Yukon Ice Patches: Role of Ice-entombed Bryophytes in Alpine Environments

Abstract

In Southwestern Yukon, alpine ice patches are rapidly retreating with climate warming. Ice patch forelands form unique alpine wetlands, creating critical habitats for diverse flora and fauna over millennia. A major component of the ice patch flora are bryophytes, which are critical to alpine ecosystems. This study will focus on the biological relevance of the Yukon ice patches as reservoirs of cryopreserved bryophyte diversity and for contribution of emergent vegetation on deglaciated ice patch forelands. The relation of emergent subfossil assemblages to the extant vegetation and the successional pattern following ice retreat of the Mount Granger ice patch were determined in Chapter II. Plants were sampled within 40m of the ice margin to document the extant diversity, and the plant succession with ice margin retreat. Non-metric multidimensional scaling (NMDS) showed a three stage succession pattern that has similar diversity to the subfossil species composition. Bryophytes have the capacity regenerate from any viable cell (totipotency), allowing them to persist through extreme conditions. Chapter III assayed regrowth of emergent ice margin samples from the Mount Granger, Gladstone, and Little Gladstone ice patches. Subfossil samples showed remarkable regrowth of bryophyte diaspores up to 4815 years old (BP cal) with 73% indicating potential regenerationl, emphasizing the viability of ancient ice patch vegetation. The results of each study reveal a cyclical role of bryophytes from exhumed assemblages that contribute to the establishment, revegetation, and maintenance of diversity in alpine ice patch ecosystems.