资源环境科技发展态势分析平台

Aims: Coppice-with-standards (CWS) management was one of the most important disturbances in Central European forests in the past. As our knowledge about the effects of coppicing on species richness and composition needs to be enhanced, we carried out vegetation studies in the currently largest CWS project in Germany. In this article we focus on two issues: 1. Coppicing induced changes and trends in species richness and composition from year to year and 2. Development of species richness and composition in 19 years of CWS restoration.

Location. Salzgitter Hohenzug mountains between Liebenburg and Goslar, Lower Saxony, Germany. Climate: subadantic to subcontinental; soil: Limestone rendzina with low water storage capacity.

Methods: In 2013 we resurveyed the plant species composition of 12 permanent plots analysed every year from 1994 till 2002. The dates of coppicing were recorded for all of these plots, which enabled us to analyse the dynamics of species richness and composition after coppicing on a year to year basis. Differences in species richness and composition were analysed using ANOVA, H-test, DCA and GLMM.

Results: In 19 years of CWS restoration mean plot species richness increased significantly, mainly attributed to the increase in woody species, such as Quercus robur and Sorbus torminalis. The Ellenberg indicator value for nutrients decreased significantly, whereas the indicator value for light increased significantly. The typical dynamic after coppicing consists of a continuous increase in shrub layer coverage and an increase in herb layer coverage with a maximum in years 3 and 4 after coppicing. Total species richness as well as richness of open habitat and forest species and true forest species also showed an increase with its maximum in years 3 and 4 after coppicing.

Conclusions: Our results showed that the alternation of light and shaded phases had a positive impact on species richness, particularly on tree regeneration. Considering the trend of decreasing species richness level in Central European forests, CWS forests play a major role in the conservation of vascular plant species diversity. In contrast to other studies, the increase in species richness after coppicing did not result from an increase in weedy, nitrogen-demanding species. The so called "nitrogen time bomb" scenario (which other authors assumed to be happening after opening the canopy) did not occur in the studied area. The low water storage capacity of the limestone rendzina soil may be one reason, as there was not sufficient water and nitrogen for the more demanding species.