Economics of Forest Thinnings and Rotation Periods for Finnish Conifer Cultures

In this study simultaneous optimization of thinnings and clear-cutting was investigated. The density-dependent whole-stand model was specified for all relevant Finnish Norway spruce (Picea abies (L.) Karst.] and Scots pine (Pinus sylvestris L.) site indices and solved by non-linear programming. Sensitivity analysis showed that in some cases and owing to endogenous thinnings the optimal rotation length may increase with the rate of interest and site fertility, and decrease with harvesting cost. The number of thinnings is more sensitive to changes in the rate of interest, logging conditions and site productivity for Scots pine stands than for Norway spruce stands. Economic optimization suggests that for both species the first thinning should be performed later than officially recommended. The last thinning should be heavier than officially recommended, especially at high rates of interest. This increases the optimal rotation length compared with solutions under restricted thinning intensity.     

Stem Form and Taper Changes After Thinning and Nitrogen Fertilization in Picea abies and Pinus sylvestris Stands

Stem form and taper changes after thinning and thinning combined with N fertilization were studied in 23 Norway spruce [Picea abies (L.) Karst.] and 46 Scots pine (Pinus sylvestris L.) stands in Sweden observed for 5-28 yrs. Average taper was calculated for the stem section 1.3-6.0 m above ground level and as the ratio between the diameter at breast height and total tree height for periods of 5-10 yrs. At the start of the experiment, before the first thinning, the dominant height was 12-15 m. Once 65% of the basal area had been removed in a single thinning from below, the remaining trees showed a strong increase in taper compared with trees in unthinned stands. Stems in stands treated with heavily recurrent thinnings from below also increased in taper, although the increases were not always statistically significant. Trees in thinned, N-fertilized Scots pine stands in middle and northern Sweden developed a more pronounced taper compared with stems in equally thinned, unfertilized stands.     

Comparison of Forest Biomass Across a Human-Induced Disturbance Gradient in Nepal's Schima-CastanopsisForests

Abstract

This paper presents estimations of aboveground tree biomass (combined for boles and branches) in Nepal's Schima-Castanopsisdominated warm-temperate forests. The biomass estimations are presented for five forest stands purposively sampled in a larger study to represent different harvesting intensities. Two categories of biomass estimates are provided: (1) for living trees that are standing, and (2) for cut trees that have been removed. Biomass of standing trees were estimated by using diameter at breast height (dbh) and total height measurements as predictor variables in appropriate regression models. Biomass of cut trees were estimated in two steps: measurements of stump diameters and heights were used first to predict dbh and total heights of cut trees; these values were then regressed to obtain biomass estimates for the missing trees. Data were gathered from 2,361 live trees and 2,962 stumps in 170 sample plots across the five forest stands. Estimates of mean standing-alive biomass ranged from a minimum of 16 ton/ha in the severely disturbed forest to a maximum of 479 ton/ha in a relatively undisturbed (reference) forest. Estimates of mean cut biomass ranged from a minimum of 24 ton/ha in a second reference forest to a maximum of 183 ton/ha in the severely disturbed forest. The biomass estimates in the relatively-undisturbed, reference forests are well above the 95% upper confidence interval of the global mean. Similar findings of high productivity have been reported for temperate forests of the Central Himalaya in India and Eastern Himalaya in Sik-kim. The findings of this study in the Nepalese Central Himalaya support the conclusion that productivity potential is high in the temperate Himalayan forests. The study's findings and methodology should be useful for preliminary development of guidelines in the region to regulate forest biomass growth, yield, and harvest.     

Impacts of bucking and delimbing alternatives on pulpwood and energy wood yields in young thinning stands in Finland

The supply of energy wood from young forests could be enhanced by altering the harvesting methods in integrated pulpwood and energy wood thinnings. In this study, effects of different bucking and delimbing options on the biomass division into energy wood, pulpwood and logging residue were estimated in integrated thinnings of young stands dominated by Scots pine (Pinus sylvestris), Norway spruce (Picea abies) or birches (Betula spp.) in Finland. Thinning options were simulated in the harvestings of model stands created on the basis of forest inventory data. Increasing the minimum top diameter of pulpwood (MTDP) expectedly increased energy wood and decreased pulpwood yields. Depending on tree species, energy wood yield increased by 36–65% when the top diameter was increased from the regular level (6 or 7 cm) to 8 cm in whole-tree harvesting, and was more than doubled when the top diameter was increased to 10 cm. Delimbed energy wood yield was increased by 240–280% when the top diameter was increased to 10 cm. Total harvesting yield in whole-tree thinnings was slightly increased by increasing top diameter. These increments in harvesting yields and reallocations of tree biomass could have an impact on large-scale forest energy potentials.     

Estimation of nutrient removals in stem-only and whole-tree harvesting of Scots pine, Norway spruce, and birch stands with generalized nutrient equations

Whole-tree harvesting (WTH), where logging residues are removed in addition to stems, is widely practised in Fennoscandian boreal forests. WTH increases the export of nutrients from forest ecosystems. The extent of nutrient removals may depend on tree species, harvesting method, and the intensity of harvesting. We developed generalized nutrient equations for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies Karsten), and birch (Betula pendula Roth and Betula pubescens Ehrh.) stands to be able to calculate the amounts of nitrogen, phosphorus, potassium, and calcium in stems and above-ground biomass (stem and crown) as a function of stand volume. The equations were based on Fennoscandian literature data from 34 pine, 26 spruce, and 5 birch stands, and they explained, depending on the tree species and nutrient, 61–99% and 56–87% of the variation in the nutrient amounts of stems and above-ground biomass, respectively. The calculations based on the equations showed that nutrient removals caused by stem-only harvesting (SOH) and WTH per harvested stem m³ were smaller in pine than in spruce and birch stands. If the same volume of stem is harvested, nutrient removals are, in general, nearly equal at thinnings and final cuttings in SOH, but larger in thinnings than final cuttings in WTH. If the principal aim is to minimize the nutrient removals per harvested stem m³, the harvesting should be done at mature pine stands. The effect of biomass removal on overall site nutrient status depends on site-specific factors such as atmospheric deposition, weathering of minerals, and the size of the nutrient pools in the soil.     

The effect of quality bucking and automatic bucking on harvesting productivity and product recovery in a pine-dominated stand

On-board computers (OBC) of harvesting machines can now provide optimized bucking (task of cutting stems into different log lengths) by relying on value and demand matrices. Despite existing benefits of these systems in certain countries, they remain largely underutilized and generally poorly understood in German mechanized forest operations. The study aimed to compare and quantify the differences in harvesting productivity and value recovery between two treatments: quality bucking (OFF) and automatic bucking (ON). A mature forest stand with a high proportion of Scots pine (Pinus sylvestris L.) was divided into plots (30 m × 100 m) where initial tests of both treatments were randomly distributed and replicated 10 times for a total of 11 plots per treatment. Pre-harvest inventory was performed on each tree targeted for removal via a commercial thinning silvicultural treatment. Mechanized harvesting was performed with an excavator-based Atlas Kern T23 Königstiger single-grip harvester. The same assortment specifications and prices were used for both treatments but on-board optimized bucking solutions were applied in the ON plots, whereas the operator had full control of the products to be recovered in the OFF plots. During harvesting operations, continuous time and motion was performed in all plots. Average harvesting productivity was higher—but not statistically significant—in OFF plots compared to ON plots by 2.0 and 0.46 m³/PMH₀ for pine and spruce trees, respectively. Even if there was no difference detected in volume recovery for both treatments and tree species, value recovery was more than 1.60 € per cubic meter higher for pine in larger diameter classes when using quality bucking. This may be due to the fact that the algorithm of the OBC is designed for pine trees with a simpler crown architecture than trees harvested in this study. Results supporting quality bucking over automatic bucking in a Scots pine-dominated stands provide important forest operational information to managers.

     

Possibilities for Harvester-based Forest Inventory in Thinnings

This study investigated the possible estimation of forest characteristics using the information collected by the harvester in first thinnings. For the analysis a complete forest inventory was carried out in a stand, which was subsequently thinned. The global mean values of tree diameter, tree height, basal area and stem density were estimated, and further, a spatial analysis was carried out to investigate whether the data collected by the harvester could be used to generate a continuous spatial model of the forest. The results indicated that the global mean diameter and height may be estimated, whereas area-related properties, such as basal area and stem density, are more difficult to estimate. The spatial distribution of the diameter and height remained similar after the thinning, whereas the basal area and stem density had become more homogeneous after the thinning. From the trees removed in the thinning a continuous spatial model of tree diameter was developed. It reproduced the spatial structure of the original trees to some extent ( R 2 = 0.27, RMSE = 14.3 mm).     

An Exploratory,Post-Harvest Comparison of Ecological and Economic Characteristics of Forest Stewardship Council Certified and Uncertified Northern Hardwood Stands∗

ABSTRACT

As more forest entities worldwide consider pursuing Forest Stewardship Council (FSC) certification, a critical question remains on whether stand-level management impacts differ between certified and uncertified forests. To begin to answer this question, we measured forest structure on three FSC-certified stands, three uncertified stands, and six adjacent unharvested reference stands (12 stands total) composed primarily of sugar maple (Acer saccharum) on non-industrial private properties in central Vermont, USA. The certified and uncertified partial harvests reduced total tree biomass and live tree carbon storage by one-third compared to reconstructed pre-harvest conditions. Both treatments also contained significantly lower densities of saplings and some mid-size trees compared to non-harvested references due to similar impacts from harvesting. The net present value of merchantable sugar maple over 10 year projections was consistently lower on certified than uncertified stands, but this difference was insignificant at discount rates from 4–8%. The certified stands contained significantly greater total residual volumes of coarse woody debris (standing and downed) than uncertified stands, although the debris was smaller than that found in unmanaged mature forests. Overall, our data suggest that FSC-certified harvested stands in northern hardwood forests have similar sugar maple timber value, aboveground live tree carbon storage value, similar live tree structure, and greater residual coarse woody debris than uncertified harvested stands.     

Mixed Forests as a Part of Sustainable Forestry in Southern Sweden

Abstract

We review and discuss the applicability of mixed stands in the context of sustainable forestry in southern Sweden. This is done from a silvicultural perspective regarding aspects such as regeneration, pre-commer-cial thinnings, production, economy, damage and policy implications. The paper is based on literature reviews and on studies performed in southern Sweden or under comparable conditions. After considering the underlying mechanisms, we find that it is possible to establish a mixed stand in the regeneration phase and sometimes even to a lower cost compared to monocultures. To keep the mixture, or to create it, with pre-commercial thinnings is, however, often more expensive. The reviewed studies, together with a new simulation, show that the effect on productivity of mixed stands compared to monocultures is minor. Some positive effects on damage (i.e., decreased levels) in mixed stands have been found. The economy and the policy implications of mixed stand management were found to be dependent on the specific stand and situations. A general finding was that research and knowledge of managing mixed stands, as compared to monocultures, are limited, which in turn could limit the applicability of mixed stand management.     

Wild Cherry (Prunus avium L.) for Timber Production: Consequences for Early Growth from Selection of Open-pollinated Single-tree Progenies in Sweden

Prunus avium L. is a fast-growing hardwood tree species that has demonstrated good production on both well-drained forest soils and farm land in southern Sweden. Growth rate and breeding value were tested in 101 open-pollinated single-tree progenies of Swedish origin and five German seed sources. After eight growing seasons and two selective thinnings the mean tree height reached 4.7 m. The mean tree height of the progenies varied between 3.3 and 6.1 m. A total rotation period of 50-60 yrs and a dominant height of 20-22 m can be expected. The results indicated great phenotypic variation within progenies and good possibilities for improving production and stem quality by early selective thinning. In terms of height growth and stem straightness the best Swedish progenies were as good as the tested German seed sources.     

Influence of individual reserve trees on nearby reproduction in two-aged Appalachian hardwood stands

In the 1970s, public opposition to clearcut harvesting in hardwood forests of the eastern United States led forest managers and scientists to consider alternative practices that retain a low-density overstory forest cover. From 1979 to 1984, a form of clearcut-with-reserves harvesting was applied in 80-year-old Appalachian mixed-hardwoods to create four experimental stands with two-aged structures. The residual stand basal area averaged 5.3 m²/ha, comprising an average of 36 reserve trees/ha. The reserve trees were evenly distributed throughout the stand, initially with considerable space between their crowns, thus providing the sunlight and seedbed conditions needed to recruit desirable shade-intolerant reproduction after harvest. This study examined the response of the 100-year-old reserve trees and the development of the 20-year-old natural reproduction located in their immediate vicinity.Diameter at breast height (Dbh), height, and relative position were recorded for all reproduction ≥2.5 cm within transects adjacent to northern red oak (Quercus rubra L.) and yellow-poplar (Liriodendron tulipifera L.) reserve trees. Each transect was divided into five zones, which represented positions relative to the reserve tree crown edge, and basal area was computed for each of three shade tolerance classes within each zone. A repeated measures ANOVA was used to compare basal area of reproduction by tolerance classes and zone. In general, basal area of reproduction, particularly that of shade-intolerant species, increased with distance from the reserve tree. Regression analyses also indicated that dbh and height of reproduction was positively related to distance from the reserve trees. Although height growth of reserve trees was similar for both species, northern red oak exhibited significantly greater dbh and crown radial growth than yellow-poplar.The results indicated that reserve trees influence the growth rate and species composition of reproduction in their immediate vicinity. Basal area of reproduction increased from 10.1 to 17.7 m²/ha with increasing distance from the reserve trees. Basal area of intolerant species more than doubled along the same gradient. Basal area of reproduction in the two-age stands was 30–40% less than that observed in even-aged stands on similar growing sites, but the reduction was offset by growth of the reserve trees. The surface area covered by the reserve tree crowns increased approximately 88% for northern red oak and 44% for yellow-poplar. Since the sphere of influence of reserve trees increases over time, forest managers must consider their long-term impact on reproduction when prescribing clearcut-with-reserves harvests and other practices that involve retaining trees for many years.     

海南霸王岭陆均松类热带山地雨林伐后林结构与物种多样性研究

霸王岭林区是海南岛最典型的热带山地雨林分布区.在该区,现存分布面积最广、资源数量最大的是热带山地雨林的各种伐后林.以霸王岭分布最广的以陆均松(Dacridium pierrii)为主的山地雨林的伐后林为对象,研究了其组成、径级、高度结构和物种多样性特征,对比分析了伐后林与原始林以及伐后林不同类型之间的异同.结果表明:原始热带山地雨林经采伐后中小乔木和灌木的优势度增大,而大乔木树种的优势度则明显下降.阳性树种的种类、数量和相对重要性随采伐破坏的程度而增加.伐后林中矮、小树木在林分中比例随采伐破坏的程度增加,而高、大树木,特别是进入主林层树木的比例则随采伐破坏的程度明显下降.从林分测树因子的变化来看,采育择伐和径级择伐的林分要优于大强度择伐和皆伐的林分.原始林的物种丰富度大于伐后林,但其多样性指数和均匀度指数大都小于伐后林.组成上与原始林相似性较大的伐后林是各种择伐后的林分,而皆伐后的林分与原始林在组成上已有很大差别.     

Modeling frequency distributions of tree height,diameter and crown area by six probability functions for open forests of <Emphasis Type="Italic">Quercus persica</Emphasis> in Iran

The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim of this research was to model the distribution of quantitative variables for Quercus persica in open forests in Iran. To investigate the probability distribution of trees in natural stands, 642 trees were selected for measurement using a systematic random sampling method. Selected trees were measured and data were analyzed. Gamma, beta, normal,lognormal, exponential and Weibull probability distributions were fitted to the height distribution of trees. Variables of distribution functions were estimated using the maximum likelihood estimation method. Actual probability and probability which derived from functions was compared using Kolmogorov–Smirnov and Anderson–Darling tests. Beta, Weibull and Weibull probability distributions explained the distributions of tree height, DBH and crown area.     

Continuous felling of small diameter trees in boom-corridors with a prototype felling head

Abstract

Simulations of the continuous felling of trees in boom-corridors have suggested that it may be possible to increase harvester productivity by a factor of 2.4 when thinning young dense stands. A prototype boom-tip mounted felling head for harvesting in this fashion was therefore built and tested in the field. Using the new head, stands with a density of 10,000 trees ha^?1 and a mean diameter at breast height (dbh) of 7 cm were felled at a speed of 0.4 m s^?1, with an efficiency of 3.5 s tree^?1. The felling speed was limited by the speed of movement of the harvester crane's boom. However, additional tests suggested that the new head could be operated at felling speeds of up to 1.3 m s^?1 when cutting trees with dbh values of up to 8 cm. The simulation that prompted this study focused on multiple felling with the crane in continuous motion at speeds of 1 m s^?1; the results obtained in this work suggest that the new felling head is capable of sustaining these speeds and so further technical development of the design (e.g. to incorporate accumulating functionality) is warranted.     

Site-index Model for Abies chephalonica in the Mount Taygetos Forest in Greece

To develop a site-index system, stem analyses data were employed, portraying 70 dominant and codominant trees growing on even-aged Abies chephalonica stands in the Mount Taygetos forest in southern Greece. Two different models were considered for the development of site-index curves: King's height/age model using the parameter prediction method for fitting site-index curves and a difference equation model. The difference model performed better, in terms of the overall appearance of the final site-index curves, at a wide range of ages. Based on the results, it was decided to adopt a difference model for the development of a site-index system for A. chephalonica stands in the Mount Taygetos forest. Breast-height age and mean height of dominant and codominant trees are the entry attributes in the site-index system in order to have a site index (height at base age, A_o=50 yrs) of a single tree or stand.     

Modelling the Growth and Management of Mixed Uneven-aged Maritime Pine - Broadleaved Species Forests in Galicia,North-western Spain

The state of mixed forests of maritime pine ( Pinus pinaster Ait.) and broadleaved species in the coastal region of Galicia (north-western Spain) was described using data from 213 circular sample plots selected among the available 4700 plots of the Spanish National Inventory. A matrix model was developed for this forest type to obtain information about the productivity and potential for sustainable management. The broadleaved species had a diameter distribution close to the inverted J-shape typical of the uneven-aged forests but for maritime pine there were many medium-sized trees and a lack of trees in the first diameter class of 15 cm. The matrix growth model was used to predict the development of mixed forests for three different management options: no harvesting in a well-stocked stand, a regime with a 5 yr harvest cycle and a residual basal area of 15 m 2 ha -1 in a well-stocked stand, and a rehabilitation management applied to an understocked stand. The results showed the possibility of applying uneven-aged silvicultural systems to these forests, leading to the production of high-value timber and to the maintenance of continuous cover and a biodiverse forest.     

Influence of Shelterwood Density on Survival and Height Increment of Picea abies Advance Growth

Abstract

The increases in the arithmetic mean diameter at breast height (dbh) of the 100, 200, 300 and 400 largest stems ha^?1 by dbh associated with six different thinning regimens for periods up to 35 years were compared, by analyses of variance, to the corresponding stem fractions in unthinned stands using permanent sample plot data. In addition, the expected mean dbh of these stand fractions at future points in time was modelled, based on site and stand data obtained at the time of the first thinning. Thirty-five years after the first thinning, the thinning from below regimens resulted in actual increases (a measure affected by both the thinning intensity and the thinning method), compared with the unthinned stands, in the mean dbh for the 100, 200, 300 and 400 largest stems ha^?1 of 2.6–9.0 cm. The corresponding genuine increases (a measure principally affected solely by the thinning intensity) were 4–11 cm. The functions predicting the future dbh of these stand fractions yielded good fits.     

Deer density effects on vegetation in aspen forest understories over site productivity and stand age gradients

Studies examining the interacting effects of ungulate herbivore pressure and site productivity on vegetation are mostly on grassland-grazing systems and have shown conflicting patterns. Here we examine the effects of deer density (>30 years differences in density between two landowners), site productivity (site index, SI) and stand age on subcanopy vegetation characteristics in 60 closed canopy, clear-cut origin Populus tremuloides dominated stands, Michigan, USA. Stand age effects were included because age varied among stands and can affect subcanopy vegetation patterns. Compared with fewer deer, stands with more deer had greater total forest floor vegetation mass, and its major components bracken fern (Pteridium aquilinum), sedge (mostly Carex pensylvanica) and trees/shrubs <0.25 m tall, but lower forb mass and lower forest floor vegetation species richness and diversity. Deer density and SI had strong interacting effects on total forest floor mass, forb mass, and species richness. Forb mass increased with SI, but only in stands with fewer deer, whilst total vegetation mass was greater in stands with more deer at lower SI and declined with SI more sharply than for stands with fewer deer. Species richness increased with SI but more so at lower than higher deer density. Deer density and age had interacting effects on mass of trees/shrubs <0.25 m tall and sedge. Compared with fewer deer, stands with more deer had greater sedge and tree/shrub mass, and sedge mass decreased and tree/shrub mass increased more sharply with age. In lower deer stands there was a dense subcanopy tree and shrub strata within and beyond the reach of deer 0.9-10 m tall whereas in higher deer stands this vegetation layer was nearly absent. We conclude that higher deer browse pressure in early successional Populus stands (1) strongly limits the recruitment of woody stems to larger (>0.9 m tall) size classes, which could affect long-term successional trajectories, and (2) diminishes forb density and species richness, especially at higher site productivity, but increases total forest floor vegetation mass (mostly bracken fern and sedge), especially at lower site productivity. Given associations of bracken fern and sedge with poorer and/or more open sites and assuming high palatability of forbs, this pattern may result from the combination of selective herbivory and higher light availability caused by limited recruitment of trees and shrubs to taller strata.     

Availability of standing trees for large cavity-nesting birds in the eastern boreal forest of Québec,Canada

Large cavity-nesting birds depend on large-diameter trees for suitable nest sites. The increased spatial extent of commercial timber harvesting is modifying forest structure across the land base and may thus compromise the availability of large trees at the landscape scale. In this study, our objectives were to (1) characterize the availability of large living and dead trees in old-growth stands dominated by different tree species and surficial deposits that encompass the range of natural cover types of eastern Québec's boreal forest; (2) analyze the distribution of trees among decay-classes; and (3) compare the availability of large trees in unharvested, remnant, and harvested stands for the entire range of decay-classes. A total of 116 line transects were distributed across unharvested forests, remnant linear forests, and cutblocks in cutover areas. Unharvested forest stands (black spruce [Picea mariana], balsam fir [Abies balsamea]–black spruce, balsam fir–white spruce [Picea glauca] and balsam fir) reflected a gradient of balsam fir dominance. The remnant forests selected were isolated for 5–15 years. Analyses were performed at two diameter cut-off values. Trees with DBH ≥20 cm were considered for availability of total trees whereas trees with DBH ≥30 cm were considered for availability of large trees. Forest stands comprised high proportions of standing dead trees (33% of all stems, 8% were large dead stems). Availability of total and large standing trees increased with the dominance of balsam fir in stands. Forest stands located on thick surficial deposits showed higher densities of large dead trees for every stand type suggesting a higher productivity on those sites. Availability of stems according to decay-classes showed a dome-shaped distribution with higher densities of snags in intermediate decay stages. However, for large stems, black spruce stands showed a significantly lower availability that was consistent across all decay-classes. In linear remnant forests, pure balsam fir stands were absent. Remnant stands thus showed a much lower availability in large trees when compared with unharvested balsam fir stands. Clearcuts had the lowest densities of dead trees across sampled stands. Current even-aged management practices clearly affect availability and recruitment of large trees, therefore forest-dwelling wildlife relying on these structures for breeding is likely to be affected by large-scale harvesting in coniferous boreal forests.     

Understanding plantation transformation using a size-structured spatial population model

Plantation transformation is a goal of increasing interest to silviculturalists. The target forest state is characterised by high variance in age and size, and an irregular spatial structure, which leads to inhomogeneous interactions between, and consequent development of, trees in the stand. This presents a difficulty for traditional methods such as yield tables, and demands a more careful consideration of stand dynamics. On the other hand, while forestry has a great heritage of simulation, the level of complexity implemented at an individual level generally precludes direct understanding of stand scale behaviours, and leads to difficulties in verification with appropriate data.A promising approach is the application of relatively simple models developed by ecologists. These can be adapted to yield accurate representations of forest stands, while being highly amenable to analysis. Motivated by data from Scots pine (Pinus sylvestris L.) stands, we here apply a simple spatial birth-death-growth model to the comparison and analysis of transformation strategies for plantation stands. The model captures the effects of neighbours in a way which retains the conceptual simplicity of a generic, analytically solvable model, while allowing insights into the driving factors of population dynamics.Timing and intensity of management interventions, as opposed to their specific criteria, are of primary importance: thinnings of a moderate intensity performed over a long period produced the best results. Variation in the strategy applied leads to more subtle effects which transformation strategies must also take into account, such as the development of variation in size of the remaining trees (increased using spatially correlated thinnings), the survival chances of regeneration and “underplanted” trees, and the overall productivity of the stand (increased using spatially homogeneous crown thinning). Finally, we demonstrate the robustness of model predictions to fundamental choices of model formulation.