2013 was a mast year. Mast refers to the seeds that are produced by certain plants.
The hard fruits of trees such as oaks, hickories, and walnuts for example are called the mast of the trees. The word mast is used to describe years that the trees produce prolific amounts of their fruit. Mast years don't occur every year and it might surprise you to learn that scientists don't have a clear handle on what triggers mast years. Consequently, mast years can't be accurately predicted. A mast year can occur twice in a row or they might be several years in between.
In mast years, trees can provide 10 times more fruit than in normal years. I know that has to be the case with the three walnut trees in my yard. While there is some speculation that mast years have a weather connection, there is no definitive research in the area.
Determining when a mast year occurs and what causes it is further complicated by the fact that in the case of red oaks, the acorns are formed in a two-year cycle. This suggests that if there is a weather connection, it could apply to the year before an actual bumper crop.
If you have taken a walk in one of the county parks or have a nut tree in your yard, then you are already well aware that 2013 was a mast year. For a time, a hike around Wolf Creek Park was like walking in a marble factory after a storage bin gave way. One afternoon this fall, it sounded like a hailstorm as falling acorns were dropping onto the roof and hood of my truck parked beneath a large bur oak tree there. I am told that a huge oak can drop up to 10,000 acorns in a mast year!
What would be an advantage to produce an overabundance of fruit during certain years? Some scientists believe it increases the chances of seedlings becoming established. In normal years, animals that consume these fruits may well find almost all of them. In mast years, the sheer number of fruits increases the odds that some will be missed by hungry mouths. Even that being the case, in our parks, I know the squirrels, deer and other animals that consume acorns are a little chubbier going into this winter because of it.
Masting takes a lot of energy! Oak trees grow slowly in a mast year and grow well the year after.