Heat wave in Giants Grove

Written by Sean

September 29, 2020

I predicted a challenging summer 2018 for the Giants Grove, but who could have foreseen the form it would take – the driest June in nearly 80 years, and no end in sight. Ireland is experiencing a heatwave, and while most of the Irish are enjoying the sunshine, I’m concerned about the Giants reaction to, and ability to deal with drought stress. The drought is severe, the worst in living memory, and we’re simply not accustomed to these conditions here. In a country known for its rain we’re receiving fire-risk warnings daily!

Although not at risk of fire, the trees in the Giants Grove are suffering under these conditions. The visible symptoms include reduced leaf development, wilting, leaf-scorch, some defoliation, and some dieback of twigs and branches. But trees are fascinating, resilient and adaptive, and these symptoms are actually signs of the trees strategies to deal with drought stress – stomatal closure, restricting shoot growth, and leaf shedding, while increasing root-to-shoot ratio through enhanced fine root development. These are the trees instinctive, evolved adaptations for minimising drought damage in order to survive.

So the trees have reacted, but so has the management – the site is being monitored closely. Soil temperatures are surprisingly cool 6 inches below the surface, and there is still some moisture at that level. This is in part an unexpected result of the ‘no chemical’ policy, as the shallow-rooting weeds have actually insulated the soil and prevented evaporation. But the ground will only get drier as the heatwave continues, and so any Giants requiring water will receive it by hand long before it is necessary.

Lord Rosse and I carried-out an official Site Inspection at the end of June to assess stocking, weed competition, deer damage and obviously the effects of the drought. It was agreed that although sections of the site appeared untidy due to the presence of thistles, there was currently no adverse effects on the Sequoias or nurse species from weed competition. In fact, on balance the overall impact of the enormous range of ‘weeds’ was generally positive. A follow-up Inspection was scheduled for the end of July.

I remain concerned for the Giants Grove. The trees have been knocked back by these extraordinary conditions, and we’ve lost 4 weeks growth which we’ll never get back. But trees are fascinating, resilient and adaptive, and the Giants will survive. The weather will break soon, and the Irish rain will return, and when that happens the Giants will leap from the ground.

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