnesota and provide access to each biome. The site covers almost 61,000 square feet. According to Jerry, it is a “coming together place,” where tree orphans from new development sites have been collected and saved along with the diversity in shrubs and ground covers. Trees were inspected for insect and disease before coming to the site, and were selected by form and quality. For every tree selected, two other candidates were rejected. One pine site was completely rejected due to the discovery of an emerging needle blight tree health issue. A private landowner came to the rescue and donated eight trees needed to fulfill the plan for the biome.

Kathleen Preece is a writer in natural resource communications; Jerry Stensing is a forester with the Bemidji Soil and Water Conservation District

Within moments of completing installation of the first 20 trees, the SWCD received word that the City of Bemidji and Menard Inc., had finalized negotiations to use the project for off-site tree replacement to fulfill tree mitigation requirements on a proposed building site for a new Menards in the community. (The City of Bemidji Tree Ordinance requires replacement trees to offset tree removal impacts on commercial construction sites. Designed in the shape of Minnesota and surrounding states and provinces, it contains primary representations of natural landscapes in geographically correct placement. The unique capacities of the SWCD to bring together multiple partners and provide planning and implementation was the foundation for the growing of this Minnesota biome. Funding came from multiple sources that included public, private and corporate contributions.

The SWCD will provide 2 years of maintenance to ensure the biomes have ‘taken’ to their Minnesota locations next to J.W. Smith. This is a story of partnerships and bringing together available resources to build a living classroom that reflects both simple and complex interactions within the natural environment. The legacy created will last for generations and provides an outdoor learning experience for students and the community’s residents. Additionally, the completed project will integrate solutions to site-specific environmental issues such as storm water management, green space, and bio-diversity. Jerry points out that—thanks to the integration of stakeholders, including community, educational system, private landowners, county government, and civic groups—the Bemidji Biome Project might be called “community-urban forest management at its best.” The story is still being written. The trees were installed during the fall of 2008, with storm water survey and detailed topographic mapping completed in the fall of 2009. Design and engineering of a storm water bio-retention system is scheduled for construction during 2010. And then there’s the prairie chapter to write. “Flying into Bemidji?” Jerry asks. “Look down as the airplane makes its approach. You will see all of Minnesota: a land of prairies, red and white pines, maples, aspens, and oaks.” When you’ve landed and you want to walk among all the biomes of Minnesota, find Jerry at www.beltramiswcd.org. He will have a few more chapters written, and will tell you more about the main characters (and maybe even what the sequel is).

The Bemidji Biomes Partners • Independent School District #31—Vision, Support, and Biomes Grant

• Minnesota Department of Agriculture—Tree Health Consultation

• Joint Planning Board—Bemidji Tree Ordinance

• Menard Inc.—Financial Contribution and Tree Donations

• City of Bemidji—Support and Assistance

• Beltrami SWCD—Financial Contribution

• Bemidji Regional Airport—Tree Donations

• USDA Natural Resources Conservation Service— Technical Assistance

• Jack Strowbridge—Tree Donations • Beltrami County and Minnesota DNR—Supplies Donations

• Bemidji Aviation Inc.—As-built Photo Flight • Collins Oakgrove—Traditional Blessings Winter 2010 • ADVOCATE

Photo: Jerry Stensing Photo: Ruth Trask

Photo: Jerry Stensing

Aerial photo of the biomes in January 2009.

Minnesota Biomes tree locations as built November 2008.

Jamie is a student from an area school whose curiosity, interest, and inquisitiveness fostered a friendship with the tree planting crew. Jamie showed up regularly to the delight of the field and planning crews.

Northland Tree Service uses the 80-inch tree spade to install the first of 145 trees. Here, Northland is bringing in a nice red oak. ADVOCATE • Winter 2010

Students began using the outdoor classroom, even as construction was underway.

Photo: Jerry Stensing

Collins Oakgrove, an educator for over 30 years, is a Red Lake Band of Chippewa Tribal Elder/Spiritual Leader. He provides a traditional spiritual blessing at the site of the first tree. Forester Jerry Stensing lights the match.

“And, on the second day, the birds returned.” —Jerry Stensing

FOREST HEALTH

Winter Damage to Trees and Shrubs—It’s Much More Than Cold Temperatures By Gary Johnson, Department of Forest Resources, University of Minnesota up buds and foliage, causing the tissues to lose too much moisture as they transpire. Most desiccation injury doesn’t kill plants, but it often makes you wish they would die. Most commonly, the evergreen foliFigure 2: “Scorched” or desiccated age “scorches” foliage such as this will be replaced or turns brown by new needles during the next from the lack of growing season… as long as the moisture, but is replaced by new buds are still alive and healthy. needles during the following growing season.

Desiccation (drying of living tissues) damage occurs very commonly on plants that have evergreen foliage or large buds. The drying winter winds on fully exposed landscape sites constantly dry out evergreen foliage tissues and large flower buds, especially on more sensitive evergreens (yews, arborvitae, hemlock). Desiccation may also happen to plants exposed to the bright southern sun of winter that warms

Cold temperatures do occasionally cause damage. True frost cracks (cracks through the wood of a stem) are partially due to cold temperatures. Unusually early autumn frosts and unusually late spring frosts can kill plant tissues either before or after they are safely in full dormancy. Plants that are hardy to -30° F temperatures when they are fully dormant can be damaged by temperatures as “warm” as 25° F when they are not dormant. Severe cold temperatures can go beyond the scorched foliage damage from desiccation injury and actually kill buds and branches, and this type of damage is difficult to prevent. Choosing plants

Photo: Gary Johnson

Mechanical damage is usually the most common and includes animal feeding damage, heavy snow and ice loads that break branches, and snow blower or plow damage. Preventing or mitigating mechanical damage relies on some sort of physical protection, either for the tree trunk or the buds and twigs. Stem protectors that soften the blow of ice and gravel from snow blowers can be as simple as corrugated plastic stem protectors. If the winter damage is primarily from animals, protecFigure 1: Crabapple stem tion needs to be more girdled by rabbit feeding off exclusionary, such as the bark. hardware cloth.

Photo: Dave Hanson

Types of winter damage. Winter damage usually falls into one of four major categories: mechanical, desiccation, cold temperatures, or chemical injury.

Photo: Gary Johnson

Most plants that chronically suffer winter damage and die are usually health stressed plants that would have died from something else. Keeping trees and shrubs healthy enough to survive the stresses of winter usually moderates the exact type of damage when possible.

Figure 3: Frost cracks extend into the trunk of trees and are the beginning of internal decay in many cases. This is a cross-section of a tree with a frost crack that extended up 20 feet from the ground. Within a few years, the tree would have been removed due to extensive decay.

Winter 2010 • ADVOCATE

Frost cracks can be minimized, however. True, one of the ingredients for damage is cold temperatures, but two other factors must be present for frost cracks to become common… otherwise, every tree would frost crack. The second factor that encourages frost cracks is the presence of a wound on the stem. Avoid stem wounding and frost crack frequency will be lessened. Finally, trees entering winter in a water-stressed condition will be more prone to frost cracks. Water trees regularly until the ground freezes, mulch over the root system to keep the soil moist, avoid or minimize any wounds to the stem and frost cracking will be kept to a minimum.

Photo: Dave Hanson

Finally, chemical injury from deicing salt spray drift or run-off may be the defining damage to plants. Plants within 60 feet of a busy highway or street are most at-risk to this type of damage. Most of the time, salt spray damages foliage and buds, disfiguring the plant but not killing it. Salt run-off that accumulates in the soil can become very toxic and eventually kill plants. Avoid these “kill-zone” areas completely or only use highly tolerant plants, such as

Figure 4: Spray salt has accumulated on the needles of this pine and will cause them to turn brown and die. Unsightly, but rarely does it kill the tree.

ADVOCATE • Winter 2010

honeylocust or Black Hill’s spruce in areas that receive spray or run-off salt. Occasionally, if there is enough space, a snow fence placed between the road and the plant materials can minimize the damage from spray salt drift, but there needs to be at least 20 feet of clearance between the 4-foot tall snow fence and the plants for it to be effective.

Photo: Gary Johnson

that in a healthy state can tolerate extremely low temperatures is the only “fail-safe” way of moderating extremely cold temperature damage.

Figure 5: Deicing salt run-off from this parking lot killed all of this grass. Imagine the fate of trees whose root systems would be in this “kill zone.”

Four “Easy Steps” to minimize winter damage: 1. Keep plants healthy, especially well‑watered until the ground freezes. Moist soil freezes slower and stays warmer than dry soil. 2. Mechanical injury requires physical protection: hardware cloth, snow fencing, deer netting. 3. Rely on mulch rather than snow. Four inches of organic mulch is as effective as a good snow cover for keeping soil warmer and roots healthy. 4. Don’t plant closer than 60 feet from highways and 30 feet from streets that use a lot of deicing salt.

MN DNR

Thinking of Spring? Think of energy conservation planting strategies

West is best Shade west and east windows to most effectively reduce air conditioning use: • Give highest priority to planting shade trees next to west windows. • Plant trees next to east windows as a second priority. • Select a tree that can be planted within 20 feet of a window and will grow at least 10 feet taller than the window. • Select trees that are strong, resistant to disease, pests and dam age from storms; and that will grow vigorously under local site conditions. • Select a tree with dense foliage, as broad in form as space permits.

Let the sun shine in • Avoid shading south windows. • If trees already exist south of windows remove their lower branches to let more winter sun under the limbs. • If you do want a tree southeast or southwest of a window: Use a “solar friendly” tree that has moderately dense foliage during the hottest times of the year, loses its leaves early in the fall as the heating season begins, and has sparse winter branches.

Remember: Take advantage of the free solar energy coming in through the south windows in the winter. The worst place to have a tree is in the yard south of a home, since the sun’s angles cause the shadow of the tree to miss the home during the summer months and always fall on the home during the winter months.

The more the merrier Maximize tree canopy cover throughout the neighborhood to maximize environmental benefits.

Up and over Where winters are long and windy, the most valuable way to reduce annual energy use is to create windbreaks. Tall trees will guide wind up and over an area to a point downwind at least 10 times the height of the windbreak. Learn more details on these strategies at: http:// www.dnr.state.mn.us/treecare/energy/strategies. html

Mystery Tree Answer: Bladdernut Staphylea trifolia

Winter 2010 • ADVOCATE

About MnSTAC The Minnesota Shade Tree Advisory Committee (MnSTAC) was established in 1974 by a group of concerned citizens to address the health and well being of community forests. MnSTAC is recognized throughout Minnesota and the country for its expertise, advice, coordination, and support for community trees. It is an organization of diverse individuals who represent a broad spectrum of tree-related interests. It fosters and supports local community tree programs across the state so healthy community forests are fully integrated into community development, infrastructure, education, and management. MnSTAC Board of Directors Katie Himanga President Steve Nicholson Vice President, Private Consultants – S&S Tree Steven Shimek MN Dept. of Agriculture Tina Markeson MN Dept. of Transportation Alan Ek University of Minnesota Dave Epperly MN DNR Forestry Jeffrey Gillman Univ. of MN Extension Service Glen Hambleton Tree Care Advisor Kit Richardson Local Tree Board Member – Minneapolis Larry Westerberg Society of American Foresters Steve Roos American Society of Landscape Architects Jim Vaugha MN Society of Arboriculture Dave Kleinhuizen MN Nursery & Landscape Assoc. Barb Spears MN Forestry Association Anne Oldakowski Soil and Water Conservation Districts Craig Johnson League of MN Cities Emily Barbeau City Forester–City of Minnetonka Kameron Kytonen City Forester–City of Andover Dave Auchter Utilities–East Central Power Deborah Karasov Non-profits–Great River Greening John Ingleman MN Corporation–Hutchinson Technologies Stephen Schott Student–University of Minnesota Ron Norenberg Citizen–DNR Region 1 – Park Rapids James Lemmerman Citizen–DNR Region 2 – Duluth Dave Moehnke Citizen–DNR Region 3 – Rochester

Meet A MnStac V.I.P. Robert “Bob” Fitch It’s really not fair to categorize folks from “the Dakotas” as coming from a treeless environment that does not foster advocates for a green world. Robert “Bob” Fitch is a shining example of why it isn’t! Bob grew up in the Sioux Falls/ Yankton area of South Dakota. His early career was focused on “words”—as a reporter, writer, and Robert Fitch editor. His career path brought him to management of differing non-profit associations, none of which were “green.” That is, until Bob joined up with the Minnesota Nursery and Landscape Association (MNLA) now serving as its executive director. He admits, “I really have a passion for everything green,” particularly as his 13-year tenure with the MNLA grows. As the state’s oldest and largest green industry trade organization, MNLA (it began in 1925 as the Minnesota Nurserymen’s Association), represents and serves nursery and greenhouse growers, garden centers, irrigation contractors, industry suppliers, and a wide range of landscape professionals. The association aims to help these members operate their businesses more successfully by providing education, networking, legislative and regulatory representation, public relations, and financial benefits through group purchasing, and other member services. Four full-time, three part-time, and a number of independent contractors handle the core of the association’s work, with over 150 individuals actively volunteering on the MNLA’s 20 active committees. Education programs and government affairs are the two cornerstones of the association. Bob suggests that a high priority in the months ahead will be finding support for tree removal and replacement in light of the pending spread of the emerald ash borer. “While dealing with EAB is going to be a significant and serious challenge,” Bob attests, “the MNLA’s connection to, and working relationship with the Minnesota Shade Tree Committee will provide a forceful front in facing what lies ahead for Minnesota’s community trees.”

For handy up-to-date links to Web sites of interest, be sure to visit

www.mnstac.org

ADVOCATE • Winter 2010

Photo:

STAC INFO & NEWS

Presorted Standard U.S. Postage PAID Permit No. 171 St. Paul, MN

Minnesota Shade Tree Advocate 500 Lafayette Road St. Paul, MN 55155-4044 RETURN SERVICE REQUESTED

Minnesota Shade Tree Advocate A quarterly newsletter published by the Minnesota Shade Tree Advisory Committee. Managing Editorial Group: Ken Holman, Gary R. Johnson, Rebecca Koetter, Karl Mueller, Lara Newberger, Jacob Ryg, Stephen Schott, and Mark Stennes. Editor-in-Chief: Kathleen Preece Design: Creative Services Unit, MNDNR Material in this newsletter is not copyrighted. Reproduction for educational purposes is encouraged. Subscriptions are free. Articles, news items, photos, and videos are welcome. This publication was produced with the support of the USDA Forest Service, Northeastern Area; State and Private Forestry.

ay is Arbor Month in Minnesota and Arbor Day, Friday, April 30, marks the beginning of an entire month of celebrating trees. For Arbor Month 2010, the Minnesota Department of Natural Resources has reissued and added content to the 2002 Arbor Month poster titled From Small Seeds Grow Big Dreams. The idea behind this year’s Arbor Month theme is to demonstrate that seeds are packed with everything for a new life. A packet of red pine seeds will accompany the poster to encourage seed germination experiments and the planting of Minnesota’s state tree.

Address inquiries to: Minnesota DNR Division of Forestry 500 Lafayette Road St. Paul, MN 55155 Printed on recycled paper using soy-based inks. Winter 2010 • ADVOCATE