There is a little patch of ground north of Grand Rapids which has always held a fascination for me. The place is now confined within an official park but back “in the day” it was a wild piece of untamed real estate ripe for exploring. Why, I remember camping there as a lad and…well, never mind, I won’t dwell on memories except to recall that I once spent the coldest night of my life in one of the thinnest of all sleeping bags in that place. There are now trails, signs, and a parking lot within the 45 acre preserve of Provin Trails Park but the central part, a desolate open sand slope, has changed little over the 40 some years I have known it.
I guess you’d call this part a black oak barren – a place scarred by forest fires back in the days of big pine. Though much of the surrounding area has been reclaimed by acres of planted pine plantations and the remainder retains some vestige of the earlier white pine forest, this spot has been sterilized to the point where little can grow on it. Or, more properly, anything that does grow there stays little.
Here large patches of open sand are weakly colonized by clusters of stunted black oak trees (see here). These bonsai oaks retain the general shape of their larger brethren in the forest below but are only 1/10 their height and a bit hunched in appearance. They grow but never seem to accomplish anything beyond staying alive yet they have a dignity about them that only age can bring (something I say to myself every time I look in the mirror). I’m not sure how old these trees are, but I’d guess that many of them are well over the century plus mark. I broke off a dead side branch and later read the growth ring evidence. This section was over 35 years old yet it was only one inch in diameter. The rings were so closely spaced that they were difficult to read.
Given the lack of nutrients and poor water retention in the soil it’s no wonder these trees are struggling to make do. These sands also get very hot under the mid-day summer sun and tend to cook everything around them. One of the few organisms that can put up with this regimen are those mini-puffballs called sand stars (see below).
When I walked this stretch the other day, as a giant among small trees, an overnight rain fall had pock-marked the sand and erased all signs of life previous to daybreak. A crisp set of lone possum tracks wove across the expanse through several newly made Sand Bee towers. These towers immediately attracted attention not only because they poked above the surface but because the makers were at home (see below). Each entrance was constructed at a slight angle with a landing, so to speak, and the bees were sitting on their porches to soak up the morning sun.
As I approached, they ducked back into their retreats momentarily before popping their fuzzy little heads back up (see below and here). They were like Prairie Dogs on a miniature scale. I can’t say with any certainty what species they were, but from general appearance (and without looking at their genitalia, I might add) they looked to be Digger Bees of the genus Andrena. Since there are around 500 North American species in this genus to pick from, you can see why I am more than happy to just call them plain Sand Bees. Since females do the tunnel construction, I can also feel confident in referring to them as she-bee sand bees.
In many ways, these little she-bees represent the spirit of the barrens. They seek out such places to dig their brood tunnels and nurture life where it is not wanted. They are solitary bees but since others are also attracted to the same open sand habitat, they’ll cluster into loose colonies. Though neighbors, they don’t borrow sugar or engage in gossip with their fellow diggers. They dig, mate, and prepare ye the way for new-bees.
Each burrow extends straight down into the sand about 6-7 inches and branches out into a dozen or so individual cells. Each cell is eventually supplied with a ball of pollen – aka bee bread – before an egg is laid upon it and the place is sealed up. The pollen comes from flowering willow catkins down in the nearby valley. This is where the females meet the he-bees, by the way.
By the time the summer sun begins to bake the sand, the adult insects are bee-gone and the new-bees are comfortably munching away on their pollen snack cakes while deep in the sandy soil. The bonsai black oaks will have sprouted tough green leaves by then and girding their loins to endure yet another year – unaware that little earth bees are growing fat beneath their scanty shade.