Effects of early thinning regime and tree status on the radial growth and wood density of Scots pine

Abstract

In this work, we studied the effects of early thinning on the radial growth and wood density over a 12-year post-thinning period in Scots pine (Pinus sylvestris L.) trees grown on a site with a rather poor nutrient supply. Ring width, early and late wood width and early wood percentage, mean intra-ring wood density and early-and late wood density were analyzed in 98 sample trees using X-ray microdensitometry. For the analyses, ten different thinning plots with post-thinning stand density varying from 575 to 3400 stems ha -1 were grouped into four classes representing heavy thinning, moderate thinning, light thinning and no thinning. We found that the radial growth in the thinned treatments increased significantly compared to that of the unthinned treatment. Despite this, the mean intra-ring wood density did not decrease significantly as a result of heavy thinning, although it was 2% less, on average (with a range of 1-4% in large and small trees), compared to that of the unthinned treatment. In the lightly thinned treatment, the mean intra-ring wood density even increased by 5%, on average (with a range 4-7% in small and large trees), but in the moderately thinned treatment, the level of change was not as clear. The thinning response of trees representing different status in a stand differed significantly and was also affected by the post-thinning stand density. Altogether, observed simultaneous increases in early and late wood widths and late wood density, but a decrease in early wood density indicate that as a result of heavy thinning, especially, un-uniformity of wood density will increase. On the other hand, although heavy thinning increased tree growth by 9-20%, on average, compared to moderate thinning, which corresponds quite well with business-as-usual management, mean wood density decreased only 0-4% depending on tree status in a stand (from large to small trees). Thus, the decrease observed in wood density was less than expected as a result of heavy thinning at an early stage of stand development, which has recently been recommended as one possible management option in Scots pine in Finland.

A palaeotemperature record for the Finnish Lakeland based on microdensitometric variations in tree rings

“…Extractives were not removed. The X-ray microdensitometry (ITRAX) scanning (Bergsten et al, 2001) was done using a step size of 25 μm intervals with the following settings for tube: voltage of 30 kV, current value of 25 mA and an exposure time of 20 ms (Peltola et al, 2007). The first year of the SA chronology occurs in AD 673.…”

Determining Ideal Timing of Row Thinning for a Cryptomeria japonica Plantation Using Event History Analysis

“…The timing of thinning is key for determining silvicultural management, although it is very challenging to determine with conventional approaches [32,44,50,51]. We demonstrate that it is possible to determine the exact ideal thinning time under different practices by analyzing dendroecological data and using event history analysis.…”

“…In our case, this would obscure the signal of failure events in event history analysis. Therefore, as suggested by Peltola et al [32], a three-year moving average window was applied to smooth the time-series data to mitigate effects of short-term climate fluctuations on tree-ring widths. This should be appropriate since the region was wet (mean annual precipitation greater than 3000 mm) [33] and annual temperature fluctuation for this near-tropical humid island was much less pronounced in comparison to other regions [34].…”

“…However, only the trees on edges received full benefit from thinning and trees were much less affected without the direct contact of opened space [43]. When a wider space is created, more resources (e.g., sunlight, nutrients, and water) are available for the dominant and predominant trees to enhance growth, especially those near the edge [32,44]. In time, canopy closure and understory vegetation coverage increased, and the accelerated growth effects of thinning were gradually reduced (Figures 3b and 4).…”

Influence of site conditions and silvicultural practice on the wood density of Scots pine (Pinus sylvestris L.) - a case study from the Doksy locality, Czech Republic

“…The variability of pine properties can be observed between individual localities and trees, and even within a single tree (Tomczak et al 2007;Kask 2015). Through the tree genotype, wood properties are largely influenced by altitude, climatic factors, by the surrounding environment and by silvicultural measures (Tsoumis 1991;Peltola et al 2007;Jelonek et al 2008Jelonek et al , 2012Roszyk et al 2016). The variability of wood properties within a trunk is crucial for the final processing of wood.…”