Cristina Ertze – 10th November 2022
I worry. It just seems to be a thing I can’t avoid doing nowadays. I worry. I worry about bills. I worry about the environment. I worry about my kids future. And I worry about nuts. Aye, nuts.
My worry has nothing to do with food intolerances or allergies, luckily. It has to do with the trees which provide these nuts and what they are just going through as I write this piece. More accurately, I worry about the long-term effects that such trees’ health has on the environment and the future of our forests and wildlife.
Some of you might have noticed the abundance of tree nuts such as acorns, beech nuts, hazel nuts and conkers (horse chestnuts) this year. Some of you might have also noticed that hedgerow berries like haws and sloes are dotting our roadsides visibly more intensely than in other years. This is due in part to something called a ‘mast year’.
Mast is the collective name for the berries and nuts produced by certain shrubs and trees. The word comes from the old English ‘mæst’ meaning fat or meat and it seems quite well suited when you think about what a basket-full of these nutritious and protein-packed gifts of nature can provide to both humans and cohabiting wildlife.
A mast year is generally how we describe a ‘bumper crop’ year which happens with some regularity among nut yielding trees. For example, here in Scotland, we would usually see a hard mast (oak, beech, sycamore) happen every 4 – 6 years, which would be different from a soft mast, which can happen more consistently among berry fruiting shrubs every couple of years.
There’s tons of debate on what will actually cause a mast year, and the technologies with which we measure some of the information we now know about trees and their complex behaviours are too recent to give a fully scientifically accurate answer. I could picture the botanists and scientists whose papers I read for my research biting their lips to not give in to the excitement of a premature hypothesis.
One thing that we do know for sure now is that deciduous trees actually coordinate their mast years. They do this through mycorrhizal fungi networks as well as by hormones in pollen. Their symbiosis with fungi and pollinating insects acts as their neural pathways and their extensions can cover thousands of acres of territory. They talk to each other and other species and tell each other whether conditions are favourable for reproduction or give each other the stink-eye if they are species like the almond tree, who prefer solitude.
It has been discovered they can actually even send nutrients directly to each other and ‘warn’ them about potentially damaging conditions (pests, temperature fluctuations, drought). They also might, as some believe is the case this year, share in collective panic and call their pals to collective emergency seeding as a desperate attempt to perpetuate their species.
As joyous as this year’s bounty has been for foragers like me (I’ve got a pillowcase full of hazel nuts the size of macadamias which came from just a couple of trees), we have to understand that a mast year comes at great expense for the tree. Whether intentionally or not, when trees do this the direct effect is known as saciation (they exceed the appetite) of their seeds’ predators (squirrels, mice, birds) and thus there is a better chance for the leftovers to actualise into viable saplings.
To produce such an excess of seeding fruit to throw the natural order out of balance requires a lot of effort and by consequence sacrifices are made. Scientists have observed that following particularly pronounced mast years, trees have been dangerously susceptible to pests, weakened tissue in their timber and it will also take them longer to recover and subsequently produce even an average yield of seeds for the next few years.
It’s a truly awesome game of checks and balances that nature is very adept at. The only problem here, as is usually the case, is human interference, and this is what takes us back to my worry state.
One of the obvious observations is that climate change is affecting nature’s rhythms and as you can imagine, periodical hard masting would be part of a chain of actions and reactions to which we don’t know the end results for yet, but from what we have seen so far, it inspires unease. On the other hand, going into more specifics, in Europe and Scotland we have two extremely important factors that unfortunately we, and the set of priorities we have chosen to live by, are guilty of.
One is the ever-demanding commercial industrialisation of food. By driving carnivore predators to extinction to make way for more easily controlled agricultural and herding farming, we have allowed certain species to become pests. Small rodents, deer and even some caterpillars are examples of creatures which are extremely efficient at reproducing in large numbers to preserve their species and which, without a natural predator, can decimate an entire forest habitat by their overpopulation. Ironically, we now have reached a point in which we ‘need’ human intervention to fix the problems we created through our initial meddling.
Unfortunately, rather than taking a hint and choosing to decrease our deforestation and reintroducing the original native wider spectrum of fauna into our forests, the more popular choice seems to be the culling of the surviving species. Britain is a cultivated island… There is so little of it which is actually wild that it will take a lot of effort to regain balance in its ecosystem. I do understand, for that reason, that the degree of healing needed will take time and that for nature to get a fair start some controlled culling might be necessary, but it is not a solution in itself.
The other is our use of pesticides, the introduction of alien species (both plant and animal) and our terrible affinity to monoculture plantations for the production of timber and raw materials. It’s not just the nuts ‘we’ like that mast. Spruce, pine, ash, etc, they all display a similar behaviour through the production of their cones and thus get affected by the same issues as oaks and beeches.
So then, when we decide to clear out a natural forest of all its broadleaf varieties to make way for more ‘useful’ construction timber and fuel efficient alternatives, and when we then decide to cover miles upon miles of land with closely packed individual trees which will have been sprayed and treated in their youth to deter pests and then we fence them all up and set lethal traps all around them to keep undesirable wildlife away… well… something’s bound to get affected in terms of that clever inter-tree communication I had mentioned earlier.
Pesticides affect the chemicals that trees will produce to send signals both to other trees and as their own efficient way of deterring the pests they deem a nuisance. Breaking the inter-species symbiosis shared by a variety of trees within a natural forest ecosystem has a direct effect on anything from the space that a new sapling will have to have a fighting chance to thrive, to the migration of birds that rely on these forests for their seasonal respite. Some trees depend thoroughly on the work that small and large animals will do around and to them for their successful reproduction.
We can see the effect of both those factors in the contrast between the decrease of population in hedgerow birds as thrushes and starlings against the dangerous overpopulation of the prolific grey squirrel. It will never be my intention to demonise a wee forest animal, but I would like to expose to you the extent to which, through the factors described above, we’ve created chaos. So, bear with me as I badmouth the poor wee grey squirrels to illustrate my point:
As the bird population dwindles due to the loss of their habitat, we sometimes forget to consider that many rodents, including the prolific and invasive grey squirrels, are omnivorous and they will steal and eat eggs from these birds’ nests and some will even eat the young chicks. Grey squirrels will have two litters per year and each can consist of anything from 3 to 9 wee kits.
The winter litter will be a direct result of the autumn bounty and winter reserves. The new generation of squirrels will be ready to leave the nest by late spring and will be ready to reproduce at one year of age; right in between those two life moments, the previous generation will go at it again and produce a summer litter.
We know how this has affected the native population of red squirrels, whose mating season starts later than their grey counterparts, and thus tend to get only the left-overs when it comes to good nesting sites and food storage dens. Their drive to store for winter months comes also a bit later than that of the grey squirrel and thus many fail, even in bumper years, to get enough food stores to survive the winter. Their physical size and the numbers in their litters are also significantly smaller than the grey squirrels’ so in the long term, their demise is worryingly exponential.
But it is not only a squirrel v. squirrel issue that should worry us. Many birds would eat the same foods and nest in similar sites. Tawny owls for example are one of the many bird species which have been left homeless by these wee clever brutes, who not only take the best spots all over the woodlands, but they are very efficient thieves and can empty a bird’s seed store in one go. They also love to gnaw at young saplings, which leaves potential new trees vulnerable to disease and deformed growth.
Simulations show that in a best case scenario (in which natural predators are reintroduced and a natural and irregular rhythm of food supply is established within their current habitats) the grey squirrel population will reach invasion levels in the Alps in no more than 35 years from now. This is catastrophic considering the great proportion of Europe already under grey squirrel domain. As we have destroyed our forests throughout the centuries, we are currently reliant on European timber. Timber is reliant on good forestry practices and the preservation of the natural ecosystem. By failing to protect our forests and wildlife, we are actually exporting our problems and leaving both them and us in a real pickle.
So, heading back to the issue of masting, there have already been reports and sightings of excessive numbers of over-excited grey squirrels hoovering up all the nut bonanza. I am no expert, but I can assume they’ll gather a very healthy winter store and plump up in body fat, which will secure a sizable litter for each female having a go at motherhood this year. Their kits will be ready to start gnawing the nutritious base of the saplings that will have grown from the nuts that didn’t get hoofed up, just as they emerge from the mossy ground.
Those few lucky saplings rescued by well-intentioned foresters and their plastic tubings, will most likely get mowed over by deer as soon as their shoots start peeking out from above the tubes (because deer will get as optimal nutrition out of the masting as rodents will and thus breed just as efficiently). Not a very optimistic future for the whole reproductive strategy of those clever and resourceful beech and oak trees gambling it all just now, considering that their seed production for the next few years will as a result probably be very scarce and that they will leave themselves vulnerable to wood compositing fungi and parasitic larvae for the next couple of years at least.
Those concerns are real, but not unusual as they come periodically with every mast year. The worrying issue is that this year has been pointed out by many to be unusually impressive in its mast vastness, even by mast year standards. The pattern does not match previous predictions, which some attribute to climate change. Some even believe that what we are experiencing this season is not purely the effects of a mast year, since pollination conditions were not optimal in the early spring in many UK regions which have experienced the bumper abundance we’ve been observing.
The yield is so bountiful that some of us worry about how long it will take the tired trees to recover and what this will mean for the next couple of years in terms of the survival of wildlife and for our own consumption of timber-based goods and the food we harvest from them. Or how this will affect trees and the rest of the ecosystem if these mean mastings get triggered with less time between each other because of climatic change and thus sending generations of trees into a suicidal overdrive.
Will we see ourselves pushed to deforest further into the wildlands to make up for the shortage of quality timber and see the return to planting fast growing conifers? If there is no food to go around after a bumper year for nut-eating rodents, fat and primed for a bountiful reproduction of their own, there is absolutely no chance on earth that there will be any seeds left on the ground to produce new saplings next year.
Also, if there is not enough food for squirrels and deer in the woods, will the starving creatures industriously make their way into agricultural land and affect the harvests that farmers have been working towards for months? Will farmers have their costs raised by the need to invest in stronger fences, culling, pest control systems? Will the displaced woodland creatures spread their ticks and parasites to other species not as equipped to put up with them?
Will the herbivore and nut foraging animals become a dangerous destructive pest in their desperate search for food sources when the trees which are now loaded with fruits give nothing but the minimal amount of food to them for a few years in a row? If small migrating birds can’t find the sanctuary they need in our tree-tops, where will they go? Some foresters are struggling to support the idea that natural regeneration is now possible in some of our non-plantation forests and they are seeing ecologically barren beech woods with no developing understory.
What are trees trying to tell us? Can we see past the good fortune of this year’s nut harvest and listen to the desperate message they seem to be trying to communicate? Will we do anything to try to reverse this on time?
I worry we can’t. I worry we won’t.