Urban Forest Adaptation to Climate Change: Key Tools and Resources

 At the 2019 NY ReLeaf Conference last July in Rochester, Dr. Leslie Brandt presented a fascinating talk about her work on urban forest adaptation to climate change, and she offered up powerful resources and tools to our community. Here’s a brief summary of those resources compiled by blog editor Michelle Sutton in consultation with Dr. Brandt.   

Background

The Climate Change Response Framework (forestadapation.org) is a collaborative, cross-boundary approach among scientists, managers, and landowners to incorporate climate change considerations into natural resource management.

The Framework’s partners are numerous and wide-ranging, including the Bureau of Indian Affairs, National Park Service, U.S.D.A. Forest Service, U.S. Geological Survey, and dozens of state and local governments, Native American tribes and tribal organizations, universities, and ecological and urban forest institutes and organizations.

The Northern Institute of Applied Climate Science (NIACS) works with partners to lead Framework activities across the Midwest and Northeast U.S. Within the Climate Change Response Framework, the Urban Forestry focus addresses urban forest vulnerability for cities and creates tools to help local managers adapt to the effects of climate change.

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Beetle, Fungus, Fungus: Research Updates on EAB, DED, and Chestnut Blight

Emerald Ash Borer. A report recently published in the Journal of Economic Entomology offers data on the newest parasitoid wasp released against the EAB beetle: Spathius galinae. One of the authors, Dr. Jian Duan of the Beneficial Insect Introduction Unit at the U.S. Department of Agriculture’s Agricultural Research Service, says including this species in the biocontrol lineup could be a game-changer. “The addition of S. galinae to the current biocontrol arsenal will provide a whole spectrum of protection for surviving ash trees,” he says. To read more, see the summary article by Melissa Mayer in Entomology Today. Photo credit: Jian Duan, Ph.D., USDA-ARS

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TREE Fund Awardees for Urban Forestry Research

A glimpse into upcoming urban forestry research: Why have a tiny percentage of ash trees survived EAB? How can LIDAR be used to improve urban forest management? How do mycorrhizae help young trees access soil moisture? Why do seemingly healthy trees fail, unpredictably impacting power lines, and how can better failure models be developed?

TREE Fund raises these funds through its annual Tour des Trees epic bike ride. It’s not too late to register to ride in the 2019 Tour des Trees or to sponsor a rider. This year’s ride is in Kentucky and Tennessee, Sept 16-20. 

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Study Findings: Front & Backyard Vegetation in Urban Forest

“Backyards are very important,” says coauthor Dexter Locke. New insights from research on “Urban form, architecture, and the structure of front and backyard vegetation,” by Alessandro Ossolaa, Dexter Locke,
Brenda Linc, and Emily Minord in the Journal of Landscape and Urban Planning. 185 (2019) 141–157

ABSTRACT
Residential yards comprise most land and green space across cities. Despite yards being ubiquitous, little comprehensive information exists on how vegetation varies between front and backyards. This hinders our ability to optimize greening interventions on private urban land.

We devised an accurate GIS algorithm to locate and classify front and backyards within residential landscapes. By applying this method to the greater Boston area, we measured vegetation structure (i.e., canopy cover, height and volume) of front and backyards with LiDAR and multispectral imagery. We further investigated relationships between urban form, architectural style, socio-economics, and the structure of front and backyard vegetation across Boston’s residential landscapes. 

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Cornell Opens New Sustainable Landscapes Trail

Students in Nina Bassuk and Peter Trowbridge’s Creating the Urban Eden class, planting the bioswale in the Peterson parking lot, the site of the recent Cornell Sustainable Landscapes Trail opening ceremony. Photo from Cornell Horticulture blog (https://blogs.cornell.edu/hort)

With excerpts from Cornell Chronicle and the CU Sustainable Landscapes Trail web page

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

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Hybrid Oaks from Nina Bassuk/UHI Available to Communities in Spring 2019

Quercus macrocarpa x Q. turbinella hybrid in UHI research plots. Photos by Nina Bassuk

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 nlb2@cornell.edu. Read on for more background about this fascinating research.   

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Nina Bassuk Reviews New Applied Tree Biology Book

Nina Bassuk Reviews Applied Tree Biology by Andrew Hirons and Peter Thomas

Reprinted from the April 2018 Arborist News (Volume 27, Number 2).

The first thing to notice in this very excellent text is the title, Applied Tree Biology. This is not exactly an arboriculture manual or a tree biology textbook. It very deftly explores tree biology and then links it to the art and practice of arboriculture. Although the “applied” part of the text is not limited to managing trees in difficult environments, there is a definite subtext focusing on the trials of trees growing in managed or urban environments.

Ten comprehensive chapters address tree structure (wood, leaves, and roots), seed growth, water relations, carbon acquisition, nutrition, interactions with other organisms, and finally, environmental challenges. Each chapter is lavishly illustrated with graphics and pictures; it is difficult to find a page that does not have some illustrative feature. Given that this book is up-to-date and rather dense in content, the illustrations are very welcome. 

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Cornell Urban Horticulture Institute Team Evaluates Condition of National Mall Elms

Cornell UHI team Barbara Neal, Bryan Denig, and Nina Bassuk assess the health of one of the iconic elms ringing the National Mall. Photo by Yoshiki Harada

In April 2018, the Cornell Urban Horticulture Institute team of Nina Bassuk, Bryan Denig, Yoshiki Harada, and Barbara Neal released an extensive report on the elms (including American elms) of the National Mall in Washington, D.C. The report details a study conducted at the request of the National Park Service to examine the current conditions of the trees and soils on the tree panels of the National Mall, and it includes a fascinating history of the landscape. Here are some highlights from the report.

The National Mall elm trees are an important planting in the monumental core, yet they face several challenges. The soils of the tree panels are very compacted, most likely due to the constant pedestrian use and the numerous large organized events that take place on the Mall. Unevenness in the size and distribution of the tree canopy has resulted from decades of mortality (often due to Dutch Elm Disease) and the planting of certain elm varieties with growth forms that are seen as incompatible with the planting as a whole.

From June 17–20, 2017, the research team conducted a tree inventory and collected soil data and samples for later analysis. In addition, in November 2017, ground penetrating radar done by Council member Gary Raffel was used to document root growth for seventeen of the trees. This report deals with the current tree and soil conditions, while management recommendations are in a separate report to be released in late 2018 or early 2019. 

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Urban Forest Ecology: Earthworms Implicated in Sugar Maple Decline

Dr. Tara Bal
Dr. Tara Bal examining earthworm activity in leaf litter.

Whoa. Worms can cause a lot of problems, as we’ve been exploring on the blog with regard to the organic matter over-consumer, Asian jumping worm. A Michigan Tech study entitled “Evidence of damage from exotic invasive earthworm activity was highly correlated to sugar maple dieback in the Upper Great Lakes region” points to … just that. That is, the way in which earthworms (which, due to glacial scraping in the past, are not native in Michigan or in New York) are directly and indirectly contributing to or causing maple decline, which has affected urban forests as well as exurban ones.

Michigan Tech did a great summary of the research and here is the abstract for the study, published in the journal Biological Invasions. The lead author is Dr. Tara Bal, who wrote her dissertation about sugar maple decline in the Upper Great Lakes Region.

Abstract

Sugar maple (Acer sacharrum Marsh.) in the western Upper Great Lakes region has recently been reported with increased crown dieback symptoms, prompting investigation of the dieback etiology across the region. Evaluation of sugar maple dieback from 2009 to 2012 across a 120 plot network in Upper Michigan, northern Wisconsin, and eastern Minnesota has indicated that forest floor disturbance impacts from exotic invasive earthworms was significantly related to maple dieback. Other plot level variables tested showed significant relationships among dieback and increased soil carbon, decreased soil manganese, and reduced herbaceous cover, each of which was also be correlated to earthworm activity. Relationships between possible causal factors and recent growth trends and seedling counts were also examined. Maple regeneration counts were not correlated with the amount of dieback. The recent mean radial increment was significantly correlated with various soil features and nutrients. This study presents significant evidence correlating sugar maple dieback in the western Upper Great Lakes region with earthworm activity, and highlights the need for considering the impacts of non-native earthworm on soil properties when assessing sugar maple health and productivity.