By Fred Jacobsen

500 years ago when Spanish explorer Hernando de Soto moved up through west central Florida his chroniclers described passing various landmarks, including mountains. This seems very odd to us today as there are no mountains there. This has also puzzled historians trying to rediscover and document the de Soto trail.

The Spanish word for mountain can also refer to any forested rise. The most likely explanation for the sighting of mountains was ancient cypress domes.

These occur in regions of depression within the marsh which results in a longer hydroperiod than surrounding marsh areas. The principle constituent of these are Cypress trees, of which two species can be found here, the bald cypress and the pond cypress. These cypress may have been 600 years old at the time and as much as 200 feet tall in the center..The term, “cypress dome” or cypress head refers to the phenomenon that the larger cypress grow in the middle of the dome, and then get progressively smaller as one goes out from the center. The conditions for growth are much better in the center as opposed to the edges.

These areas are nearly circular, and often surrounded by marl prairies or herbaceous marsh community with few trees. Near the centers of the domes, the soils are usually composed of a thick layer of organic material, subtended by a sandy mineral layer or sometimes by fractured limestone. The central parts of cypress domes often contain standing water year-round. Closer to the edges of the solution holes, the organic mantle on the soil surfaces is thinner and more likely to be subtended by sands with some limestone or fragmented limestone. Hydroperiods in these areas are also long, but they are not likely to be submerged during the dry season.

In the margins of cypress domes, the community becomes transitional with the surrounding marl prairies, so that nutrient-rich organic material is not common in the soils, and the soils often become desiccated during the dry season. Limestone usually occurs near the substrate surface, so trees are often unable to establish root systems beneath this layer of rock. This substrate is marginal for cypress trees, so that the trees that survive in this area are usually less robust and attain a smaller stature than those near the wetter central part of the dome. Also, since the trees in this marginal area are scattered and do not form a complete canopy, sufficient sunlight reaches the ground to support a substantial grass community, similar to that found in the adjacent prairies.

Dry season fires are common in prairie communities and they are carried into the cypress ecotone by the grassy ground cover. These fires ordinarily don’t kill the cypress trees, but can damage them enough to slow their growth. Thus, a difference in habitat conditions occurs, from a moist, nutrient-rich substrate with almost no fires near the center of the dome to a seasonally dry, nutrient-poor substrate with frequent fires at the periphery. The result is a community that supports tall, vigorous trees near the center of the dome with progressively shorter, less vigorous trees toward the margins.
 

The cypress domes would have appeared to these early explorers as small trees growing up the side of a hill or small mountain.

Extensive logging of cypress stands during the late 19th and early 20th centuries nearly wiped cypress domes from the landscape. For those cypress domes that survived, the oldest standing trees are usually less than 100 years old and much smaller than historically.

More research needs to be done to locate the cypress domes that would have marked the de Soto trail.