The tree is huge, with spreading branches that cover the whole property. The trunk is sculptural, the root flare picturesque, and the foliage gives welcome shade. Birds nest in the branches and lizards run up and down. Ancient trees evoke feelings of peace and wonder.
But the arborist thinks the tree should come down – “Better safe than sorry.” Is this what should happen? How do we evaluate the health and structure of old trees?
Stately trees of a “certain age” are thought of in many ways. We call them Veteran Trees, Ancient Ones, Valuable Assets, Historical Witnesses, or Dangerous Liabilities. Our point of view reflects both our knowledge and also our lack of knowledge. Although we love the idea of an old tree supporting decades of wildlife and enduring through generations, the fact is that old trees present a unique set of challenges for the arborist, particularly in cities and towns.
As trees age, their vigor and incremental annual growth begin to slow. Foliage can begin to die back as the tree allocates water and minerals to maintenance or defense at the expense of growth. Wound response can take longer and use valuable resources. Organisms that recycle dead wood can establish themselves on old bark or root flares. The interior of branches and trunks can develop cavities that can compromise structural integrity. For these reasons, mature trees take thoughtful evaluation and special care.
Is there recent research on tree health and aging? Do we know all there is to know about tree risk assessment? Are we prepared to work safely in older trees? Do our customers listen to lawyers instead of scientists?
Coming up on September 23, the Arizona Community Tree Council’s Annual Conference has as its theme “Nurturing Our Natural Heritage: Developing and Caring for Mature Trees.” The event will be held at the Prescott Resort and Conference Center. Mark your calendars to attend and learn from some of the region’s experts. (see the ACTC web site for more information)
The Keynote Speaker for the ACTC Conference will be Nelda Matheny, Founder and President of HortScience, Inc. Nelda is a world-class writer, tree advocate, and creative researcher who has agreed to give two presentations on mature trees. Her first talk will be “Aging Trees: An Overview of What We Know”, and the second is “What’s New: ISA’s Best Management Practices/ Tree Risk Assessment”. All arborists in the region should plan to come learn from a respected member of the International Society of Arboriculture. (To hear Nelda talk twice in one day is worth the price of admission, in my opinion!)
To address problems that large trees have with insect and diseases, Bob Celaya from USFS will speak on ‘Forest/Woodlands Insects and Disease’ and Peter Warren from Pima County Cooperative Extension will speak on ‘Insects in Trees’. Tree failures and how they are recorded will be covered by Kathryn Hahne, Certified Arborist with Pima County Cooperative Extension.
Large trees can give us clues to fire history, and we want to protect our properties from increasingly-common summer wildfires. We are fortunate to have Cliff Pearlburg from the Arizona State Land Department speaking on ‘Firewise Landscapes’, and Rex Adams from the UA Laboratory of Tree Ring Research explaining how tree rings in ancient trees can teach about fires in the past.
Working in older trees can prove to be a safety challenge. Juan Barba, Consulting Arborist will be demonstrating safety techniques, and John Eisenhower of Integrity Trees will show how root excavation can expose girdling roots that can cause trunk instability. There will be a program on chain saw safety, too.
We’ll also have Paul Chambers of Australian Outback nursery speaking on trees from Australia, Cado Daily from Cochise County cooperative Extension explaining key points when designing water catchments for trees, and an overview of declining tree health in cities with Dr. Chris Martin of ASU.
In addition, an entire track of qualified speakers will give the candidates for the ISA Certification Exam a chance to review all domains. Speakers will spend the whole day reviewing subjects to be covered on the upcoming ISA Certified Arborist Exam (contact the ISA web site for more info on the test).
On Saturday the 23rd, at the same site, A Plant Problem / Diagnosis Workshop will offer another day of classes specifically designed to earn OPM CEUs. Charge for this workshop is separate from the main conference, but the two can be combined for a savings. (again, see website for more details.)
No matter what your experience level, the Arizona Community Tree Council’s annual conference will provide you with new insights, a chance to learn from the best experts, the fun of the annual silent auction, some great networking opportunities, give-aways and prizes, and lots of CEUs. Please plan to join us in Prescott on September 22 for the annual ACTC Conference, and for the Plant Diagnosis Workshop on September 23, 2011.