What’s Growing at the Harriet Irving Botanical Gardens: Acorns

What’s Growing at the Harriet Irving Botanical Gardens: Acorns
By Melanie Priesnitz

If you spend time outdoors you will have noticed an abundance of acorns on the ground this year.  Many people think that a bumper crop is a ‘messy’ nuisance. Biking and walking on acorns is like balancing on marbles, and having tiny wooden missiles drop on your head or parked car is unpleasant. The creatures in the Acadian Forest, however, look upon a wealth of acorns with great excitement. A plentiful year means an increased chance of survival through the cold winter months.

There are many legends and stories about what a bumper crop of acorns means. Some say that it’s an indication of a cold winter ahead or that it’s a result of a dry spring. The scientific truth is that we don’t really know. We can make educated guesses but we don’t have definitive evidence. We do know that oak trees go through sporadic cycles of acorn production. Every 2 to 5 years oaks tend to have a ‘mast year’ where production increases significantly. We also know that acorns of red oaks take two seasons to develop. So if there is a connection to environmental factors it would be due to weather that occurred two years back, likely in the spring when the nuts are forming.

In a mast year a mature oak can drop as many as 10,000 acorns which is up to 10 times more than in an average year. This is significant, as often only 1 in 10,000 acorns make it to a tree. This rapid increase in production is exhausting, so growth in mast years slows temporarily and improves the year after. If Oak trees in Nova Scotia are having a mast year, chances are oaks for hundreds of thousands of miles are in the same boat. This leads us to believe that chemical signaling may be occurring. As you can well imagine the cycle of acorns affects the populations of woodland creatures. Some even think that oak trees change their acorn production to control the populations of predators. So think twice this year before you try to rake up the ‘messy’ acorns in your yard. Know that they are there for a reason and are a welcome sight, and important food source, for a variety of fauna.

Harriet Irving Botanical Gardens
Acadia University