Effects of soil acidification and liming on ground flora establishment after clear-felling of Norway spruce in Sweden

Abstract

We used 2 long-term field experiments with Norway spruce Picea abies (L.) Karst. to investigate the influence of lime, acid sulphur compounds, or nitrogen (1 site) on the rate of recruitment of new vascular species after clear-fellings. On the study sites, Farabol in southern Sweden and Fäxboda in south–central Sweden, the chemical treatments had been applied before clear-felling and whole-tree harvesting. An additional, post-harvest experiment was conducted at Farabol in which lime, hardened wood-ash, or logging residues were applied. A germination experiment including seven species was carried out in a greenhouse using sifted humus from Fäxboda that was sampled 2 years before clear-felling. The clear-fellings resulted in establishment of many ephemeral species. The number of newly established species was greater than the number of disappeared species. There was an overall positive correlation with pH in the humus layer and the number of newly established species. The treatment effects differed between the sites, probably reflecting differences in total dose and initial soil conditions. Farabol is characterised by more acid soils and greater atmospheric deposition of S and N than Fäxboda. At Farabol, liming (in total 6000 kg limestone ha −1 distributed over 12 years) resulted in about 20 new species established after clear-felling, four times more species than in untreated, sulphur-treated, or nitrogen-fertilised plots. At Fäxboda, where lime (2000 kg dolomite ha −1), sulphuric acid, and elementary S had been applied 16 years before clear-felling, the number of newly established species was about 15, and no effect of the treatments was revealed. The post-harvest treatments at Farabol showed that wood-ash and logging residues had similar effects as lime on the establishment of new species. The pot experiment showed that liming or acidification can affect the germination of seeds. Compared with untreated soil, a greater proportion of seeds of Primula veris ( P. veris) and Senecio sylvaticus ( S. sylvaticus) germinated in limed soil and the germination of P. veris was lower in acid- or sulphur-treated soils. The germination of Vaccinium myrtillus ( V. myrtillus) seeds was negatively affected by liming. No effects of the treatments were discovered on the germination of Deschampsia flexuosa, Calamagrostis arundinacea, Galeopsis bifida ( G. bifida), or Poa nemoralis. The soil water in the pot experiment had higher pH, higher concentrations of Ca and Mg, and higher NO 3 −/NH 4 + ratios in limed soil compared with other treatments. Nomenclature of plants follows Lid (1985).