Why does it seem that over the past few years acorn production is no longer occurring on our oaks in Pennsylvania?
Filed under: Habitat Management, Tree Plots
Acorn production is primarily determined by successful pollination and photosynthesis.
A late frost or other weather event when the flowers are being pollinated is the most common cause of failed pollination. Red oaks produce flowers every year. However, flowers pollinated last year are the origins of acorns this year.
In other words, red oaks set flowers one year and they become flowers the next year. So, if there was a killing frost, etc., last year while red oaks were pollinating, there wouldn’t be an acorn crop this year.
Once the flowers are pollinated, it requires a lot of energy to grow an acorn and trees gain energy by photosynthesis. The more leaves a tree has that are receiving full sunlight, the more photosynthesis can occur, and hence the more energy the tree can gain.
In many oak stands in the USA, the trees are too crowded and their crowns are limited in size due to competition. Therefore, there are relatively very few leaves that receive full sunlight and are able to produce energy at full capacity.
It’s likely the oak stand at your property has experienced some weather events during the pollination season and that the trees have a lot of competition.