NATURE NOTE - Number 62 Acorns February 14, 2023
I always ask for your comments on NATURE NOTES, and this time a reader’s email prompted this particular note. I had it on my “to do” list, but his inquiry moved it up the list. So, Scott, here is …
Our Current Topic: Acorns
Acorns are often a young person’s early exposure to nature and what’s in the forest. They seem to find these – maybe because little kids are close to the ground – and their parents explain that these are seeds from oak trees. Ok, a good first step, but there is a lot more about acorns we can learn. So let’s start with identification. Acorns can be used to identify the species of oaks. Each species produces a different type of acorn. Some are long and slender, some are mostly enclosed in the cap, some have ridges along the side, concentric circles on the bottom, and on and on, but I’ll let you grab a good field guide and see for yourself if you can use the acorn to identify the oak (Among the best and cheapest guide is produced by the Virginia Department of Forestry, called Common Native Trees of Virginia. Go to www.dof.virginia.gov.) Next, let’s note that oaks fall into the white oak or red oak groups. In general, white oaks have rounded lobes and red oaks have pointed lobes. As far as acorns, white oaks produce acorns each year (more below), while red oaks require two years for acorns to be produced. These red oak immature acorns will remain on the tree over winter, and will drop the next fall. As many folks may have noticed, the quantity of acorns each year is not consistent. Some years with optimal growing conditions in the spring will produce heavy crops of white oak acorns that same fall, and the red oaks will produce heavy crops the following fall – eighteen months later. This seems to occur on an area basis instead of individual trees. So if one tree in an area has a heavy crop, others around it will also produce a heavy crop. Some estimates indicate that a single large oak might generate from 2000 to 7000 acorns in one season. However, after a heavy crop, it may be a number of years before another heavy crop is produced. Some references say up to 10 years. There is a logical reason for this. Producing acorns requires a lot of energy by the tree – focusing it on acorn production at the expense of building roots, stems and other plant tissue. So it’s “catch up” time for the tree after a heavy oak production in order to continue growing elsewhere. This does not mean growth stops during acorn production, but it can be reduced. So now let’s look at an interesting side to all of this. Nature has a way of making things interesting and somewhat complicated. Every kid knows squirrels eat acorns. But consider this: the white oak acorns that drop in the fall are different then the red oak acorns, both chemically and structurally. The white oak acorns do not do well when lying around on the ground over the winter. Their structure quickly break downs and the acorn is ruined. So the squirrels know this, and will consume the white oak acorns as soon as they are on the ground. Of course some are missed and these will sprout, often on top of the ground, and start a new tree in the spring. The red oak acorns however, are much better suited to longer term winter storage. These are the ones the squirrels will recover and bury somewhere for later consumption in the winter or early spring. Like the rest of us, squirrels sometimes forget where they have left something. These stashed acorns often get forgotten by the squirrel, and these are the ones that survive the winter unmolested and begin germinating in the spring. Often squirrels will carry these acorns considerable distances from the tree, thus allowing oak seedlings to expand beyond the original site. Squirrels are not the only animal that is heavily dependent on the “masting” of trees (masting refers to the production of acorns as well as some pine cones and other woody fruits such as Beech). Acorns also make up a significant portion of deer, turkey and Blue Jay diets as well. The populations of these species are influenced somewhat by the amount of acorns produced each year. A period of poor production will result in a drop of these animal populations. Following a heavy mast year, the populations will increase, other factors being unchanged. Deer hunters are well aware of masting on deer populations and movement. A bad acorn crop will force the deer to move over a wider range to find other food, often exposing them to hunters. This is also why August is often difficult for deer to find food. The younger tender plants they have eaten over the summer are gone, and the acorns have yet to drop.
It should be easy to find acorns on the ground during any fall outing or on the red oaks during winter. Point these out to your scouts. Make them aware of more than “acorns come from oaks and squirrels eat ‘em”. Collect some off of the ground and then identify the leafless oak tree in the winter. Nature. It’s all connected. It’s all interesting.