OOS 23-2 - Bugs and fire: Patterns of arthropod diversity in frequently burned longleaf pine

Wednesday, August 9, 2017: 8:20 AM
Portland Blrm 257, Oregon Convention Center
Lora A. Richards, EECB, University of Nevada, Reno, NV

Longleaf pine (Pinus palustris) forests are classic fire adapted systems in that they are dependent on fire to maintain forest structure, interactions, and levels of diversity that define these forests. While role of fire in maintaining plant diversity in these ecosystems is well documented, less is known about the impacts of fire on arthropods in any fire adapted system. Working within prescribed burns in the longleaf pine forests at Eglin Air Force Base in the Florida panhandle we investigated the effects of fire on arthropod communities before, during and post-fire through the use of sticky traps and malaise traps. Specimens were organized by morphospecies and identified to family and assigned to a trophic guild. Abundance and richness of morphospecies were used to calculate Shannon (H’) and inverse-Simpson (1/D) diversity indices for community composition and fire stage comparisons.


Malaise trap sampling efforts resulted in a collection of 9,498 individuals comprised of 11 arthropod orders represented by 432 morphospecies (n) and four trophic guilds. Overall arthropod diversity decreased both during and immediately after fire and increased post burn. Hymenoptera (n=111), Diptera (n=133), and Lepidoptera (n=41) showed the greatest increase in diversity post fire. Orthoptera (n=26) were the only order to increase in diversity during the fire indicating a dispersal response to burning and subsequent decrease in diversity post burn suggesting delayed recolonization. Results from sticky traps illustrated a significant dispersal response, with substantial numbers of arthropods trapped while moving up the trees, with over six times more insects captured during a fire compared to control traps in unburned areas. Trophic guild analyses showed increased diversity of herbivores, detritivores, and parasitoids with a significant decrease in predator diversity over time since burn. The greatest increase in taxonomic diversity was seen in three highly vagile orders, dispersal ability may give greater resilience to mobile taxa and provide increased recolonization potential as the vegetative habitat returns post fire. Trophic diversity response indicates that bottom-up regulation is resulting in decreased predator diversity and latent recoveries in parasitoids and detritivores. Quantifying the diversity of the overall arthropod community allows for multiple comparisons in the responses of numerous taxa enhancing the understanding of ecosystem response to disturbance.