Effects of initial stand states on optimal thinning regime and rotation ofPicea abiesstands

Abstract

This study analysed the effects of young stand characteristics on optimal thinning regime and length of rotation periods for even-aged Norway spruce [Picea abies (L.) Karst.] stands. Stand development was based on a distance-independent, individual-tree growth model. The young stand data were collected from 12 well-stocked Norway spruce stands in southern Finland. Results showed that optimal thinning regimes and rotation period depend on site quality and initial stand characteristics. At the first thinning, optimal thinning type depended on initial density. Thinning from both ends of the diameter distribution turned out to be optimal for initially dense stands. At the second and subsequent thinnings, thinning from above was clearly superior. At a low interest rate, thinning from below was optimal for the first thinning regardless of stocking level. For the study data, optimal rotation periods varied from 61 to 92 years at 3% interest rate. The high variation in length of rotation period was due to the sensitivity of optimal length of rotation period to site qualities, initial stand structure and density.

Applying a process-based model in Norway spruce management

“…Later he continues ''In the process, we have realized that we are interested mostly in the value of forest output rather than in its quantity, and that the method to maximize this value is yet to be discovered''. Haight et al, 1992;Valsta, 1992a;Pukkala and Miina, 1998;Hyytiäi-nen et al, 2004;Cao et al, 2006). Given the aim of maximizing volume yield, the optimality of thinnings from above is far less obvious than in the case of maximizing BLV.…”

“…There is a handful of studies with optimization for even-aged Norway spruce (Solberg and Haight, 1991;Valsta, 1992a;Miina and Pukkala, 2000;Hyytiäinen and Tahvonen, 2002;Cao et al, 2006;Hyytiäinen et al, 2010). All of them use empirical-statistical growth models.…”

“…In most existing studies thinning intensities are defined for a limited number of tree classes and linear interpolation over the diameter range is used to find thinning intensities of the other tree classes (Valsta, 1992a;Hyytiäinen et al, 2004;Cao et al, 2006). However, it can be shown that linear interpolation may produce modeling artefacts and distortions on the optimal solutions.…”

Optimal management of uneven-aged Norway spruce stands

“…Hyytiäinen et al (2010) perform detailed computations for optimal even-aged management for the Finnish Forest Extension Service Tapio to be used in developing official Finnish silvicultural guidelines. The computations for Norway spruce were based on the detailed single-tree model and optimization procedure developed in Valsta (1992) and Cao et al (2005). The maximized bare land values of this study are given in Table 3, column (2) for interest rates between 1% and 5% (excluding the proportional profit tax of 29%).…”

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

“…One major challenge of thinning is to determine the effective time of thinning, which varies among biotic (e.g., species types, stand density), abiotic (mainly substrate fertility), and management-related factors. Sophisticated methods such as dynamic programming, numerical optimization, or stand growth models can be used to derive the information [4][5][6][7][8][9][10][11][12]. However, most of these approaches are complex and require a wide array of long-term monitoring data including thin age, site index, initial stocking, residual stocking and/or rotation length that make the implementations challenging [13][14][15][16].…”