Your chances of surviving a severe drought are best if you are not too tall, or too small – if you are a tree that is. New research reveals that about 18 metres (59ft) is the optimum height for a tree to have maximum resilience to extreme drought conditions.
Prolonged periods of hot, dry weather are tough for trees, but some trees fare better than others. Peipei Xu from Beijing Normal University in China and her colleagues studied tree-growth data gathered during a severe drought in the south-western US in 2002. They found that the taller the tree the greater the struggle to transport water up its long trunk to the leaves. Meanwhile, smaller trees tended to have shorter roots and less ability to reach deep water. The findings, which are published in Environmental Research Letters, showed that medium height trees – about 18 metres – had the greatest resilience to severe drought.
This suggests that forests with a mix of short and tall trees may be at higher risk during a severe drought than those with a medium-height canopy. The scientists hope their findings will help foresters decide which trees to plant and how to manage their forests to maximise survival in hot, dry summers.
