Arthropod response to prescription burning at the soil-litter interface in oak-pine forests.

摘要

In the southeastern US, forest managers are returning repetitive fire to the landscape to facilitate regeneration of desirable species. The increased use of prescribed fire generates questions regarding the effects of single- and multiple-burning events on leaf-litter and ground-dwelling arthropods, and recovery of these arthropods following fire disturbance. In this study, the effects of early season single- and multiple-burns were assessed on leaf-litter arthropods and ground-dwelling arthropods in oak-pine forests in Kentucky, USA for two growing seasons following fire disturbance. The canopy consisted of shortleaf pine (Pinus echinata), black oak (Quercus velutina), tulip poplar (Liriodendron tulipifera) and red maple (Acer rubrum), and an understorey of sourwood (Oxydendrum arboreum), sassafras (Sassafras albidum), flowering dogwood (Cornus florida) and American holly (Ilex opaca). Arthropods were sampled by leaf-litter extraction and pitfall trapping, where pitfall trapping was restricted to single-burned areas. For each sampling method, arthropod abundance, diversity, richness, and evenness were calculated at the family or ordinal level. Forest characteristics were also surveyed to measure impacts from the prescribed fires and to assess variability in the forest environment. Leaf-litter arthropod abundance was devastated by burning, and resurgence of populations was not evident until the second growing season in the multiple-burned areas. In single-burned plots, litter arthropod abundance remained low for the duration of the study possibly due to greater fire intensity relative to the multiple-burn plots. Leaf-litter arthropod diversity was not affected by either burn regime. Burning decreased leaf-litter arthropod richness and increased leaf-litter arthropod evenness, but these effects were only marginally significant. Prescription burning had no impact on ground-dwelling arthropod abundance, diversity, or richness, but arthropod community evenness increased following the single-burn disturbance. In the principal components analysis (PCA), burning was a major gradient explaining 46% of the variation in the data. Burning decreased leaf-litter cover and depth and lower canopy cover, and contributed to the variance explained by PCA. Our data confirm that prescription burning is accomplishing its management goal of removing undesirable lower-canopy cover in the mixed hardwood forests of the Cumberland Plateau. Following early-season, low-intensity burns, recovery of leaf-litter arthropods was not evident until two-growing seasons after fire disturbance. Any differences we observed could be attributed to lower fire intensity in forests that are repeatedly burned. Prescribed burns should be utilized on a rotation greater than 2 years to allow resurgence of the leaf-litter arthropod community and recovery of the leaf-litter habitat..