Mast years
Twice in the last week I have been taken by surprise by an acorn.
Not by the amazing realisation that from the tiny nuts creating a carpet on the track I walk down each day grow the mighty oak trees I walk beneath.
Not by the speed with which they have turned from bright shiny green to dull brown.
But by the thud of one falling on my car roof a day or so ago and one falling onto me as I walked under a tree today.
It has been a noteworthy year for acorns; similarly it has been a bumper year for rowan berries, sloes and raspberries.
The autumn of 2020 was a bumper year and many of us noticed that and commented on it. Back then I wondered if the reason we spotted this abundance of nuts and berries was due to our renewed connection to the natural world brought about by lockdown.
We planted thousands of trees on our croft, but 2020 was my first autumn living in the Sunart ancient oaklands on the peninsula and it took me back to my primary school playground which had many mature trees casting spiky encased shiny conkers, sycamore ‘helicopters’ and bunches of ash ‘keys’.
The act of gathering autumn nature treasures to fill my pockets suddenly became a comforting call back to childhood.
I recall reading some phenological explanations of the large number of nuts, seeds and berries in 2020 at the time.
Phenology is the study of seasonal cycles of biological events, such as bird migration, breeding seasons, hibernation in wild animals and flowering and seed production in plants.
I revisited some of that reading this week after my second up close and personal encounter with an acorn and learned about mast years.
The nuts, seeds, berries and cones which trees and shrubs produce each year are their way of reproducing. While essential to ensure continuation of the species, the production of these comes at a cost of energy to the tree so they do not produce them in the same numbers every year, with years of abundance happening every three to 10 years instead of annually.
The amazing fact is, rather than being random or specific to individual trees, or even close to each other’s areas, it appears the bumper crops, or mast years, happen across the country.
As is so often the case with nature, we do not fully understand why but we have theories on the possible reasons.
I had previously heard a good year for nuts and berries meant it would be a harsh winter and often wondered how this could be true.
If weather forecasters are not able to predict more than a week or so in advance, how can trees possibly be aware in autumn what winter may bring?
The idea that a testing winter for birds and small mammals could be provided for by generous rowan trees is an interesting one but perhaps ties into the theory of ‘predator satiation’.
This is the theory that a few lean years of nut and seed production will control the population of creatures which feed upon them – effectively reducing the numbers
of squirrels, mice, badgers and birds such as jays.
When numbers are sufficiently low to ensure there will be leftovers, a mast year happens which leaves a surplus uneaten to germinate and grow into the next generation of trees.
Those rowan and holly berries which rely on being eaten and pooped back out by birds may indeed thrive most in years when other food sources are scarce and they are spread far and wide by birds travelling far to find sustenance.
My close encounter with a surprise acorn was far from as scientifically powerful as Newton and his falling apple, but it certainly sent me on a quest for some nature-related knowledge.
Maybe those tiny acorns are responsible for more than just mighty oaks in a few hundred years time.
Photographs
Nic Goddard. NO F30 Nic Goddard byline pic
NO_F41_CroftlessCrofter 01
NO_F41_CroftlessCrofter 02