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• Crown and branch sizes decrease ~20% per 25% increase in neighborhood density. • >15-cm-diameter appendages develop in ~160 ± 60 yr due to neighborhood density. • Appendages associated with reiterated trunks strongly correlate with crown injury. • An empirical neighborhood-density and injury-based developmental model is presented. • Aggregate Picea crown structure develops ~100% faster than in Psuedotsuga menziesii. Large trees are critically important for structuring ecosystems and providing habitat, and trees with complex crowns provide more of these services than comparably sized trees with simple crowns. Forest managers are increasingly emulating old-growth structure by retaining various densities of aggregated and dispersed trees. This study explores how individual within-crown complexity develops in a wide range of tree densities and interprets them in terms of management goals. Stratified LiDAR data were used to select 36 Picea sitchensis trees 55 to 91 m tall and from the complete range of tree densities in Olympic rainforests. These were climbed, three-dimensionally mapped—including the trunk and every appendage—to quantify tree allometry and habitat-related structures within their crowns. Sampled trees were then aged with crossdated increment cores to construct a chronosequence of crown development. The sample ranged from 70 to 250 cm diameter and 100 to 400 years old. Circular 30 m radius plots were installed around each tree to quantify neighborhood density. An additional 19 trees ranging from 10 to 94 m tall were added to the sample (N = 55) to describe baseline crown development and then compared to the 36-tree sample in which we modeled how this baseline is altered by neighborhood competition. After ∼200 yr, crown mass increases faster than trunk mass due to accumulation and growth of large appendages. The largest neighbors within 25 m compete with Picea , reducing trunk and appendage diameters as well as crown volume by roughly 20% for each 25% increase in density for a given tree age. Reduced growth and higher mortality of lower-crown appendages in dense forests delays development of large (>15 cm diameter) appendages for over 100 yr. Abundance of structures associated with reiterated trunks is unrelated to neighborhood density but increases with crown damage. These findings contribute to an empirically-based conceptual framework for crown development in Picea and interpretation of management guidelines. Picea is then compared to Pseudotsuga menziesii —another well-studied tall conifer of Olympic rainforests. Picea accumulates ecologically important crown structures much faster than Pseudotsuga yet has roughly half the longevity, indicating that these co-occurring species have complementary functions. Because of its shade tolerance and extremely rapid growth in rainforests, Picea can be used to accelerate development of complex crown structures in forests typically planted with Pseudotsuga after logging. [ABSTRACT FROM AUTHOR]

Bark beetles (Curculionidae: Scolytinae) can cause widespread tree mortality, and change the structure, composition, and function of forests; however, limited data is available on bark beetle infestation of true fir forests. Although Polygraphus proximus Brandford (Coleoptera: Scolytidae) causes rapid degradation of large areas of natural and planted fir forests in Russia, the species is not present in large numbers and does not cause mass mortality in central Japanese subalpine/subarctic forests dominated by Abies veitchii . Furthermore, the relationship between P . proximus infestation and tree trunk diameter has not yet been studied to determine if the insect has a preference for trees of a certain diameter, although tree trunk diameter is often a crucial parameter affecting bark beetle colonization and tree mortality. We investigated P . proximus attack on A . veitchii and the association between the resulting tree mortality and tree trunk diameter at two sites in Honshu and Hokkaido, Japan. Polygraphus proximus colonized and utilized standing A . veitchii trees and fresh-cut logs. Both live and standing dead A . veitchii trees were attacked with high frequency: 331 (70.0%) of 473 trees in Honshu, and 121 (88.3%) of 137 trees in Hokkaido. Abies veitchii mortality was 38.1% in Honshu and 59.1% in Hokkaido. The proportion of trees with entry holes was significantly higher in small-diameter trees than in large-diameter trees in Honshu. Small-diameter trees also had significantly more holes than large-diameter trees in Honshu. On the other hand, there were no significant relationships between tree trunk diameter, and the presence and the number of holes in Hokkaido. Large-diameter trees were better able to survive P . proximus attacks in both sites. This study suggests that the beetles attack small-diameter trunk trees in early phase of mass mortality and then gradually attack large-diameter trunk trees with the increasing beetle attack. Polygraphus proximus may be influencing forest structure of A . veitchii . Enhanced colonization of small-diameter trees by P . proximus may act as a trigger of mass mortality and result in higher tree mortality might pose a threat to the regeneration of A . veitchii forests in Japanese subalpine/subarctic areas. [ABSTRACT FROM AUTHOR]

The world is experiencing serious threats from invasive alien plants that impact on ecosystem services provision. Although a lot of investment has been made in trying to come up with ways to control the spread of alien species, the majority of these ways have not been successful. Understanding the response of different tree size categories to mechanical control such as ‘cut and ring barking’ may bring long lasting solutions to the field of invasion biology. In order to understand the effect of cutting height and size (basal diameter) on control of Acacia mearnsii , we sampled plots in which all trees were cleared in the past 12, 9, 6 and 3 years. We recorded the number of stumps that coppiced and that were killed by ‘cut and ring barking’ method. We also recorded the number of coppices that were produced on each stump. Cutting height and diameter of the tree had an effect on survival. Trees with larger diameters and cut at the greatest height had lower chances of survival. Our findings confirm at least 50% success for small diameter size classes and 100% for diameters >16 cm. We conclude that mechanical control using ‘cut and ring barking’ should be used in the control of A. mearnsii , but complemented with fire, biological and chemical control in order to suppress recruitment from the seed bank. [ABSTRACT FROM AUTHOR]

Structurally diverse forests provide resilience to an array of disturbances and are a mainstay of multiple-resource management. Silviculture based on natural disturbance can increase structural heterogeneity while providing other ecological and economic benefits. One useful silvicultural tool for promoting structural heterogeneity is retention harvesting, whereby a portion of forest stands are left unlogged, transitioning even-aged stands to multi-aged. We report stand and tree dynamics 11 years after retention harvest in a central Montana Rocky Mountain lodgepole pine forest with evidence for a mixed-severity fire regime. Treatments were implemented on 16 experimental units with prescriptions for two 50% overstory basal area retention patterns (Aggregated and Dispersed) crossed with two levels of prescribed fire use (Burned and Unburned). The aim of this study was to identify (1) how retention harvest spatial pattern affects stand dynamics, (2) if stand dynamics after retention treatments are more simply attributable to tree size and competition, or if retention pattern affects dynamics beyond those measures, and (3) how stem and basal area heterogeneity varied over the 11-year measurement period. Retention pattern affected overstory density, growth, mortality, and regeneration density and stocking. After controlling for the fine-scale factors of tree size and competition, overstory mortality, regeneration stocking, and regeneration height growth did not vary by treatment-scale factors. Fine-scaled factors explained significant variation in overstory basal area growth, but at the scale of experimental units, growth was also greater in Dispersed treatments. Prescribed burning interacted with retention pattern to influence overstory tree growth, increased overstory mortality, and increased regeneration height growth. Overstory heterogeneity (e.g., in basal area) degraded more rapidly in treatments with the Dispersed spatial pattern than Aggregated. This study evaluates novel silvicultural treatments in a lodgepole pine forest and highlights the tradeoffs between retention patterns combined with broadcast burning on forest change. Our results are useful for planning silvicultural treatments in multiple-use forests designed to promote structural complexity and resilience to disturbances. [ABSTRACT FROM AUTHOR]

Tree crowns are commonly measured to understand tree growth and stand dynamics. Crown ratio (CR--crown depth-to-total height ratio) is significantly affected by a number of tree-and stand-level characteristics and other factors as well. Generalized mixed-effects CR models were developed using a large dataset (measurements from 14,669 trees of Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica (L.)) acquired from permanent research plots in various parts of the Czech Republic. Among several tree- and stand-level variables evaluated, diameter at breast height, height to crown base, dominant height, basal area of trees larger in diameter than a focal tree, relative spacing index, and variables describing the effects of species mixture and canopy height differentiation significantly contributed to CR variation. We included sample-plot-level variations caused by randomness in the data and other stochastic factors into the CR models using the mixed-effects modeling approach. The logistic function, which predicts the values between 0 and 1, was chosen to develop the generalized CR mixed-effects model. A large proportion of the CR variation (R²adj ≈ 0.63 (Norway spruce); 0.72 (European beech)) was described by generalized mixed-effects model without significant residual trends. Testing the CR model against a part of the model fitting dataset confirmed its high prediction precision. Our CR model can be useful for growth simulation using inventory databases that lack crown measures. Other potential implications of our CR models in forest management are mentioned in the article. [ABSTRACT FROM AUTHOR]

The sweet cherry tree shows an acrotonic growth habit and grows as a forest wood. Apical dominance is important in sweet cherries and commercial growth is not possible without human intervention. It is thus difficult to obtain a good tree shape and enough shoots and leaves for quality and a plentiful crop in cherry trees. For this reason, many studies have been carried out in cherries to obtain enough lateral shoots and leaves using different methods. These procedures included Perlan application, pruning (heading), bud management (bud selection, bud removal), girdling, notching, and scoring. The present study aimed to encourage leaf and shoot growth by various applications such as Perlan (BA+GA4+7), bud management, and bud management + Perlan in sweet cherries in 2015-2017. The Perlan, bud management, and bud management + Perlan applications were applied to trees of the Regina/CAB 6P combination just before bud break. These applications affected the diameter, length and number of primary shoots on the leader, number of 2-year-old shoots bearing fruit, and also the leaf area. Besides this, the applications affected tree volume. In general, the best results in terms of features were from bud management + Perlan. [ABSTRACT FROM AUTHOR]

New fire disturbance regimes under accelerating global environmental change can have unprecedented consequences for ecosystem resilience, lessening ecosystem natural regeneration. In the Mediterranean Basin, fire-dependent obligate seeder forests that are prone to increasingly frequent stand-replacing fires and then salvaged logged repeatedly can be vulnerable to additional disturbances for decades. In this study, we investigated, for the first time, the cumulative and interactive effects of two large high-severity fires at a short (<15-year) return interval and the subsequent burned timber harvesting with biomass removal on the post-disturbance recovery of such forests. We further assessed the type and amount of the material legacies (deadwood) that persisted through the different post-disturbance successional trajectories, as well as the influence of these legacies on forest regeneration. The early recovery of the studied forests after two consecutive large fires and post-fire logging was, in the first place, driven by fire repetition, which led to reduced seedling recruitment and enhanced regrowth of resprouter shrubs. Despite no interactive effects between fire and logging were detected after a single large fire event, two repeated fires followed by salvage harvesting had a greater negative impact than two fires alone (synergistic effects) on seedling establishment; while a lower positive impact (subadditive effects) on the recovery of resprouter shrubs. There was also an interaction modification effect in which fire repetition worsened the per-unit impact of salvage logging on forest regeneration. Nonetheless, the residual legacies, i.e., fine and coarse woody debris (unburned needles, downed branches, pieces of deadwood, and burned pine cones) that remained after the manual harvesting of the burned trees, aided seedling re-establishment and hindered the regrowth of the shrubby understorey. These findings indicate that high-intensity salvage logging after two large high-severity fires at a short return interval is inadvisable in fire-prone serotinous pine forests, unless it explicitly retains the key material legacies that help tree natural regeneration and enhance ecosystem resilience to the next disturbance. [ABSTRACT FROM AUTHOR]

The quantification of forest stand dynamics and structural characteristics within the development phases can be useful in facing with new challenges in the close to nature forestry. The formation of gaps is known as a critical part of the natural dynamics of oriental beech stands. This research was carried out to describe the structural features of naturally regenerated oriental beech stands in the gap formation phase using a set of stand structure quantification indices. Our results revealed that gaps have an average size of 178 m² and are closed mostly by oriental beech and velvet maple, while gap formation is done exclusively by beech. Also stands have slightly heterogeneous diameter distributions and uniform tree height. The average number of trees per hectare and the average of stocking volume were 379 stem ha-1 and 514.8 m3 ha-1, respectively. Furthermore, the mean value of dead tree volume was 36.3 m3 ha-1. The average mingling was 0.23 and tree-to-tree interval calculated and 4.87 m. Meanwhile, the mean value of diameter and height differentiation were 0.45 and 0.87 m, respectively. Knowledge on formation of natural gaps is useful for planning management interventions that are in accordance with natural process of development of the stands and exhibit minimum deviation from natural processes. We can conclude that harvesting in the gap formation phase led to shifting stand to the next phase and accelerate the natural gap phase scale disturbance. Removing trees in other phases does not emulate natural stand development pathways. [ABSTRACT FROM AUTHOR]

This study investigated the growth response of mature, isolated reserve trees ( n = 528) in two multiaged silvicultural systems in the Acadian Forest Ecosystem Research Project (AFERP). Absolute and percent increases in basal area increment (BAI; cm2·year−1) were assessed for the five predominant reserve tree species in AFERP: Acer rubrum L., Picea rubens Sarg., Pinus strobus L., Thuja occidentalis L., and Tsuga canadensis (L.) Carrière. Absolute growth was significantly greater in the large-gap treatment (23.7 ± 1.1 cm2·year−1; mean ± SE) than in the small-gap treatment (16.3 ± 0.9 cm2·year−1). Percent growth increase was greater in the small-gap treatment (187.6% ± 15.8%) than in the large-gap treatment (143.4% ± 19.3%), and both treatments had greater percent increases than the unharvested control (9.6% ± 5.2%). Species differed in their response to treatment. Pinus strobus had the greatest absolute increase (large-gap, 52.5 cm2·year−1), while Tsuga canadensis (large-gap, 270% ± 71.6%) and Acer rubrum (small-gap, 262% ± 42.4%) had the greatest percent increases. Growth responses typically diminished with increasing tree size and pretreatment growth rate; however, reserve trees showed greater growth responses than their paired analogues in the control across all initial tree sizes and prior growth rates. The results suggest that these silivicultural systems accelerate the development of large trees. [ABSTRACT FROM AUTHOR]

Retention harvesting shows great promise for restoring and maintaining forest structural and compositional diversity. However, economical, comprehensive monitoring is needed to advance understanding of the effectiveness of these management strategies through time. We investigate multitemporal winter Landsat sensor data (capturing snow ground cover at 7.6 cm and 106.7 cm depths) as a tool for discriminating between and providing regional estimates of both residual forest basal area (BA) and downed coarse woody material (DCWM) volume following retention harvesting in Minnesota, USA. Measurements from 34 ground plots were used with Landsat predictor variables to estimate these two biophysical forest parameters. According to similar studies, results for DCWM volume estimation are considered adequate, with an R2adj = 0.54 and absolute RMSE (RMSEa) = 19.02 m3·ha−1. Residual forest BA estimates were similar: total BA R2adj = 0.55 (RMSEa = 1.85 m2·ha−1), hardwood BA R2adj = 0.67 (RMSEa = 1.23 m2·ha−1), and conifer BA R2adj = 0.52 (RMSEa = 0.94 m2·ha−1). Use of winter Landsat imagery was key to quantifying these important forest biophysical parameters - a tool that carries the potential to transform our understanding of the impact of human and natural disturbance regimes on northern forest ecosystems. [ABSTRACT FROM AUTHOR]

When explaining the dynamics of individual trees, the incorporation of size and distance of neighboring trees into a model can improve the prediction of growth and mortality. Several methods have been proposed to define the number of competing trees based on variable zone radii and the principles of angle count sampling. The task of measuring position-dependent competition indices appears to be ideally suited for permanent sample plots and long-term studies of growth and yield (production), where the marginal effort of remeasurement is concentrated on measuring size attributes of survivor trees and the occasional distance of a new sample tree. The proposed competition index is based on point sampling with a variable basal area factor (BAFV) that is partially derived from the Spurr (1962) competition index. Point sampling is a fast, easy, and inexpensive methodology for selecting the number of competing trees, and the new BAFV methodology proved to be very efficient for estimating growth. With the selection of an appropriate basal area factor, it is possible to reduce the number of subject trees and competition trees in the sample, and eliminate the need for edge correction methods. Although the index value assigned to the subject tree using the BAFV is biased, an appropriate correction is presented and discussed. The average competition index obtained from using the corrected value for the subject tree and the BAFV for the competing trees equals the stand level estimate of basal area. [ABSTRACT FROM AUTHOR]

A method for automatic stem detection and stem profile estimation based on terrestrial laser scanning (TLS) was validated. The root-mean-square error was approximately 1 cm for stem diameter estimations. The method contains a new way of extracting the flatness saliency feature using the centroid of a subset of a point cloud within a voxel cell that approximates the point by point calculations. The loss of accuracy is outweighed by a much higher computational speed, making it possible to cover large datasets. The algorithm introduces a new way to connect surface patches belonging to a stem and investigates if they belong to curved surfaces. Thereby, cylindrical objects, like stems, are found in the pre-filtering stage. The algorithm uses a new cylinder fitting method that estimates the axis direction by transforming the TLS points into a radial-angular coordinate system and evaluates the deviations by a moving window convex hull algorithm. Once the axis direction is found, the cylinder center is chosen as the position with the smallest radial deviations. The cylinder fitting method works on a point cloud in both the single-scan setup, as well as a multiple scan setup of a TLS system. [ABSTRACT FROM AUTHOR]

Diameter at breast height has been estimated from mobile laser scanning using a new set of methods. A 2D laser scanner was mounted facing forward, tilted nine degrees downwards, on a car. The trajectory was recorded using inertial navigation and visual SLAM (simultaneous localization and mapping). The laser scanner data, the trajectory and the orientation were used to calculate a 3D point cloud. Clusters representing trees were extracted line-wise to reduce the effects of uncertainty in the positioning system. The intensity of the laser echoes was used to filter out unreliable echoes only grazing a stem. The movement was used to obtain measurements from a larger part of the stem, and multiple lines from different views were used for the circle fit. Two trigonometric methods and two circle fit methods were tested. The best results with bias 2.3% (6 mm) and root mean squared error 14% (37 mm) were acquired with the circle fit on multiple 2D projected clusters. The method was evaluated compared to field data at five test areas with approximately 300 caliper-measured trees within a 10-m working range. The results show that this method is viable for stem measurements from a moving vehicle, for example a forest harvester. [ABSTRACT FROM AUTHOR]

Climate change scenarios forecast rising temperatures for the Mediterranean region, which could enhance the vulnerability to drought stress in forest ecosystems. The long-term effects of climate forcing on tree performance can be, however, modulated by other environmental factors, such as competition and rising atmospheric CO2 concentrations., We assessed the concomitant effect of competition, climate and CO2 concentrations on the tree-ring δ13C-derived intrinsic water-use efficiency ( iWUE) and basal area increments ( BAI) of species with different drought tolerance: two Mediterranean deciduous species ( Quercus faginea Lam. and Quercus pyrenaica Willd.) and one conifer ( Pinus sylvestris L.). Additionally, given that competition may be managed to mitigate the effect of increasing drought stress, we further examined the influence of this variable on iWUE and growth using data compiled from the literature, providing the first review on the response of iWUE to competition., Competition had no significant effect on iWUE in any of the three species studied, whereas, as expected, growth rates were significantly higher under low-competition levels. This was consistent with the literature review, which showed that shifts in iWUE with competition changes are rare; supporting the hypothesis that leaf-level gas exchange tends to be a homeostatic trait. In the long term, the three species exhibited a significant increasing trend in iWUE due to the combined effect of increased CO2 concentration, climate and age. Growth, however, was mostly affected by competition and climate and in most cases was not enhanced as a result of the increase in iWUE., Synthesis. Regardless of their functional response to drought, trees respond to reduced competition through the structural shifts such as increased radial growth rather than leaf-level gas exchange adjustments. CO2 and climate are, therefore, the main drivers of iWUE variability, rather than competition. Thus, if temperature-induced drought becomes limiting, reducing competition for resources may not offset the detrimental effect of increasing drought stress on tree physiology and growth decline may occur without a CO2 fertilization effect. [ABSTRACT FROM AUTHOR]

The article presents the author's views on the better understanding of the changes in the trees development and growth and forest productivity through binding the long-term wood functioning and nitrogen deposition. Topics mention including the worldwide nitrogen cycle, tree growth and wood formation and wood functional traits.

Wind disturbance profoundly shapes temperate forests but few studies have evaluated patterns and mechanisms of long-term forest dynamics following major windthrows. In 1990, we initiated a large hurricane simulation experiment in a 0.8-ha manipulation (pulldown) and 0.6-ha control area of a maturing Quercus rubra-Acer rubrum forest in New England. We toppled 276 trees in the pulldown, using a winch and cable, in the northwesterly direction of natural treefall from major hurricanes. Eighty percent of canopy trees and two-thirds of all trees > 5 cm dbh (diameter at breast height) suffered direct and indirect damage. We used 20 years of measurements to evaluate the trajectory and mechanisms of forest response after intense disturbance. Based on the patch size and disturbance magnitude, we expected pioneer tree and understory species to drive succession. The first decade of analyses emphasized tree seedling establishment and sprouting by damaged trees as the dominant mechanisms of forest recovery in this extensive damaged area. However, despite 80% canopy damage and 8000-m² patch size, surviving overstory and advance regeneration controlled longer-term forest development. Residual oaks make up 42% of stand basal area after 20 years. The new cohort of trees, dominated by black birch advance regeneration, contributes 30% of stand basal area. There were shifts in understory vegetation composition and cover, but few species were gained or lost after 20 years. Stand productivity rebounded quickly (litterfall recovered to pre-disturbance levels in six years), but we predict that basal area in the pulldown will lag behind the control (which gained 6 m²/ha over 20 years) for decades to come. This controlled experiment showed that although the scale and intensity of damage were great, abundant advance regeneration, understory vegetation, and damaged trees remained, allowing the forest to resist changes in ecosystem processes and invasion by new species. [ABSTRACT FROM AUTHOR]

The US Forest Service's Forest Inventory and Analysis (FIA) program collects information on trees in areas that meet its definition of forest. However, the inventory excludes trees in areas that do not meet this definition, such as those found in urban areas, in isolated patches, in areas with sparse or predominantly herbaceous vegetation, in narrow strips (e.g., shelterbelts), or in riparian areas. In the Great Plains States, little is known about the tree resource in these noninventoried, nonforest areas, and there is a great deal of concern about the potential impact of invasive pests, such as the emerald ash borer. To address this knowledge gap, FIA's National Inventory and Monitoring Applications Center has partnered with state cooperators and others in a project called the Great Plains Initiative to design and implement an inventory of trees in nonforest areas. The goal of the inventory is to characterize the nonforest tree resource using methods compatible with those of FIA so a holistic understanding of the resource can be obtained by integrating the two surveys. The goal of this paper is to describe the process of designing and implementing the survey, including plot and sample design, and to present some example results from a reporting tool we developed. [ABSTRACT FROM AUTHOR]

Abstract: Long-term tree and seedling growth and survivorship data from permanent sample plots established in a neotropical dry forest in Jamaica from 1998 to 2008 were used to (1) model growth (periodic annual increment) and survivorship dynamics, (2) cluster structural and functional types, and (3) estimate the age of selected tropical dry forest tree species. A statistical comparison of parameter estimates derived from a generalized linear model (GLM) of each species to a reference species was used to group individuals based on size (DBH and height), and demographic dynamics (periodic annual increment and survivorship). We identified two groups of species based on structural types (canopy and sub-canopy species), three groups of species based on periodic annual increment (fast, intermediate, and slow growing) and four groups of species based on the probability of survivorship of seedlings and trees (very low probability of seedling survivorship but high tree survivorship (two groups); high survivorship throughout the DBH classes; very low survivorship, regardless of stem size). The composition of the groups was mixed, and included individuals of both structural types, and with different periodic annual increment and survival probabilities. The dichotomy of guilds found in tropical rainforests (pioneer and climax species) was not found in this forest. Individual and group GLMs incorporating empirical relationships between periodic annual increment and survivorship, across a spectrum of ontogenies and DBH’s, were also generated. The periodic annual increment models were then used to estimate the time taken by a newly germinated seedling to reach the largest recorded DBH. The fastest growing species was the hemi-cryptophyte Clusia flava which was estimated to take 74years to reach its maximum recorded size (12.1cm DBH), whereas the slowest growing species, Ziziphus sarcomphalus, was estimated to take 399years to reach its maximum size (24.4cm DBH). These dry forest trees were estimated to reach their maximum size (which was one-half or one-third of the largest DBH recorded for tropical rainforests) in a time similar to tropical rainforest trees. Some of the tree species are ubiquitous to other neotropical dry forests; therefore, our equations for periodic annual increment and survivorship can be applied elsewhere in the region. [Copyright &y& Elsevier]

Abstract: Empirical, statistically based models were used to describe the growth and development of Eucalyptus nitens plantations for a range of site productivities and the standard biomass and pulp silvicultural regime currently applied in Northern Spain. The results obtained, along with data gathered from a network of 68 plots, 48 trees felled for biomass estimations and 73 trees sampled for foliar area estimation were used to parameterize the 3-PG model for this species in Northern Spain. Most parameters associated with allometric relationships and partitioning (i.e. bark and branch fraction, basic density, age modifier and mortality) were derived from local data, and the remaining parameters were obtained from published studies on E. nitens or default values previously used for E. globulus. The parameterized model was validated with data from three trials measured from age 3years until age 8–14years, and performed better than the empirical model in terms of total stand under bark volume, mean diameter at breast height, basal area and foliar biomass. The process-based model was then used to forecast changes in plantations subjected to a clearwood regime, initializing the model at age 3years, considering 3 prunings, 2 thinnings and lengthening the rotation to 18years. This integrated regime was able to provide biomass for bioenergy, pulp or fibreboard wood and also solid wood, with thinning operations assisting the financial viability, and was a potentially good alternative for productive sites. [Copyright &y& Elsevier]

A period of stagnation in silver fir development has been recorded in all felled trees in selection forests of Serbia (233 trees on Mt. Goc and 451 trees on Mt. Tara). In the selection forests on Mt. Goc, the stagnation stage ranges between 40 and 330 years, but on Mt. Tara, it ranges from 15 to 185 years. It was concluded that the duration was caused not by the ecological and productivity potential (site class) of the soil for fir development, but primarily by the growth space, resulting from the application of single-tree selection or group selection systems. It was also found that the duration of latent state and tree sizes attained over that phase (except for height, and that was to a lesser extent) did not affect the silver fir tree development in the post-stagnation period. [ABSTRACT FROM AUTHOR]

The container type used in nursery culture is among the most important determinants of containerised seedling quality. The objective of the present study was to analyse root and shoot growth, root growth potential, and photochemical efficiency of seedlings of Picea abies, Robinia pseudoacacia, Pinus brutia, and Pinus nigra cultivated for 5 weeks in mini-plugs of 2 different cavity depths (37 and 60 mm). The results showed that precultivation of P. nigra and, to a lesser extent, of R. pseudoacacia in deeper mini-plug containers improved seedling morphological attributes and quality, but shallow containers produced better quality seedlings of P. abies. In P. brutia, the use of shallow containers led to the development of a superior root system, while the use of deeper containers produced seedlings with better above-ground characteristics. [ABSTRACT FROM AUTHOR]

Wood specific gravity is the single best descriptor of wood functional properties and tree life-history traits, and it is the most important variable in estimating carbon stocks in forests. Tropical pioneer trees produce wood of increasing specific gravity across the trunk radius as they grow in stature. Here, we tested whether radial increases in wood specific gravity were dependent on a tree's diameter or its age by comparing trees of different diameters within cohorts. We cored trunks of four pioneer species in naturally regenerating, even-aged stands in the lowland, wet forests of Costa Rica. For each core, specific gravity was determined for 1-cm radial wood segments, pith to bark. Increases across the radius were evident in all four species studied, and in four different stands for one species. For any given species in a given stand, the rate of radial increase in specific gravity as a function of radial distance from the pith was greater in smaller diameter trees. As the trees in a stand represent a colonizing cohort, these results strongly suggest that the radial increases in specific gravity in lowland pioneers are associated with tree age, not with tree diameter. Furthermore, the specific gravity of the outermost wood was not associated with tree radius, further negating size dependence. One consequence of these results is that species-specific biomass estimates for trees in secondary forests are likely to be confounded by age, as diameter alone may be a poor indicator of specific gravity in individual trees for pioneers of tropical wet forests. Abstract in Spanish is available at [ABSTRACT FROM AUTHOR]

Uneven-aged management of northern hardwoods frequently relies on diameter distributions in evaluating and controlling stand structure. However, the minimum tree diameter used to analyze diameter distributions varies among studies and may affect the interpretation of distribution shapes and, subsequently, stand structure. It has been suggested that the use of larger minimum diameters in the construction of these distributions would cause rotated sigmoid stand structures to exhibit a negative exponential distribution shape. To test this hypothesis, we constructed diameter distributions using minimum diameters of 3.0 and 13.0 cm for seven northern hardwood stands. Differences in distribution shape were observed only in unmanaged stands, in which three distribution shapes classified as rotated sigmoid using a 3.0-cm minimum diameter were classified as increasing-q when the 13.0-cm minimum diameter was used. [ABSTRACT FROM AUTHOR]

•Long-term juvenile growth patterns of tropical trees were studied to test two hypotheses: fast-growing juvenile trees have a higher chance of reaching the canopy (‘juvenile selection effect’); and tree growth has increased over time (‘historical growth increase’). •Tree-ring analysis was applied to test these hypotheses for five tree species from three moist forest sites in Bolivia, using samples from 459 individuals. Basal area increment was calculated from ring widths, for trees < 30 cm in diameter. •For three out of five species, a juvenile selection effect was found in rings formed by small juveniles. Thus, extant adult trees in these species have had higher juvenile growth rates than extant juvenile trees. By contrast, rings formed by somewhat larger juveniles in four species showed the opposite pattern: a historical growth increase. For most size classes of > 10 cm diameter none of the patterns was found. •Fast juvenile growth may be essential to enable tropical trees to reach the forest canopy, especially for small juvenile trees in the dark forest understorey. The historical growth increase requires cautious interpretation, but may be partially attributable to CO2 fertilization. [ABSTRACT FROM AUTHOR]

Growth indexes of 47 7-year-old progeny forests of Acacia mearnsii in Huangmian forest farm were measured. A. mearnsii plantation was managed for producing both tannin and timber, and considering the tannin yield and timber volume growth index, the family types fall into superior family type (the superior type), to-be superior type (the medium type), and preliminarily eliminated type (the elimination type). Eight superior families can be used for production, namely No.169, No.114, No.177, No.32, No.3, No.145, No.158 and No.134. [ABSTRACT FROM AUTHOR]

The boreal forest of higher latitudes constitutes a reservoir of trees of great ecological importance and unknown economic potential, but the stand dynamics in these regions still remain essentially unexplored. This paper examines the change in age and size structures during stand development on the northern border of the natural closed boreal forest in Quebec, Canada. Height, diameter, and age of trees were measured in 18 plots with stand ages between 77 and 340 years. The occurrence, size, and origin (layer or seed) of seedlings and saplings were assessed in subplots. Tree density ranged from 600 to 3750 trees·ha–1. Picea mariana (Mill.) BSP was the dominant species, mainly originating by layering. A cluster analysis segregated plots into even-aged and uneven-aged stands according to tree age, but size distribution of trees, saplings, and seedlings did not differ statistically between the two groups. Even-aged stands exhibited a 60% probability of assuming an uneven-aged structure between 120 and 200 years after stand initiation. At high latitudes, the closed boreal forest of P. mariana appears homogeneously sized, with similar distributions of diameter and height across all stages of stand development. [ABSTRACT FROM AUTHOR]

Abstract: Planting stock type and quality can have an important impact on early growth rates of plantations. The goal of this study was to evaluate early growth and root/shoot development of different planting materials in typical heavy clay soils of northwestern Quebec. Using one-year-old bareroot hybrid poplar dormant stock, four planting materials were compared: (1) regular bareroot stock, (2) rootstock (stem pruned before planting), (3) whips (roots pruned before planting), and (4) cuttings (30cm stem sections taken from the basal portion of bareroot trees, i.e. roots and shoot pruned). Rooted stock types (bareroot and rootstock) produced, on average, 1.2 times larger trees than unrooted stock types (cuttings and whips). However, shoot-pruned stock types (rootstocks and cuttings) reached similar heights and basal diameters as unpruned stock types (bareroots and whips), during the first growing season. Shoot pruning reduced leaf carbon isotopic ratios, suggesting that unpruned stock types were water-stressed during the first growing season. The stress was most likely caused by early leaf development while root growth occurred later in the summer. We conclude that shoot pruning bareroot stock is a useful management option to reduce planting stress without compromising early growth rates of hybrid poplars. [Copyright &y& Elsevier]

Relationships between stand growth and structural diversity were examined in spruce-dominated forests in New Brunswick, Canada. Net growth, survivor growth, mortality, and recruitment represented stand growth, and tree species, size, and height diversity indices were used to describe structural diversity. Mixed-effects second-order polynomial regressions were employed for statistical analysis. Results showed stand structural diversity had a significant positive effect on net growth and survivor growth by volume but not on mortality and recruitment. Among the tested diversity indices, the integrated diversity of tree species and height contributed most to stand net growth and survivor growth. Structural diversity showed increasing trends throughout the developmental stages from young, immature, mature, and overmature forest stands. This relationship between stand growth and structural diversity may be due to stands featuring high structural diversity that enhances niche complementarities of resource use because trees exist within different horizontal and vertical layers, and strong competition resulted from size differences among trees. It is recommended to include effects of species and structural diversity in forest growth modeling initiatives. Moreover, uneven-aged stand management in conjunction with selective or partial cutting to maintain high structural diversity is also recommended to maintain biodiversity and rapid growth in spruce-dominated forests. [ABSTRACT FROM AUTHOR]

In the Pacific Northwest, state agencies have adopted definitions of mature and old-growth forest, with minimum size and age criteria for the largest trees, as part of a program to protect rare forest habitats. State wetland rating and priority habitat protection guidelines use these criteria to identify mature and old-growth forested wetlands; however, these definitions are based on the characteristics of upland habitats and may not be applicable to wetlands. In this study, data from forested wetlands in western Washington were analyzed to estimate growth rates for five tree species: western red cedar, Sitka spruce, western hemlock, red alder, and shore pine. Estimated average diameter for mature forest is 46 cm (18 inches) and for old-growth 69 cm (27 inches), significantly smaller than the standard size criteria of 53 cm (21 inches) and 81 cm (32 inches), respectively. These results may be more appropriate as size criteria for these forest stages; however, growth rates varied widely between different wetlands and between trees in the same wetland. The great variation in growth rates calls into question the validity of estimating the age of a stand based on the size of trees. Consideration should be given to applying a higher degree of protection to all forested wetlands dominated by coniferous trees, regardless of the size of the trees. [ABSTRACT FROM AUTHOR]

Tree crown shape is an important trait affecting the light environment in forest canopies. We examined genetic and environmental effects on outer crown shape of young single-family stands of loblolly pine (Pinus taeda L.). Crown diameter profiles were measured after canopy closure at four experimental sites in the southeastern US. The two examined families of contrasting aboveground productivity differed in crown length but not in their outer crown shapes or crown shape ratios, defined as the ratio of crown diameter to crown length. Within each site, intensive silvicultural treatment, consisting of fertilization and control of competing vegetation, had little effect upon crown shape. A strongly significant effect of site on crown shape parameters was found in the family grown at all four experimental sites; however, density differences among the experimental series likely accounted for a part of the across-sites variation in crown shape. In contrast to other studies on crown shape in trees, and to findings at age 2 years in the same stands, we conclude that family effects on the outer crown shape were small compared with the environmental effects in these 5-year-old pine plantations, following canopy closure. [ABSTRACT FROM AUTHOR]

A field trial of cuttings and seedlings of Scots pine (Pinus sylvestris L.) was measured after 1, 2, 9 and 10 years. Growth-related and stem form characteristics of rooted cuttings were compared with those of seedlings of the same origin. The cuttings were shorter than the seedlings throughout the experiment, but the difference became smaller with age. The ranking of cuttings and seedlings by average height was already the same after one growing season regardless of the differences in planting heights of the cuttings, indicating that the genetic origin affected the height more than the initial planting height. The growth patterns of the cuttings were similar to those of the seedlings. The bole straightness and stem taper after 10 years in the field were similar in both plant types, but not stable, indicating that the use of cuttings for stem quality selection at an early age has no advantages over the use of seedlings. In conclusion, the consistent performance of cuttings compared with seedlings of the same origin indicates that performance of cuttings is a valid measure of their genetic potential and that cuttings can be used to speed up selection in breeding programmes with Scots pine. [ABSTRACT FROM AUTHOR]

Trees are known to modify their growth in windy climates, but these responses have not previously been linked to alterations in anchorage strength. The effects of stem mass, soil group, rooting depth and wind exposure (Detailed Aspect Method of Scoring (DAMS)) on anchorage were modelled using data from experiments where Sitka spruce (Picea sitchensis (Bong.) Carr.) trees had been mechanically overturned. Regressions of critical turning moment against stem mass were performed on combinations of soil group (mineral, gleyed mineral, peaty mineral and deep peat) and rooting depth (40, 40-80 and >80 cm), with DAMS as an additional factor. Correlations of DAMS with critical turning moment were positive for all combinations, and DAMS had a positive effect on the slope of all critical turning moment against stem mass regressions. When DAMS was added to the model, it increased the variance accounted for, from 66.5 to 71.2 per cent. When revised anchorage coefficients were applied to the ForestGALES wind risk model, critical wind speeds and associated return times for a 55-year-old stand were reduced on a relatively sheltered DAMS 14 site and increased on a wind-exposed DAMS 18 site. The implications of trees developing stronger anchorage in locations with greater wind exposure are discussed in relation to management of wind risk. [ABSTRACT FROM AUTHOR]

This study presents a predictive dynamic model developed to analyse the mechanical response of trees submitted to a turbulent airflow. This finite-element model integrates a three-dimensional description of tree architecture and is driven by fluctuating drag forces applied on all parts. For validation purposes, instantaneous wind velocities and wind-induced stem displacements of two trees were recorded in a mature Maritime pine stand (Pinus pinaster) at several heights. The tree geometrical and physical characteristics were measured to describe their architecture. No model parameter was adjusted. Tree motions appear to be driven by wind pulses reflecting turbulence intermittency. No evidence is found for resonant behaviour. In the mean wind direction, the simulated oscillations agree well with the measured time series. The underestimation of tree movement in the cross-stream direction outlines the importance of torque behaviour on the predictive accuracy of the model. The mechanical transfer functions of the modelled trees show vibration peak frequencies very similar to the measured ones. At higher frequencies, the simulated damping appears overestimated, with the set of parameters used. The model provides a sound basis to further investigate the influence of tree aerial architecture and turbulence structure on tree stability to wind. [ABSTRACT FROM AUTHOR]

Multinomial logistic (MNL) regression was employed to estimate the transition probabilities of a matrix growth model for dry forests of the eastern Bolivian lowlands. Probabilities of mortality, stability, and upgrowth of a size and species group were estimated as a function of tree and stand attributes influencing growth and mortality. Data for model estimation were drawn from logged and undisturbed permanent sample plots (PSPs) measured over 6 and 7 years in Chiquitania forests south of Concepción, Santa Cruz, Bolivia. The estimated transition probabilities of the MNL models are not significantly different from those derived from PSP data by the conventional approach of employing simple mean proportions of observed movements per guild and size class. MNL estimation is advantageous in that it generates a smoother distribution of transition probabilities across size classes, correcting for variance in the data and model estimation errors imposed by limited samples. Moreover, the MNL approach allows deterministic, stochastic, and dynamic prediction of forest evolution, while preserving the simple linear form of matrix models that facilitates their integration into economic optimization studies. [ABSTRACT FROM AUTHOR]

We analyzed the growth patterns of Thujopsis dolabrata var. hondai trees in an old plantation (161 years old), where no silvicultural treatments (e.g., thinning) have been conducted since the initial planting. The analysis focused on understanding individual growth under a long-term self-thinning process, and the stand-level stemwood production at the mature stage was evaluated. Nine canopy-layer trees and one suppressed tree were used for the analysis of annual increments in stem diameters, heights, and stemwood volumes for a given past year using the ring-width data. Both the diameter (at basal portion) and height of all the canopy-layer trees increased at similar rates during the early stage (i.e., 60–70 years after planting); however, after this period, only the height growth rates declined sharply. The annual growth rates of stemwood volume also simultaneously leveled off at the stand age of 40–60 years. Subsequently, the patterns diverged conspicuously, e.g., the growth rates were maintained or increased in some individuals, while it gradually decreased in the case of others until the present year. The divergence of growth pattern was likely to be triggered by intertree competition at several decades after the onset of canopy closure. The current stemwood production of the sample trees, including the suppressed one, was positively correlated with certain size parameters such as stem diameter at breast height and sapwood area at a height of 4 m. Based on the diameter-base allometry, the total stand stemwood production was estimated to be about 12.8 m3 ha−1 year−1. This estimate was higher than those of some old natural T. dolabrata forests (2.0–8.6 m3 ha−1 year−1) that have been well managed by repetitive selection thinning. Furthermore, individual mean stemwood production of the study plantation (0.03 m3 tree−1 year−1) was within the range of these natural stands (0.01–0.05 m3 tree−1 year−1). These comparisons suggested that the old T. dolabrata plantation still maintained a relatively high stemwood production potential despite the absence of artificial controls of tree density in the past. In terms of timber production, this fact implied that a rather long rotation (>100 years) can be applicable in the management of T. dolabrata plantations. [ABSTRACT FROM AUTHOR]

Questions: Which demographic and life-history differences are found among 95 sympatric tree species? Are there correlations among demographic parameters within this assemblage? Location: Central Amazonian rain forest. Methods: Using long-term data from 24 I-ha permanent plots, eight characteristics were estimated for each species: wood density, annual mortality rate, annual recruitment rate, mean stem diameter, maximum stem diameter, mean stemgrowth rate, maximum stem-growth rate, population density. Results: An ordination analysis revealed that tree characteristics varied along two major axes of variation, the major gradient expressing light requirements and successional status, and the second gradient related to tree size. Along these gradients, four relatively discrete tree guilds could be distinguished: fast-growing pioneer species, shade-tolerant subcanopy species, canopy trees, and emergent species. Pioneers were uncommon and most trees were canopy or emergent species, which frequently had low mortality and recruitment. Wood density was negatively associated with tree mortality, recruitment, and growth rates when all species were considered. Growth rates varied markedly among and within species, with pioneers exhibiting far faster and less variable growth rates than did the other species. Slow growth in subcanopy species relative to canopy and emergent trees was not a simple consequence of mean tree size, but apparently resulted from physiological constraints imposed by low-light and other conditions in the forest understorey. Conclusions: Trees of Amazonian rain forests could be classified with some success into four relatively distinctive guilds. However, several demographic and life-history traits, such as those that distinguish early and late successional species, probably vary along a continuum, rather than being naturally grouped into relatively discrete categories. [ABSTRACT FROM AUTHOR]

European forestry strategies place emphasis on developing alternative management practices to clearfelling within commercial forests as a means of increasing the non-market benefits of sustainable forestry. In the UK, many thousands of hectares of forest are being transformed to continuous cover forestry and a number of minimum intervention natural reserves are being created to encourage the development of old-growth conditions. This paper defines the term ‘old growth’ in the context of upland spruce-dominated plantations in Britain and evaluates different options for the location, design and management of old-growth areas to enhance biodiversity. Evidence outside of Britain from semi-natural analogues of upland spruce plantations suggests that old growth can develop 100–200 years after stand initiation in those parts of the landscape not subject to frequent catastrophic disturbance by wind and fire. Old-growth stands in these forests are characterized by a high proportion of large, old trees, multiple age classes and high volumes of fallen and standing deadwood. Studies of old spruce stands in the British uplands suggest that old-growth features can begin to develop after 80–100 years, conferring substantial benefits to species-groups such as hole-nesting birds, mammals (e.g. red squirrel), bryophytes, lichens and fungi. Based on the likelihood of wind damage it is suggested that ∼50 per cent of the current land area in upland Britain could support large patches (50–100+ ha) of old growth. To enhance colonization by woodland species, these old-growth patches should be within 2 km of existing semi-natural woodland, managed ideally on a minimum intervention basis. If production of timber was also an objective, old-growth stands could be managed by single tree selection or small group-fell silviculture, provided that over-prolific regeneration of shade-tolerant conifers was controlled and some deadwood and veteran trees were maintained. In surrounding areas subject to normal patch-clearfelling, small enclaves of old-growth forest (0.25–2 ha) could be retained to provide temporary habitat for species and facilitate dispersal through the landscape. The planning and design of old-growth areas needs to be considered at the landscape scale to ensure an appropriate balance between old growth and other types of woodland and non-woodland habitats. An imaginative approach to incentives will be required to encourage positive management for old growth. [ABSTRACT FROM AUTHOR]

The aim of this study was to quantify the effects of different soil scarification methods on tree growth. Soil scarification influenced stem volume and stem biomass yield of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) in a 17-year-old field trial in boreal Sweden. Soil scarification (disc trenching, mounding and ploughing) resulted in an average stem volume yield of 3.1 and 34.2 m³ ha-1 on the poor and intermediate sites, respectively, while corresponding values for no soil scarification were 0.9 and 16.7 m³ ha-1. In comparison to no scarification, ploughing increased volume yields by 500% on the poor site and by 200% on the intermediate sites. The ranking according to stem volume yield was ploughing > disc trenching = mounding ≥ no soil scarification. Averaged over the two sites, the mean annual increment of stem biomass was 219% and 145% higher (in d.w., 0.26 kg and 0.34 kg per sample tree) after ploughing compared with no soil scarification, for the average and dominant sample trees, respectively. Although not significant, the increased growth rate after soil scarification decreased the average stem basic wood density of the sample trees with 1.6% and 5.3%, at the poor and intermediate sites, respectively. In conclusion, soil scarification significantly increased the 17-year stem volume yield compared with no scarification. The results also indicate that the difference in stem biomass yield between ploughing and the other methods, especially no soil scarification, will increase even more in the near future. [ABSTRACT FROM AUTHOR]

This article presents information on a study related to age, reproduction and biomass allocation in Rhopalostylis sapida. It is estimated that mature palms at the Huapai site shed two fronds per year on average. Few individuals shed either fewer or more fronds during 1983/84. Frond shedding is associated with inflorescence development and occurs almost solely during the period December through May. Age estimation is tentative but the calculated ages of 150-250 years would not be unusual for a palm. Researcher R. Hnatiuk estimated individuals of Livistonia eastonii in northwestern Australian woodlands to be up to 280 years of age with rare individuals perhaps much older. In the field site described here, nikau is absent from the early stages of the kauri forest succession.

The article discusses the patchy distribution of rain forest tree species and the processes of rainforest regeneration. The vegetation in a plot of twelve-year-old plot regrowth in an experimental clearing in a virgin subtropical rain forest is recorded in detail and analysed by various numerical techniques. Problems concerning the subject include the regeneration of the canopy, the size and age-class representation of canopy, and the time scale of seedling and sapling mortality during sucession. It is mentioned taht a patchy structure has developed and that patches differ quantitatively in composition rather than qualitatively.

In Romania it is necessary a sustained effort to extend the forest areas through artificial regeneration. This paper aimed to study the correlation between the heights and diameters of Quercus petraea trees obtained from seed reserves and their seed production. They were chosen 80 trees situated in four Quercus petraea seed reserves of Cluj county. The trees selected were located at a distance of 30 meters from each other. It has been found that the two measured variables (core diameter and trees height) were directly and positive correlated. The increase of the value of a variable leads to an increase in the other variable. Choosing trees with special qualities have a huge impact for transmitting genetic gain to new generations. Comprehensive analysis of stationary and vegetation characteristics resulted in reproductive material with significant values as seeds quality and adaptability. [ABSTRACT FROM AUTHOR]

This article reviews the various models that have been used to describe the relationships between gene trees and species trees. Molecular phylogeny has focused mainly on improving models for the reconstruction of gene trees based on sequence alignments. Yet, most phylogeneticists seek to reveal the history of species. Although the histories of genes and species are tightly linked, they are seldom identical, because genes duplicate, are lost or horizontally transferred, and because alleles can coexist in populations for periods that may span several speciation events. Building models describing the relationship between gene and species trees can thus improve the reconstruction of gene trees when a species tree is known, and vice versa. Several approaches have been proposed to solve the problem in one direction or the other, but in general neither gene trees nor species trees are known. Only a few studies have attempted to jointly infer gene trees and species trees. These models account for gene duplication and loss, transfer or incomplete lineage sorting. Some of them consider several types of events together, but none exists currently that considers the full repertoire of processes that generate gene trees along the species tree. Simulations as well as empirical studies on genomic data show that combining gene tree–species tree models with models of sequence evolution improves gene tree reconstruction. In turn, these better gene trees provide a more reliable basis for studying genome evolution or reconstructing ancestral chromosomes and ancestral gene sequences. We predict that gene tree–species tree methods that can deal with genomic data sets will be instrumental to advancing our understanding of genomic evolution. [ABSTRACT FROM AUTHOR]