Rare inland reindeer lichens at Mima Mounds in southwest Washington State

Isolated populations of four reindeer lichen species and varieties co-occur in a unique relict prairie habitat at Mima Mounds Natural Area Preserve, southwest Washington State, USA. The prairie is the type locality for mima mounds, unusual geologic features providing topographical variation that influences vegetation patterns. Reindeer lichens ( Cladonia subgenus Cladina ) are usually more typical of northern boreal regions and are very rare in inland valley habitats of the western states outside of Alaska. Our study established distributional, ecological, chemotypic, and phylogenetic information for the target species. The species that at first appeared to be C. arbuscula was revealed by DNA sequences to be C. ciliata var. tenuis . We found that topography was not as important as recent fire history in explaining reindeer lichen distribution; in the future, prescribed fire is likely to benefit reindeer lichens so long as it preserves pockets of refugia as propagule sources. We also detected moderate air pollution stress, which is projected to have impacts on lichen abundances and community compositions in the near future. Chemotype analysis revealed 6 reindeer lichen chemotypes, of which 2 are rare (C. ciliata var. tenuis and C. portentosa subsp. pacifica f. decolorans ). Phylogenetic analyses supported previous species concepts, showing C. portentosa is distinct from the closely-related group that includes C. rangiferina and two varieties of C. ciliata . We synthesized our findings to provide a key for distinguishing the reindeer lichens of Mima Prairie. We suggested that rare inland reindeer lichens may benefit from small prescribed burns and sowing of propagules in disturbed areas, as well as continued monitoring and designation as state sensitive species.