Native Plants, Habitat Restoration, and Other Science Snippets from Athens, Georgia

Sunday: 5 April 2009

The Number is 542  -  @ 08:40:00
And I'll have more to say about that number.

Rain is in the forecast here, for tonight and early Monday, with a wraparound that brings cold weather with the possibility of snow late Monday night and Tuesday morning. Imagine that, snow in the first week of April. Here! Hopefully the temperatures won't get down to quite the subfreezing levels of April 7-8, 2007.

Nonetheless, dogwoods are in flower here. And who doesn't like Cornus florida? A usually modest small tree, it exerts its flagrance only twice during the year - in spring with its large white bracts, and in the autumn with the resulting bright red berries.

The white "petals" are not petals, they're bracts, modified leaves. Each of these heads sports 18-20 actual flowers, the green buds in the middle. They haven't opened yet, but when they do you'll see that each has the required, though tiny, sepals, petals, stamens, and pistil.

You might wonder at the TE designation on the USDA distribution map next door. It seems that Cornus florida is endangered, exploitably vulnerable, and threatened in ME, NY, and VT, respectively.

It's not easy getting a landscape shot of the drift of dogwoods through the understory. The eyes have the ability to shift minutely and pick up on the flowering trees through the maze of light colored tree trunks and branches. The camera does not. Best time to photograph is at dusk or dawn, or on a dark rainy day.

The Constitution of the Springs of the Sparkleberry mandates a census once a century.

OK, it doesn't, but I've spent the last few days wandering around counting dogwoods. For the most part I counted dogwoods in flower, but I also included larger plants that weren't in flower, when I ran across them. I probably missed anything under ten years old, so this is probably something of an undercount. The several hour excursions were ideal for Gene, who accompanied me on most of them. Credit where it's due.

Scattered unevenly through 40 acres there are at minimum 542 dogwoods of significant age. The distribution is kind of interesting, so here's a scan of the annotated map.

The densest population of dogwoods is southeast of the house, in the area I've marked "A." This is a fairly elevated area, with large loblolly pines and a young hardwood understory that is dominated by dogwoods. A slightly lesser density is found west of the house along the slopes that support a similar plant community.

The area along the south property marked B is very low density, and this isn't too surprising. This was a part of the property purchased in 1994, and sometime around 1991 when we moved out here the former owners had it clear cut of the pine growth. Since then a very dense stand of pines have grown up from the seeds dropped way back then. It's not a very nice habitat for hardwoods yet, and the few dogwoods are mostly on the outer edges of that clear cut area.

The area northeast of the house, marked C, is also fairly low density. At least part of the reason may be an abundance of young and old walnuts.

Elsewhere dogwoods are found most abundantly on slopes, but not particularly in the lower areas along SBS Creek or the floodplain along Goulding Creek. The dogwoods that do grow in these low areas don't look particularly good. They have a lot of moss growing on them, and seem to drop a lot of branches.

A couple of decades ago there was a scare about anthracnose, a mildew that attacked dogwoods. Mostly it seemed that dogwoods that were in closed, moist environments were at risk, and I suspect it's just not the best place for them.

I suspect that this number of dogwoods, impressive thought it is, is a fairly common density in areas that have not been too disturbed, nor, paradoxically, allowed to develop undisturbed for too long. Dogwoods seem to be a kind of intermediate denizen of the oak-hickory ecosystem. You won't find them early following a disturbance, not until the pines have thinned and matured. And once the competing, larger hardwoods have attained their towering heights, I suspect the canopy is then too overbearing, and the dogwoods will disappear.

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