Tuesday, October 13, 2009

Learning about the rhythm of the trees

Previously we looked at the under-ripened nuts of the Yellow Buckeye. Such a nut probably is not going to be of much value to any animals. But what about the ripened nuts?

A "cracked" buckeye nut outside of a known chipmunk hole.

Chewed apart buckeye husk

A different nut from the one above, but in a similarly destroyed state.

Obviously someone (presumably a chipmunk) was able make use of these mature nuts, but how on earth did they manage to get into the nuts? One thing's for sure: I don't want that critter biting me anytime soon - yikes! And how did the chipmunk go about extracting the meat from the nut? I can imagine what it must have looked like to see a chipmunk with his arm stuck in that nut, trying to get the meat out (can you picture it?).

This chipmunk was lucky that he got any nut meat at all, though. My reason for saying this is because there is a conspicuous lack of nuts in our yard this year. We have quite a few nut-bearing trees on our property, like Black Walnut, Yellow Buckeye, Shagbark Hickory, and several species of oak. Last year was a very "nutty" year, with an over-abundance of Black Walnuts painting our driveway and the Shagbark Hickories providing us with some tasty snacks (see my post about it here).

But it's not just our trees. There seems to be a consensus that this is definitely a dry year far as the nuts are concerned in this corner of southeast Ohio. I've heard similar reports from one friend who lives in a different area of the county and from another friend in a neighboring county. Interestingly, I just read a post over on Leedra's blog (she's in Tennessee) about how one of her trees (a chestnut of some sort, we think) has branches that are breaking because they are so weighed down with nuts.

So what's up with the lackluster nut production this year? Of course, my curiosity leads me to do dangerous things, like researching such mysterious subjects on the internets (and learning to plug in the right combination of words on Google until I find what I'm looking for). The answer to what is going on is all about the masting cycle of the trees.

I've heard of the term "masting" before, but I didn't really realize the scope of it until now. A mast year is "a phenomenon when the fruit (mast) produced by trees in a given year is exponentially higher than the average" (from dictionary.com). Apparently other fruit-bearing plants (not just trees) experience this phenomena as well. From the reading I have done, masting in plants is not a process that is well-understood, but there are quite a few hypotheses. One of these hypotheses is that during a mast year, so many nuts fall that any nut-eating predators will easily have their fill, and thus leave behind plenty of nuts to be propagated in subsequent years. (This hypothesis is called "predator satiation".) Another proposed hypothesis is that the creation of flowers (and thus fruit) is a very energy-intensive process, and that the trees need time to "recharge" after a period of such prodigious production. Most of a tree's energy during a non-mast year is spent on growth, whereas less time is devoted to growth during a mast year.

Masting is a cyclical occurrence, and while there is likely no hard and fast rule for how often a mast year will come along, reports that I have read indicate that anywhere between 3 and 7 years will pass between mast years. What happens during those in-between years is... well, not much as far as fruit/nut production goes. It seems like an all-or-nothing type of situation. Of course it's not really "nothing," but it could definitely be characterized as "very little." Last year, due to the over-abundance of nuts in our woods, we had very little problem with squirrels at the bird feeders. This year is a completely different story: it is now common to see 5 or 6 gray squirrels at the feeders at once, and the flying squirrels have seen their numbers go as high as 8 10 at a time recently. The chipmunks have also started visiting our feeders, which is a first according to my observations.

Cheek pouches stuffed to the max!

Another aspect of the masting process is called "synchrony." This is when a group of trees over a large area coordinate to mast in the same year. This explains why my friends who live within a 30-mile radius from me are seeing similar patterns in their trees. I would expect those who live in eastern Tennessee, like Leedra, to see lots of nuts this year. It is unknown how this synchrony is achieved, although some think climate conditions might be a contributing factor. Amazing, isn't it?

So I have to ask you, all my blogging friends who are spread far and wide, what trends in tree nut production are YOU observing in your neck of the woods? I would LOVE to hear about it!


Nature As Is said...

Interesting...no for whatever reason I can't picture the Chipmunk pulling the meat out of that nut....But the shot of them at your feeder made me smile....and a small laugh escaped my lips couldn't help it.

Shelley said...

Hmm...I don't think I have any nut trees on my property unfortunately - wish I did! Loved your chipmunk! I have a couple that I hand feed right now - the walnuts I give them are their favorite!

Steve Willson said...

Mast producers at Blue Jay Barrens seem to be on the same cycle as your trees. Oaks in particular produced huge quantities of acorns last year. Walnuts have produced an average sized crop this year. Oaks and hickories have had a noticeably light crop.

Kelly said...

This is a wonderful post, Heather...very interesting! Thanks for doing the research. I'll watch along the Little Miami Trail, and see what I notice. We had a cherry mast year last spring and a mulberry mast year last spring as well, but this spring was very light, so it sounds like our trees might be following the same pattern as yours.

Meg said...

Interesting, indeed--John was talking to someone about our apple trees which apparently had a mast year last summer--this year, nuthin'. This person suggested pinching off (it is called something more technical than that) the extra blossoms when a tree is loaded like that, so as to keep the trees fruiting more evenly. I have no idea if nut tree farmers do that or not, but it would make sense.
Now that I've read your post, 0ur walnut trees do seem to be down a bit this year. Hmmm.

"outside a known chipmunk hole." I love that : )

Monika said...

Very informative Heather. I never really knew anything about masting. I was wondering if trees synchronize their masting when I got to the end of your post! It seems like it might be more beneficial for them NOT to synchronize, both for the animals that depend on them for food and because if there's some other factor (weather, etc.) that's especially good or bad on a given year they would "spread out their chances" of success or failure, so to speak. Does that make sense?

Heather said...

Crista - A chipmunk with cheeks full of seed can bring a laugh out from anyone. Silly little buggers!

Shelley - Are there any animals that don't come and tap you on the arm asking to be hand-fed from you? That's awesome.

Steve - Good to know. After reading your recent persimmon post I thought you might say you had lots of nuts, but I guess I was wrong about that.

Kelly - I will have to try to note this phenomenon more closely in other fruit-bearing trees (like crab apples and the like) and see what kind of patterns emerge over the years.

Meg - I have wondered myself how fruit farmers keep their trees producing evenly year after year - the pinching of flowers must be part of that plan. I would imagine it works similarly for those who harvest nuts for a living.

Monika - Yes, what you say makes perfect sense to me, but from the reading I have done, it sounds like the synchrony works more in their favor than not. Apparently there is a lot more going on within the whole process that I didn't even get into here, such as whole food chains being affected by the mast years and non-mast years, and it all has an amazing way of balancing out. It seems like most researchers don't think weather has a whole lot to do with the process, partly because there's just no way for the trees to "predict" when the weather's going to be good or bad and get themselves into gear accordingly. (Does all that make sense?)

Andy said...

Very informative

Heather said...

Andy - I'm glad this was an informative post for you!