Carbohydrate dynamics in mature Pinuselliottii var. elliottii trees

Abstract

Starch is the main carbohydrate storage form in conifers and is derived from the translocation of photosynthate (soluble sugars) in the phloem. We examined seasonal patterns in concentrations of both carbohydrate forms in the needles, twigs and branches, stems, and coarse and fine roots of mature Pinuselliottii Engelm. var. elliottii trees in a north Florida plantation. Starch showed marked and similar seasonality in all the tissues, with maxima in the late winter near the time of the inception of new growth in the spring. Sugars showed little seasonality, except in the fine roots. Repeated fertilization had little effect on either sugar or starch concentrations in all tissues. Using published biomass data from these same stands, we estimated that coarse roots store more than half of the starch in these stands over the year, with foliage and fine roots storing less than 5%.