Effects of Burning Season and Frequency on Saw Palmetto (Serenoa repens) Flowing and Fruiting

Carrington, Mary; Mullahey, Jeff; Tanner, George

The objective of this two- to three-year study is to compare saw palmetto flowering and fruiting between recent growing-season and winter bums, and between sites burned frequently and infrequently in the past. Author Introduction: Within the last five years, harvesting of saw palmetto (Serenoa repens) fruits from Florida rangelands and other natural areas has increased dramatically. Driving this harvest has been a demand from European markets for an extract from the fruits used to treat benign prostatic hyperplasia in older men (Braeckman 1994). As a consequence of the increased economic value of saw palmetto fruits, private landowners are interested in identifying methods to maximize saw palmetto fruit production. At the same time, however, public land managers and environmentalists are concerned that harvesting of saw palmettos may be in direct competition with wildlife species that eat the fruits. Managing production of saw palmetto fruits to meet the needs of an international market, private landowners and wildlife populations will require an understanding of factors that influence fruiting. Although saw palmetto is an extremely abundant, fire-adapted species in Florida, little research has been conducted on the effects of burning on fruit production. Burning is a potential method for managing saw palmetto fruit production, since saw palmettos typically flower profusely within a year after fires (Abrahamson 1984, 1995). Fires are common in pine flatwoods and dry prairie communities where saw palmettos are most abundant, but burning regimes may differ widely among individual sites. For example, sites are burned in different seasons, and with different frequencies. These differences in burning regime may result in distinctive saw palmetto flowering and fruiting responses. Saw palmetto sites are burned either during the growing season or during the dry fall and winter months. Natural, lightning-ignited fires in saw palmetto communities are most common during the growing season, from late spring through summer. In addition to natural growing season bums, people conduct controlled bums in saw palmetto sites primarily for rangeland management purposes. These human-caused fires historically have occurred during the October to March dry season (Abrahamson and Hartnett 1990). Private landowners in Florida continue to bum primarily during the fall and winter because vegetation is relatively easy to ignite, and fires are easier to control. Sites containing saw palmetto not only are burned in different seasons, but also have a range of different past fire frequencies. At one extreme, land in central and southwest Florida managed for cattle production (native range) often has a history of frequent burns. Ranchers typically bum areas of native range every two to three years. At the other extreme, less intensively managed areas may have had one or no fires in the past several decades. The objective of this two- to three-year study is to compare saw palmetto flowering and fruiting between recent growing-season and winter bums, and between sites burned frequently and infrequently in the past. Information from this study will help to determine the burning season and burning frequency most likely to result in optimal saw palmetto flowering and fruiting.