Life in the Slow Lane: Palmetto Seedlings Exhibit Remarkable Survival but Slow Growth in Florida's Nutrient-Poor Uplands

The palmettos Serenoa repens and Sabal etonia are foundation species in many peninsular Florida vegetative associations. We monitored survival and growth of palmetto seedlings using two cohorts found in different vegetative associations. Mixed-species cohorts containing both Serenoa repens and Sabal etonia were individually tagged in 1989 and have been monitored until 2008. One cohort (N = 100 seedlings) is in an "inopina-phase" scrubby flatwoods and a second cohort (N = 78 seedlings) is in a "wiregrass-phase" flatwoods. The sand substrates at both sites are nutrient-poor Entisols that show rapid permeability, low available-water capacity, and acidic pH. In addition to experiencing seasonal and variable annual precipitation patterns, these cohorts endured a severe and prolonged drought during 1999-2001 as well as an intense fire at the height of this drought. Seedlings showed remarkable survivorship, with 57% of the flatwoods cohort and 35% of the scrubby flatwoods cohort surviving from 1989 until 2008. In spite of their high survival, the seedlings experienced minimal height and crown width increases during the 19-year study. Height increase from 1989 to 2008 for the flatwoods cohort was a modest <0.5 cm per year and that of scrubby flatwoods was similar to 0.3 cm per year. Serenoa repens and Sabal etonia seedlings show extraordinary persistence and tolerance but at a cost of exceptionally slow growth rates. These data suggest that: (1) the transition from seedlings to reproductive palmettos in nutrient-poor Florida uplands takes multiple decades; and, (2) the restoration of palmettos as foundation species in disturbed sites will require effort.