Insect Herbivory Following Fire on Lyonia fruticosa, an Ericaceous Shrub of Florida Scrub

Abstract

The influential role of fire in shaping Florida scrub vegetation is well documented; however, relatively less is known about the role of fire on trophic interactions such as those between plants and herbivores. Here we examined the response of insect herbivory to time-since-fire and succession on Lyonia fruticosa (Michx.) G.S. Torr. (Ericaceae), a shrub found in scrub of south-central Florida. We measured herbivory on > 200 plants across a time-since-fire gradient of 7 sites (ranging from 0.6-8.7 yr) by (1) surveying recently flushed leaves for 3 mo to control for leaf age, and (2) surveying herbivory across whole plants irrespective of leaf age. We also recorded damage types (chewing, scraping, and mining) to determine how herbivore guilds were affected by time-since-fire. Using generalized additive models, we found herbivory increased for 5 to 6 yr post-fire with 59.8% of the deviance explained by time-since-fire in flushed leaf surveys and 76.6% in whole plant surveys. Chewing was the dominant damage type and increased for 5 yr post-fire. Scraping and mining damage were less frequent and unaffected by time-since-fire within the range studied. Additionally, we modeled the post-fire responses of L. fruticosa traits (height, stems, flowering, and leaf area), and found that most changes in growth and reproduction occurred within the first 4 to 6 yr post-fire. Herbivory levels increased as plants recovered and peaked in yr 5 and 6 post-fire indicating insect herbivores, like the plants, are well adapted to the dynamic, pyrogenic landscape.