Friday puzzle solved!

Lots of brainstorming over the weekend, and all the answers were legitimate.  A few people came close with the observation that the roots looked like they had grown over something.  And that’s exactly right:

This is a great example of nurse log decomposition.  When the tree on the right first began growing (and it could have been decades ago), it sent lateral roots out, over, and around the nurse log to reach the soil.  As the nurse log degraded, the tree’s roots were left high and dry, outlining the girth of the original log.

Does this natural example have application in managed landscapes?  Absolutely!  As several of you pointed out, removal of soil or organic matter by erosion or decomposition can leave woody roots exposed.  If these roots are injured by feet or tools, they can lose their bark and become open to disease or pests.  These are the structural roots of the tree, and if their stability is compromised, so is that of the tree.

(Though this tree has had some injury to its roots (probably from hikers), it’s unlikely to fail as it’s pretty small. )

Published by

Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and an Associate Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - "The Garden Professors" Facebook group - Books:

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