Survival, growth and needle element concentrations of Picea abies (L.) Karst. seedlings after brash removal in a previously N fertilized stand

Abstract

Export of nutrients after whole-tree harvest (WTH), i.e. harvesting nearly all of the aboveground parts of the trees, may affect the long-term sustainability of forest production. The aim of this study was to investigate the effects on planted Picea abies (L.) Karst. seedlings (in terms of survival, growth, and elemental concentrations in needles) of brash removal at final felling on unfertilized control plots, and others that had been fertilized with 4 × 120–600 = 480–2400 kg N ha −1 in the form of urea, prior to harvest. During the first six growing seasons after planting, the survival rate of originally planted seedlings was not affected by the brash removal. For replacement seedlings, the survival rate during the first 5 years after planting tended to be somewhat higher on plots where the brash was removed compared with plots where the brash was left on site, as in a conventional harvest (CH). The survival was not affected by the pre-harvest N fertilization. The height development of the seedlings was not influenced by either of the two treatments. However, the mean volume per seedling tended to be larger in the WTH than in the CH-plots for replacement seedlings, but not for originally planted seedlings. Needles from seedlings in the CH-plots showed significantly higher concentrations of N, S, B and Cu compared with needles from seedlings in the WTH-plots. The previous N fertilization did not influence the element concentrations. The results indicate that survival and early growth of planted P. abies seedlings were marginally affected after WTH compared with CH on the studied site, where the supply of plant-available N was indicated to not be limiting for tree growth.