Many trees show the last two years bark striations. Thin white vertical lines (necrosis) on the outer bark of the trunk. Sometimes horizontally in pairs of 3 or five lines. There is no explanation for this increase.
It has been postulated that this is related to the ever increasing electromagnetic fields in the environment, perhaps in combination with air pollution.
Necrosis of the protective layers of dead cells (phellum) at the site of striations is an early sign of injury and prevents normal bark expansion. The effect has not been studied but when necroses occur the tree is more prone to disease. Science canít give us an answer of its cause. There is now an urgent need for further research on this topic.