In Europe, salvage-logging is a common management activity to partially recover economic value from wind disturbed forests. In the near future, wind damage to forests is predicted to increase due to ...climate change. Therefore, an economic assessment of wind damage effects on recovered timber value is useful information in the decision-making process. In this study, we aim to assess the influence of different stem damage heights on the monetary value of recovered timber. We simulated stem breakage at three heights for the Scots pine (
L.): 3, 5, and 7 m. For comparison, we used an uprooted tree without stem breakage. Our results revealed that the most negative influence on the recovered timber value was stem breakage at 3 m, which decreased the monetary value by 35%. The stem breakage at 5 and 7 m decreased the recovered timber value by 9–10%. Over the analysed period (2006–2017), no significant differences in the monetary value of the recovered timber were found between uprooted lumber and stems with breakage at 5 and 7 m. The price fluctuations in the market have a significant influence on the recovered timber value, which might cause a larger decrease in monetary value than stem breakage.
Pruning requires significant investment, therefore, the aim of the study was to characterize occlusion of branch wounds and changes in radial increment as well as frequency of browsing damages after ...pruning of Norway spruce (
(L.) Karst.) in order to provide data for financial calculations and recommendations for practical forestry. Altogether 1,614 pruned and 4,368 unpruned trees from 45 Norway spruce stands were measured and cored. Degree of wound occlusion and browsing damages were assessed, and additional volume increment estimated in each stand. Pruning resulted in significant increase of length of branch-free section: for unpruned trees it was 0.3 ± 0.07 m, but for pruned 3.4 ± 0.10 m. Branch wounds for most of the trees (68%) were filled with resin (occluded), for lower share of trees (31%) – still open, but for some trees (1%) completely occluded. Branch wound occlusion rate was not affected by differences in stand density, but was significantly affected by stand age: proportion of trees with occluded branch scars increased with age. Trees with occluded branch wounds had a significantly higher increase in tree ring width after the pruning in comparison to the period before pruning than trees with open branch wounds, emphasizing the importance of radial increment in development of branch-free layer of wood. Pruning resulted in minor (−7% or −0.28 ± 0.05 m
ha
) reduction of annual increment that was statistically significant only up to 3 years after this forest management activity for stands younger than 17 years and with mean height up to 10.5 m. Pruned trees were significantly more browsed than unpruned (6.1% and 2.7%, respectively).
The long-term (50 years) effect of whole-tree harvesting (stump harvesting) on ground vegetation in experimental drained Norway spruce (
(L.) Karst.) stands was studied. We used a chronosequence ...approach to assess the long-term impact of whole-tree harvesting (WTH) on stands’ ground vegetation. WTH stands were compared with four control stands with different age and with the same forest type: young stand (15 years), middle-aged stand (45 years), mature stand (110 years) and over-mature stand (140 years). Species richness was similar between the WTH stand and middle-aged stand (61 and 60 species, respectively). Shannon-Wiener diversity indices in the WTH and middle-aged stand (3.40 and 3.19, respectively) indicated that the stands were similar to each other. A community similarity analysis showed that the composition of vegetation was similar between the WTH and middle-aged stand, although some species like
and
occurred only in the WTH stand. The study showed that a period of 50 years is sufficient for ground vegetation of a typical drained spruce forest to recover after WTH management.
Abstract
The breeding of forest tree species in the Baltic region has notably contributed to wood production for the bioeconomy. Growth modelling is used for long-term estimates of forest ...development. However, usually based on data from unimproved stands, they may underestimate the growth of improved trees. Accordingly, it is important to identify and integrate the altered stand dynamics associated with improved planting stock into existing growth models to accurately capture the resulting gains or, alternatively, develop new functions specifically designed for improved trees. We used the generalized algebraic difference approach to model and analyze height growth patterns of Scots pine and silver birch with different genetic improvement levels (improved forest reproductive material categories ‘qualified’ and ‘tested’). Modelling was based on 14 260 and 55 926 height–age series from open-pollinated progeny trials in Latvia and Lithuania with an age range of 3–46 and 5–22 years for pine and birch, respectively. Dynamic generalized algebraic difference approach forms of commonly applied height growth functions with forest reproductive material-category-specific sets of coefficients were tested. The dynamic form of the Chapman–Richards and King–Prodan equations had the best fit for Scots pine and silver birch, respectively. The expected height growth of the category ‘tested’ was slightly better than the one for ‘qualified’, with more distinct differences in silver birch. The model with forest reproductive material-category-specific coefficients reflected the actual growth of improved trees; however, such application is limited to sites with medium and high site indices, where improved planting stock is typically used. We recommend the model for young stands up to the age of 20 and 40 years for pine and birch, respectively, considering the empirical data cover on which the functions are based. A unified dynamic height model with the same functional form but category-specific parameterization for different improvement levels allows a practical applicability and effective communication amongst diverse users, thereby promoting the utilization of the model amongst forest owners and managers who possess information regarding the origin of planting stock.
The projected northwards shift in the distribution suggests an expansion of European beech (
Fagus sylvatica
L.) into the Baltics and an increase of its commercial potential there. Furthermore, ...recent studies have shown good long-term survival of underplanted, yet non-rereleased beech under the presumedly limiting climate of the eastern part of Latvia, thus supporting the advance of the thermophilic species. Hence, the estimation of the responses of the underplanted beech to shelterwood removal is a logical step in the assessment of the specie’s growth potential. To analyse the effect of conventionally managed mature coniferous shelterwood thinning on the growth of underplanted European beech, six thinning treatments (100, 75, and 50% of canopy, second canopy storey, second canopy storey with understorey removed, and the control) were tested in the 33-year-old northeasternmost experimental plantation in Europe. Growth responses were evaluated five years after the treatment, when beech was 38 years old. The survival and growth responses to shelterwood thinning and local characteristics at the tree and stand level were estimated using linear models. The post-treatment survival/mortality was independent, yet the dimensions of beech, particularly stem diameter, were significantly affected by shelterwood thinning intensity (positively). Regarding tree height, the response was somewhat weaker compared to that of stem diameter, while being disproportional to thinning intensity, with moderate thinning having the strongest positive effect. The estimated positive responsiveness of beech to shelterwood thinning suggested increasing growth potential of the species and expansion in the Baltics. Though the responses of beech were moderate probably due to the age and harsher climate.
In any forest stand, the theoretically modelled output of sawlogs (the most valuable roundwood assortments) will differ from what is actually obtained. The aim of this study was to assess whether it ...is possible to characterise this difference by site properties or forest inventory parameters for birch, black alder, and aspen. We compared theoretically modelled sawlog recovery with actual recovery according to harvester data from final fellings. The difference between the theoretically modelled and actually recovered sawlog outcomes varied from −24.32 to −60.96 percentage points, with overestimations reaching up to three times for aspen. The differences in yield of sawlogs varied among soil types and increased with age and the average diameter of a tree. The sawlog recovery was underestimated up to the mean diameter at breast height of 16 cm and age of 20 years while being overestimated for larger and older trees. The results highlight the necessity to consider decreasing wood quality with increasing age to account for decay, such as stem rot, in assortment tables.
•Generalized additive model was used to analyse weather-growth relationships.•In the mid-part of species range, weather-growth responses were non-linear.•Growth showed generally positive response to ...winter temperature.•Responses to summer temperature mostly showed local optima.•Responses to the precipitation related variables showed thresholds of sensitivity.
Under changing climate, temporal and spatial stability (stationarity) of growth responses of trees to weather and climate, which has often been presumed without explicit testing, is crucial for prediction of productivity and sustainability of forests. However, considering evolutionary adaptation of tree populations to wide spatiotemporal ecological gradients, extrapolation of linear responses, which could be observed in limited parts of the gradients (certain locality), can result in biased results. Accordingly, the plasticity of responses of tree-ring width of the eastern Baltic populations of Scots pine (Pinus sylvestris L.) to meteorological conditions across the regional climatic gradient was assessed using a mixed generalized additive model. The linear responses were assessed using a bootstrapped correlation analysis for comparison. The radial growth responses of the eastern Baltic population of Scots pine showed explicit regional gradients according to the local climates, indicating gradual shifts in the effects of winter temperature and summer moisture regime. Accordingly, temperature in late-winter and summer, as well as summer water deficit were identified as the main regional drivers of tree-ring width. Their effects were generally non-linear, indicating explicit spatiotemporal gradients in growth responses in the mid-part of species distribution. This also implied limited efficiency of simple linear models for the assessment of radial growth under moderate conditions. The responses to summer temperature indicated local optima, while the responses to drought index showed threshold values. The responses to winter temperature indicated positive effect of warming on growth. In some stands, specific non-stationary responses though were evident, suggesting that trees have adapted (specialized) to certain local climatic conditions, which are changing and thus explaining temporal shifts in growth responses. Nevertheless, the estimated responses suggested phenotypical adaptability limits of the eastern Baltic populations of Scots pine in a longer term, supporting the necessity of climate-smart management for sustainability of forest in the region in the future.
•Competition among seedlings after germination was studied in a climate chamber.•Temperature increase differently affected growth of temperate tree species.•Species composition altered tradeoffs in ...competitiveness of seedlings.•European beech showed superior competitiveness northwards from its native range.
Mixed stands are advised for reduction of impacts of natural hazards, and species composition can largely affect sustainability and productivity of the stands. Early development of a stands after a stand-replacing disturbance can have considerable legacy effects on growth via alterations in the diversity-productivity relationships. Accordingly compatibility of growth and competitiveness of different species is one of the key issues for susceptibility of mixed stands. A two-year chamber experiment was conducted to assess early growth and intra- and inter-specific competition for light and soil resources among the seedlings of temperate tree species simulating the predicted effect of warming (presuming optimal moisture regime). Five species, which have high economic importance or potential to become so in the eastern Baltic region (Scots pine, Norway spruce, silver birch, red oak, and European beech) were studied. Among the studied species, European beech had the fastest height growth and competitiveness, suggesting ability to concur a stable niche outside its natural range, particularly under increased temperature. Beech also maintained high competitiveness despite the damages suffered during the overwintering, supporting legacy effects of early development and suggesting invasive properties. Among the studied, Norway spruce had the slowest growth and suffered the highest competition, which is in line with predicted changes in forest composition. Scots pine, silver birch, and red oak showed intermediate growth and competitiveness, particularly when growing together, suggesting balanced development and optimal productivity of such mixed stands. Nevertheless, growth and competitiveness of these species was reduced by increased temperature, indicating negative effects of warming.
Coupling growth with periods of favourable weather conditions minimizes risks of frost damage and maximizes annual height increment. The phenology of the formation of height increment is therefore a ...trait related to the adaptability of trees to annual weather fluctuations. Strong genetic control of the timing of the onset and cessation of shoot elongation has been reported for Norway spruce, but little is known about its fluctuations that occur during the growth period. The strength of the genetic control of the height growth rate was assessed for young (6 years old) Norway spruce progenies originating from six open-pollinated stands from two local provenance regions. In 2010, the length of the growing period for the studied trees was ca. 60 days. Trees from the more continental provenance region, which had later onset and cessation of height growth (by ca. 2.5 days), exhibited slightly lower increments (by ca. 1%). Accordingly, the provenance region had a significant effect on height growth at the beginning and end of the growing period. Nevertheless, considerable genetic control of the growth rate was found throughout the entire growing period (particularly at the beginning and cessation, ha2 ≥ 0.20), except for a week-long interval around mid-summer (ha2 = 0.07). Similarly, the coefficient of additive genetic variation suggested that breeding could be applied for the improvement of height growth intensity throughout the season. The phenotypic correlations between weekly growth rates and tree height (before growth) were mostly non-significant, suggesting varying mechanisms of control, hence possibility for simultaneous improvement of the traits by breeding.
The dieback of common ash (Fraxinus excelsior L.) has dramatically decreased the abundance of the species in Europe; however, tolerance of trees varies regionally. The tolerance of trees is ...considered to be a result of synergy of genetic and environmental factors, suggesting an uneven future potential of populations. This also implies that wide extrapolations would be biased and local information is needed. Survival of ash during 2005–2020, as well as stand- and tree-level variables affecting them was assessed based on four surveys of 15 permanent sampling plots from an eastern Baltic region (Latvia) using an additive model. Although at the beginning of dieback a relatively low mortality rate was observed, it increased during the 2015–2020 period, which was caused by dying of the most tolerant trees, though single trees have survived. In the studied stands, ash has been gradually replaced by other local tree species, though some recruitment of ash was locally observed, implying formation of mixed broadleaved stands with slight ash admixture. The survival of trees was related to tree height and position within a stand (relative height and local density), though the relationships were nonlinear, indicating presence of critical conditions. Regarding temporal changes, survival rapidly dropped during the first 16 years, stabilizing at a relatively low level. Although low recruitment of ash still implies plummeting economic importance of the species, the observed responses of survival, as well as the recruitment, imply potential to locally improve the survival of ash via management (tending), hopefully providing time for natural resistance to develop.
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