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Seasonal changes in foliage biomass and age composition of live and falling needles in Scots pine saplings treated with sulphuric acid, urea, or lime

Tarabuła T.

Polish Journal of Ecology

2002

Vol. 50, nr 3

371-380

Using destructive sampling, seasonal dynamics of needle biomass and age composition of foliage and needle fall were studied in a Scots pine forest under conditions of various chemical soil treatments. Foliage mass was primarily affected by needle age and season, while treatment effect was relatively minor. Overall mean foliage mass per tree increased from 734 g in April to 870 g in August, and then decreased to 595 g in November. In general, proportion of current needles to the foliage grew from zero in April to more than 50% in late November. Proportion of one-year-old (c+1) needles decreased relatively slightly (from 55 to 41%), while that of two-year-old ([większe lub równe] c+2) needles declined from 45% in spring to less than 6% of the total foliage in autumn. Significant treatment effects comprised reduced total mass of needles, particularly current ones (Acid), increased mass of [większe lub równe] c+2 needles (Lime), and a clear dominance (absolute and relative) of c+1 over [większe lub równe] c+2 needles (Urea), when compare with the untreated stand (Control). Within- and between-treatment variations were generally lower in the case of relative proportions than absolute values of cohort biomass. In most plots, more than half of needles shed over the entire study period were [większe lub równe] c+2, while current needles contributed about 10% to the needle fall. In contrast to other plots, composition of needle fall at the Urea treatment was shifted toward a greater contribution of younger needles.