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2014 Fall 2014


leaves Fall 2014

Cait Anastis, Editor Jackie Klisuric, Graphic Design

administration Clement W. Hamilton President and CEO Jim Ansberry Director of Finance David Burke Research Department Chairman Roger Gettig Director of Horticulture and Conservation Brian Parsons Director of Planning and Special Projects James F. Pelowski Interim Director of Development Paul C. Spector Director of Education and Public Programs


Nancy Spelman Director of Human Resources and Safety

board of directors




4 6 Pierson Creek Valley 10 Partnerships

8 9 Bird Bio 12 Plant This, Not That 17 Ask Greg 18 Research

Construction Begins on

Canopy Walk And Emergent Tower

A Hidden Gem

Holden Reaches Out To New Community Partners

11 Volunteers 14 Oh Deer, Oh Deer:

Cultivating Holden’s Emergent Leaders Studying The Long-term Impacts Of Deer On The Forest Understory

On the Cover: Fagus sylvatica ‘Horizontalis’ (weeping European beech)

Plant Profile

Acer palmatum (Japanese maple)

American Crow

Elaeagnus umbellata (autumn olive)

News and Highlights

Paul R. Abbey, Chairman Jonathan E. Dick, Vice Chairman Sarah L. Gries, Vice Chairman Peter S. Hellman, Vice Chairman Stephen J. Knerly, Vice Chairman Joseph J. Mahovlic, Vice Chairman C. W. Eliot Paine, Vice Chairman Robert R. Galloway, Secretary Thomas D. Anderson Barbara Brown Christopher A. Cullis Paul E. DiCorleto, PhD Michael C. Marino Cynthia A. Moore-Hardy

Ellen W. Jones Nordell Robin Schachat Lynn C. Shiverick K.K. Sullivan Timothy L. Swanson Michael T. Victor

directors emeriti Constance Norweb Abbey Ralph W. Abelt Jeanette Grasselli Brown Miriam N. Gale Henry R. Hatch Arlene M. Holden-Loftin

T. Dixon Long Henry L. Meyer III William J. O’Neill Jr. John Sherwin Jr. Penelope Theis

honorary directors Mary Groves Alison C. Jones

Thomas W. Seabright Helen Whitehouse

Volume 12, Number 4 ©The Holden Arboretum Leaves (ISSN 0518-2662) is a class and events magazine published quarterly by The Holden Arboretum for $10 per year for members (included in membership fee) and $55 per year for nonmembers


Periodicals postage paid at Mentor, Ohio



Postmaster: Please send address changes to Leaves: The Holden Arboretum, 9500 Sperry Road, Kirtland, Ohio 44094-5172

As this issue of Leaves goes to press, big news on the Holden front is our impending partnership with the Cleveland Botanical Garden. We will keep our members and friends informed as we flesh out and implement this groundbreaking relationship. Exciting times, indeed!

from the president It is natural that we should celebrate all the new projects at Holden; the Eliot and Linda Paine Rhododendron Discovery Garden, the R. Henry Norweb Jr. Tree Allée and the soon-to-be-built canopy walk and emergent tower certainly are exciting additions to our landscape. But of equal, albeit more subtle, significance are the improvements and repurposings that also are underway, making long-standing Holden features and facilities more useful and engaging to visitors. Perhaps the most conspicuous of such improvements have been the renovated Corning Library; turning the former sugarbush into the Working Woods, including transforming the evaporator building into our most-utilized schoolchildren’s classrooms; and restoring the stream and landscape downhill from Heath Pond in the Helen Layer Rhododendron Garden. In addition, just this spring we completed renewing Hawgood Hill, the stunning azalea display that visitors see across Heath Pond on entering the Layer Garden. Other improvements are being undertaken to tease out interesting stories that are implicit in our gardens, which may be evident to the horticultural cognoscenti, but which should be accessible to our general avid audiences. Our mantra is, a great garden at Holden has three attributes: it should be beautiful, it should showcase unusual plants, and it should tell stories that engage and even transform our guests. A case in point is our Myrtle S. Holden Wildflower Garden, whose plant collections and design illustrate the diversity of Ohio’s native flora. The garden’s stories now are being brought to light by thoughtful horticultural work by gardeners Ann Rzepka and Dawn Gerlica, and by new interpretive signage being developed by Marian Williams, manager of information services, and intern Eva Rodriguez for installation next year.


we’ve been installing temporary exhibits showing how to care for trees (and how not to) and, this year, the actual monetary value of trees to a homeowner, through services such as energy conservation and stormwater control. So, as you enjoy our new gardens and features, please also enjoy our more subtle improvements. And thank you, through your membership and support, for making them possible.

Clement W. Hamilton, PhD President and CEO

Fall 2014

Even the Arthur S. Holden Sr. Hedge Collection, which we tend to take for granted, is experiencing a renaissance. Several species of traditional hedge plants have turned out to be aggressive invaders of our native forests, such as Euonymus alatus (burning bush). Over the past couple years we have replaced them with noninvasive alternatives, serving as a physical manifestation of the “plant this, not that” theme we feature in each issue of Leaves. And in the midst of that display, which is just south of the Corning Visitor Center,






Construction begins on

Canopy Walk and Emergent Tower by Vicki McDonald, marketing and public relations specialist

Work has started on The Holden Arboretum’s newest feature, a canopy walk and emergent tower that will offer visitors a uniquely different perspective on trees, forests and birds. The new structure is being named in honor of Judith Murch and in memory of Maynard H. Murch IV, both long-time Holden supporters. The 500’ long elevated walkway, 65 feet above a tributary of Pierson Creek, will include four suspension bridges. The emergent tower will allow visitors to view Holden’s woodlands from more than 120 feet from the ground. The first platform of the canopy walk will be accessible, and the structure will include various safety precautions including a 4’ high metal mesh guard allowing visitors of all ages to enjoy the experience. Holden has hired Phoenix Experiential Designs from Sugar Grove, N. C. to construct the canopy walk. Phoenix is a leader in the adventure building industry with a portfolio that boasts extraordinary structures including climbing towers, challenge courses and canopy walkways all over the world. Located on the north side of Sherwin Pond about 1/2 mile from the Warren H. Corning Visitor Center, the canopy walk will take guests over the Pierson Creek ravine. Once construction is complete, visitors will gain entrance to the Canopy Walk near Sherwin Pond in the Helen S. Layer Rhododendron Garden. The emergent tower will be accessible from the Daus Memorial Trail. Holden will use the structure for visitor engagement, youth and adult education programming, and access to trees for scientific research. The project is expected to be finished in 2015 but the opening date is not yet confirmed. Prefabrication of the structure is taking place at High Country Woodworking, a 30,000 square foot shop in Boone, N.C. Pieces will be cut and bundled before being shipped to Holden where they will be airlifted to the building site. On-site construction started in the spring and will continue through the summer and fall. None of the existing trails or paths will be interrupted during the construction. Holden welcomes guests to view the building of this state-of-the art observation structure during visits to the grounds.

Canopy Walk and Emergent Tower locations


Emergent Tower

Daus Memorial Canopy Walk


Sherwin Pond


Heath Pond


1 in = 100 feet

Fall 2014

This map was prepared by: The Holden Arboretum 9500 Sperry Road Kirtland Hills, Ohio 44094


Pierson Creek Valley:

A Hidden Gem by Betsy Burrell, Holden volunteer

Less than a half-mile walk from Holden’s Corning Visitor Center is an often overlooked spot: the Pierson Creek Valley. This pristine area has a unique story to tell about our natural history, and guided hikes led by volunteer naturalists are a wonderful way to learn more about why this valley is so extraordinary. Pierson Creek begins near the Sperry Road entrance to The Holden Arboretum, flowing generally northward through Holden to its northern border, emptying into the East Branch Chagrin River in Kirtland Hills near Booth Road. It creates a valley through the peaceful woods for its entire length. The creek carries mostly groundwater from springs and rainwater free of lawn or agricultural runoff, which accounts for its pristine clarity and ability to support many native species of plants, animals, insects and aquatic life. For much of its length the valley is a steep ravine with forested sides creating a cool and shady environment that displays a delightful and almost mysterious panorama for visitors.

A Buried Pre-Glacial Valley


The Pierson Creek Valley is a miniature version of what the valley looked like 75,000 years ago, before the last glacial advance in Northeastern Ohio. The valley was part of a well-developed, fast-flowing stream and river system, which moved in a northerly direction. The valley walls were higher, the waterfalls steeper and the valley wider. When the Wisconsin glaciation moved through this area, it deposited glacial till into the valley, filling the valley to an unknown height. Ten thousand years ago, new streams created by the retreat of the glacier followed the path of least resistance - the original stream and riverbeds. This process continues today as the creek cuts through the till which overlays the original bedrock. When you stand in the valley admiring the delicate, ephemeral beauty of a wildflower or fern, think about the buried pre-glacial valley below you, its depths unknown.



Geologist and Holden volunteer, Pat Biliter, developed the training program for the guides who lead the groups into Pierson Creek Valley. “Pierson Creek is a perfect example of a very healthy stream system,” he said. “In many ways, it is more pristine than Little Mountain and Stebbins Gulch because [most of ] the watershed of the creek is protected – a hidden gem that lies in the warm embrace of The Holden Arboretum. You can read all this by looking at the creatures that live in the creek – it’s in a near-perfect environment that is very much like it was thousands of years ago.” Groups will begin their tour through second growth forest, moving through mature, mixed deciduous hardwoods along the higher elevations of Woodland Trail and Pierson Creek Loop, proceeding down into the valley. The steep sides of the ravine provide a sheltered home for the Eastern hemlocks that love these cool, moist and shady locations. Along the stream bed are species such as sycamore, witch-hazel, yellow birch, cottonwood and spicebush. Pierson Creek’s glacial history is easily seen throughout the ravine. In the past 12,000 years since the receding of the glaciers, the creek has cut through the materials deposited the glaciers, or glacier till, by the creating a steep-sided channel. Erosion, over time, has exposed the Chagrin shale bedrock. Cutting into the main ravine are smaller side channels that carry seasonal rain and meltwater down to the creek, creating “young” ravines that show the progression of erosion in creating the landscape.


The waters of Pierson Creek supports a riparian habitat under a canopy of trees that shade the waterway, maintaining cool temperatures and regulating the dissolved oxygen levels. “Pierson Creek is a stream in a natural condition. The water is clear, cool, odorless and safe for wading,” Biliter continues. “Everything is in biological and chemical balance, providing the perfect environment for healthy biodiversity.” Participants on the tour spend much of their time in the clean waters of the creek searching for frogs, salamanders, insects and aquatic organisms found only in healthy stream environments, Biliter said.

Riparian habitat: Derived from the Latin word meaning “bank”: the zone paralleling the banks of a natural stream that provides food, shelter, water and space for individual organisms and populations of organisms that depend on stream-side habitat. The characteristics of the valley provide a rich plant community distinctly different from areas along the ridges. In springtime, wildflowers, ferns, liverworts, scouring rush and clubmoss emerge, found alongside the creek itself and on the valley floor. You may spot or recognize the calls of the blueheaded vireo, black-throated green warbler, Canada warbler, Blackburnian warbler, winter wren and dark-eyed juncos that have chosen Pierson Valley as their summer nesting spot.

Your naturalist guide will point out the treasures of this hidden habitat: flora and fauna, geological formations, stream formation, things to look and listen for; the benefits of a forested riparian system. “I love doing these hikes,” said Mary Schmidt of Gates Mills, a Holden member and frequent participant in guided hikes. “I find the guides extremely knowledgeable; they explain what I’m seeing and enrich my experience.” These 3-1/2 hour-long guided hikes are open to adults and children 12 years and over. The ravine is steep but has been made accessible by a long flight of wooden stairs. It is a workout of a climb coming back up, but benches along the way provide opportunities for people who need them to catch their breath . Part of the valley floor is boardwalk so as not to disturb delicate plants; further along the ravine it is generally unimproved and somewhat rugged going. A walking stick and shoes that can get wet are good equipment to have with you. For families with younger children, stream discovery packs can be checked out for a self-guided exploration of the creek and surrounding area, or refer to the Children’s Discovery Section of the class schedule in this issue for other available programs on Pierson Creek. Enrich your Holden experience – learn more about the beauty around you with a guided journey into Pierson Creek, which is $5 for members and $15 for nonmembers, and is offered monthly. See the listing in the Events Calender and Class Schedule for more information.



The Flora - A Unique Community The dynamic valley system creates a rich plant community distinctly different from the plant communities along the ridges. Fresh nutrients are continuously leached downward from the valley walls and uncovered from shifting soils. These nutrients, along with increased sunlight and abundant moisture, provide superb growing conditions for the flora of Pierson Creek Valley.




Fall 2014



Acer palmatum

A beautiful small tree with gorgeous foliage and refined habit, Japanese maple is prized by landscape designers from east to west. The native range of Acer palmatum includes the islands of Honshu, Shikoku and Kyushu in Japan, and southern Korea. The people of Japan have admired and appreciated these trees as far back as the seventh century, and have cultivated numerous selections of distinctive varieties since the 17th century.

Japanese maple by Ethan Johnson, plant records curator

Cultivated Japanese maples are grouped with regard to leaf type with the dissectum group, for example, having leaf lobes very deeply divided and deeply dissected into sublobes. At The Holden Arboretum the first specimen of cut leaf Japanese Maples was obtained from Klyn Nurseries in Perry, Ohio, in 1955 and planted at Lantern Court in 1964. It is located on the rise west of the Salamander Pool and now measures about 5.5’ tall by 15’ wide with serpentine branching. The foliage is reddish purple in spring, mixed with green in summer, turning bright orange and yellow for two to three weeks in October and November. In the Eliot and Linda Paine Rhododendron Discovery Garden the red cutleaf Japanese maple cultivar that was planted in 2012 is ‘Tamuke yama’. It was listed as far back as 1710 and is arguably still the best performer of its group in our climate. The matsumurae group have very deeply divided but not dissected leaves – ‘Burgundy Lace’ is in this group. In the Paine Rhododendron Discovery Garden, the redleaved ‘Bloodgood’, the standard in the nursery trade, and a relative newcomer, ‘Trompenburg’ are near one another for comparison. A ‘Trompenburg’ planted at Lantern Court in 2004 as a 5’ tall tree now measures 17’ tall and 19’ wide. The fruit of ‘Trompenburg’ are often held upright, which is a distinguishing characteristic of the Shirasawa maple, but not of Japanese maple. Although it is reported in the literature that ‘Trompenburg’ leafs out two weeks later than ‘Bloodgood’, I have not noticed this here and suspect that the observation was made either in Europe or the Pacific Northwest. In the Helen S. Layer Rhododendron Garden south of Heath Pond three weeping Japanese maples, Acer palmatum ‘Ryusen’, continued on page 17 JACKIE KLISURIC


plant facts




Soil type

Full sun to part shade

Moist, well-drained, acidic

Mature size

Best location

20’-30’ tall by 25’-35’ wide

USDA Zones (5b) 6a - 8b



Local garden centers


American Crow

(Corvus brachyrhynchos) by Rebecca Thompson, Growing Students in Science program coordinator

American crows are highly adaptable, very intelligent birds. They are one of only a few species of bird that has been observed using and modifying tools to obtain food. Their habitats range from open woods to urban neighborhoods. They can be seen in treetops, fields and roadsides. They tend to avoid unbroken expanses of forest, which has enabled them to thrive around people. American crows are opportunist when it comes to food. They are not finicky and will eat a wide variety of food depending on the season and availability. Their diet consists of anything from nuts and grains to small animals such as earthworms and mice. They eat many insects including some crop pests. In wetland habitats they will forage for fish, young turtles, crayfish, mussels and clams. They have been observed eating eggs and nestlings of other bird species including sparrows, robins and jays. A small part of their diet includes dead animals and garbage. In some areas American crows can maintain a territory with family groups year round. They are highly social birds, more often seen in groups than alone, and will gather in groups to forage for food. When they are foraging, one or two crows will be a lookout; if danger approaches they will sound the alarm. Most of the year American crows leave their territory to roost and join large flocks otherwise known as murders. Winter roosts have been documented numbering into the tens of thousands or more.


continued on page 17

bird facts Range


Widespread range across southern Canada and the continental United States except southwestern deserts; northern populations migrate south in the winter to the United States

Most common loud repeated caw-caw-caw

Size 17-21 inch; Wingspan: 33-39 inch

Best location to view at Holden Sperry Road, Corning Visitor Center Picnic Area, Crabapple Collection

Fall 2014

Description Male and female large, glossy purple-black feathers with a black bill and legs; tail, short and rounded or squared off at the end



Holden Reaches Out

To New Community Partners By James Pelowski, interim director of development Although The Holden Arboretum is fairly self-contained in its 3,600 acres, its reach across Northeast Ohio (and nationally) is broad and varied. Cutting across every department at Holden, there are many formal partnerships and informal collaborations with private and public institutions and organizations. These partnerships increase the impact Holden has in the community by forging new relationships and allowing us to do more with our resources. In the next several issues of Leaves, we will be highlighting some of those educational, research and practical arrangements. One new Holden partnership that is developing is with the Jewish Federation of Cleveland and the Maltz Museum. On Feb. 3, 2015, the three organizations will be hosting a Tu BiSh’vat Seder at the Corning Visitor Center.


“Tu BiSh’vat is considered the birthday of the trees, celebrating the importance of, and the need to preserve, nature,” according to an article in a recent edition of Kesher, a newsletter published by the Jewish Education Center of Cleveland. “Today in Israel, Tu Bish’vat is observed as a national holiday, affirming the people’s connection to the land. Students plant trees together as a class, and new or unique fruits – especially those seven species native to Israel, including figs, dates, grapes and pomegranates – are eaten. While it may seem ironic that the New Year (or “birthday”) of the trees is celebrated when snow covers Ohio, in Israel, this is the time of year the almond trees are starting to bloom, giving hope of life renewed as the Spring season begins.”


Invitations for the Tu BiSh’vat Seder will be extended in early January 2015. We anticipate that this occasion will be the first of many cooperative ventures with the Jewish Federation and the Maltz Museum.


Cultivating Holden’s


Emergent Leaders by Robin Ott, volunteer coordinator Over the past five years, Holden’s presence in the greater Cleveland community and outreach to young families has increased. Consequently, the number of early and mid-career professionals interested in becoming involved with our organization has also expanded. In response to this growing trend, Holden recently launched an exciting initiative, our Emergent Leaders program, as a new way for our younger members to support the organization and connect with other like-minded people. The purpose of this initiative is to provide early and mid-career professionals who love nature the ability to engage in Holden’s mission through social, volunteer, leadership and educational opportunities. This year, a group of young volunteer leaders assisted with the Illumination at Woodland Twilight Gala and After Party. This summer, a steering committee of volunteers and staff was formed. The group plans to develop a calendar of events and opportunities to attract new audiences and members to Holden, as well as serve as a sounding board for the organization in matters of interest to young professionals and families. Not only will Emergent Leaders help provide greater awareness of and support for Holden, but the program seeks to provide members with the opportunity to sharpen or develop leadership skills, network with fellow nature lovers and learn how they can be an active advocate for the environment.

Want to get involved?

- Andrew Coleman “Holden has been one of my favorite places to experience nature since I was a child. We had family picnics and walks around the lake when I was young, I explored the fields and forests as a teen, and I was married here last year. Holden has had an important role in developing my love of nature throughout it all. I want Holden to continue to thrive and flourish so that many more can know the joys and fulfillment that come from a nature-filled life.” - Christine Cassella “I fell in love with Holden Arboretum after my first visit three years ago. I couldn’t believe that this beautiful, peaceful place was only a short drive from my home, and I never even knew! I love the feeling of sharing that sense of wonder with others, seeing their amazement as they discover this fantastic place for the first time. I am excited to be part of this new Emergent Leaders Steering Committee; it will allow me an opportunity to use my own passion for Holden to help develop it for the future by bringing a fresh perspective to help shape upcoming events and activities. I am hoping this will help attract a whole new group of people who can discover and fall in love with Holden just as I have. “ - Heidi Whittemore PHOTOS BY ROBIN OTT

Fall 2014

We welcome all early and mid-career professionals who love Holden and nature to join our Emergent Leaders mailing list, or learn how to get involved in the initiative, by contacting Robin Ott, volunteer coordinator, at 440.602.8003.

“Unlike many memberships, Holden Arboretum is a year-round hub of activity for me. Crosscountry skiing in the Winter provides a nice reprieve from the indoor blues and Summer hikes with my dog is a good way to spend a summer afternoon or morning. It’s pretty amazing that the bulk of my time spent is also done without crowds or mobs of people … it’s my own personal retreat.”


plant this not that

by Amy Bastion, education seasonal

Thousands of plants have been introduced to the United States from other parts of the world. Some have come here accidentally in seed stock, while others were brought here intentionally for horticultural use. A small number of these introduced plants have gotten a little too comfortable in their new environment. Because they have no native predators and produce a lot of fruit and seed that are efficiently dispersed, they are invading natural areas. The aggressiveness of these invasive plants affects natural areas and wildlife by decreasing biodiversity, competing with native and rare plants and eliminating wildlife habitat and food sources. Plant This, Not That features a list of native alternatives to a commonly used landscape plant that has become invasive. The alternatives were chosen because their characteristics – form, flowers, fruit or fall color – are similar to that of the invasive and fulfill the same landscaping need. Plants that are native to Ohio are recommended when possible as native species are generally well-adapted to local climates and provide additional resources for wildlife. However, there are many non-native plants on the market that are also non-invasive and possess great ornamental value.

The Invasive

Elaeagnus umbellata (autumn olive) The autumn olive is a non-native, deciduous shrub that can grow up to 20 feet tall. Native to countries from eastern Asia to Afghanistan, it was introduced into our area for erosion control and landscaping purposes in 1830. In the 1950s the plant was promoted as a wonderful landscaping addition for wildlife habitat, food and cover. The autumn olive is rapid growing and quickly re-establishes after it is cut down or burned. Because it leafs out early in the spring, it often shades out native species, which can reduce plant diversity. While autumn olive can fix nitrogen in the soil and adapt to poor soils, it can also disrupt nutrient cycles in native plant communities. Autumn olive flower and foliage. The leaves of the plant are held alternate on the same stem and are Chris Evans, Illinois Wildlife Action Plan, small, oval, and dark green. They have silver scales on the underside of the leaves and wavy edges. E. umbellata also has small, light creamyellow clusters of fragrant flowers, which bloom in April to June. Autumn olive is a prolific fruit-bearing plant. The fruits are small, round and red to pink during the fall, but silvery with brown scales when immature. Just like the leaves and fruit, the bark is silvery with brown scales, but with age can turn to a light grey or even a grayish brown.


The shrub comes to flowering age three years after germination. Pull plants before fruiting to avoid the spread of seeds by birds and mammals.


Autumn olive stand. Leslie J. Mehrhoff, University of Connecticut,

The Alternatives Alnus incana ssp. rugosa (speckled alder) Alders are not given the respect they deserve! The speckled alder has a host of alternate names: gray alder, hoary alder, hazel alder and swamp alder. This particular species is easily trained into tree form by trimming off the lower branches. It can grow up to 30 feet tall. The bark is gray, reddish or brown, and thin and smooth with irregular plates and obvious white lenticels – spongy openings for gas exchange. Its leaves are oval shaped with a dull, dark green color. Wide tolerance of different soil types is a hallmark of this species. Speckled alders can even aid in the rehabilitation of disturbed soils, such as old mine sites. This high tolerance for adverse soil conditions make the species useful for erosion control. The roots of the speckled alder are colonized by nitrogen-fixing bacteria, which help to promote tree growth. It provides food for songbirds, such as redpolls, goldfinches and woodcock.

Speckled alder bark with lenticels.

Bill Cook, Michigan State University,

Aronia arbutifolia (red chokeberry) Aronia arbutifolia, better known as the red chokeberry, is native to Ohio. It is a small shrub, growing approximately 6-8 feet in height and 4 feet in width. It is multi-stemmed and can grow new stems from roots and stumps. Red chokeberries prefer rich, moist, well-drained soil but can also tolerate poor soils. It grows in colonies and is fantastic for naturalistic landscaping. The leaves have an alternate arrangement, with a green, glossy appearance and turn orange-red in the fall. The berries are small, brilliant red and round. Red chokeberry have five-petaled white flowers with red anthers. The bright berries can add some welcome color to our often gray Ohio winters!

Red chokeberry flower, foliage and fruit.

Karan A. Rawlins, University of Georgia,

Corylus americana (American hazelnut)

American hazelnut flower and foliage. Vern Wilkins Indiana University

Fall 2014

The American hazelnut is a deciduous shrub. At maturity, it can range from 10 to 16 feet in height and eight to 13 feet in spread. It is a leggy shrub, with a fast growth rate and a coarse texture. The leaves are alternating, broadly oval, with a heart-shaped or rounded base, are doubly serrated and hairy on the underside. C. americana is monoecious, meaning male and female flowers are both found on the same shrub. Male flowers are in long, pendulous, clustered stalks (catkins) and female flowers are tiny and clustered together near the ends of twigs. Most notably, the American hazelnut produces nuts. Hazelnuts, or filberts, are smaller than acorns, but have a higher nutritional value than acorns or beechnuts. They can be eaten raw or ground into flour. Hazelnuts have significant wildlife value and are eaten by squirrels, foxes, deer, turkey, woodpeckers, pheasants and northern bobwhite. This shrub is planted both as an ornamental and for naturalization and can grow in full sun to partial shade. Once established, it is very drought tolerant. The leaves turn yellow or red in the fall. They also grow in colonies, which can be beneficial when creating a natural barrier in your yard.


Oh Deer, Oh Deer:

Studying the long-term impacts of deer on the forest understory by Sheryl Petersen, postdoctoral researcher Editor’s note: Petersen’s research is funded by the R. Henry Norweb, Jr. Fellowship for Scientific Research in Horticulture

As the forest trees light up The Holden Arboretum with fall colors, it is easy to forget that all of the action in the temperate forest – in terms of plant biodiversity, at least – is really in the understory and herbaceous layers beneath those beautiful canopy trees. The herbaceous layer may contain up to an average of 80 percent of the total number of species found within a forest – what is called species richness. Much of this richness comes from the herbs themselves, especially the ephemeral spring wildflowers, but this layer also includes woody shrub and tree seedlings. Unfortunately, scientists examining long-term data have noticed a decline in the richness and abundance of many temperate forests’ understories over the past several decades. For example, in northern Wisconsin, herbaceous layers are becoming increasingly homogeneous as fewer, more generalist species dominate. These changes could be the symptoms of several chronic stressors driven by human activity, including climate change, nutrient deposition and invasive species. Studying these threats can help us anticipate and respond to changes in forest understory vegetation and thus protect the diversity, productivity, and regeneration capacity of our native forests into the future.

Oh deer!


One key driver of change in forest understory communities is the abundance of herbivores, especially large ungulates, such as whitetailed deer (Odocoileus virginianus). In the eastern United States, white-tailed deer populations have undergone a bust and boom. These native herbivores were nearly driven to extinction in the early 1900s. Subsequent conservation efforts allowed populations to recover, but they have continued to rise over the decades as humans have created a landscape with abundant food sources and few predators. It is estimated that current white-tailed deer densities in some small parks have even increased up to 20-fold over population sizes prior to European colonization of North America.


Changes in deer abundance can have a large effect on forest plant community composition and regeneration. Browse damage and soil compaction can reduce the growth, survivorship, and reproduction of individual plants. In turn, this can reduce or even extirpate populations of sensitive species, prevent tree regeneration, and shift community composition from palatable to less palatable species. These changes in the understory plant community can also indirectly impact other organisms such as arthropods and breeding birds that rely on specific plant species in the understory or the physical structure of the understory to complete their life cycles.

Evidence for the recovery of forest understories from the effects of overabundant deer is mixed. Some studies in which research plots were protected from deer indicate that forest communities can recover, especially if high deer densities are a relatively recent phenomenon. For example, at Trillium Trail Nature Reserve in Pennsylvania, where deer became overabundant in the early 1990s, fencing out deer in the early 2000s led to dramatic increases in Trillium population size over six years. However, other studies suggest that recovery can take a long time (decades) or may simply not be possible when species have been extirpated by intense herbivory or when overabundant deer interact with other threats to forest health. For example, at Cades Cove, Great Smokey Mountains National Park, where deer population peaked in the 1970s, fencing out deer in the 2000s only led to a modest recovery of species that had survived up to that point, but not to a recovery of the once abundant Trillium populations.

Holden gets exclusive At Holden the deer population has been managed for decades, and recent deer densities are around 8-12 deer per square km (20-30 deer per square mile). These densities may be over our target density of 4-8 deer per square kilometer (10-20 per square mile), but are far from some of the highest densities that occur in Northeast Ohio. Even so, some gardens and collections at Holden still require deer fences to protect them from browsing. The very visible damage done to Holden’s gardens and collections begs the question: Is the health and diversity of Holden’s nearly 3000 acres of forest also impacted by deer? If so, what is the potential for recovery? Efforts to systematically address these questions began in 2005 with the initiation of two separate deer exclosure studies. Deer exclosures are fenced areas meant to exclude deer and prevent browsing on plants. The exclosures are typically paired with unfenced control plots so vegetation can be compared between the two treatments. One of Holden’s exclosure studies is a landscape-scale initiative conducted by Mike Watson, Holden’s conservation biologist. This study addresses deer impact across four natural areas – Stebbins Gulch, Pierson Valley, the Baldwin floodplain and Little Mountain – using pairs of plots distributed in the interiors of five major forest types: beech-maple, oakmaple, floodplain, hemlock- hardwoods and mixed mesophtytic. Another study, established at Holden by Case Western Reserve University (CWRU) researchers Paul Drewa, Sandra Albro and Nellie Kahlil, examines whether deer impact differs between forest edges and interiors using plots in two beech-maple forests. Following completion of a short-term project, the CWRU edge/ interior plots were given to Holden’s research department and have been maintained by research staff with assistance from Holden’s conservation staff. In both studies, plots are 10 x 10-m (about 30 x 30-ft) in size, and deer were excluded using 2.4-m tall fences constructed of polypropylene mesh that allows small mammals and birds to get in, but keeps larger mammals out. When plots were first set up, data on deer impact and vegetation were collected, including herbaceous layer plant community and understory tree regeneration data. This monitoring has been repeated every few years in the landscape exclosures, but had not been collected in the edge/interior exclosures since 2007. In 2013, funding provided by the R. Henry Norweb Jr. Fellowship for Scientific Research in Horticulture enabled re-sampling of the edge/interior study plots, eight years after exclosure establishment, and examination of data collected thus far across both sets of exclosures at Holden.

to forest understories across most of the landscape. However, the scarcity of some browse sensitive species such as Trillium suggests that deer have not always been at sustainable levels. Thus, it could also be that recovery of forest understories has been very slow because of local extinction of plant species. Another explanation is that other environmental factors could be affecting herb layer communities such as chronic acid deposition, non-native worm invasion, and legacies of former land-use. These can also interact with deer herbivory to exacerbate the impact and impede recovery. Overall, this suggests that excluding deer may not be sufficient for recovery of herbaceous layer communities, and active restoration of extirpated species along with alleviation of other threats may be warranted and requires further investigation.

Long-term studies are like fine wine The work presented here is just the first step to quantifying long-term effects of deer herbivory in Holden’s forests, and there is still much to do. Already, analysis of additional monitoring data is underway to examine if tree regeneration and other forest layers respond to deer exclusion in a similar manner to the herbaceous layer community. However, the value of long-term research and data collections at Holden extends well beyond their initial questions. For example, they can be used for addressing population and community changes in response to climate change or other alterations in environment. Already, the deer exclosure studies are providing the groundwork for additional investigation into relationships between deer, invasive earthworms and forest understories. Watson began including earthworm sampling in his annual monitoring of the landscape exclosure plots in 2010. Additionally, a team of researchers from Case Western Reserve University and the University of Akron are utilizing Holden’s landscape exclosures as well as a network of exclosures across Northeast Ohio to examine this issue at a regional level. Thus, long-term studies can be leveraged to address additional questions and become valuable resources that mature with age.

Slow recovery Our initial findings of herbaceous layer community data from plots that have been in place from five to eight years have revealed some expected patterns. Different study sites and forest types exhibit distinct plant communities, and forest edges differ from forest interiors. Yet, we found few differences between plots that were protected from or exposed to deer, especially in forest interiors. There was one exception. At a single site in the edge/interior study, deer exclosure and control plots exhibited differences in plant communities. Much of this difference was driven by plots along the forest edge where grasses and invasive shrubs such as honeysuckle and privet were abundant, but native species had a slight advantage in plots where deer were excluded.


Fall 2014

There are several possible explanations for the lack of dramatic effects of deer exclusion on these forest plant communities. Perhaps recent efforts at Holden to manage its deer population at sustainable densities have been effective in preventing damage


Holden Hires

New Urban Forester The Holden Arboretum’s mission is to promote “the beauty and importance of trees and other woody plants to create sustainable and healthy communities in the Great Lakes region and beyond.” In pursuit of that mission, Holden recently hired Chad Clink to serve as its community forester. The newly created position is targeted at expanding the organization’s outreach efforts in Northeast Ohio.


the Broadway Chad Clink teamed up with Neighborhood House Services (NHS) to Beautify the Broadway in June. The initiative provides outreach education and engagement while providing tree care to trees in the St. Clair and E. 55 neighborhood.

Clink will serve as an advocate for scientifically based urban forest management throughout the region, said Paul Spector, director of education and public programs. “The Greater Cleveland region has recognized the value of trees in improving the livability of our communities and there are many outstanding initiatives underway throughout the area,” Spector said. “We hope to collaborate with these public and private institutions in order to enhance and expand on their efforts.” Holden is excited about the opportunities this new position will create. “We are excited to have Chad join our staff in this new position,” Spector said. “His extensive training and experience, along with Holden’s expertise in education and research, will allow us to immediately contribute to the ongoing efforts and others that develop as we work towards a greener Northeast Ohio.” Holden’s new community forester will help to promote the aesthetic, environmental, and economic value of trees and forests to communities and will be collaborating with governmental and professional organizations while educating the public. A Board Certified Master Arborist, Clink is a graduate of Kent State University’s horticulture program and studied natural resource management through the University of Idaho. He is a certified Municipal Specialist with the International Society of Arboriculture and has traveled the country extensively assisting with urban forest assessments and working with communities to understand the benefits and value of healthy forests and sustainable green infrastructure. Clink hopes to bring that experience to Cleveland especially into the neighborhoods needing the most assistance. His first step as community forester will be to gain awareness of urban and community forestry initiatives in Northeast Ohio to find ways to share his expertise and become more involved. One of the opportunities he anticipates is getting communities to think about trees during the planning process. While many people understand the aesthetic value trees offer, additional benefits trees provide a community may not be clearly understood and could be overlooked in the planning process, Clink said. His experience will benefit both long-established cities as well as communities in various stages of development and redevelopment as he offers guidance and education on managing their current green resources and advocates for the planting and maintenance of trees during planning. “Research indicates that healthy trees and green infrastructure provide significant health and economic benefits to communities,” Clink said. “Trees are a great resource. They decrease pollution through carbon sequestration, reduce the negative impacts of storm water and help prevent erosion among many other things.”


He is also looking forward to meeting Holden’s members.


“I’m very passionate about arboriculture and urban forestry, and I hope Holden’s members will be excited to learn about those activities because of the benefits that trees provide all of us,” he said. “Whether you’re a home owner, a business owner or a community advocate, you can benefit from urban forests, so why not come learn about them?”



ask Greg

Acer palmatum (continued from page 8) grace Hawgood Hill. Planted in 2014 ‘Ryusen’ needs to be trained to a desired height. At Lantern Court Acer palmatum ‘Seiryu’ a tree-form with deeply dissected leaves turns brilliant reddish shades from late October to early or even mid November in some years. Unfortunately, fall snow storms can bring an abrupt end to the color display and can result in structural damage to the trees. Japanese maples can lose limbs in fall snow storms. The pine-bark Japanese maple, ‘Nishiki gawa’ at Lantern Court lost a limb in Oct. 2013 and suffered significant winter 2014 branch dieback. ‘Seiryu’ also had some dieback. The tendency of both ‘Nishiki gawa’ and ‘Seiryu’ to go dormant later in fall than the Japanese maples that did not suffer dieback suggests late leaf drop as an indicator of questionable winter hardiness in northeast Ohio. Most Acer palmatum cultivars lost vegetative buds in the winter of 2014 and resorted to producing new leaves from adventitious buds hidden beneath the bark that flushed in mid to late May, 2-3 weeks after the primary buds produced leaves. In some years such as 2012, leaves broke bud by the first week of April, making them prone to hard spring frosts. The Easter freeze of 2007 killed the foliage in April, but new leaves appeared in May and plants recovered fairly quickly. The small purplish-red flowers appear with the new leaves, although none were present in 2014 due to the harsh winter which included a -16 degree F. low in February. Two of the newly planted trees in the Paine Rhododendron Discovery Garden had bark split on their main trunks that, combined with an infestation of Ambrosia beetles, killed them this spring. Commercial tree wrap serves to prevent winter sun scald and bark split on trunks of thin barked trees such as these. To guard against rodents chewing the bark during winter, hardware cloth can be used. In the landscape, Japanese maples have become popular, especially the purplish-red foliaged forms with dissected leaves. They are not as expensive as they used to be and are striking in combination with conifers, azaleas, and a number of other plants including Japanese forest grass (Hakonechloa macra ‘Aureola’) that are available in local garden centers. The cutleaf forms typically grow 8-10’ tall after several decades but can be kept to 4-5’ with annual pruning. Winter (late Jan.-Feb.) and summer (June-July) are the best times to prune. To shorten branches, simply cut back stems as close as possible to pairs of side shoots.

American Crow (continued from page 9) American crows do not breed until they are at least two years old, and many do not breed until they are four or more. In early May both members of a breeding pair and non-breeding young build a nest in a fork of a tree or tall shrub. Nests are made of sticks and twigs lined with bark and cushioned with rootlets, grasses, fur or moss. Females usually lay four to five greenishblue speckled eggs with blotches of olive. Females incubate the eggs for 18 days. Young are tended by both parents and leave the nest in 35 days but may stay with the family group for years.


During a recent severe storm my tree was damaged. Can I save it and how?

This is a common concern of homeowners, and the answer is “it really depends.” There are different kinds of damage that can occur from storms. These include lightning damage, stem failure, blow-over, and branch and crown damage. After a storm event it is important to evaluate and assess the damage. The tree assessment will determine whether damage is superficial, treatable or beyond repair. In some cases the damage is so severe that after pruning and repairing the crown the remaining tree might not continue to survive or it might not have much aesthetic value in the landscape. It is important to remember that trees don’t heal; they just surround a wound with new growth. This means that the damage is still there and might become a point of failure in future storms. For larger trees it will be important to call in an arborist to determine the damage and, if the tree is salvageable, the best solution for repairs. Often homeowners want to do the work themselves. Though it is understandable, arborists have the knowledge to assess damaged or diseased trees, as well as the skills and equipment needed to do the repairs safely. Tree work can be dangerous without the necessary knowledge and skills, potentially leading to damage or injury to life and property. You can locate a certified arborist using the search function on the International Society of Arboriculture’s website, ( Sometimes we see trees that have tipped in storms but are in otherwise good condition. If of a manageable size they can be saved. For larger trees, an arborist will be needed. First the tree must be righted and then supported with at least two “guys” – wire cables tied to the trunk – at about 2/3 of the height from the ground. These should be tied securely, but not too tightly, to prevent girdling. The guy wires should be placed to pull in the opposite direction of the tip or fall and must be set at angles from each other. It is important if you have an uprooted tree to keep the roots moist and to set it upright as soon as possible. If the roots dry out then the tree will die. Also, after resetting the tree, any gaps between the roots and surrounding soil should be filled in with soil. Finish with mulching to a maximum depth of 2-3”. Additional watering will be needed any week that less than one inch of rain falls. Trees are a great investment into our homes and communities and provide many benefits. Some storm damage can be minimized or prevented through the proper planting of the tree. Appropriate maintenance of the tree through pruning and managing the tree for health will also help maintain it for generations to come.

Fall 2014

According to the North American Breeding Bird Survey, American crow population has slightly increased with the onset of deforestation. However American crows are very sensitive to West Nile virus which was introduced to North America in 1999. Virtually all crows that contract West Nile die within one week. American crows in diverse habitats are less likely to come down with the disease than crows in species-poor areas. Nevertheless, long-term populations are generally stable.

by Greg Wright, nursery supervisor


Research News and Highlights News Research hosts interns studying plant biology and ecology Several undergraduate students completed internships this summer within the research department. Students worked on topics ranging from plant and microbial ecology, to plant morphology and physiology, and forest ecology. The following students completed internships this year: Jaynell Nicholson (Kent State University) and Callie Dowrey (Indiana University) worked with Juliana Medeiros; Mary Kay Klenkar (Ohio State University) and Alexa Wagner (Kent State University) worked with David Burke; and Anthony Minerovic (Kent State University), Abigail Hoffman (Duke University), and Jonathan Brandt (Vassar College) worked with Kurt Smemo.

Holden hosts national rhododendron society meeting The Holden Arboretum hosted the 68th annual international convention of the American Rhododendron Society, which was held May 15-18. Steve Krebs, director of Holden’s David G. Leach Research Station, served as organizer for the meeting. Holden gardens, including the Eliot and Linda Paine Rhododendron Discovery Garden and the Leach Research Station, featured

prominently in the convention tours. Keynote speakers included Ian Adams, who gave a photographic tour of natural rural gardens and historical areas of Northeast Ohio, and Clem Hamilton, Holden’s president and CEO, who spoke about the history of rhododendron exploration and hybridization in the 19th century.

Highlights Will tolerance to cold effect the ability of desert plants to expand their ranges with global climate change?


Will deserts expand as the climate warms? If the distribution of desert plants is currently limited by freezing temperatures, then the global extent of desert plant communities may increase with rising temperatures. But, freezing tolerance may vary across populations of desert plants, such that the response of one may not accurately predict that of others. A recent paper by Holden scientist Juliana Medeiros, Ph.D., and collaborator Will Pockman, Ph.D., (University of New Mexico) (American Journal of Botany 101:598-607) examines the possibility that freezing tolerance varies among populations of creosote bush (Larrea), the most common evergreen shrub in the warm deserts of North and South America. They examined wood structure, which is an important component of freezing tolerance in plants: wood contains a continuous column of water that links leaves to soil, but freezing temperatures can cause the introduction of air bubbles into the water column, cutting off water supply to leaves. Medeiros’ study found evidence that Larrea populations


solve this problem in different ways, providing evidence that the effects of climate change will likely differ depending on the population in question. Some Larrea populations have wood anatomical features that resist freezing damage, but these features limit growth rate when freezing is absent. As the climate warms, these populations are less likely to benefit, but rather may be out-competed by faster growing plant species. In contrast, other Larrea populations exhibit phenotypic plasticity, or the ability to alter wood characteristics in response to the growing environment. These populations produce wood that is freezeresistant during the fall and wood that allows for rapid growth rate in the spring. In this way, they limit freeze damage but restrict their growth to more favorable times of the year. This will likely improve the ability of these Larrea populations to expand and compete with faster growing species as the climate warms.

shorts Corning Lake Drained For Restoration Project Work started on the latest New Leaf Capital project this spring as water was drained from Corning Lake so that crews could start dredging and restoring this Holden landmark. While on the surface, Corning Lake is a beautiful setting that draws both birds and birdwatchers to its shores, beneath the surface, problems exist. Sediment has built up, making the lake shallower, which has reduced levels of oxygen in the water and eliminated the depths needed for aquatic life to survive the winter. The lake’s condition has led to a decline in the wildlife it attracts to its waters and shores. Work to restore the lake started in May, when the lake was drained in preparation for dredging. The project will include increasing the depth of the lake to up to 10 feet in spots, according to Brian Parsons, director of planning and special projects. The work also includes improvements to the Corning Lake dam, the restoration of Lotus Pond in the Display Garden and the installation of a new stream garden that will flow along the new R. Henry

Norweb Jr. Tree Allée from Corning Lake to Lotus Pond. New submergent and emergent aquatic plants will be added, and fish will be reintroduced into the lake to create a more self-sustaining ecosystem. While the project will improve both the lake and pond aesthetically and environmentally, it will also enhance the quality of water flowing into the Pierson Creek watershed. The project also provided an opportunity to help out one of the Cleveland Metroparks. While there was an overabundant population of nuphar advena (spatterdock) at Corning Lake, which was preventing other plants and species from flourishing, the Euclid Creek Reservation was in need of the plant. In moderate amounts, spatterdock provides an excellent habitat for fish and other aquatic life. Crews were able to remove some of the water plant from Holden and transplant it in the Euclid park.

Cleveland Clinic Researcher Joins Holden Board of Directors The Holden Arboretum recently announced the appointment Paul E. DiCorleto, PhD, to its Board of Trustees. DiCorleto was appointed at a board meeting on Feb. 26. He brings research expertise as well as board experience to Holden’s current 18 member board.

in atherosclerosis and other inflammatory diseases. He has been with the Cleveland Clinic since 1982, having served previously as chair of the Department of Cell Biology and as an associate chief of staff. He is a member of the Clinic’s Board of Governors and Board of Trustees.

DiCorleto is the Sherwin-Page Chair at the Cleveland Clinic Lerner Research Institute (LRI) and Professor and Chair of the Department of Molecular Medicine at the Case Western Reserve University School of Medicine. DiCorleto also oversees the Clinic’s Center for Clinical Research, which provides infrastructure support and oversight for all human subjects research at Cleveland Clinic.

DiCorleto is a Community Board member of the Cleveland State University (CSU) Board of Trustees and a member of the Board of Directors of the CSU Research Corporation. He is also a member of the Governance Board of the Cleveland Center for Membrane and Structural Biology of Case Western Reserve University.

He received his undergraduate training in chemistry at Rensselaer Polytechnic Institute and his doctorate in biochemistry from Cornell University. DiCorleto is a vascular cell biologist with extensive experience in the role of endothelial cell signaling pathways and gene expression

“Holden continues to attract outstanding leaders to join our Board of Directors,” said Paul Abbey, chairman of the board. “Holden is a viable, well-funded organization that continues to be a great asset, contributing beauty and sustainability to the region and beyond.”

Lake Erie Birding Trail Program The birds of Lake Eire will be the focus as the Blackbrook Audubon chapter hosts guest speaker Jim McCormac, president of the Ohio Ornithological Society, at 7pm, Tuesday, Nov. 18 in the Reinberger Room of the Corning Visitor Center. Tremendous numbers and diversity of migrant songbirds fill lakeside woodlands in spring and fall. Waterbirds galore pack marshes and the open lake waters, and interesting marsh birds breed in coastal

wetlands. Winter brings hardy northern ducks, gulls, and raptors. There is never a dull season on the Lake Erie Birding Trail. McCormac will be highlighting some of the 88 popular and less well-known birding locations all along Ohio’s Lake Erie coast, commonly sighted species and noteworthy rarities. The Lake Erie Birding Trail Guidebook will be available to purchase at the Holden store.

Fall 2014


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Leaves Magazine Fall 2014  

Leaves Magazine is the quarterly publication of The Holden Arboretum, focused on horticulture, conservation, education and ecological resear...

Leaves Magazine Fall 2014  

Leaves Magazine is the quarterly publication of The Holden Arboretum, focused on horticulture, conservation, education and ecological resear...