I've just read an interesting article about masting. Masting is the phenomenon of heavy seed production in some years, followed by a scarcity of seed production in other years. California oaks have this characteristic. Masting is thought to be an evolutionary adaptation whereby predators of the seed are starved for a few years, reducing populations which are then more easily satiated in years of plenty giving the "left over" seed better chance at sprouting.
The most interesting aspect of masting is that it is temporally correlated across large distances. Locally, an entire woodland community might be masting and the odds are good that similar species hundreds of miles away will be doing the same thing.
The article is marred by an error, previously made in this very blog (as a working assumption, I'll add), but subsequently corrected. The authors make great hay with the fact that the most obvious possible correlating factor, rainfall, is normally distributed, something that Grace and I have discussed previously and emphatically disproved, at least for southern California.
Ultimately the authors conclude that temperatures in April, which are likewise correlated over large distances, are likely to be responsible for masting.
Grow more oaks.