This fall hasn’t been good for traveling, big weddings, or harvest festivals, but it has been another great year for acorns! 2020 is one for the history books, and now in New England we can add “mast year” to its list of offerings. A mast year is when certain trees synchronize their seed production and deliver a bumper crop. In New Hampshire, we notice this most with acorns but beech trees, hickories, pines and many other trees can also do this large scale synchronization.
As Steve Roberge, the UNH Extension Specialist for Forest Resources puts it, “A good mast year is like leaving a bunch of banana peels just waiting for you to slip on all over the forest!” In a big year, over 250,000 acorns can be found in one acre of woods in New Hampshire – that’s equivalent to five acorns per square foot. Compare that to an off-year when there is only one acorn per square foot. It’s enough to drive you nuts!
According to Steve, who spent a year studying oak sapling in graduate school, what we are experiencing today with regards to acorns really started two springs ago. That’s when our current crop first got started. The conditions must have been right – warm, breezy and relatively dry. The flowers, which are wind pollinated, would have then set. A tiny acorn began to grow and those are the nuts we see today. Usually when these prime spring conditions exist, it’s a regional trend and all the oaks will be well pollinated and a couple years later it will be a big year for acorns.
There are some theories that this synchronization is aided by the trees’ pheromones, chemicals released and received by the oaks. These chemical messages might help to increase the number of flowers the tree puts out. Others speculate that trees communicate through their deep root systems with the aid of fungal relationships, in what’s been called a “wood wide web.” Some researchers suggest this underground network signals the oaks to increase flower production, resulting in more acorns.
Even if we haven’t quite cracked the code of how it happens, researchers think they know why it happens. Hardy mast years, like this year, overwhelm the seed eaters. Gray squirrels, one of the main consumers, spend all fall burying each acorn they collect in its own little hole. During high mast years, when the forest floor is littered with acorns, squirrels up their scatter hoarding behavior, stashing away more acorns then they could ever eat. The more acorns there are the further away the squirrel buries the nuts from where it found them. These outlying seeds, cached far from the shade of their mother tree, often go unclaimed and grow into the next generation of oak trees.
Acorns are quite charming for a seed. Under their cozy cap and inside the polished brown shell lies a nut rich in protein and high in calories and fat. This is the powerhouse of our Northern forests. Acorns fuel our food web – from diminutive deer mice to hulking black bears. Even true carnivores like bobcats rely on the elemental, accumulated energy of many acorns, conveyed via the bodies of mice or squirrels. In the US, over 100 different species of vertebrates are known to consume this seed. From the usual suspects like squirrels, chipmunks, and deer to some surprising consumers like wood ducks, blue jays and crows, acorns are an indispensable component of many wild animals’ diets.
But have you ever tasted one of these northern red oak acorns? The best description would be – it tastes a lot like battery acid – bitter. The harsh flavor is from naturally occurring compounds known as tannins. The distinctive unpleasant taste might act to discourage its seeds from being consumed.
When researchers observed squirrels in a forest with red and white oak trees, they discovered some interesting behavior. Squirrels consume the white oak acorns on the spot. These acorns have less tannin than red oak and are therefore more palatable. In these forests, squirrels have consistently been seen burying the red oak acorns for later consumption. It isn’t that the squirrel is just eating the best thing first. Rather, the squirrel is discriminating in what it stocks up on for the lean winter months. Red oak acorns are higher in protein, calories and fat and they actually store better through the season. Not only that, as the red oak acorn is stored, the level of tannin decreases, making the nut not only a protein packed meal but a better tasting one at that.
Remember last spring when our shops ran out of flour? This could happen again but if you get busy now and like a squirrel, collect a whole bunch of acorns, you can turn this wild seed into a nutty flour. It’s a perfect pandemic pastime. Check out this new book by acorn aficionado Marcie Lee Mayer, “Eating Acorns: Field Guide—Cookbook—Inspiration” and get cracking!
Susie Spikol is the Community Program Director for the Harris Center for Conservation Education in Hancock.