Abundant acorns on the forest floor – is 2020 a mast year?

Those who enjoy a venture into nature’s many corners around Northumberland may have noticed something unusual in the recent autumnal months; a greater than usual flurry of maple seeds (often known as “helicopters”) and acorns littering the forest floor. This has prompted naturalists to conclude that 2020 is likely a mast year for British woodland species, a year in which trees such as oak, beech and maple produce bumper crops of fruit. Mast years generally occur between every five and ten years and are usually accompanied by a boom in populations of seed and fruit-eating animals (known as frugivores) taking advantage of the bounty.

The causes of mast years are rather ambiguous, although it is clear that they are an evolutionary adaption for successful tree reproduction. A generally accepted theory for the reason behind masting is that of predator satiation; in non-mast years, low crop yields keep predator populations low, meaning that the frugivores will be unable to consume the bumper crop produced during mast years, ensuring seeds have a chance at germination during spring months. Naturalists have also concluded that excess fruit production takes a great deal of energy, after which species must recuperate, and accumulate new energy reserves before being able to mast again.

But how do woodland species coordinate their masting across the UK? There are several theories. The synchronisation of mast years of trees of the same species is thought to increase the odds of viable offspring production through maximising their reproductive potential in a process known as pollen coupling; trees that are out of sync, meanwhile, are removed from the gene pool. Coordination is also likely to be linked to weather at the time of flowering; oak, beech, and maple trees rely on windblown pollen for fertilisation, meaning warm and windy spring weather conditions may lead to bumper crop in autumn. Another possibility is that of “communication” between trees via chemical signals, similar to those which trigger defensive mechanisms in plants when neighbouring species are damaged.

But while shrouded in mystery, mast years are undoubtedly great news for the birds and mammals such as jays and squirrels dependent on the crop produced. We wildlife lovers meanwhile, can enjoy the sight of a prosperous, bountiful autumn in the many woodlands around Northumbria.

By Polly Stevens

About the Author

I’m a student at Newcastle uni studying geography. I’m really interested in natural history and think that conserving it is about the most important thing we can do! I love spending time outdoors and have enjoyed exploring the Northumbrian countryside while I’ve been studying up here – I’ve also spent a lot of time at the coast as I surf a lot! When I’ve finished uni I really hope to work outdoors with nature, especially in conservation, as its definitely what I enjoy doing most.