Species Persistence |
When
people learn of a survey of plant species found at a particular
locality, they often wonder whether certain species will still be
present at that locality a year or more later. The answer is not simple.
Some species (not necessarily the exact, same plants as were found
earlier) may continue to be present, while others will have
disappeared long ago. Much depends on the type of species, and how
robust its reproductive capability is.
Tree species have the best chance of persisting from year to year, or even over long periods of time. Assuming that no direct human intervention (like logging) has occurred, trees could live for decades or centuries. Of course, some tree species may succumb to fungal infections or insect predation. American chestnuts used to be abundant in these parts, but have since nearly been eradicated by disease. Eastern hemlocks are currently at risk of being destroyed in large numbers by woolly adelgids. Shrubs species also fare well with respect to longevity, but their long term survival can't be taken for granted either, for the same reasons. Woody vines ( lianas ) are often aggressive species, and may spread across large swaths of land, climbing tall trees or blanketing shorter vegetation. There used to be a small mountain maple tree (Acer spicatum) near the lower entrance to the gorge trail, but in just one season, it succumbed to an extremely aggressive riverbank grape vine. Herbaceous plants have less assurance of surviving long term, unless they are capable of reproducing at rates that exceed their rates of attrition. This applies equally to annuals, biennials and perennials. Many weedy species produce vast quantities of seeds which are adaptable to a large variety of ecological conditions. We're all familiar with the common dandelion, for example, which can survive just about anywhere. The ability to compete with a variety of other plant species is also a factor in species survival. Examples of competition with aggressive species are taking place in real time in the "vacant lot" section that was surveyed during this project. Over 130 different species were identified at the "vacant lot" from 2017 to 2022. Many of those species have been eliminated by other highly aggressive species. Mugwort (Artemisia vulgaris) is spreading vegetatively out of control in the "vacant lot", and elsewhere. Eastern sycamore tree seedlings (Platanus occidentalis) that were one or two feet tall in 2017 are now (in 2022) over fifteen feet tall, and towering over everything around them, shading out most of the sun-loving herbaceous plants below. Then there is human interference. The "Amphitheater", located at the base of the falls, has a large swimming hole. Once every year or two, the Park brings in heavy equipment to dredge the swimming hole of sediment deposited by Buttermilk Creek. That equipment tears up a portion of the ground leading up to the creek bed near and within the swimming hole. Many low-growing, weedy, adventive species abound in that disturbed ground. They were surveyed during this project, and appear on the project species list, but some will probably not be there any more. On the other hand, new species could be introduced to that site on tire treads of heavy equipment. The above discussion serves as a caveat to those hoping to find particular plant species that were documented in these pages. Maybe you'll find them, perhaps not. But not all is hopeless. The
nicer sections of the gorge trail, and immediately adjacent areas,
remain as more nearly intact natural communities, less impacted by human
disturbance, invasive species, pestilence or disease. Your chances
of finding species listed herein for those sections will be much
greater. Basically, the smaller the human footprint, the more
intact and stable those plant communities will remain. One more
final caveat: invasive species are not far away from the nicer
sections of the gorge trail, and unless those invasives
are managed by the Park, those sections will look very different in
coming years. |
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