Now that some rain has come, I have time to write about the lack of it. Instead of endlessly hauling jugs of water by wheelbarrow, up and down the trail to stressed plantings. Those of you living in dry and drought prone places are used to this, but here in the humid state of Kentucky, the hottest and driest September on record was tough. Particularly following the longest wettest period anyone can remember, during which we planted hundreds of native trees and shrubs. Like a stock market afflicted with irrational exuberance, it felt like the party would never end…
…And then it did. But, beyond the anxiety of wondering if young plantings will survive, it’s been an opportunity to learn. What happens in this little fragment when high heat and drought stress combine? Considering that the forest is representative of so many other little bits of woodland (the state of nature throughout the eastern US), what’s happening here is likely happening across the board. Though some rain has come and the heat subsided, this drought is not over. Climate predictions for the Midwest predict more rain in winter and spring, but also a hotter, drier summer and fall.
One big lesson, which I had read about but not experienced – Spicebush (the shrub we are heavily planting for habitat restoration) doesn’t tolerate dryness well. Its roots are shallow, and adapted to having moisture available near the surface. Hundreds of young and midsize Spicebush have either recruited from seed or been planted in the last six years, and many were tested in the past couple months. A typical response on drier sites was the withering and death of all foliage, followed by branch dieback. But Spicebush shrubs in the bottomlands stayed green, despite the fact that the soil felt just as dry.
Another realization that sinks in better when you don’t just read it in a textbook – periodic drought can be viewed as one of many limiting factors in both the micro and macro distribution of plants and animals. The geographical ranges of living things are ever fluctuating in response to drought – expansion into drier areas may happen in wet periods, but be pushed back again in hot, dry ones.
Here in this forest we meddled a bit, by watering and heavily mulching Spicebush on dry slopes that likely would have died. The reason for this madness was practical; they will be dug up and moved this winter to more favorable sites that lack shrub cover.
In early October we got the first fall rain, and I was very happy to be soaked as I walked around and took pictures. It felt odd to be wet in the midst of such dryness.
The effect of the drought varied quite a bit according to slope, exposure, shade, and proximity to a drainage. Perennials like Pokeweed, Wingstem and White snakeroot had grown exceptionally tall in the heavy spring and early summer rains, and on sunny hillsides their withering stems flopped over.
One effect of the drought I expect to see is a faster decline of the many EAB afflicted ash trees. The number of weakened and dead ash trees that will come crashing down in fall and winter storms is likely to be greater each year, since ash wood decays quickly.
Fortunately for birds and other animals, the three springs that emerge along the southern slope of the forest did not dry up. No doubt amphibians and Box turtles were drawn to these areas that still had soil moist enough to burrow into.
These two were spotted in the middle of the trail on a hot dry day in September – for male boxies at least, life must go on despite the weather. The female is one of the study turtles wearing a tranmitter – the wire can be seen at the back of her carapace, as well as some dried epoxy where a transmitter had been placed previously.
Considering the potential long lifespan of Box turtles, adults likely cope with numerous drought periods. The genus Terrepene is undoubtedly drought and fire adapted; the Ornate box turtle and its subspecies the Desert box turtle occupy some of the more arid parts of North America. The Three toed box turtle, a subspecies of the Eastern box turtle is found in the somewhat drier region just west of the Mississippi river. Even Terrepene carolina, the boxie of eastern forests, can spend long periods of time just burrowed down in dry weather.
Some animals, I suspect, may even profit from the die back of dense herbaceous cover that occurred over the past couple months.
A resident pair of Red shouldered hawks is often seen hunting near the Louisville Nature Center parking area. They were there a few days ago, calling loudly to each other, and I was able to get some pics.
It was only after viewing the images enlarged that I noticed one of the hawks was busy eating prey at the time – the bit of pinkness draped over the limb, to the right of the bird’s feet, appears to be part of a small rodent. The withered condition of the usually dense weedy cover in this area led me to wonder – could more open ground in the forest make it easier for these raptors to spot small critters? With any change in the environment, however slight or short term, there are bound to be winners and losers.
This little learning experience with drought is a way of beginning to understand the impacts of increasing weather extremes at a local level. Despite the fast pace of plant and animal declines and extinctions, natural systems overall are pretty resilient. It’s just that a rapidly changing environment will only favor the adaptable ones.