API Summer 2021

READING THE TREES

Learn how to read the tree leaves, along with other signs and symptoms, to identify biotic and environmental issues.

If you have trees on your course, you’ve probably experienced the challenge of articulating your tree observations to an arborist. Your explanation likely elicited follow-up questions. “Was the mushroom growing on the tree, or next to it?” “Did you see actual evidence of in- sects?” That’s because the answers to these questions provide clues to the reasons why trees are declining or reacting in certain ways. Learning how to read trees will help you and your staff make educated decisions on tree and ecosystem management throughout your course. To better diagnose and explain tree issues, you should learn to recognize whether the

tree stress you are observing is a result of biotic or abiotic factors, and under- stand the differences between signs and symptoms.

BY KATIE HOGAN, KATHERINE TAYLOR, AND SCOTT BAKER, TREE SOLUTIONS, INC.

BIOTIC VS. ABIOTIC FACTORS

Biotic issues are caused by the living organisms of the ecosystem, such as insects, fungi, bacteria, plants, and animals. Abiotic disorders are caused by nonliving physical and chemical fac- tors that derive from the earth and its surrounding atmospheric layers. Abiotic factors that impact trees can include drought, sunscald, freeze, nutrient deficiencies, and improper pesticide applications.

BIOTIC (“PERTAINING TO LIFE”)

ABIOTIC (“NOT LIVING”)

Factors or stressors that are living parts of an ecosystem.

Factors or stressors derived from the earth and atmosphere, typically involving nonliving, chemical, or physical components.

For example: insects, fungi, bacteria, plants, animals

For example: soil, water, drought, light, minerals, gases, wind, temperature, chemicals

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