The value of edge habitat is well understood to ecology – those transition zones between forest and meadow, field and stream, river and riparian area. These areas tend to be very valuable to many birds and mammals as they contain diversity of plant species and provide two types of habitat and shelter. These areas also pose great opportunities for the observant naturalist.
Just as topography has transition zones, so do the seasons. Shoulder seasons are times of great change across all habitats and trophic levels and we are fortunate in Virginia to have four distinct seasons. This fall has been a relatively long season with leaves turning late, warm days and night temperatures hovering around freezing. There are still a few maples and oaks in full color, providing a feast for the eyes before the drab shades of winter descend.
We were pleased to hold a naturalist stroll at the farm in early September, one of the transition times between the heat of summer and the cool of autumn. Master naturalist Jack Price led the walk along the edge habitat created by the Shenandoah River and the native warm season grass meadow.
“We are in that transition period and you have probably already seen and experienced changes around yourself; for example what do you hear at night now that you didn’t hear five or six weeks ago?” Mr. Price asked the group.
“Crickets!” exclaimed one participant. “It is really loud at night”.
Mr. Price agreed, the night is now filled with the songs of crickets and katydids and, during the daytime, cicadas calling for a mate. “And think in July, you didn’t hear that.”
Mr. Price also mentioned he had observed screech owls being more active at night. He theorizes this is due to the number of nocturnal insects and the fact that migrations have started.
He mentioned the monarch butterflies coming through from the north on their way to Mexico, the chill-adverse tropical birds heading to southern climes and dragonflies, including the common green darner, that migrates in large numbers.
“No one knows for sure where all the final spots are because they go to a number of places,” Mr. Price noted of the green darners.
Of course, the most obvious visual indication of fall is the change in tree and shrub foliage.
“When fall comes and as [a] tree starts to shut down its activity, there is a layer right where the leaf joins the stem – called the abscission layer – and what the tree does is basically put a door down, the abscission layer gets activated and cuts off that flow of moisture and sugars and once photosynthesis stops that is what allows colors that you would not have been able to observe come to the forefront – yellow first, and if there are red or other colors in there, they will come out. The layer gets triggered by temperature and length of day,” Says Mr. Price.
Autumn in the east tends to be very colorful due to our five most common hardwood trees: northern red oak, tulip tree, red maple, sassafras and sycamore. Each of these species turn bright shades, making our mountains a patchwork of reds, oranges and yellows.
We also discussed “fruit flags”, those bright berries whose color alerts birds that they are ready to be eaten. In particular, spicebush berries are valuable as they contain 40% fat, the highest content of any berry available this time of year; they provide nutrition to birds fattening up for winter or for powering their flights south. Because of their small size, spicebush is also prized by small mammals which can reach the berries from the ground.
We planned to walk further along the river trail at the farm but kept stopping to admire various trees, inspect wildflowers and take photographs.
The river trail at the White House Farm continues to become increasingly interesting as we install additional native wildflowers and shrubs, thanks in part to the Pure Water Forum which provided grant support and the volunteers from the Oakbrook Church Stewards of Creation.