Acorns flooding your yard? There's a reason why

DES MOINES, Iowa —

There's an ecological reason for the surplus of acorns flooding Iowa's yards.

Certain breeds of tree native to Iowa are experiencing a "mast year." According to the Iowa Department of Natural Resources, a mast year is a period when trees produce excess mast — that's the fruit that some trees produce, such as acorns and walnuts. White and burr oaks, black walnut, and shagbark hickory trees are all experiencing mast years.

The DNR said the phenomenon isn't harmful to the trees, although it may slow growth, since the trees are putting more of their energy toward mast production.

In several central Iowa cities, residents are responsible for keeping mast debris like acorns off their sidewalks. KCCI checked the city codes of Des Moines, Clive, Urbandale, Ankeny, and Altoon