Cupola Pond, Missouri Vegetation History

 

    Understanding the ecological vegetation history of different regions allows us to understand the interaction between organisms and large climatic changes. However, it also allows us to use communities that do not have modern analogs to understanding present-day flora formation. In a 2017 paper by Jones et al., they investigate the vegetation history after the last glacial maximum (LGM) at Cupola Pond, Missouri in the Ozark highlands (Fig 1). Not only did they link major vegetation changes to major climatic changes, but they also provided sample populations across three no-analog populations. This research allowed for a better understanding of the history of the unglaciated southeastern United States and an ability to understand new vegetation communities. The finding of multiple no-analog communities also demonstrates that many sets of present-day species may not have existed in the past.

            Updating a study done by Smith (1984), Jones et al. (2017) found that at Cupola Pond, the main contributor to these vegetation shifts after the LGM were large climatic events like the Bølling-Allerød and Younger Dryas. These unique events resulted in the creation of communities that have no modern-day analogs. Pollen fossils at this study site dated back to 21,000 yr BP and illustrated a population of conifer-dominated forest with mainly Picea, spruce, and Pinus, pine, genera. Around 17,500 yr BP saw a rise of Quercus, oak, an increase of Picea, and a decrease of Pinus. The next shift occurred following the Bølling-Allerød event that began 14,700 yr BP (Fig 2). The Bølling-Allerød was a sudden warm and moist period that occurred following the cooler Older Dryas period. The vegetation experienced a large transition to Quercus and Fraxinus, ash, trees while the Picea and Pinus genera were on the decline. This population lasted throughout the Bølling-Allerød until 12,900 yr BP when the Younger Dryas event began (Fig 2). While other regions across North America saw cooler and dryer weather during the Younger Dryas, analysis of subfossil wood shows that Cupola Pond experienced increased moisture. This moisture caused the Fraxinus and Pinus to decrease and the Ostrya/Carpinus, hornbeams, and Carya, hickory, genera to increase. Cupola Pond did not experience its next change in vegetation until 11,00 yr BP which was 700 yr after the ending of the Younger Dryas event.

    While this link between population shifts and larger climate events is important, the novelty of the study came from samples collected to describe three different no-analog populations between the LGM and the Holocene. No-analog communities are important because it illustrates the large species range of vegetation and gives us a possible future population that we could see if the climate continues to be altered. However, findings of no-analog communities complicate our understanding of why present-day flora exists in the way that they do. Sets of species that we see today may not have a similar community in the past and thus we must investigate why they appeared in that form. From 21,000 yr BP to 17,000 yr BP the conifer-dominated forest had its modern-day analog in the modern boreal forest. The first no-analog community began 17,00 yr BP and lasted until 15,500 yr BP (Fig 2). The community had high Picea and Pinus, substantial Quercus, and low Fraxinus populations. The second non-analog community began 15,500 yr BP and lasted until the end of the Bølling-Allerød (Fig 2). It was characterized by low Pinus and high Picea, Quercus, and Fraxinus populations. Finally, the third no-analog community was between 12,700 yr BP to 11,00 yr BP (Fig 2). It is described as having declining Pinus, Picea, and Fraxinus populations while seeing a rise of Ostrya/Carpinus and Carya populations. The presence of three non-analog communities between the LGM and the Holocene signifies a high composition turnover and an earlier beginning to the first no-analog community.

No-analog communities and the link between vegetation transitions and climate changes allows us to predict what the world could look like in the future. The Quercus-Carya forests of the Conrad Environmental Research Area, where I have collected plants, are most similar to the third no-analog community at Cupola Pond but appear in Iowa. This shows how sets of species have shifted geographically throughout time as the suitable environments have shifted. There are still, however, differences in these communities demonstrating how we still have gaps of knowledge in understanding why and how present-day communities formed. We should use these no-analog communities to find the main ecological contributors causing their formation and then look at the relationship between these factors and modern-day populations.

 

Works Cited

Jones, R.A., Williams, J.W., Jackson, S.T., 2017. Vegetation history since the last glacial maximum in the Ozark highlands (USA): a new record from Cupola Pond, Missouri. Quaternary Science Reviews 170, 174–187. https://doi.org/10.1016/j.quascirev.2017.06.024