Lichen Community Response to Prescribed Burning and Thinning in Southern Pine Forests of the Mid-Atlantic Coastal Plain, USA

The effects of prescribed burning and thinning on lichen communities is a poorly understood aspect of biodiversity conservation, despite the widespread use of these practices to achieve conservation-oriented land management goals. To address this knowledge gap we documented apparent changes in the diversity and abundance of lichens following 0 to 2 growing-season burns preceded by 0 to 1 commercial thinnings within nine southern pine dominated stands on the Delmarva Peninsula of Maryland, USA. Corticolous lichens growing on the stems and within the canopies of pines and co-occurring hardwoods were identified to species and fractional coverage was estimated; growth forms and reproductive modes were also determined. A total of 93 lichen taxa were recorded on the 19 tree species (4 pines, 15 hardwoods) represented in this study. Burning emerged as a strong driver of reductions in lichen diversity ( P = 0.002), whereas thinning in the absence of burning did not ( P = 0.279). In general, we found that lichens growing on tree bases and lower bole sections were more strongly impacted by burning, both in terms of diversity and cover, than those residing in the canopy. The apparent refugia represented by the canopy was qualified by the limited overlap in lichen species composition observed among the various sampling heights. This work calls attention to an understudied component of biodiversity that appears to be sensitive to fire management; however, we suggest that these results need to be interpreted in the context of altered disturbance regimes and the trajectory of community assembly resulting from long-term fire exclusion.