by shaman » Tue Mar 17, 2009 6:54 am
If memory serves me correctly, there are four things that moderate acorn production.
Nutrients-- nuff said. However, don't expect a bumper crop from spreading a little fertilizer around the base of the tree. It takes a lot of work and a lot of fertilizer to affect a grove of oak trees.
Temperature-- Some years, we get cold temperatures as the oak trees begin tasseling. If those flowers get frozen off, the acorn production will be down. Here in the Greater Ohio Valley, this is a big factor.
Rain -- Spring rain levels can affect acorn production, but so can summer levels.
Periodicity -- White oak fruit every year, the red oaks produce acorns every other year. In the latter case, the acorns are started in year 1, but stay on the branch in nascent form and mature in year 2.
There are a lot of other factors as well. Take insects. Normally the are not a huge factor in the big scheme of things, but last year we got a visit from the cicadas. The cicadas lay eggs in the tender young branches and they then die and fall off. That's also where the acorns form. Last year was a bust for acorns. However, the cicadas prune the trees and this causes a lot of growth in the succeeding few years. If we get good rain and warm temperature like we've been having, I'm expecting a bumper crop of acorns.
One weird thing that studies have shown: oak trees seem to have a built in variability to their acorn production such that it keeps the squirrels in check. There is a natural 10 year cycle in acorn production. Towards the end of the cycle, the oaks produce a lot of acorns. This causes the squirrel population to rise dramatically. Then all of a sudden, the oaks will go blank on acorns for a season or two and the squirrel population plummets. The next year, the oaks produce bumper crops of acorns and there are more than average numbers of acorns surviving and sprouting.