Changes in the Above- and Below-ground Biomass and Nutrient Pools of Ground Vegetation After Clear-cutting of a Mixed Boreal Forest

Abstract

Ground vegetation may act as a sink for nutrients after clear-cutting and thus decrease leaching losses. Biomass and nutrient (N, P, K, Ca) pools of ground vegetation (mosses, roots and above-ground parts of field layer) were determined one year before and five years after clear-cutting of a Norway spruce (Picea abies (L.) H. Karst.) dominated boreal mixed forest stand in eastern Finland (63°51¢ N, 28°58¢ E). Before clear-cutting the average biomass of ground vegetation was 5307 kg ha )1 , with nutrient contents of 46.9 kg N ha )1 , 4.1 kg P ha )1 , 16.2 kg K ha )1 and 13.9 kg Ca ha )1 . The biomass and nutrient pools decreased after clear-cutting being lowest in the second year, the biomass decreasing by 46-65% in the cut plots. The nutrient pools decreased as follows: N 54-72%, P 36-68%, K 51-71% and Ca 57-74%. The decrease in ground vegetation nutrient uptake, and the observed reduced depth of rooting may decrease nutrient retention after clear-cutting and decomposing dead ground vegetation is a potential source of leached nutrients. These negative effects of clear-cutting on the nutrient binding capacity of ground vegetation was short-lived since the total biomass and nutrient pools returned to pre-cutting levels or were even greater by the end of the 5-year study period.

Effects of clear-cutting and slash removal on soil water chemistry and forest-floor vegetation in a nutrient optimised Norway spruce stand

“…Additionally, the importance of the forestfloor vegetation is underestimated by this study since nitrogen storage in roots and rhizomes was not measured. Results of Palviainen et al (2005a) indicate that the belowground biomass of the forest floor vegetation may be as large as the aboveground parts.…”

“…), can dominate the pre-harvest forest-floor vegetation. Commonly, as a result of clear-cut of the forest the biomass of these species decreases (Palviainen et al 2005a) and early successional species (e.g. graminoids) increase in abundance (Bergstedt and Milberg 2001;Palviainen et al 2005b).…”

Water and nitrogen processes along a typical water flowpath and streamwater exports from a forested catchment and changes after clear-cutting: a modelling study

“…Grip, 1982;Bredemeier et al, 1998;Ahtiainen and Huttunen, 1999;Pardo et al, 2002). Increased N exports are detected mainly as elevated NO 3 -N levels in streams but elevated NH 4 -N levels have also been reported (Moldan and Wright, 1998a;Bäumler and Zech, 1999).…”

“…In high N deposition areas or in catchments with fertile soil, stream water N concentrations increase rather quickly, whereas in low deposition areas or in nutrient-poor catchments, the response can be delayed and small (Bredemeier et al, 1998). Although N export may increase many times after clearcutting (Ahtiainen and Huttunen, 1999;Pardo et al, 2002), it does not exceed the deposition inputs, except if the soils are N saturated (Akselsson et al, 2004).…”

“…After clear-cutting, ground vegetation can be a significant N sink (Likens et al, 1970;Fahey et al, 1991;Emmet et al, 1991;Palviainen et al, 2005) and conditions may favour grasses but suppress dwarf shrubs and mosses (Nykvist, 1997). Species favoured after clear-cutting often have high N content, leading to an accumulation of N in the ground vegetation (Fahey et al, 1991;Mou et al, 1993;Palviainen et al, 2005).…”