This summer hit a milestone in UK climate history. Records for extreme heat and low rainfall were broken as we experienced the hottest day on record. The effect on our health and economy was widely reported, but what effect do extreme heatwaves have on trees?
Temperatures peaked above 40°C in several places and night-time temperatures were the highest ever recorded. It was also the driest July in over 20 years.
Heatwaves often go hand-in-hand with drought. A lack of water can cause serious problems for trees and make it look as though you’re seeing a very early autumn.
In dry weather, the sugars in leaves become concentrated and the leaves produce more anthocyanin (red and pink colour pigments). Consequently, the leaves turn redder or brown, and the tree may shed them to preserve the moisture in its branches and trunk.
Senior horticultural advisor at the Royal Horticultural Society Leigh Hunt told BBC News that Autumn came early: “Physiologically, the plants are not responding to autumn conditions; that’s why we term it loosely as ‘false autumn.’” Hunt also said that older trees with a large root network could survive drought, but younger trees planted in poor soil could die.
“The heat is stressing trees so much that that cycle of photosynthesis has just not been able to carry on in the tree, and the trees are enacting their hormones that they use in autumn to just retract and ensure their survival,” Rosie Walker of the Woodland Trust said in an interview with BBC Radio 5 Live.
The two species currently most impacted by this phenomenon are silver birch and rowan, Walker said. The Woodland Trust recorded the first leaf turn for silver birch on August 12, “which is incredibly early,” Walker added.
What can you do? Young trees are particularly susceptible to drought, so here are our three top tips for looking after your young trees in hot conditions:
- Plant young trees in the right weather conditions to optimise the growing environment. Autumn (October) through to early Spring (February) is best
- Plant young trees carefully: a planting pit deep and large big enough for the root ball is essential to enable the roots to thrive
- Water young trees regularly: Every little will help, and newly planted trees need daily watering for 6 months and weekly watering for a further six months (if there is no or only light rain). Recycled domestic waste water is fine for this if it isn’t full of strong chemicals
For advice and information about your trees, or a quote for tree work, contact Andrew
E: Andrew@primarytreesurgeons.co.uk P: 01256 817369 or M: 07771 883061
Twitter: @PrimaryTreeSurg