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Highlights • Data from even- and uneven-aged spruce stands used to assess response to cuttings. • A stand basal area growth model predicted cutting responses without bias. • Growth rate of uneven-aged stands was 20% lower than in even-aged stands. • Growth response to cuttings was notably quicker in even-aged spruce stands. Abstract This study evaluated the basal area growth of Norway spruce stands subjected to different management strategies; specifically, even-aged (EA) stands treated with thinning from below and uneven-aged (UEA) stands treated with selective cutting. Analysis was based on extensive empirical data obtained from permanent long-term experiments established in 23 even-aged and 26 uneven-aged Norway spruce (Picea abies (L.) Karst.) stands in Southern and Central Finland. The specific goals were to determine whether there are differences in: (a) the relationship between the stocking level and the stand basal area growth, (b) the stand basal area growth rates at a given stocking level, and (c) the stand basal area growth responses to cuttings between EA and UEA stands. A model-based approach was adopted in the analysis. Modelling was used to describe general trends and patterns in the data, emphasising the effects of overall stand density, cutting intensity, and management strategy on post-treatment stand growth. A model for a stand basal-area growth was fitted as a mixed linear model to the pooled data from EA and UEA stands. Model simulations were conducted to elucidate how the treatment of stands affects the predicted stand basal area growth. The analysis revealed a clear general effect of stocking level on stand basal area growth for all data. Growth increased with increasing stocking density. There was a significant difference in the stand basal area growth of EA stands and UEA stands. The growth of UEA stands was ca. 20% smaller than that of EA stands. There were also major differences in the timing and magnitude of the growth response to cutting between EA and UEA stands. Post treatment growth was noticeably slower in UEA stands than in EA stands, especially during the first 10 years after cutting. The results clearly show that the growth response of the trees remaining in EA stands is faster and greater than that in UEA stands, enhancing the stand basal area growth. [ABSTRACT FROM AUTHOR]

Norway spruce cone crops in individual trees from two seed ripening years 2012 and 2014 were studied. Data were collected from five stands in southern Finland, managed by single-tree selection harvests since the 1980s. The upper third of living crown of each individual tree was photographed for digital cone counting with image analysis. The average number of cones per tree for trees bearing any cones was 92 in 2014 and 66 in 2012. Highest cone numbers found per individual tree were 526 in the year 2014 and 364 in the year 2012. Of all trees studied, 55.5% produced cones during both years, 9.6% produced cones once and 34.9% did not produce cones in 2012 or 2014. The number of cones per tree in 2014 was positively correlated with tree diameter at breast height and the presence of cones (at least twenty) in that particular individual two years earlier and negatively correlated with local basal area. The quality of the seed crop in 2014 as determined in two of the stands was poor. Based on X-ray analyses, 44% of seeds were empty, 29% were damaged by insects feeding on seeds ( Plemeliella abietina or Megastigmus strobilobius ) and only 25% were full and capable of germination. The results have implications for management practices in uneven-aged Norway spruce stands. It is suggested that at each harvest entry, some large, prolific trees should be retained in order to increase the total number of seeds produced in a stand to enhance regeneration and the recruitment of new seedlings. [ABSTRACT FROM AUTHOR]

Stand development after heavy diameter-limit cutting in spruce forests in southern Finland was addressed in this study. Tree diameter growth, regeneration and undergrowth, stand structure, and volume yield level were addressed with data from an experimental set of six stands. They were harvested once with a breast-height diameter limit of 21–23 cm and left to recover for 26–29 years until remeasured and studied. Spruce regeneration was abundantly present with an average of 5000 seedlings (height 3–129 cm) ha −1 . Additionally, there were some 500 saplings (diameter at breast height 0.1–4.0 cm) ha −1 , which included both the regeneration established and developed after the harvest and included seedlings and saplings that were already present before the harvest. Trees in all size classes reacted to partial release with accelerating diameter increment without substantial lag. Trees with a high initial diameter had a consistently higher average growth rate than smaller trees. The stands had recovered quite well and evolved into fully stocked stands with a high number of trees in the lower canopy layers, implicating good prospects for the application of sustainable single tree selection. The average stand volume growth was 4.9 m 3 ha −1 year −1 , which was close to the level achieved in single tree selection with spruce in the area. Heavy diameter-limit cutting had not resulted in the depletion or destruction of stands. [ABSTRACT FROM AUTHOR]

• Natural regeneration was highest when tree density was low and mineral soil exposed. • With site preparation more trees can be retained, maintaining the same seedling number. • Seedling growth was low in denser stands and negligible in unthinned control stands. In northern boreal region the growth of forests is slow, and yield and profit are low, which is why low reforestation costs are important for profitable forestry. If natural regeneration is successful, expensive artificial forest regeneration (planting or direct seeding) can be avoided. In this study, we look at the impact of overstory density and site preparation on natural regeneration and seedling growth of Scots pine. Study stands were established in different parts of Northern Finland and in each stand following treatments: 50, 150 and 250 trees ha−1 or unthinned control, where the stand density was ≥ 250 trees ha−1, were randomly allocated to experimental plots. In addition, site preparation (disc trenching, 4000–5000 m ha−1) was carried out on two experimental plots in which tree density was either 50 or 150 trees ha−1. In the experimental stands seedling number, age and growth were monitored for 11 years. Monitoring revealed that the number of seedlings increased with decreasing tree density. Average seedling height growth was very low or even non-existent in the unthinned control and in the densest (250 trees ha−1) treatment, but increased when the density of trees decreased. The highest seedling number and the highest growth were achieved when the tree density was 50 trees ha−1 and the soil was prepared to expose mineral soil. Achieving e.g. 2000 seedlings ha−1, would need about 40% exposition of mineral soil. The required low tree density implies that not only seed supply from seed trees and site preparation is important for regeneration success in northern boreal Scots pine forests but also the reduction of competition by mature trees. [ABSTRACT FROM AUTHOR]

• We derived structural traits from Terrestrial Laser Scanning data to describe even-aged and uneven-aged boreal forests. • The total amount of plant material was similar between management types. • The differences between management types could be quantified by examining the vertical layering. • Uneven-aged stands were more structurally heterogeneous than even-aged stands, where heterogeneity increased with stand age. Forest management practices modify the composition and three-dimensional structure of boreal forests. Such changes affect light regimes, microclimate and habitat availability in forests, thus contributing to the regulation of ecosystem functioning and biodiversity. Compared to traditional even-aged forestry, prevalent in Fennoscandia since the mid-20th century, uneven-aged forestry has emerged as an alternative approach that may lead to more diverse and resilient forests, as well as a more sustainable provision of ecosystem services. However, the biophysical impacts of uneven-aged strategies have not yet been robustly quantified. Here, we present a detailed assessment of the structural characteristics of even-aged and uneven-aged boreal forest stands in southern Finland, aiming to clarify how these different management approaches regulate three-dimensional forest structure. Using terrestrial laser scanning, we derived and compared several structural traits closely linked to forest functioning. We found that, although different management types result in similar patterns in total plant material, they differ significantly on how plant material is allocated within vertical strata. Moreover, we demonstrated that commonly used structural diversity metrics cannot not capture the morphological intricacies arising from the three-dimensional dispersion of plant material inside the forest stand. Our results highlight the dynamic nature of even-aged forests, where the structural characteristics change with the rotation, whereas uneven-aged forest structures are more stable over time. Precise quantification of forest structure will help to understand which attributes impact the environmental functions and conditions that modify ecosystem services, and how these are altered with forest management. [ABSTRACT FROM AUTHOR]

Uneven-aged forest management is suggested to be a sustainable management alternative in boreal forests, but knowledge on applicable harvest intensities is very limited as majority of the studies has focused on even-aged management practices. The ecosystem model EFIMOD was used to assess the effect of selection cuttings on ecosystem production, carbon sequestration and volume increment in spruce stands. The model was calibrated and validated against experimental data from 20 permanent forest plots in southern Finland where stand responses to uneven-aged management had been monitored for 25 years. The simulated scenarios started with planting trees on bare land, simulation of first decades according to even-aged management, and a subsequent transformation into uneven-aged stand structure and management. Simulated selection cutting scenarios contained variations of both harvest interval (10–30 years) and postharvest stand density (basal area 8–16 m 2 ha −1 ). We hypothesized that longer harvest intervals and higher post-harvest basal areas will positively affect the net ecosystem production, nitrogen use efficiency, and forest carbon sequestration. The results presented here are for a period of 90 years. Simulations showed that net ecosystem production (NEP) increased from 0.25 to 0.5 kg m −2 a −1 of carbon with longer harvest intervals and higher postharvest density, and was generally less than that at undisturbed development. Nitrogen use efficiency (NUE) varied from 100 kg NPP per kg consumed N for heavy cuttings to 300 kg NPP per kg consumed N for light removal of trees. Changes in soil carbon stocks were negative for most scenarios (5–20% decline in terms of total soil C), and the decline was most pronounced with lowest postharvest density and short harvest intervals. The volume of harvested timber was between 320 and 400 m 3 ha −1 for a 60-year period. Longer harvest intervals resulted in increased timber production. Stem volume growth (5–7 m 3 ha −1 a −1 ) was equally affected by both harvesting parameters. The cumulative volume of deadwood of 80–120 m 3 ha −1 was substantially higher with the longest harvest interval (30 years) than with the shorter alternatives where it comprised 40–60 m 3 ha −1 . The simulations provide novel results on different harvesting options for uneven-aged forest management of boreal Norway spruce stands. These results fill a gap in knowledge on ecosystem responses to alternative management regimes and support the development of sustainable management practices. [ABSTRACT FROM AUTHOR]

Highlights: [•] Evaluation of forest management options in native Año Nuevo Pinus radiata stands. [•] Affect of gap size on survival and growth of Pinus radiata seedlings. [•] Affect of site treatment on survival and growth of Pinus radiata seedlings. [•] Seedling survival and growth of various Pinus radiata genetic strains. [•] Screening trials of Pinus radiata seedlings of known pitch canker resistance. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to describe the dynamics of seedling establishment and development in spruce-dominated uneven-aged boreal forests. The study was based on empirical data from 15 stands with permanent plots, which had been intensively monitored for 10 years in southern Finland. All trees (height>1.3m) were measured every fifth year. Regeneration was measured on 64 permanent sample plots (4m2) in each stand. The establishment of first-year seedlings was analysed on a yearly basis. The survival and development of older Norway spruce (Picea abies (L.) H. Karst.) seedlings were analysed based on observations made every five years. The establishment of spruce seedlings was closely correlated with the abundance of seed crops. Seedling cohorts originating from abundant seed crops were clearly detectable in the development of seedling height distributions over time. It took about 15 years for spruce seedlings to reach a height level of 15–30cm. Local basal area had hardly any effect on the emergence or survival of small spruce seedlings, while the number of higher spruce seedlings decreased with increasing local basal area. [Copyright &y& Elsevier]

Abstract: The study focused on the initial development of oak (Quercus robur L.) seedlings on former agricultural fields with or without treeshelters. Additionally, planting and direct seeding were preliminary compared in terms of a parallel small-scale seeding trial. The influence of treeshelters was examined using 120-cm-high polypropylene tubes. Initial success was assessed in terms of average survival rate and seedling height during a 5-year-period after establishment. The study was based on 8 experimental plots, with 3 sheltering treatments (100, 50 and 0% of the seedlings sheltered). A set of seeding plots were established adjacent to the planting experiments. The average survival rate for the planted seedlings was 75–83%. Sheltering had accelerated the height growth of the planted oaks substantially (average height was 60cm for 0% sheltered, 82cm with 50%, and 101cm for 100% sheltered). The sheltered and unsheltered seedlings in the 50% treatment exhibited growth and mortality similar to the 100 and 0% treatments, respectively. The seeded seedlings were much smaller (average 34cm) and their combined emergence and survival rate (average 56%) was lower than the survival rate in planting. Since the seeding plots did not belong to the same block design as the planting treatments, differences between seeded and planted seedlings were not statistically tested. The seedlings in all treatments were subjected to rapidly increasing competition by the remarkably proliferating weed vegetation, resulting in poor growth and vigor, and high mortality rate in direct seeding but much less so in planting. With an unexpectedly low incidence of herbivory in the study stands, the survival rate of unsheltered seedlings was not significantly lower than that of sheltered seedlings. [Copyright &y& Elsevier]

Abstract: The aim of the study was to model the regeneration establishment, and the survival and development of established seedlings in uneven-aged, Norway spruce (Picea abies (L.) H. Karst.) forest stands in southern Finland. Models were based on a 5-year monitoring period of permanent sample plots established in forest stands managed by selective harvests. Separate models were obtained for spruce, birch (Betula pendula Roth and Betula pubescens Ehrh.) and aspen (Populus tremula L.), all of which were well represented in the data. Since the stand structure of uneven-aged forests is irregular, spatial variation in competition factors and species composition were considered in the modelling. Due to the spatially hierarchical correlation structures of the data, a mixed modelling technique was applied in the estimation of the model parameters. Establishment models were developed for the number and initial height of established seedlings that had attained the set threshold height limit of 10cm during a 5-year period and thereafter survived until the end of the period. Prediction models were also developed for the survival, height increment and diameter at breast height of juvenile trees that were at least 10cm tall at the beginning of the 5-year period. The latter model is needed only when juvenile tree models are replaced with models for advanced trees. Simulations conducted for demonstration and validation purposes revealed that the regeneration establishment and juvenile growth models can be applied to construct a simulation system for the optimisation of uneven-aged spruce stands in southern Finland. [Copyright &y& Elsevier]

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Abstract: The sustainability of indigenous Monterey pine (Pinus radiata D. Don) at Año Nuevo stands in the central coast of California was examined. The foremost management objective in these stands is to establish and maintain stand structures that ensure a sustainable presence of the species in terms of uneven-aged management. The major threats are the proliferation of shade-tolerant tree species and the pitch canker (Fusarium circinatum) disease. The study was based on data from 17 systematically placed sample plots, measured once, in one stand with a very high degree of variation in stand structure and species composition. The results indicated that the sustainability of Monterey pine is not assured by existing stand structures. Monterey pine regeneration is almost completely lacking. Intensive shading and competition from high stand densities of shade-tolerant broadleaf trees are inhibiting regeneration, and growth of seedlings and saplings. Pitch canker is affecting growth, vigor, and competitive status of Monterey pine, but its progress and long-term impact remain unknown. Single tree or group selection cuttings, combined with treatments that enhance regeneration, are urgently required for the promotion of Monterey pine. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to examine the effects of type and amount of ground vegetation and substrate on the germination and early survival of Norway spruce (Picea abies (L.) Karst) seedlings in uneven-aged stands on mineral soils in Southern Finland. The study was conducted on two permanent plots representing average site quality for spruce stands in the area. A gradient in selection cut intensity and residual stand density was imposed across each of the two permanent plots. Regeneration and vegetation surveys were repeated annually on a grid of unmanipulated microplots and on a set of soil treatment microplots. The results indicated that the number of spruce germinants per unit area was positively correlated with herb cover but negatively correlated with total plant cover. Germinant density was also related to vegetation-free seedbed conditions, high overstory competition index and presence of larger spruce seedlings. Regeneration microsites dominated by moss or with plants with a relatively high light demand were associated with low germinant numbers. Bare humus layer and decayed stumps seemed to promote germinant emergence. Exposure of mineral soil resulted in germination rates that were 4.3–6.9 times higher than in undisturbed conditions during the first growing season. [Copyright &y& Elsevier]

The purpose of the study was to examine the effect of retained Scots pine (Pinus sylvestris L.) trees in the context of even-aged management systems on height, diameter growth, and branching of individual Scots pine seedlings and seedling stands in Southern Finland. A modeling and simulation approach was applied. Empirical models were constructed using data sets acquired from temporary sample plots in nine stands. The models were used to simulate tree height, diameter, and branch diameter growth. Results indicate that Scots pine trees retained in Scots pine seedling stands had not brought about unstocked or very poorly stocked patches around their bases in the study stands. Each retained tree of 25–40 cm in diameter reduced the height growth potential of Scots pine seedlings about 9–17% within a circle of 10 m radius. Retained tree competition did not result in reduced tree diameter for a given height. Retained tree influence on the diameter of the thickest branch of a seedling was rather small for practical applications, but the sum branch cross-sectional area was reduced, especially on fertile sites. In stand level simulations, the retention of 48 ha−1 trees of 25 cm average diameter and 21 m height on a rather poor site resulted in 15 years in about 5–7% decrease in seedling height, 6–8% decrease in diameter, and 2–5% decrease in maximum branch diameter compared to no retention, varying with the seedling stand density. The effect of the spatial pattern of retention in random, regular, or clustered structures on seedling growth was marginal. [Copyright &y& Elsevier]

Focuses on productivity and economics of mixed two-storied Norway spruce and birch stands in southern Finland. Examination of plantation with empirical stand structure, growth and yield; Development of the spruce stand; Yield loss for the spruce stand due to growth retardation.

Abstract: The main energy sources of soil microorganisms are litter fall, root litter and exudation. The amount on these carbon inputs vary according to basal area of the forest stand. We hypothesized that soil microbes utilizing these soil carbon sources relate to the basal area of trees. We measured the amount of soil microbial biomass, soil respiration and microbial community structure as determined by phospholipid fatty acid (PLFA) profiles in the humus layer (FH) of an even-aged stand of Scots pine (Pinus sylvestris L.) with four different basal area levels ranging from 19.9m2 ha−1 in the study plot Kasper 1 to 35.7m2 ha−1 in Kasper 4. Increasing trend in basal respiration, total PLFAs and fungal-to-bacterial ratio was observed from Kasper 1 to Kasper 3 (basal area 29.2m2 ha−1). The soil microbial community structure in Kasper 3 differed from that of the other study plots. [Copyright &y& Elsevier]