J. D. Sauerländer's Verlag, Bad Orb

This study’s objective was to check the applicability of the phytomass and elemental stock model “PhytoCalc” under clear-cut conditions. Two model versions were consulted, focussing upon 4 widespread and biomass-rich species at small clear-cuts within even-aged Picea abies stands in central German highlands and 1 appropriate species within them: Oxalis acetosella L., Digitalis purpurea L., Deschampsia flexuosa (L.) Drejer, Pteridium aquilinum (L.) Kuhn and Rubus idaeus L. Both PhytoCalc versions failed at clear-cut sites for now, because the balances of energy, matter and water, influencing the understorey phytomass here, are significantly different compared to the forest stand. Liming effects, deviations in harvesting time and user bias were found to be possible sources of error as well as the determination of the 2 simple model parameters ground coverage and mean shoot length can be challenging in some special cases. Nevertheless, PhytoCalc was found to be an easy, cheap and fast approach that should be chased further one to obtain dry weight and elemental stocks of understorey phytomass. So e. g. the model seems to be applicable for wooden species of low height too, as shown with juvenile, up to 1 m high Picea abies. The calibrations efforts should now first focus on reliable functions for dry weight even under extreme conditions like clear-cuts for as much species as possible.

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