Seasonal variability of organic matter and N input with litterfall in Scots pine stands

Abstract

As part of the SANA subproject on organic matter and N turnover, the seasonal variability of mass input and N concentration of Scots pine litter was recorded by monthly collections at three sites of historically different air pollution and fertilization impacts. Furthermore, seasonal growth dynamics, biomass production and litter (= necromass) input to the forest floor from the ground vegetation was analysed in detail. The ground vegetation biomass differs obviously at the chosen sites according to their deposition history, being dominated by Vaccinium myrtillus and Avenellaflexuosa, only Avenellaflexuosa or Calamagrostis epigeios, Rubus sp., and Brachypodium sylvaticum. It was hypothesised that pine litter mass would also differ between the three sites. In addition, N fertilization and deposition of alkaline dusts and SO₂ should exert an effect on the chemical composition of living and dead plant tissues and thus on the amount of N returned to the forest floor via litterfall. In this paper the seasonal variability of organic matter and N input from Scots pine and ground vegetation at the SANA-sites is described and data are compared among sites. Further nutrient element concentrations in litter from pines and ground vegetation are published by Bergmann et al. (this volume).