Conservation of a Florida Endemic Carnivorous Plant: Godfrey’s Butterwort (Pinguicula ionantha)

Abstract

For conservation and recovery efforts to be effective under the Endangered Species Act, knowledge of the factors which make a species rare must be gained. In order to meet conservation goals, this study focuses on the habitat availability and demography of a federally threatened carnivorous plant species, Pinguicula ionantha. The majority of existing P. ionantha populations occur in the Apalachicola National Forest (ANF), the largest National Forest east of the Mississippi. Presence data from 28 confirmed populations and a randomly generated psuedo-absence dataset were overlaid onto spectral data from Landsat 5 TM images and a Digital Elevation Model (DEMs). Generalized additive models were used to develop spatially explicit predictive models to identify potential P. ionantha populations within the ANF. Validation tests of this map ranged in accuracy between 75 - 83%. The resulting predictive map found 36.4 km2 (3.0%) of potential P. ionantha habitat in the Apalachicola district of the ANF and aided the in the discovery of seven previously unrecorded populations of this rare plant. The bog/savannah habitat, where P. ionantha occurs, is defined as a fire-dependent community. Prescribed fire is a common management tool in this ecosystem yet, until the current study, no information on the influence of fire on P. ionantha was available. Multi-state mark recapture models with dead recoveries were used to estimate survival and transition probabilities for over 2313 individuals in 12 populations. These estimates were then used to parameterize matrix models used in a regression-based Life Table Response Experiment (LTRE). Nearly 60% of the variation in population growth rate was explained by days since last fire. Population growth rate (lambda) was greater than 1.0 and increased with days since fire until 430 days. After this time, lambda decreased, becoming less than one after 1200 days. Positive growth rates were found for both dormant- and growing-season burns, but the timing of these effects were different. Frequent fires (1-3 year interval) were predicted to maximize population growth of P. ionantha populations. Fecundity and growth contributed the most to post-fire population growth. Current prescribed fire intervals used at the study sites are effective at maintaining populations of this rare species.