THE EFFECT OF WINTER FIELD CONDITIONS ON THE DISTRIBUTION OF TWO SPECIES OF UMBILICARIA

Abstract

SUMMARYTwo lichen species of the genus Umbilicaria were transplanted into each other's habitat in order to determine the role of winter field conditions in regulating distribution patterns. U. vellea (L.) Ach., which normally grows in a steeply inclined, snow free habitat, was transplated into the level-ground, snow-covered habitat of U. deusta (L.) Baum. The opposite was done for U. deusta. Suitable controls to test the effect of transplanting were also run for both species. The reciprocal transplantation was done in each of two years, one of which had a normal snow load, the other which had almost no snow cover.The effect of reciprocal transplantation was to reduce significantly the carbon fixing ability in U. vellea in the year with the normal snow-load. Transplantation had no effect on U. deusta. The effects on COg exchange were only slight for U. vellea in the year with the lesser snow-load. It is therefore concluded that existing winter field conditions, and especially the nature of the snow cover, maintain the existing distribution pattern of the lichens in the field.

THE EFFECT OF WINTER FIELD CONDITIONS ON THE DISTRIBUTION OF TWO SPECIES OF UMBILICARIA

“…Reports of earlier experiments (Kallio & Heinonen, 1971;Kappen & Lange, 1972;Larson, 1982) had suggested that U. vellea was sensitive to frost damage, although the experiments were often of too long duration (nine months) to be directly relevant to the field. Field and laboratory studies also suggested that U. vellea failed to store photosynthetic products (starch and lipid) in algal cells prior to overwintering (Scott & Larson, 1985, 1986. Thus insufficient respiratory reserves were available to enable U. vellea to withstand three months in the U. deusta habitat where a low level of dark respiration would be occurring under the snow pack.…”

“…Thalli were analyzed for net COj exchange using discrete sample infrared gas analysis (Larson & Kershaw, 1975) and conditions described previously (Scott & Larson, 1985). Statistical procedures were the same as tbose used in Scott & Larson, 1985); non-parametric analyses (Colquhoun, 1971) were used throughout because of a high frequency of heterogeneity of variance that was not easily removed by data transformations.…”

“…150 thalli of U. vellea and U. deusta were randomly harvested from two sites described previously (Scott & Larson, 1985).…”

“…However, such an 0028-646X/86/020327 +17 $03.00 © 1986 The New Phytologist approach was adopted in a research programme which has been described in Scott & Larson (1984, 1985a and which is concluded in this paper. In previous work (Scott & Larson 1984, 1985 evidence was provided that Umbilicaria vellea (L.) Ach. and U. deusta (L.) Baum.…”

EFFECTS OF A SIMULATED ACID RAIN EPISODE ON PHOTOSYNTHESIS AND RECOVERY IN THE CARIBOU‐FORAGE LICHENS, CLADINA STELLARIS (OPIZ.) BRODO AND CLADINA RANGIFERINA (L.) WIGG.

“…Because photosynthetic rates for lichens tend to be non-homogeneous (Lechowicz, 1982;Scott & Larson, 1985), it was decided that non-parametric procedures would be used. Accordingly, a Kruskal-Wallis one-way ANOVA by ranks was used (a) to determine significant differences in NPR between pH treatments (one ANOVA was performed for each of the four time intervals) and (b) to compare changes in NPR within a pH treatment group over the 1-week period (one ANOVA was performed for each of the four treatments).…”