Leaf-litter arthropod community structure and abundance in a recently burned montane longleaf pine ridge
The effects of fire on arthropod communities are poorly understood due to highly variable responses in different ecosystems and conditions. The objectives of this study were to 1) evaluate the short-term impacts of prescribed burning on leaf litter arthropods in a longleaf pine ecosystem where fire has been historically suppressed, and 2) to determine the interactive effects of burn treatment and environmental factors such as litter depth, moisture, or slope aspect on arthropod communities. The study was carried out at Oak Mountain State Park in Pelham, AL where prescribed burning had been initiated in an area of historic mountain longleaf pine and mixed hardwood forest after a period of fire suppression. Pitfall traps and Berlese funnels were used to sample leaf-litter arthropods, which were identified to the lowest possible taxonomic level and sorted into feeding guilds (herbivores, predators, and detritivores).
Overall faunal, predatory, and detritivore abundances were significantly higher in unburned plots. Leaf litter depth and moisture covaried and were greater in the unburned plots. This evidence corroborates previous studies that suggest bottom-up limitation in detritus-based food webs impacts all trophic levels and other studies that show decreased abundance after prescribed burning. Reduction of leaf litter represents a simultaneous limitation in the availability of food, water, and cover/structure for detritivores. A three month accumulation of new litter after a burn will not fully restore this lost resource base, and populations of detritivores in a burned area likely will be slow to recover. Without detritivores as prey, predators, which may also need cover and moisture in addition to food, also will be slow to recolonize the burn area. Further study is necessary to evaluate prescribed burning’s impact on the arthropod biodiversity. Understanding these questions could help inform management decisions by clarifying how community and ecosystem dynamics change where controlled burning is initiated after long-standing regimes of fire suppression.