Humboldt: Essay on the Geography of Plants

3 Biogeography

Plate from Humboldt and Bonpland’s Essay on the Geography of Plants, from the Biodiversity Heritage Library.

When they returned to Paris after their five year expedition (1799-1804) to Latin America, the first publication Alexander von Humboldt and Aimé Bonpland produced was Essay on the Geography of Plants (1805).  This book was really Humboldt’s conception, but since Bonpland was a botanist and had contributed his expertise throughout their journey, Humboldt thought it was fitting that Bonpland’s name should be on the essay as well (Humboldt & Bonpland, 2009).  The evidence they accumulated on the trip was central to Humboldt’s argument, and he set about writing a first draft right after their ascent of Mt. Chimborazo, one of the highest mountains in the Andes.  However, many of the ideas Humboldt presented to demonstrate how geography determines the plant life growing in a particular place, were conceived much earlier when he met George Forster who had been on Captain James Cook’s second round-the-world expedition.  Forster had broad knowledge of vegetation in very different environments and opened Humboldt’s eyes to how plant life varied with access to water, with altitude, and with distance from the equator.

Humboldt wasn’t very interested in taxonomy, in identifying new species, and among the plant descriptions in the first of their 7 botanical journals that logged the plants they collected, Humboldt wrote nine descriptions and Bonpland 682 (Lack, 2009).  This did not mean that plants weren’t important to Humboldt’s vision of the world, rather he was more interested in how the environment influenced the ability of a particular plant to survive in a particular environment.  He didn’t see plants so much as isolated entities but as part of a larger picture, and there is visual evidence of this in the Essay.  The main portion of the book is an explanation of a large diagram—originally printed 2’x3’—that is a complex blend of image and text (see above).  The center panel depicts two peaks in the Andes, Chimborazo and Cotopaxi, both of which Bonpland and Humboldt had climbed.  To the right of them, is a cross-section of the two labeled with the plants found there.

In 1824, Humboldt published a similar diagram where he moved some of the plants to different elevations.  Pierre Moret and his collaborators (2019) have recently revisited these images and compared the plants in the diagrams with the specimens Humboldt and Bonpland collected.  They found that Humboldt’s primary data above the tree line were collected mostly on Mt. Antisana.  Moret’s went to the collection area and found that over 200 years, the tree line has shifted about 215-266 meters.  This is a fascinating study of how old data can illuminate present environmental issues, while at the same time shedding light on how data was used in the past.  There is a great deal more in this image, including subterranean plants that had intrigued Humboldt since his days as a mine inspector in Germany when he studied and wrote about the plants, lichen, and algae he found in the caves and mines where he worked as a mine inspector (Anthony, 2018).

So far, I’ve only discussed the central panel of the Tableau, but there are seventeen other columns, eight to the right and nine to the left of the mountain diagram.  These include elevation, atmospheric pressure, humidity, etc. at various altitudes.  In other words, one chart summarizes a great deal of the data the team collected on their trip.  What is most important to Humboldt is the relationship between elevation and other phenomena.  His major finding is that elevation relates to temperature in influencing what plants grow where:  plants found at a particular elevation, will be found at a lower elevation but at higher latitude, in other words, further north or south of the equator.  In his introduction to a recent edition of the Essay, Stephen Jackson (2009) argues that Humboldt held to the “primacy of plant geography in his overall vision of the world, whereby vegetation is both the most obvious surface manifestation of climate and the determinant of many other natural and human features” (p. 17).  Humboldt is often designated the father of plant geography because of this essay, but he drew on the work of many others who had gone before him.  He is notable because he used his experiences in South America to synthesize a great deal of information and present it in a striking format, drawing on the growing use of diagrams in geological studies (Rudwick, 1976).

At several points in the essay Humboldt noted the environmental damage done by agriculture as forests were replaced by fields that quickly lost their fertility, leaving a degraded and useless landscape that affected local weather patterns.  These observations were taken up and enlarged upon by others in the 19th century who were influenced by his writings.  Henry David Thoreau saw the unity of nature much as Humboldt did, George Perkins Marsh wrote of the toll taken by forest destruction in the United States as did John Muir, and in Humboldt’s native land, Ernst Haeckel coined the term ecology to describe the interrelations among species and the nonliving environment.  They all had read Humboldt and were passionate about his impact on them.  The Essay was one such influence; in the next post I’ll discuss another.

References

Anthony, P. (2018). Mining as the working world of Alexander von Humboldt’s plant geography and vertical cartography. Isis, 109(1), 28–55.

Humboldt, A. von, & Bonpland, A. (2009). Essay on the Geography of Plants (S. T. Jackson, Ed.; S. Romanowski, Trans.). Chicago, IL: University of Chicago Press.

Jackson, S. (2009). Introduction: Humboldt, ecology, and the cosmos. In S. Jackson (Ed.), & S. Romanowski (Trans.), Essay on the Geography of Plants (pp. 1–46). Chicago, IL: University of Chicago Press.

Lack, H. W. (2009). Alexander von Humboldt and the Botanical Exploration of the Americas. New York, NY: Prestel.

Moret, P., Muriel, P., Jaramillo, R., & Dangles, O. (2019). Humboldt’s Tableau Physique revisited. Proceedings of the National Academy of Sciences, 201904585. https://doi.org/10.1073/pnas.1904585116

Rudwick, M. (1976). The emergence of a visual language for geological science. History of Science, 14, 149–195.

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