In hot and steamy June of 2017, a team of researchers and arborists from Cornell University’s Urban Horticulture Institute (UHI), headed up by UHI Director Nina Bassuk, worked dawn to dusk evaluating the condition of the American elms and soils on the National Mall in Washington DC. This iconic landscape is often referred to as “America’s Front Lawn,” and the National Mall turf grass was fully renovated between 2010 and 2016, involving infrastructure upgrades, at a cost of $40 million dollars. Now, UHI hopes the Mall trees will get the same level of attention.
Bassuk and then-graduate student Yoshiki Harada worked together on soil evaluation, taking 108 soil samples back to Cornell, while ISA Board Certified Master Arborist Barbara Neal and UHI Visiting Fellow Bryan Denig performed an ISA Level 2 evaluation of the National Mall’s 550 trees. Bassuk and team also used ground penetration radar on a sample of 16 of the trees to find out precisely where the roots are.
On October 5th, 2018, Nina Bassuk led a tour of the new Sustainable Landscapes Trail on the Cornell campus after an opening ceremony in which, instead of ribbon-cutting, officials celebrated with a “downpour” of water onto the permeable asphalt of the Peterson parking lot, which is underlain by CU-Structural Soil and also features a large bioswale.
A number of the 20 sites along the Trail are associated with the Urban Horticulture Institute/Nina Bassuk, including chinkapin oaks (Quercus muehlenbergii) in CU Soil outside Stocking Hall, goldenrain trees (Koelreuteria paniculata) and silver lindens (Tilia tomentosa) in CU Soil outside Weill Hall, the Tower Road Bioswale, the Ag Quad Biodetention Basins, and the Mann Library Entrance SITES Accredited Garden. Many of these projects involved Nina Bassuk and Peter Trowbridge “Creating the Urban Eden” students in their implementation. For instance, the creation of the Rice Hall Bioswale involved students using the research-based “Scoop and Dump” technique described here.
For nearly 15 years, Nina Bassuk and her grad students at the Cornell Urban Horticulture Institute (UHI) have been developing hybrid oaks for exceptional tolerance of urban conditions (drought, alkaline soil, etc.) Bassuk now has 230 hybrid oaks of 2-3 inch caliper in her research fields. “I’d be happy for villages and cities in NY to plant them out so I can continue to evaluate them over time,” she says.
She is offering them to municipalities of any size in April of 2019. The cost would be $50 per tree to cover the B&B process. Communities could arrange for transportation or pick the trees up themselves. Bassuk says it would be preferable to have at least five trees go to any one community so she can efficiently evaluate them around the state.
If your community would like to plant at least five of these unique, new oak hybrids, please contact Nina Bassuk at email@example.com. Read on for more background about this fascinating research.
“For plants to thrive in stormwater retention areas, they need to be able to tolerate both dry and periodically saturated soils,” says UHI Director Nina Bassuk, professor in the Horticulture Section of the School of Integrative Plant Science. “These can be tough sites with high pH and salt levels, so it’s important to choose the right plants for the job.”
In addition to profiling more than 35 shrubs—including their hardiness, sun and soil requirements, potential pest issues, and deer resistance—the guide also details site assessment and design considerations for stormwater retention structures. Descriptions also include cultivar information and ecological impacts, such as attractiveness to pollinators. Download the guide here.
From the Urban Forestry and Urban Greening paper’s Abstract:
On the Cornell University campus a long-term study has measured the impacts of a soil remediation strategy on plant growth and soil quality using the Cornell Soil Health Test. The Scoop & Dump (S&D) process of soil remediation consists of physically fracturing compacted urban soils, incorporating large quantities (33% by volume) of compost with the use of a backhoe, and annually top dressing with mulch. This study was designed to investigate the impact of this remediation technique for the amelioration of compaction and degradation of soils in the urbanized environment.
From the Urban Forestry and Urban Greening paper’s Conclusion:
The authors found that the Scoop & Dump method of soil remediation showed improvement in soil quality indicators – bulk density, resistance, aggregate stability, potentially mineralizable nitrogen, active carbon and organic matter content – compared to unamended sites. Over a period of 12 years, soil quality indicators – bulk density, active carbon and potentially mineralizable nitrogen – improved over time showing long-term beneficial effects of using the Scoop & Dump Technique.
The application of the Scoop & Dump soil remediation strategy is an appropriate method for restoring soils damaged by heavy equipment, building construction and urbanization impacts. With minimal annual maintenance including the addition of shredded bark mulch, these improvements in soil quality are maintained or enhanced over time. This technique offers a practical, research-based tool for green industry professionals, arborists and landscape contractors and has a strong potential for improving soil quality using locally sourced materials and sustainable methods.
Sax, M.S., Bassuk, N., van Es, H., Rakow, D., Long-Term Remediation of Compacted Urban Soils by Physical Fracturing and Incorporation of Compost, Urban Forestry and Urban Greening (2017), http://dx.doi.org/10.1016/j.ufug.2017.03.023
Regal Prince is the trademark name for Quercus x warei ‘Long’, a narrow, upright hybrid of fastigiate English oak (Quercus robur f. fastigiata) and swamp white oak (Quercus bicolor). Its leaves are clearly intermediate in shape and are glossy and leathery like those of swamp white oak. In Ithaca, Nina Bassuk and Andy Hillman first planted Regal Prince in 2005, and the oaks have performed well there ever since.
“It’s a good tree for tight spaces—not a shade tree as such,” says Cornell Urban Horticulture Institute Director Bassuk. “It has the shape of the fastigiate English oak but is more tolerant of poor drainage and is mildew resistant, unlike Q. robur. It also tolerates a higher pH than does straight Q. bicolor. During last summer’s drought its foliage stayed green throughout so it appears both wet and dry tolerant (after establishment of course).”
Cornell Urban Horticulture Institute Director Nina Bassuk and Dept of Horticulture Post-doctoral Associate Fred Cowett recently published a paper called “Street Tree Diversity in Three Northeastern U.S. States” in Arboriculture & Urban Forestry, the scientific journal of the International Society of Arboriculture. What follows is the abstract, and the full paper is here.
Abstract. Street tree diversity is widely viewed as a key component in the resilience of street tree populations to pests, diseases, and climate change. Assessment of street tree diversity is considered integral to sustainable street tree management and preservation of the ecosystem services and social benefits that street trees provide. This paper assesses street tree diversity in three northeastern U.S. states— New Jersey, New York, and Pennsylvania—by analyzing municipal street tree inventory data stratified by the 2012 USDA Plant Hardiness Zones. Despite the lesson learned from the historical devastation of overplanted American elms (Ulmus americana) by Dutch elm disease, and awareness of the contemporary threats posed to ashes (Fraxinus spp.) by the emerald ash borer (Agrilus planipennis) and to maples (Acer spp.), and other tree genera by the Asian longhorned beetle (Anoplophora glabripennis), results presented here indicate a current concentration of street trees among a relatively small number of species and genera, and in particular the dominance of maples as street trees. Results also show a positive relationship between street tree diversity and warmer average minimum winter temperatures. Consequently, there is a clear need in all three states for greater species and genus diversity in statewide and municipal street tree populations. However, meaningful impediments exist to increasing street tree diversity, especially in the short term.
This is THE publication to share with your municipality’s engineers and leadership, to show the why and how of CU-Structural Soil.
CU-Structural Soil®, also known as CU-Soil®, is a two-part system comprised of a rigid stone “lattice” that meets engineering requirements for a load-bearing paving base, and a quantity of uncompacted soil that supports tree root growth.
The first section of the Guide discusses the role of soil volume and how to calculate how much soil volume a tree needs. No matter how well matched your tree species is to its site, limited soil volume is something few trees can abide, much less thrive in.
The Guide goes on to give the case for CU-Structural Soil in particular, and answers FAQs like “How much CU-Soil will I need?”, “How do you plant trees in CU-Soil?”, “Can it be retrofitted for use under existing trees?”, and “How is irrigation and drainage handled?” It also explains how to obtain CU-Soil that meets quality control specifications. (This, by the way, is why CU-Soil is licensed—to ensure quality control. Otherwise, anyone could mix up rocks and soil and claim to be selling “CU-Soil.”)
by NYC Parks Director of Street Tree Planting Matthew Stephens and Taking Root Editor Michelle Sutton
We coauthored this story questioning commonly held beliefs about “fall hazards,” mostly as it applies to B&B trees, but we also discuss the interaction of the fall season with other production methods, like bare root. The section, “The Five Branches of Transplanting Success,” should be of interest to anyone planting trees, period! With the help of Nina Bassuk and others, we tried to break down the complex interactions at work with transplanting. This article originally ran in Arbor Age (Fall 2015).
The nursery industry is reluctant to dig certain species of trees in the fall, yet the “fall hazards” lists can vary significantly among nurseries. Also varying is the experience of nursery customers, including city foresters who plant hundreds or thousands of trees each year. In addition to digging season, there are other interacting factors at play in the fall planting picture.
A More Nuanced Look
Cornell Urban Horticulture Institute Director and street tree expert Dr. Nina Bassuk says, “Those fall hazards lists are generalizations. Typically the trees that appear on those lists are trees that are more difficult to transplant, period. In spring they don’t become easy to transplant; they’re just observed to be easier in the spring than in the fall.”
Tree Pittsburgh Director of Urban Forestry Matthew Erb has overseen the planting of more than 25,000 trees (mostly B&B) since 2008. “I’m sure if you look hard enough, you will find nearly every species on someone’s fall hazard list,” he says.
Thanks to Nina Bassuk’s research and extension efforts in bare root transplanting technology, tens of thousands of trees have been planted in New York and the greater Northeast that would otherwise not have been. In 2014 alone, 8800 bare root trees were purchased by 93 municipalities across 11 states from Schichtel’s Nursery in Western NY.
Schichtel’s Sales Manager Jim Kisker, who has partnered with Nina on bare root and other research since 1990, says the vast majority of the nursery’s bare root sales go to municipalities that are using her bare root technique. Kisker says, “When I listen to some of our municipal customers give presentations on the success they’re having with bare root, they’re up in the exceptional 93-96 % survival rate with the dip and bag method. We know it works, because the same municipalities come back every year. Some have been buying from us, with this method, for 10-15 years and in some cases, 20-plus years.”
NYS DEC Urban Forestry Program Manager Mary Kramarchyk says, “When learning about volunteer efforts across the state, I find it uplifting that so many local tree stewards already know about bare-root tree planting and that they find it much easier to do than balled and burlap trees.”