Hierarchies of habitat: Diapensia lapponica on the Avalon Peninsula

Abstract

Arctic-alpine flora are known for their resilience to the selective pressures of their associated climate, glacial history, and geology. The coastal barrens of the Avalon Peninsula of Newfoundland are a unique region with arctic-alpine flora, best demonstrated by the persistence of arctic-alpine species, Diapensia lapponica, yet occur at low elevation within a temperate climate. This thesis examines their functioning and persistence within the local plant communities from a hierarchical perspective aiding in interpretations of the species range on a regional scale. Our results show that D. lapponica is capable of ameliorating extreme temperatures over the course of the warmest and coldest months on the Avalon Peninsula, which suggests it has an important role as a microhabitat provider for species less resilient to the environmental conditions. On a local scale, we found that D. lapponica exists in a habitat with a very specific set of requirements for persistence including high ground, and relatively low to medium species diversity including those that are generally slow-growing species and are unlikely to be highly competitive. We also compared this plant community to other locations regionally across eastern North America. Here, we found that the plant communities associated with the presence of D. lapponica follow latitudinal and elevational gradients. This research provides important empirical findings on the association of ground cover, microtopography, and microclimate with the way that D. lapponica persists on the Avalon Peninsula which can help to inform future conservation and management of these populations on the island.