NATURE NOTE – Number 55 October 28, 2022
Introduction:
Many folks will look at a forest and assume that the forest they are seeing has always been there in the same form they see it today. This is usually far from reality. Forests are developed and changed over time. Seldom are there places in this country where forests have not seen disturbances; major ones such as the ice age in areas to our north, earthquakes and volcanos (again, not so much here), major forest fires (not necessarily man-caused); wide-spread diseases (the Chestnut blight in the early 1900’s – See NATURE NOTE #23), insect infestations, or minor ones like storms or hurricanes. Humans have helped with disturbances such as development of agriculture lands, urban development, infrastructure construction, or timber harvesting. Once this disturbance occurs, the former forest is altered in some way. It may be minor, such as a storm that topples a few trees (creating an open space in the forest), or it may be major such as converting hardwood forests of the Mississippi Delta to cotton fields 200 years ago. The frequency of these disturbances as well as the severity will produce varying degrees of change, but regardless, the forces of nature start to respond by trying to reestablish a new forest similar to the old forest that was disturbed. This is done over time by something called:
Our Current Topic: Plant succession
Alter the disturbance there may be nothing but bare soil left where the forest once stood. But this won’t stay this way for long. Usually within the first growing season, it will become apparent that “something” is starting to grow again. It won’t be new trees, but most likely it will be a crop of annual plants that we might call weeds (crabgrass, Chickweed, wild mustard, ragweed). Often it will be an invasive species rather than a native plant. Why is this? Well, that bare soil is likely to contain long dormant seeds from years ago. And since they are not native, they do not have to contend with competition of their normal rivals, nor are they likely to have many predators. Thus they get a head-start over native seeds in this newly formed harsh environment. The seeds are characteristically very hardy, and can grow in dry, sunny places. Many of these new seeds are very light and are blown in from adjacent areas. At the end of this first season, these annuals will produce huge quantities of seeds for the following year as the adult plants die and start to become part of the soil of the future. However, by the 2nd or maybe 3rd growing season, some of the native seeds have arrived by wind or birds, and are starting to grow in this old field Quite often they grow taller than the original annuals, and the shade they produce is not favorable to the original annuals. These plants that are now starting to produce a field of native perennials. Now you may start to see Goldenrod, Blacked-eyed Susan, and assorted asters. After 3 or 4 years, you might start to see plants starting to arrive that have woody stems that don’t die back in the fall. It’s the beginning of shrubs or maybe even trees that can thrive in lots of sunlight. Initially, it may be very patchy, as the plants will reflect the somewhat random landing of seeds from adjacent trees or shrubs. As these shrubs or trees grow they will over-shade much of the smaller perennials that will disappear. After a few years, depending on many variables, the woody plants will start to dominate. In our area the trees will often be Red Cedar, Black Locust, Tulip poplar, Red Maple, Virginia Pine, or other pioneer species. Their growth will continue for years and they often form thick stands of fast growing trees. But underneath this new forest, there is likely to be some other species beginning to grow under the heavy shade these pioneer species are providing. These new species, called shade tolerant species, are the beginning of the next succession of the forest that will eventually rise above the thick pines, maples, etc. and become the dominant species in the more mature, or climax, forest. The speed at which this occurs will vary greatly depending on such factors as soil, elevation, available moisture, direction of the slope, and other variables. But the process is the same. Other terms may be used to describe some of this process, such as ecological succession, or intermediate forests, but the process, the constant change that is occurring, is what is important to understand. The change is rather rapid at first, and easy to see, but as the forest becomes established, the change slows and becomes much more subtle.
Also, it is important to understand the impact of this changing forest is having on wildlife. Since wildlife depends on plants for food at some point in their food chain, moving from a small-seed and heavy wildflower environment that may favor some bird and insect species to a more dense shrub environment to a mature stand of trees producing nuts and fruit will certainly shift the wildlife inhabiting that stage of the forest.
Opportunities:
Younger scouts might not be ready for some of the concepts offered here, but they can certainly be shown how all of our landscape is not the same and how it is moving through plant succession. Simply watch a vacant lot, an old garden plot, or an old pasture along the highway, to see different stages of succession. Watch how “weeds” quickly take over an abandoned lot or neglected yard. Give it time and you’ll see little trees soon.
If you have a Red Maple in your yard, note all the little maple trees that sprout up in your mulch beds or lawn margins. This is that large tree trying to establish more maple trees in a “disturbed area” that is currently without plants. As I have said many times before, no one has pointed out these things to young scouts. Do it. Make them think. Make them wonder. Most likely they will finish school without anyone ever pointing out the plant succession concept to them. Maybe you could do it.
As always, thanks for reading NATURE NOTES and introducing scouts to nature. Contact me with comments.
Bob Garst
