Impact of intensive forest management on soil quality and natural regeneration of Norway spruce

Abstract

The northern boreal forests in Fennoscandia have been managed for decades using clear-cut harvesting and subsequent mechanical site preparation (MSP). MSP is intended to reduce competing vegetation, improve soil temperature and water conditions as well as mobilize nutrients for the use by outplanted seedlings. The use of heavy machinery, particularly bulldozerdriven Marttiini-plough, has raised concerns about soil quality and therefore sustainability of forest productivity and forest floor diversity. We applied soil physical measurements and inventories of naturally established Norway spruce (Picea abies (L.) Karst.) to investigate these concerns 16-18 years after intensive forest management in Finnish Lapland. MSP with Marttiiniplough had inverted Podzol soil profile and created the following micro-sites: trench, tilt and untreated (UTR) soil between the ploughed tracks at former spruce sites. The soil electrical conductivity (EC a ) and soil solution conductivity (EC w ) at micro-sites of spruce seedling/ saplings, differed significantly (p<0.001). The majority of spruce individuals (60%) were established on UTR (mean EC a =0.54±0.34 mSm −1 ), while the proportion on tilt was minor (34%, EC a =0.35±0.18 mSm −1 ) and almost absent on trench (6%, EC a =0.12±0.11 mSm −1 ). In a similar way, the soil quality decreased such that EC wUTR = 11.7 ± 9.1mSm −1 > EC wTILT = 10.7 ± 9.2mSm −1 > EC wTRENCH = 2.2 ± 2.9mSm −1 . Spruce individuals at UTR (mean height 127±89 cm) and tilt (111±74 cm) were significantly (p<0.001) taller compared to those in trench (32±44 cm). The five study sites were surrounded by mature Norway spruce stands, yet only 0-14% of spruce seedlings/ saplings were found on the MSP-exposed mineral soil. These results imply that intensive forest practices result in losses in soil nutrient supply, hence endangering sustainability of the soil quality, and therefore occasionally hamper natural regeneration of Norway spruce.

Post‐fire regeneration inMediterranean reforested sites as affected by mechanical site preparation: lessons for restoration

“…), 18 yr (Sutinen et al. ) and 24 yr (Baoyin & Li ). In abandoned agricultural land, effects of ploughing on vegetation community structure were evident after about 100 yr in a temperate coastal (Eberhardt et al.…”

“…; Sutinen et al. ), through reduction of competition, exposure of mineral soil, improvement of soil temperature and water conditions, and mobilization of nutrients. Ploughing also serves as a tool for ecological restoration (Sampaio et al.…”

“…; Sutinen et al. ) or were reversed during the transition from early to late post‐treatment phases (Fraser et al. ).…”

“…Ploughing has long been used to promote both forest plantings (Lieffers & Beck 1994;Shakesby et al 2002;Mallik 2003) and natural regeneration (Fraser et al 2004;Sutinen et al 2010), through reduction of competition, exposure of mineral soil, improvement of soil temperature and water conditions, and mobilization of nutrients. Ploughing also serves as a tool for ecological restoration (Sampaio et al 2007;Baoyin & Li 2009).…”

“…The effects of ploughing on vegetation regeneration and succession have been shown to be variable and even contradictory. Although the common practice of ploughing to promote forest regeneration has proven useful in some cases (Karlsson 1996;Mallik 2003), its effects were adverse in others (Sampaio et al 2007;Sutinen et al 2010) or were reversed during the transition from early to late post-treatment phases (Fraser et al 2006). When used for rangeland restoration, ploughing was shown to increase grassland production, but reduce species richness and community complexity (Baoyin & Li 2009).…”