Trees in Snow
Photo: Simon Koopmann

When was the last time you went to the doctor with an illness and s/he suggested a treatment involving leeches? Or maybe you had a sore throat and decided to dip a flannel cloth in coal oil, (kerosene) and tie it around your throat, to ease the pain.

Home remedies are often based on observations but often result in misinformation that may not bear out under the scrutiny of research. Some are still used (think honey and lemon for a sore throat)  but others have been found to be ineffective or even dangerous.

Like medical research, tree research  has come a long way over the years, and it continues to change as new information becomes available.  Thanks in part to the Tree Research and Education Endowment Fund (TREE Fund), we are learning new ways to plant, prune, and care for trees so that they grow to provide all the benefits we expect of them.

Winter often finds us with more “inside” time. It is an excellent time of the year to catch up on your reading while learning about new ideas and research. By educating yourself about new practices of tree care and management and implementing those practices, your community will be planting – and caring for – an asset, not a liability.

This edition of Tree Link is dedicated to reading and learning. Happy reading! Happy New Year!

Tree Board University

This is a unique online training that will help you learn more about trees, about people, and about serving in a citizen advisory role in your city, town, or village.

Growing the Tree Out of the Box – Tree Space Design 

Casey Trees, a non-profit tree planting organization in Washington DC, along with an advisory group of arborists, urban foresters, landscape architects and horticulturists collaborated to create design standards that will enable trees in urban environments to not only survive, but to also thrive. The designs maintain space for pedestrians while providing adequate soil volume for root growth and preventing soil compaction.

This report presents a matrix of recommended soil volumes based on sidewalk width along with design options to achieve those soil volumes.

Design methods include open soil areas, covered soil areas and root paths. Although the report is based on design conditions in Washington, DC, the recommendations are applicable for any urban area with similar characteristics.

Deflecting Roots Near Sidewalks

Roots meet sidewalk. The outcome is often not a pretty picture. This research paper, by Dr. Ed Gilman at the University of Florida, examines several sidewalk installation techniques used to avoid infrastructure damage. Surprisingly, researchers found that using a clean gravel layer under the sidewalk held the greatest promise of reducing sidewalk damage, especially on well-drained sites

Developing a Preventive Pruning Program for Young Trees  

Tree planting is only the first step in growing a community forest. By establishing a preventive pruning program, municipalities can minimize the risks of tree defects. Some of the more common defects that can be mitigated include co-dominant stems (forked tops) and low branches that either split from the tree leaving huge wounds, or result in large pruning cuts when branches are removed. This booklet helps the tree manager determine the objectives of a pruning program to develop a pruning plan and cycle. Included is a discussion of how to make proper pruning cuts, how to identify and correct existing structural problems, and pruning to promote strong tree structure. This is another great publication from the University of Florida authored by Ed Gilman and Amanda Bisson.

Urban Tree Risk Management: A Community Guide to Program Design and Implementation 

This publication by USDA Forest Service Northeastern Area State and Private Forestry  researchers is a fully illustrated, easy to read training manual written for community leaders, administrators, city foresters, parks and public works staff, and private tree care practitioners. The manual is designed to assist communities design, adopt and implement tree risk management programs, and train field staff to detect, assess, and correct hazardous defects in urban trees. Examples of tree defects, risk rating systems, and species selection were chosen to depict tree species and conditions that occur in the Northeastern United States but are applicable to urban forests here in the west.

How to Recognize Hazardous Defects in Trees

A “hazard tree” is one with structural defect(s) that are  likely to cause failure of all or part of the tree, and could strike a “target.” A target can be a vehicle, building, or place where people gather such as a park bench, picnic table, street, or backyard. The natural variability of trees, the severity of their defects, and the different sites where they grow makes hazard tree evaluation a complex process, and nothing can substitute for a professional assessment by a certified arborist. However, this brochure can help homeowners and land managers recognize hazardous defects in trees to help guide decisions about whether corrective actions or additional evaluation is required.

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