Urban trees generally live a shorter life than their forest counterparts. Yet in many cities, a small number of trees reach great size and age.  These trees may be pre-settlement trees left in place during a city’s growth, or trees planted early in the life of a city.  Although not common, large old trees are significant assets and sometimes significant liabilities to cities. The symposium will begin with two case studies of ancient tree management in urban landscapes and then address risks and benefits and risk management of large urban trees. The symposium will conclude with a panel discussion on emerging guidelines for management of large trees in urban environments.

•    Opening Remarks and Moderater - Bryant Scharenboch, PhD, Morton Arboretum
•    Longevity and management in ancient urban trees of the Bluegrass – Tom Kimmerer, Venerable Trees
•    Preservation of large trees at the University of Pennsylvania - While all trees within our urban landscapes are valuable, large trees play a particularly vital role as the most important green infrastructure element.  Large trees provide the greatest environmental, economic, and social benefits, and fundamentally contribute to the health and welfare of almost 80 per cent of the US population and over half the world population living in urban areas. However, as a tree grows and tree-related benefits increase, tree-related risk concurrently increases, since large, mature specimens are more likely to shed increasingly larger branches or develop conditions predisposing the whole tree to failure.  This presentation will discuss how tree-related risks and benefits are assessed and evaluated, and how tree owners and managers strive to balance their risk tolerance with the many benefits trees contribute to our urban communities.- Jason Lubar, Morris Arboretum
• Elderly trees are quite different from young trees. Their appearance, physiology, needs, cultural tolerances, and other aspects require unique attention. As arborists it is essential that we understand these differences and change the way we interact with elderly trees. This session will discuss, in very simple basic terms, how to identify elderly trees, discuss the contrasts from younger trees, and discuss how as arborists our treatments of elderly trees need to adapt.-Norm Easey,  Florida Chapter ISA
• Managing Mature Trees Under Limited Water/Drought Conditions  – The City of Austin, Texas has an estimated 200,000 trees in managed park lands.  Of this population, roughly half are considered to be established trees, and about 7% are mature trees.  In 2011, Texas experienced one of the worst drought years in history, resulting in a loss of an estimated 5.6 million urban trees.  Drought has persisted in the state, leaving the lake system which supplies water to the City of Austin at extremely low levels.   The City has had watering restrictions in place for several years now, and without significant rainfall, is expected to further restrict water usage.  This has made protecting the mature trees in our parks even more challenging.  This presentation will outline the steps that we are taking to manage our mature trees through this time of drought and water restrictions, and how we are attempting to engage the community to help.– Lara Schuman, City of Austin, TX
• Panel Discussion - Developing guidelines for management of large, old trees