Mast Years: What’s Up with Nut Production?

The last of this season’s walnuts linger on the tree

Autumn is here. Leaves are changing and falling off area trees. The other things falling off area trees this time of year are nuts. Mast is the term for the amount of nuts or fruit produced.

Have you noticed an abundance of nuts this season as compared to other years? Or perhaps a few less? When nut production is overly abundant, it is considered a mast year. Why do trees produce more nuts one year versus others though? Ultimately, that mystery is at the root of the tree’s survival.

Mast Years: Why is Nut Production Higher Some Years?

Why is nut production higher in some years?

For nut producing trees, a higher mast boosts the odds of more new trees sprouting. For every nut that falls, there is the possibility of a new tree, right? Not necessarily.

Nuts are a food source for many animals. Squirrels, mice, deer, and birds collect fallen nuts to store for winter. In lower yield years, the success of sprouting may be greatly reduced by foraging animals. Conversely, in a mast year, more than enough nuts are produced to feed wildlife and for the tree to reproduce.

Interestingly, in lower yield years, the presence of what some might consider pests—ie. mice, squirrels, and other rodents—is also greatly reduced. A little science lesson; animal populations rise and fall depending upon their food source. Trees are an important part of nature and their nut production helps wildlife and humans alike.

Weather & Nut Production

Weather may play a factor in nut production

But do trees really care about animal populations? Not likely. So survival of the species aside, why else might nut production fluctuate from one year to the next? Scientists have debated this, but it seems that weather is a factor.

Trees tend to produce nuts in a cyclical fashion. Walnuts tend to have two mast years over a five-year period. White oaks produce acorns every year, but produce a larger yield every few years. Red oaks lean more towards nut production every few years. From one genus and species to the next, nut production is different. What all nut producing trees have in common though, is how the weather affects them.

Temperature and rainfall affect the health of trees. A late frost can kill flowers on trees. Drought can put a tree into a state of stress. When sufficient rainfall and warm temperatures are prevalent though, a tree thrives. As some trees begin nut production a year or two before they produce nuts, a bountiful year may have more to do with the previous year’s weather than what this season’s weather patterns reflect.

That being said, a high mast year may occur in some areas of the country, but not in others. Not surprising, as different areas can have diverse micro-climates due to their proximity to lakes, mountains, or valleys, for example.

So when you factor in the weather, animals, and a tree’s natural nut production cycle, there are many reasons why you might see more nuts one year over another. Keep that in mind if you are planning on harvesting a few nuts of your own this year. You never know if next year might be a mast year, therefore a bigger and better harvest!

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