Invited review: climate change impacts in polar regions: lessons from Antarctic moss bank archives

Abstract

Mosses are the dominant plants in polar and boreal regions, areas which are experiencing rapid impacts of regional warming. Long-term monitoring programmes provide some records of the rate of recent climate change, but moss peat banks contain an unrivalled temporal record of past climate change on terrestrial plant Antarctic systems. We summarise the current understanding of climatic proxies and determinants of moss growth for contrasting continental and maritime Antarctic regions, as informed by 13C and 18O signals in organic material. Rates of moss accumulation are more than three times higher in the maritime Antarctic than continental Antarctica with growing season length being a critical determinant of growth rate, and high carbon isotope discrimination values reflecting optimal hydration conditions. Correlation plots of 13C and 18O values show that species (Chorisodontium aciphyllum / Polytrichum strictum) and growth form (hummock / bank) are the major determinants of measured isotope ratios. The interplay between moss growth form, photosynthetic physiology, water status and isotope composition are compared with developments of secondary proxies, such as chlorophyll fluorescence. These approaches provide a framework to consider the potential impact of climate change on terrestrial Antarctic habitats as well as having implications for future studies of temperate, boreal and Arctic peatlands. There are many urgent ecological and environmental problems in the Arctic related to mosses in a changing climate, but the geographical ranges of species and life-forms are difficult to track individually. Our goal was to translate what we have learned from the more simple systems in Antarctica, for application to Arctic habitats.

Moss δ13C: an accurate proxy for past water environments in polar regions

“…In terms of gaining long‐term information about past climate, this serves our purpose well. However, our research suggests that intraseasonal shifts in growth water could be assessed through δ 13 C SUGAR under less stressful conditions such as the maritime Antarctic (see Royles & Griffiths, ).…”

“…Hence, δ 13 C values are less negative (less discrimination against isotopically heavier 13 CO 2 ) when plants are covered by diffusion‐limiting water films. Conversely, δ 13 C values are more negative when plants are drier and diffusion and photosynthetic rates optimized, as RuBisCO consistently favors the isotopically lighter 12 CO 2 molecules (Rice, ; Royles & Griffiths, ).…”

Transformations of landscape and peat‐forming ecosystems in response to late Holocene climate change in the western Antarctic Peninsula

“…These rather high values either suggest uncertainties in chronology and accumulation rate calculations or a solar radiation-amplified moss production. The δ 18 O values of Polytrichum cellulose show a 4‰ variation since 1970 A.D. with a slight increase after 1980 A.D., also suggesting a warming climate [Royles and Griffiths, 2015]. The δ 18 O values of Polytrichum cellulose show a 4‰ variation since 1970 A.D. with a slight increase after 1980 A.D., also suggesting a warming climate [Royles and Griffiths, 2015].…”

“…Despite their potential as high-resolution paleo archives [Fenton and Smith, 1982;Royles et al, 2013], peat deposits from maritime Antarctica remain largely unexplored. These semiombrotrophic peatbanks are composed of only a few moss species, including two dominant turf mosses Polytrichum strictum and Chorisodontium aciphyllum, which may simplify the interpretation of geochemistry-based climate reconstructions [Royles and Griffiths, 2015]. These peatbanks preserve their own long-term history of ecosystem changes in their accumulated peat deposits [Fenton and Smith, 1982], which can inform past climate change.…”

Angiosperm symbioses with non‐mycorrhizal fungal partners enhance N acquisition from ancient organic matter in a warming maritime Antarctic

“…). This organic matter has become increasingly bioavailable as mean air temperatures have risen in the maritime Antarctic, leading to progressive thawing of the moss banks (Royles et al ; Abrams et al ; Royles & Griffiths ; Amesbury et al ).…”