Jf. Johnstone et Ghr. Henry, RETROSPECTIVE ANALYSIS OF GROWTH AND REPRODUCTION IN CASSIOPE TETRAGONA AND RELATIONS TO CLIMATE IN THE CANADIAN HIGH ARCTIC, Arctic and alpine research, 29(4), 1997, pp. 459-469
Techniques of retrospective growth analysis, adapted from dendrochrono
logy, were applied to Cassiope tetragona, an evergreen dwarf-shrub, sa
mpled at Alexandra Fiord, Ellesmere Island, Canada. A new method of de
limiting annual growth increments through patterns in leaf node placem
ent along a stem was utilized. Chronologies of mean annual stem elonga
tion leaf production, and flower production were developed, and estima
tes of these parameters agree with those obtained for other arctic pop
ulations of C. tetragona. Stem elongation and leaf production were pos
itively correlated in the same year. Flower production was positively
correlated with growth in the previous year, but negatively correlated
with growth in the same year. This pattern was interpreted as the eff
ects of resource allocation strategies, namely, the preemption of with
in-plant resources by flower production once flowering is initiated. A
ll chronologies were significantly correlated with climate records fro
m Alexandra Fiord and Eureka, Ellesmere Island, with the majority of s
ignificant correlations occurring with June and July temperatures. Flo
wer production appeared to be most sensitive to variations in summer t
emperatures, and climate response functions which included previous gr
owth explained up to 84% of the variation in the flowering chronology.
Unstandardized leaf and flower number chronologies were used to provi
de an independent test of the climate transfer function presented in H
avstrom et al. (1995). The results indicate that C. tetragona may be u
sed successfully to generate proxy climate data, although use of stand
ardized chronologies is recommended. Two predictive models for July te
mperatures at Alexandra Fiord, based on standardized chronologies, are
presented to provide future opportunities for verification and applic
ation of this technique.