Nina Bassuk gave this talk on her and Peter Trowbridge’s behalf for the recent virtual New England Chapter ISA Conference. This video provides the very latest synthesis of their research on and experience with creating sustainable urban landscapes.
What’s a tree worth?
In what has become an annual tradition (save, sadly, for the spring of 2020), students in Nina Bassuk’s Creating the Urban Eden: Woody Plant Selection, Design, and Landscape Establishment class at Cornell are helping to make people more aware of the full value of trees. In a typical spring, they hang bright green “price tags” on trunks around the Ag Quad that show the dollar value of a tree’s ecosystem services. The students use i-Tree to enter data and calculate ecosystem service value.
Read the full story on the Cornell Urban Horticulture Institute blog.
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 firstname.lastname@example.org. Read on for more background about this fascinating research.
Cornell’s Urban Horticulture Institute (UHI) has released the second edition of its Woody Shrubs for Stormwater Retention Practices (Northeast and Mid-Atlantic Regions). The updated and expanded 57-page guide is an essential resource for choosing plants that can provide low-maintenance, attractive cover for filter strips, swales, rain gardens, and other stormwater retention and infiltration practices.
“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.
In their recent paper in Urban Forestry and Urban Greening, “Long-Term Remediation of Compacted Urban Soils by Physical Fracturing and Incorporation of Compost,” study authors Miles Sax, Nina Bassuk, Harold van Es, and Don Rakow published their findings after twelve years of applied research. The technique, “Scoop & Dump Soil Remediation,” was introduced in a previous Council blog post about Urban Horticulture Institute research.
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.
Recently, the Cornell Urban Horticulture Institute, headed by Nina Bassuk, published a 57-page Comprehensive Guide to CU-Structural Soil.
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.”)