Physiological aspects of the ecology of Dicranum fuscescens in the subarctic. II. Seasonal patterns of organic nutrient content

Abstract

Individual plants of Dicranum fuscescens were collected from two field sites (a highland semitundra and a lowland lichen woodland) near Schefferville, Quebec (latitude 55° N), for 4½ months during 1974. Collections were made at 2-week intervals from June until the 2nd week in October. Samples were separated into green and brown shoot components and oven-dried. Subsequently analyses were carried out to determine concentrations of total carbohydrates (sugar and starch) and lipids in the respective tissues. Total carbohydrates were found to increase in the green tissues towards the end of the season reaching a maximum of between 10 and 10.5% ash-free tissue dry weight in October. Lipid concentrations showed a maximum of between 3.6 and 4.0% ash-free dry weight during July and subsequently declined, in the same tissues. Seasonal trends of nutrient concentration in the brown portions of the shoot were not marked.An investigation of biomass distribution in complete plants of D. fuscescens revealed that brown shoots accounted for more than half of the total. Mean lengths of these parts of the shoot were about twice those of the upper stem.