Element Fluxes with Litterfall in Mature Stands of Norway Spruce and European Beech in Bavaria, South Germany

Abstract

Litterfall is the largest natural inflow of organic material and nutrients to the forest floor and in most European forests is dominated by that from the trees. The chemical composition of this material and the temperature and moisture content of the upper soillayers are considered to be the main factors control-ling the turnover rates of the shed litter and the release of nutrients. Thus they also determine the quantity of nutrients released and the accumulation of humus and nutrients. Few larger studies have been made on litterfall on a Euro-pean basis. For needles of Norway spruce and different pine species, Berg and Meentemeyer (2001) made a study covering the main part of western Europe, whereas for European beech, for example, few values have been published. Nutrient concentrations in foliar litter vary with the litter species, climate, and pollution level (e.g. Berg and McClaugherty 2003). In general, it appears that in unpolluted stands beech is richer in the main nutrients than spruce and beech leaf litter often has a concentration of around 9 mg N g-l, whereas spruce may have only half that concentration (Staaf 1982; Berg and McClaugherty 2003). In stands with N pollution or in stands subject to N fer-tilization, the concentration of N in litter will increase above the level consid-ered to be normal (e.g. Berg and Tamm 1991). Further, in such polluted stands, the difference in between-species N concentration in foliar litter may be less pronounced, and at the N-polluted site Solling in central Germany the average N concentration in a stand of European beech was 12.7 mg g-l and in one with Norway spruce it was 10.7 mg g-l (Matzner et al. 1982). An increased N level in litter often means an increased or changed level of other nutrients, at least for those that structurally are connected to N, such as P and S but also K (Berg and McClaugherty 2003). Norway spruce ne edle lit-ter appeared to differ from a more general pattern, and Berg and Tamm (1991) investigating the variation between sets of nutrients in spruce ne edle litter after N fertilization found that the concentrations ofN were significantly related to those of S, Ca, Mn, Al, and Zn. Ecological Studies, Vol. 172 E. Matzner (Ed.), Biogeochemistry of Forested Catchments in aChanging Environment © Springer-Verlag Berlin Heidelberg 2004 272 B. Berg and P. Gerstberger It has been found that a changed chemical composition of foliar litter may change the accumulation rate of humus in the forest floor and thus also the storage rate of nutrients, for example N (e.g. Berg and McClaugherty 2003; Berg, this Vol.). This means that although there is areturn of nutrients to the forest floor with litterfaIl, not all nutrients are available for plant uptake. Such far-going influences of N additions, either in the form of deposition or as N fertilization, dearly motivate a doser investigation of nutrient budgets with the intention of finding deviations from the normal pattern. With a changed chemical composition of foliar litter the flow of nutrients back to the soil sys-tem is also changed. A higher concentration of N in foliar litter could thus result in changed levels of other nutrients in the humus leading to a changed pattern in the nutrient supply. The aim of this chapter is to present and evaluate the return of nutrients in two N-polluted stands of Norway spruce and European beech. For this pur-pose, litterfall was collected at both stands and analyzed for the nutrients N, P, S, K, Ca, Mg, Mn, Al, and Fe. We compared the returned amounts at the two sites and used data from an additional site at Solling (Matzner 1988).