Effect of habitat structure on reproduction and prey capture of a rare carnivorous plant, Pinguicula lutea

Abstract

Habitat degradation is one of the greatest threats to biodiversity worldwide and the main contributor to the decline of many carnivorous plant species. For carnivorous plants in the southeastern United States, including many Pinguicula species (butterwort, Lentibulariaceae), degradation via altered fire regime has been implicated in their decline. Despite this decline, limited empirical research has been conducted examining the influence of habitat structural changes (through natural succession or human management) on reproduction and prey capture by carnivorous plants. The objectives of our study were to compare reproduction and prey capture for Pinguicula lutea (yellow butterwort) in habitats with different vegetation structures in the Florida Panhandle, where differences were largely due to management history. Pinguicula lutea is a self-compatible carnivorous plant that inhabits fire-dependent longleaf pine savannas of the southeastern United States and is threatened in the state of Florida. In 2014 and 2015, 13 sites were identified occupying three different habitat structures: maintained (intermittently mowed), grassy (dominated by Aristida stricta var. beyrichiana), and woody (encroachment by Hypericum and Ilex). Reproductive output was determined by assessing fruit set and ovule fertilization rate at each site. Additionally, prey availability and prey capture were assessed at each habitat site. In general, there were no differences in either measure of reproduction across habitat structure types. There were differences in prey abundance of Collembola, Diptera, and total arthropods both in terms of availability and capture. Total arthropod availability and prey capture were lowest in grassy sites compared to maintained habitat sites and woody habitat sites. Microclimatic conditions associated with each habitat structure and leaf morphology or physiology could explain the observed arthropod abundance and prey capture patterns. This study is the first ecological assessment of plant–insect interactions for Pinguicula species of the southeastern US and highlights the importance of habitat quality and management for this understudied group of carnivorous plants.