Self-organized spatial patterning of microtopographic features is a trademark characteristic of the Everglades landscape. Alternating elevated ridges and open water sloughs produce heterogeneous habitats for an array of flora and fauna. Extensive drainage and anthropogenic modifications over the past century have altered the Everglades’ hydrology, resulting in drier conditions facilitating widespread ridge expansion into sloughs and thus an increasingly homogenous landscape. Wildfire is an important ecological force in the central Everglades and can influence landscape vegetation distribution. As a ridge is consumed by fire the margin may be reduced and smoothed, preventing ridge expansion and maintaining landscape heterogeneity. To investigate fire as a patterning mechanism in the central Everglades, we examined the relationship between fire regime and ridge shape complexity. Historic fire records and water level gauges from the EDEN monitoring network were used to identify four 1 km2 study sites of similar hydroperiod representing a chronosequence of time since fire and varying fire frequencies. High-accuracy GPS receivers were used to map the perimeter of every ridge within each site. Shape complexity, the distribution of ridge sizes, and percentage of the site occupied by ridges were calculated in ArcGIS and compared among sites.
Results/Conclusions
More recently and frequently burned sites contain ridges that have been reduced in size and complexity, with smaller ridges often completely removed. Smaller and less complex ridges result in lower overall landscape ridge area and promote greater landscape heterogeneity. Over longer fire-free periods, ridges will continue to become larger and more complex as rhizotomous sawgrass (Cladium jamaicense) spreads from the margin into the adjacent sloughs, resulting in an overall more homogenous landscape. While feedbacks between plants and hydrology control formation of patterned microtopography in peatlands, fire may play a key role in maintenance of patterning in this fire-adapted landscape.