The effects of strimmer damage to young ash trees (Fraxinus excelsior L.)

ABSTRACT

Strimming near the bases of young trees can often cause wounds that remove outer bark and cause damage, dysfunction and death to the living tissues of the tree, making trees vulnerable to pathogen ingress.

This study conducted quantitative research into the effect of mechanical wounding by causing strimmer damage to 88 fifteen-year-old ash trees (Fraxinus excelsior L.) in a woodland setting. Damaged specimens were sequentially harvested and wound parameters measured over a 2-year period and compared to a control. Inner bark death, sapwood discolouration and the formation of woundwood caused by this wounding was analysed.

In addition, two industry questionnaires were issued to gather the opinions of those in a supervisory/management position and those directly involved with grounds maintenance operations that involved strimming near to trees.

Results from the strimmer-damaged ash trees identified that the initial wound size increased by, on average, 46.5% over the first 8 months after injury, due to the necrosis of inner bark adjacent to the wounds. The extent of the sapwood exposed was correlated with the length of time taken for the wounds to occlude, most of them occluding within one growing season. The associated questionnaires identified that strimmer damage to urban trees is seen daily by some operatives and that managers favour operator training over other solutions to this problem.

We conclude that advanced technical training of operatives is essential as a preventive measure against strimmer damage to trees but that other methods of tree protection should also be considered.

KEYWORDS:

• Grounds maintenance
• strimmer damage
• tree establishment
• urban forestry
• wound response

Acknowledgements

The authors would like to thank Simon Clarke for allowing the use of his land to strim and then fell the trees used for this study, to Simon Ballett for supplying the vinyl stickers used for this research, to Laura Power for creating the drawings for Figure 1 of this article and to all respondents who kindly completed one of our two questionnaires.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Sally A. Schuck

Sally A. Schuck is the curriculum lead in arboriculture at Merrist Wood College and she is a recent graduate of the MSc online course in Arboriculture and Urban Forestry delivered by Myerscough College, England.

Duncan Slater

Duncan Slater is a senior lecturer in arboriculture at Myerscough College, England, course tutor for the MSc in Arboriculture and Urban Forestry and a chartered forester. His research interests include tree biomechanics, tree decay, tree risk management and urban forestry.