Regeneration of Little Ice Age bryophytes emerging from a polar glacier with implications of totipotency in extreme environments

Abstract

Across the Canadian Arctic Archipelago, widespread ice retreat during the 20th century has sharply accelerated since 2004. In Sverdrup Pass, central Ellesmere Island, rapid glacier retreat is exposing intact plant communities whose radiocarbon dates demonstrate entombment during the Little Ice Age (1550–1850 AD). The exhumed bryophyte assemblages have exceptional structural integrity (i.e., setae, stem structures, leaf hair points) and have remarkable species richness (60 of 144 extant taxa in Sverdrup Pass). Although the populations are often discolored (blackened), some have developed green stem apices or lateral branches suggesting in vivo regrowth. To test their biological viability, Little Ice Age populations emerging from the ice margin were collected for in vitro growth experiments. Our results include a unique successful regeneration of subglacial bryophytes following 400 y of ice entombment. This finding demonstrates the totipotent capacity of bryophytes, the ability of a cell to dedifferentiate into a meristematic state (analogous to stem cells) and develop a new plant. In polar ecosystems, regrowth of bryophyte tissue buried by ice for 400 y significantly expands our understanding of their role in recolonization of polar landscapes (past or present). Regeneration of subglacial bryophytes broadens the concept of Ice Age refugia, traditionally confined to survival of land plants to sites above and beyond glacier margins. Our results emphasize the unrecognized resilience of bryophytes, which are commonly overlooked vis-a-vis their contribution to the establishment, colonization, and maintenance of polar terrestrial ecosystems.

Can mosses serve as model organisms for forest research?

“…Their occurrence in many extreme habitats such as the Antarctic tundra and deserts implies the existence of many yet unknown moss-specific survival mechanisms (Oliver et al 2005;Roads et al 2014). The resilience of mosses could recently be demonstrated with the successful regeneration of subglacial bryophytes following 400 years of ice entombment (Farge et al 2013) and even by the regrowth of over 1500-year-old moss from the Antarctic permafrost (Roads et al 2014).…”

Pioneer zone geo-ecological change: Observations from a chronosequence on the Storbreen glacier foreland, Jotunheimen, southern Norway

“…The largely unweathered sediment, being freshly deposited till, is close to neutral in reaction (Messer, 1988;Vater and Matthews, 2015) due to the high base saturation despite a low cation exchange capacity in the absence of a clay-humus complex (Matthews, 1992;Ugolini, 1966). On exposure from beneath the retreating glacier, the terrain may also be considered devoid of life and hence deglacierization represents the initiation of a true primary succession (Matthews, 1999; but see La Farge et al, 2013). However, microbial life may occur in subglacial sediments (Moiroud and Gonnet, 1975;Skidmore et al, 2000) and bryophytes have been known to survive glacial overriding and later exposure in proglacial areas (La Farge et al, 2013).…”

“…On exposure from beneath the retreating glacier, the terrain may also be considered devoid of life and hence deglacierization represents the initiation of a true primary succession (Matthews, 1999; but see La Farge et al, 2013). However, microbial life may occur in subglacial sediments (Moiroud and Gonnet, 1975;Skidmore et al, 2000) and bryophytes have been known to survive glacial overriding and later exposure in proglacial areas (La Farge et al, 2013). Moreover, ancient carbon released from melting glacier ice may contribute to the food resources that are available for earlycolonizing microflora (Bardgett et al, 2007) and invertebrates (Hågvar and Ohlson, 2013), as well as for downstream microbial life (Singer et al, 2012).…”

Rapid wastage of the Hazen Plateau ice caps, northeastern Ellesmere Island, Nunavut, Canada

“…From radiocarbon dates on rooted tundra plants exposed by receding cold-based ice caps on Baffin Island -given that the plants are killed when the snow line drops below the collection sites - Miller et al (2013) were able to construct a record of summer temperatures over Arctic Canada for the past 5000 years. La Farge et al (2013) discovered that ice loss in Sverdrup Pass, Ellesmere Island, has exposed nearly intact plant communities for which radiocarbon dates point to entombment during the LIA. They also found that these recently exposed, subglacial bryophytes can regenerate, which may have important implications for recolonization of polar landscapes.…”