Norway spruce (Picea abies L.) regeneration and growth of understory trees under single-tree selection silviculture in Finland

Abstract

This study presents empirical data on regeneration and growth of understory trees and constructs simple models for predicting these characteristics at various stand structure and post-thinning standing volume levels. The field experiment was established on a grass/herb mineral soil site in central Finland. Regeneration and understory tree growth data were collected from 24 Norway spruce (Picea abies L.)-dominated mixed substands. Seedlings with heights from 5 to 130 cm were measured in 1996 and 2007. In addition, the annual height growth of Norway spruce seedlings was measured in 2007. The spatial pattern of the substands varied from clustered to regular with a decreasing standing volume. Stand complexity was uniform across the range of standing volume. In the 2007 survey, the amount of Norway spruce regeneration increased from approximately 400 to 5,000 seedlings ha -1 when the post-thinning standing volume level was reduced from 230 to 90 m 3 ha -1 , respectively. Nearly no seedlings were found when the standing volume was over 300 m 3 ha -1 . The annual diameter increment in Norway spruce understory (dbh \ 5 cm) trees decreased, on the average, from 2.3 to 0.3 mm with an increase in the standing volume level from 90 to 340 m 3 ha -1 , respectively; their height growth showed also a decreasing trend when the standing volume increased. The results indicated that a post-thinning standing volume lower than 150 m 3 ha -1 with a regular overstory spatial structure provides a suitable environment for regeneration and growth of Norway spruce understory trees in the studied forest type.

Short-term development of a multilayered forest stand after target diameter harvest in southern Sweden

“…However, after harvest, the height growth rates became more similar. The annual height growth rates of the spruce seedlings were in line with comparable studies in Norway, Estonia, and Finland (Granhus 2001;Metslaid et al 2005;Eerikäinen et al 2014), but substantial increases may be expected in the future according to findings by Granhus et al (2008), Lin et al (2012), and Eerikäinen et al (2014), which included longer observation periods. For the first 5 years, the observed height growth of seedlings in this study was also within the range reported for regeneration under shelterwood in southern Sweden by Örlander and Karlsson (2000), Nilsson et al 2002, andNilsson et al (2006).…”

Natural Regeneration in a Multi-Layered Pinus sylvestris-Picea abies Forest after Target Diameter Harvest and Soil Scarification

“…However, the absolute height growth of all seedlings was less than previously reported for advanced regeneration under shelterwood and in stands under transformation towards more heterogeneous stand structure [10,13,14,51]. On the other hand, the magnitude was larger than observed for newly established seedlings under shelterwood [8,9] and in boreal Norway spruce single-tree selection stands [4,5,53].…”

Comparing individual-tree approaches for predicting height growth of underplanted seedlings

“…Area-wide measures of canopy structure sampled at the stand or plot have been used to predict seedling growth (Brandeis et al 2001;Chrimes and Nilson 2005;Lin et al 2012). Other research has predicted growth using point-based metrics of canopy structure observed at each seedling (Jain et al 2004;Krueger et al 2007).…”