Save Plants

Silky stewartia was not the only species of stewartia established at PHA: the conditions on Martha’s Vineyard are almost ideal for growing them and the Asiatic species have found comfortable homes next to the two North American species (silky stewartia and mountain stewartia – S. ovata). As those early stewartias grew, so did PHA’s work with this special genus. PHA currently maintains 70 trees representing 22 taxa in the genus, is working on developing the two North American species for horticulture, and serves as the international cultivar registrar for the group. In 2006, the collection was recognized as a Nationally Accredited Collection by what is now the Plant Collections Network. Accreditation as a national collection recognizes PHA’s commitment to understand and save these plants.

Around this time, PHA’s mission began to focus more on conservation. New infrastructure, including a greenhouse added in 2007, allowed the arboretum to grow as a horticultural conservation entity. In 2015, curatorial intern Victoria Stewart developed a web-based pictorial key as a comprehensive resource on the genus, using a monograph of the stewartia produced in the 1970s by PHA Director Emeritus Stephen Spongberg. In recognition of this contribution and PHA’s history of research, collection, and horticultural success with the genus, the International Society for Horticultural Science appointed PHA the international cultivar registration authority for stewartia. This designation has helped PHA connect to plant breeders, commercial growers, and other arboreta as they intensified efforts to grow their own stewartia collection and develop propagation protocols.

Collection trips in search of stewartias throughout Asia continue. At home, PHA is dedicated to the two North American species, establishing genetically representative collections and advancing horticultural practice. Silky stewartia and mountain stewartia are both recognized as Globally Secure (G4) species. However, populations are declining in several southern states, with local designations ranging from Vulnerable (S3) to Critically Imperiled (S1). Silky stewartia’s natural propensity to grow in rich floodplain terraces – historically attractive to settlers and farmers – makes it particularly susceptible to habitat loss. The mountain stewartia has also been a victim of habitat loss and other threats. PHA is addressing this challenge by working with collaborators to make accessions of both species throughout their natural range. The team – informally known as the Stewartia Working Group – consists of Mt. Cuba Center (a new CPC Participating Institution), Smithgall Woodland Garden of the Atlanta Botanical Garden, and other southern gardens.

Once seeds or cuttings are obtained, the next challenge is to actually grow the plants. While Polly found some success with seeds, the 20-month germination process can lead to low germination rates, longer exposures to fungi, and other complications. Cuttings come with a different challenge – getting the juvenile trees through winter. The solution on both fronts may be found through PHA’s upgrades to lab-quality refrigeration equipment. More precise and stable temperatures, along with information gleaned from a literature review, have resulted in an increased percentage of cuttings breaking dormancy after overwintering (around 65% on average) and recent successes in seed germination.

PHA is making great strides toward establishing propagation protocols for both silky and mountain stewartia. Why is this so important for conservation? Quite simply, a population in the wild can’t be restored from a single plant. Propagation protocols support ex situ collection development for at-risk species, enabling arboreta to maintain diverse collections and produce plants for in situ restoration.

PHA currently has an impressive 11 wild-collected accessions of silky stewartia and 10 of mountain stewartia – representing 98% and 63%, respectively, of their accessions. While continuing to build its own stewartia collection, the arboretum also plans to help establish insurance populations at different institutions, in collaboration with the Stewartia Working Group. Every additional site at which stewartias can be conserved and viewed offers an opportunity to introduce more people to these stunningly beautiful trees. Perhaps one day Polly’s cultivars of these unique but vulnerable North American native species will find their home in more public gardens, to be grown and appreciated more widely.

In 1967, the United States Department of the Interior designated several of the Holden Arboretum’s forests as National Natural Landmarks. Two examples are Stebbins Gulch and Bole Woods, which cover over 800 acres of contiguous forest. Tree ring analysis has identified old growth remnants in large portions of the forest in Stebbins Gulch, including chestnut oaks over 400 years old and beech trees over 250 years old. During European settlement, forests in Ohio were cut down for industrial uses and lands were converted to agriculture – a common occurrence across much of the eastern United States. Most of Holden’s forests reflect this legacy of past agricultural land use, presenting both a challenge and an opportunity for conservation.

The majority of our woodland is about 100 years old, having developed following agricultural abandonment in the 1930’s and 1940’s. These woodlands are generally species-poor and lack structural characteristics and other features seen in our mature, old growth stands. Consequently, they may not be resilient to the long-term effects of a changing climate. Since invasive plants and overabundant herbivores can suppress plant diversity, our traditional management of these young woodlands has focused on controlling invasive plants – such as garlic mustard (Alliaria petiolata) and buckthorn (Rhamnus cathartica) – and overabundant populations of white-tailed deer (Odocoileus virginianus). Yet more than two decades of such management was unable to restore to the younger woodlands the diversity and features of the adjoining old growth forests. This called for a change in management approach.

In 2014, arboretum researchers began intensive surveys across all 2,600 acres of our forested landscape. We used a quick survey method developed in-house, called the RUFA (Rapid Upland Forest Assessment) method (Burke et al., 2016). It allows for assessment of forest ecological integrity – the degree to which a forest has the diversity and structural characteristic of a mature forest stand – in less than 30 minutes. The RUFA methods enable us to rapidly identify structural and composition differences between young and old forest stands, then determine what intervention may be needed to restore missing features. Rather than focusing on specific types of plant communities, our goal is to maximize diversity of native tree, shrub, and herbaceous forest plants, while increasing important structural characteristics, such as snags, light gaps, and coarse woody debris. We also work to maximize the diversity of animal and insect populations supported by these key forest structural components. One of the best insurance policies against climate change is increased biodiversity, since diverse systems are more stable in the face of environmental change.

In 2018, we undertook two major restoration projects at Holden to create the conditions for more biodiverse, resilient forests. First, we applied standard forestry management techniques to increase diversity and support important forest structural components on approximately 84 hectares (207 acres) of young secondary growth forest. Our methods included improvement cuts, timber stand improvement (invasive species management and grape vine control), or a combination of both. Holden researchers are actively monitoring the site to determine long-term effects on forest biodiversity and function.

In addition, we have made 27 hectares (67 acres) of this managed forest accessible to the public as the Working Woods Learning Forest. With 85% of forested lands in Ohio privately owned, preservation and promotion of healthy and biodiverse forests requires engagement with private landowners. Courses and programs offered at Working Woods – many in collaboration with the Ohio Division of Natural Resources – engage both private landowners and industry professionals to encourage proper forest management and promote climate resilient forestry practices. To paraphrase Aldo Leopold, the future of conservation lies in the private landowner considering the public interest. Holden’s Working Woods program is our effort to create more biodiverse, climate resilient forests – not only on our own lands, but throughout northern Ohio.

References:

Burke DJ, Knisely C, Watson ML, Carrino-Kyker SR, and Mauk RL (2016) The effects of agricultural history on forest ecological integrity as determined by a rapid forest assessment method. Forest Ecology and Management 378: 1–13

Developing a natural reforestation design model requires a series of steps, beginning with a thorough site evaluation. Data collected from soil mapping, corridor connectivity analysis, and examination of historical land use provide a foundation for determining an ecological restoration target for each annual planting project. Species are then selected to increase biodiversity and promote resilience to our changing climate, using a two-part prioritization based on locally adapted seed – collected from known wild origin – and research-based predictions of hardiness to anticipated climate variations. For each whole-site planting, an appropriate seed mix is defined to establish a seed bank of herbaceous plants that will tolerate a variety of light conditions as the trees mature and form a canopy. This strategy is key to inhibiting non-native colonization and setting a healthy trajectory for establishment of locally appropriate species. Both trees and shrubs are included to support a forest structure that will progress from mid-story layers to a mature canopy over time. The Arboretum team also uses management case study data to vary model parameters such as layout, tree protection from herbivory, and vegetation maintenance, homing in on the most efficient and cost-effective methods to reduce fossil fuel inputs during the first decade of establishment.

The Arboretum’s natural resource management program has met with many successes to date. Importantly, the ecosystem approach has served rare species well. On the nearly 2,000-acre reserve land, the conservation team maintains stable populations of the three-birds orchid (Triphora trianthophora), listed as rare or threatened throughout much of its range in North America.  Preservation and forest site management have been key to ensuring viability of this population, despite changes to the light regime following increasingly frequent storm events that damage the canopy.

The Arboretum’s goals are ambitious, and its work includes several challenges – especially in the areas of building capacity, funding and infrastructure.  One particularly difficult task is to accurately anticipate extreme weather events – increased precipitation, more frequent flooding, and drought caused by extreme heat waves – and devise ways to mitigate them using current resources.  Like many organizations, the program could benefit from additional funding and infrastructure. Yet optimism runs high. According to Director of Land Conservation Shana Byrd, “We believe that with enough innovation, creativity, and drive to succeed, our strategy of demonstrating the results of our efforts, sharing outcomes through peer-to-peer training, actively building the next generation of horticulture and conservation professionals through our advance training programs, and seeking support from our community and partners to help us reach the next rung on our ladder will help us address these challenges.”

Shana’s statement recognizes that the Arboretum’s work is not done in a vacuum. Partners contribute valuable insight, support and capacity. The Ohio State University, Denison University, and other academic institutions help the Arboretum advance its research objectives through collaborative studies of living collections and natural areas. Key partners in capacity-building include the regional Rural Action Inc., and the federal Corporation for National and Community Service.

In addition to hands-on conservation work, the Arboretum places equal emphasis on involving the community and inspiring them to protect native species in their own backyards. A significant achievement is the establishment of an active and dedicated group of volunteers, AmeriCorps national service members, and Environmental Professionals Training Program trainees – all essential to achieving the conservation and natural resource goals of the organization. Another major contribution is the Arboretum’s Greenbelt Initiative, which provides a community consultation resource to local businesses to support the installation of conservation-focused landscapes throughout the region. The Ohio Native Plant Month organization recently designated the Arboretum as a Native Plant Learning Center in recognition of its many contributions to educating the public about the values of native plants, including convening an Ohio Native Plant Network, stimulating diverse stakeholders to promote the use of native plants in a landscape context, and a multitude of educational workshops and symposiums that demonstrate the value of our nation’s native flora.

Looking to the future, the Arboretum team will build on their successes to advance the applied science of ecological restoration, focusing on wide-ranging value for the conservation of native plants. Strategies include educating the public on the critical need to conserve plants for individual well-being, demonstrating the value in innovative conservation and restoration approaches, training the next generation of conservation and horticulture professionals, and empowering communities by teaching practical ways to create native landscapes that support biodiversity at home. The Arboretum looks forward to building capacity for its growing focus on botanic research, to enable conservationists to plan more resilient natural areas and working landscapes with capacity to endure the changes anticipated in years to come.

When did you first fall in love with plants?

I have always loved forests, and my career in tree conservation could have been predicted from a young age. Two experiences were probably the most formative. First were numerous weekend backpacking trips in Kentucky, Virginia, and Indiana throughout middle school and high school. Seeing the forest change as we hiked up mountains; seeing the same forest in different seasons and types of weather; seeing forests with different types of human impact; and understanding the web of life, change, and ecology – all had a great impact. Second was becoming aware of high levels of deforestation of the Amazon rainforest around my eighth-grade year – the images, news stories, and statistics during one of the peaks of tropical deforestation gave me a desire to contribute to conservation.

What was your career path to Tree Conservation Biologist?

After these formative experiences with forests, combined with my curiosity and inquisitiveness, I knew I wanted to be a biologist of some type. I pictured myself at the Forest Service or some other organization with a strong mission and a long-timeframe vision. I also really enjoyed university and was on the track to become a professor. But during graduate school at the University of Notre Dame and afterwards – when I spent two years in Europe working on conservation policy, then working at the University of Tennessee – I learned about botanic gardens and seed banks, and I knew that this could be a great place for me. In fact, it was CPC members Naomi Fraga (California Botanic Garden) and Michael Way (Kew Millennium Seed Bank Project) who really helped immerse me in the botanic garden world! I will always be indebted to their kind invitations to visit their institutions, discuss my work, and learn about plant conservation challenges to work on, which helped me bridge the gap between my academic background and applied work.

What advice do you have for newcomers to the field of plant conservation?

This is a hard one, because there’s not just one career type or contribution that can be made to plant conservation. All skills and backgrounds are needed, from taxonomy and botany to data science, communication, and horticulture. One important thing is to have some interdisciplinary training – to have a specialty, but also wide knowledge across multiple fields. It’s also valuable to cultivate networks of people you meet – because plant conservation sure is a team effort!

Please share about one of your current projects at The Morton Arboretum.

A team of colleagues at The Morton Arboretum are trying to quantify and understand the conservation value of our tree collections by collecting metrics beyond the number of species. For several decades, botanic gardens have been seeking ways to increase conservation value – the usefulness of our collections to conservation, horticulture, tree breeding, scientific understanding, and more. We apply a data-driven approach that uses phylogenetic, genetic, and environmental tools, along with cultivar checklists and assessments of threatened species, to quantify our progress towards these different elements of ‘value.’ To begin with, we are focusing on four genera that have different strengths and histories (Malus, Ulmus, Quercus and Tilia). We hope that our work will assist decision-making for accessioning and deaccessioning, as well as our ability to measure changes to The Morton Arboretum collections over time. This work is generously supported by the Institute for Museum and Library Services grant MA-30-18-0273-1.8.

What are some of the challenges you face in your work?

The challenges that come to mind are common to most of us working in nonprofits or in conservation or scientific areas: funding; balancing a host of tasks, from administration to recruiting to balancing budgets; and finding time for reading about advances in the field. But I am blessed to be in a really great line of work with great colleagues, and I have lots of help tackling these challenges. Another big challenge for me is one that most conservationists face – determining when I have done enough and taking time away from work to recharge, when there is so much that needs to be done! A final challenge has been learning how to engage with international conservation policy, such as the post-2020 global biodiversity framework at the upcoming Convention on Biological Diversity. Crafting policy wording that is short and clear, and reaching a middle ground between complexity and simplicity, has been a process of trial and error over several years.

What emerging science (methods, approaches, discoveries) and/or trends in conservation excite you most?

I’ve been really excited over the past decade to see science becoming more open with data, protocols, and more, including databases and tools that are free to access online. I have high hopes that this will make conservation more effective and will increase cooperation – including understanding who is safeguarding what, which germination protocols work for what species, who has expertise that can help in a given place, and where species are most threatened. I am also excited by advances in saving recalcitrant seeds, and I look forward to the upcoming conference on exceptional species conservation!

What advice would you give to the public who want to learn more about how they can help save imperiled plant species?

Sign up for the CPC newsletter! I read it each month and get a lot out of it – inspiration and ideas. Other sources of learning include The Nature Conservancy and the news websites Mongabay and Yale Environment 360, which cover all sorts of environmental and conservation issues around the world. Of course, the podcast In Defense of Plants is a unique and informative resource as well. Lastly, be sure to find and visit your local botanic gardens!