Dendrochronological Potential of the Arctic Dwarf-Shrub Cassiope tetragona

Abstract

In this report, we describe the use of dendrochronological techniques on the circumpolar, evergreen dwarf-shrub, Cassiope tetragona. Using techniques such as crossdating and standardization, and the software programs COFECHA and ARSTAN, we developed C. tetragona growth and reproduction chronologies for sites in the Canadian High Arctic. High-resolution chronologies may be used to reconstruct past climate and phase changes in large-scale modes of atmospheric circulation (e.g. Arctic Oscillation, North Atlantic Oscillation), to investigate the growth and reproductive responses of the plant to ambient and manipulated environmental variables, and to reconstruct the plant's past ecohydrology (␦ 18 O, ␦D, ␦ 13 C), gas exchange (␦ 13 C) and mineral nutrition (␦ 15 N). As C. tetragona is a circumpolar species, chronologies may be developed throughout the Arctic at sites where no trees exist, and thus provide new information on the past climate and environmental history of sites and regions previously unstudied.

Retrospective growth analysis of the dwarf shrub Cassiope tetragona allows local estimation of vascular plant productivity in high arctic Svalbard

“…Dendrochronological analyses of the dwarf shrub C. tetragona commonly report considerable between‐year variability in growth and sensitivity to a variety of climatic variables, including summer temperature, throughout the Arctic (e.g. Callaghan et al., ; Johnstone & Henry, ; Rayback & Henry, ; Rayback et al., ; Rozema et al., ). Some studies use this feature for historical reconstruction of past climate (Rayback & Henry, ; Weijers et al., ).…”

Experimental icing affects growth, mortality, and flowering in a high Arctic dwarf shrub

“…). However, there are high levels of individual variability believed to result from within‐plant resource partitioning, plant architecture, and associated micro‐environmental conditions (Rayback & Henry, ).…”

Annual growth of Cassiope tetragona as a proxy for Arctic climate: developing correlative and experimental transfer functions to reconstruct past summer temperature on a millennial time scale

“…We may however consider the wave‐like patterns of annual growth of the long‐lived evergreen dwarf shrub Cassiope tetragona (L.) D. Don (Hultén 1968) as a tree‐ring equivalent to be applied as a proxy for Arctic summer temperature. The possibilities for climate reconstruction and the dendrochronological potential of C. tetragona have been described earlier by Callaghan et al (1989) and Havström et al (1993, 1995) working in Scandinavia and on Svalbard; Welker et al (2005) and Rayback & Henry (2005, 2006) for the Canadian high Arctic. To use annual growth of C. tetragona as a proxy for Arctic summer temperature, it should meet the following requirements: (a) large geographical range and abundant occurrence over the Arctic regions of Europe, Asia and North America, (b) a sensitive (annual) growth response to variation of Arctic (summer) temperature based on correlative and experimental evidence, leading to transfer functions to reconstruct past temperatures, (c) High resolution, preferably annual, and multiannual chronologies, (d) Long‐term preservation of leaves and stems both above‐ and belowground in the tundra soil, on a decadal, centennial or millenial time scale, i.e.…”