Saturday, November 19, 2005

A Butternut Grove

During my walk today I visited the clearing area at the northeastern corner of the woodlot referred to as Area G in the woodlot management plan. Area G is the only clearing in the whole woodlot which was not intentionally kept open through cultivation or clear cutting. It should in time have grown in with trees and yet there is but a thin and sparse planting of several poplar trees and others. I always wondered why is this so? This area had very old and well rotted cedar tree stumps which were cut some 30 or more years ago. In fact there was evidence that it was cleared at least 45 years ago. The field has remained undisturbed for all these years and yet but few trees took root as well as grass and some small herbaceous vines.

Having become sensitised to the plight of the butternut tree [Juglans cinerea L.] and the fact that in certain parts of North America it is becoming an endangered species due to major die off created by the butternut canker, I have become more experienced at identifying the tree. So during this visit to area G to my amazement I found very many butternut trees in area. Many were dead trunks with the characteristic butternut canker scares, some were alive but in poor condition and a few others seemed still healthy. I counted some 3 dozen trees or remains of trees all together. Now that the trees were bare it was easier to identify and count them all. One butternut tree was much larger than the others and may well have been the parent that provided the seed source for the rest. It had a dbh (diameter at breast height) of 35 cm (14 in.). In forestry, the stem diameter of a tree is measured at breast height or 1.3 metres (approx. 4 feet) above the ground hence the term dbh.

I have long wondered why area G stayed clear and think I may have hit upon the answer. The butternut tree has an interesting characteristic in that it produces Juglone toxin in its roots. Other plants whose roots touch the butternut root will draw this toxin and wilt and even die. This also occurs with black walnut. The article at published by the University of Wisconsin well describes this phenomenon. This provides a plausible explanation for why area G is so lightly treed. One has to wonder then if reforestation of the area will work at all without removing all the roots of the dead butternut trees, a ridiculously arduous and prohibitively expensive job. Buckthorn and the elm also adversely affect or stunt the growth of neighbouring plants near their roots, but I am not sure if these species use the same process, something to investigate for another post.


Peter Leenhouts said...


The black walnut, Juglans nigra, also produces this toxin. But there are at least twenty plants that can survive and even thrive under a black walnut tree (I recall seeing a list in an ornamental gardening book). It would be interesting to know what kinds of plants and/or trees are growing in the butternut grove.


Woodlot_Manager said...


Next time you are over, I should show you the butternut grove and how sparse the vegetation is there. I will see what plants are surviving as soon as I can try to identify them during the summer.