Regeneration of mature Norway spruce stands: early effects of selective cutting and clear cutting on seepage water quality and soil fertility.

Wendelin Weis,Christian Huber,Axel Gattlein

doi:10.1100/tsw.2001.327

Abstract

The cutting of trees influences element turnover in the forest ecosystem. The reduction of plant uptake, as well as an increased mineralization and nitrification due to higher soil temperature and soil moisture, can lead to considerable losses of nutrients from the main rooting zone. This may result in a reduced soil fertility and a decrease in drinking water quality due to high nitrate concentrations in the seepage water. In Bavaria (Germany) selective cutting is preferred to clear cutting when initiating the regeneration of Norway spruce stands with European beech. This paper summarizes the early effects of both forest management practices on soil fertility and seepage water quality for three different sites. Shown are the concentrations of nitrogen and base cations in the seepage water as well as the water and ion fluxes during the first year after tree cut. Nutrient inputs decreased on thinned plots and even more at clear-cuts. Nitrate concentrations in the seepage water are hardly affected by moderate thinning; however, on clear-cuts, the nitrate concentration increases significantly, and base cations are lost from the upper mineral soil. This effect is less obvious at sites where a dense ground vegetation, which is able to take up excess nitrogen, exists.

Highlights

In Germany, and especially in Bavaria, official forest management on public forest land aims at the preservation and re-establishment of stable and productive mixed forests in accordance with the specific site conditions
At Ebersberg and Höglwald, where from the beginning of our study, the control plots showed higher nitrate levels compared to the manipulated plots, the nitrate concentrations after selective cutting are comparable to or even lower than the corresponding concentration from the control plots; the impact of selective cutting on nitrate concentration is clearly visible at Flossenbürg, where the thinning was more concentrated to the center of the plot
The nitrate in 40-cm depth is accompanied mostly by aluminum because the base saturation in the upper mineral soil is low; calcium and especially magnesium are removed from the upper soil as well (Fig. 3)

Summary

Introduction

In Germany, and especially in Bavaria, official forest management on public forest land aims at the preservation and re-establishment of stable and productive mixed forests in accordance with the specific site conditions. Wherever possible, mature Norway spruce stands (Picea abies (L.) Karst) are regenerated with European beech (Fagus sylvatica L.) and other broadleaf species[1]. 5 years old) are planted after a more-or-less intense thinning of the mature spruce stand if no natural regeneration with beech occurs. Thinning influences the input of water and elements as well as microclimatic conditions, the uptake of nutrients, and the development of the ground vegetation. The element cycling in the soil is altered. In nitrogen-saturated systems there may be high losses of nitrogen from the ecosystem during regeneration; which affect the seepage water and soil quality due to nitrate leaching and, induced output of nutrient cations. In the long run this may lead to less fertile soils and nutritional deficiencies in the young trees

Methods

Results

Conclusion