Studies of the Seasonal Course of Carbon Uptake of Eriophorum Vaginatum in a Moorland Habitat: I. Leaf Production and Senescence

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Abstract
(1) The seasonal dynamics of leaf production and senescence of Eriophorum vaginatum, growing on a high-altitude blanket bog, were examined at Moor House Nature Reserve in the northern Pennines. (2) A demographic analysis, based upon repeated observations of individual shoots, was carried out in 1977-79. In 1977, leaf production was 24 ± 8 g m-2 year-1, the peak biomass of 38 ± 5 g m-2 being attained in July and maintained until September when there was a sharp decline. (3) Direct observations of the shoots showed a consistent pattern over the 3 years. The net number of leaves rose from April to September; there was a continuous flux of leaves into and out of the population during the entire growing season. Leaf emergence rate was maximal in June--September. Leaf death rate showed a sharp increase in September-October. There was also substantial leaf mortality during winter. (4) Consistent differences were observed in both the type of leaf survivorship curve and leaf longevity, depending upon the date of appearance. Cohorts appearing at the start and at the end of the growing season exhibited a Deevey Type I curve while mid-season cohorts showed Deevey Type II curves. Early season cohorts completed their life cycle during one growing season, whereas late-season cohorts required two growing seasons. (5) The pattern of leaf emergence and senescence led to an age-structure which was dominated by overwintering leaves for a major part of the growing season. Late season cohorts were particularly significant in contributing to leaf expansion at the start of the season.