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Growth elements and stand structure of an artificially established Norway spruce stand were presented at age 37 and 62-yr on the basis of a single permanent sample plot and their changes analyzed. The stand was established with 4500 seedlings per hectare. At age 37-yr on the permanent sample plot, 2600 trees per hectare were recorded with basal area of 43.52 m2•ha−1 and standing volume of 319,97 m3•ha−1. At stand age 62-yr, 878 trees per hectare were recorded with basal area of 42.61 m2•ha−1 and standing volume of 454,48 m3•ha−1. First selective thinning, conducted at mean aspirant’s height of 17.6 m (500 trees per hectare) at age 37-yr was characterized as a moderate (28.3% trees per hectare and 23.5% volume thinned) thinning from below (qd = 0.88). Out of the remaining number of trees (1823 per hectare), in the following period between 38-62-yr, 956 trees per hectare (52.4%) were removed, mostly through sanitary cutting that can be characterized as thinning from below (qd = 0.68). Out of the initially selected aspirants at age 37-yr, 220 elite trees were selected at age 62-yr due to the effects of self-thinning in the stand and unfavorable exogenous factors as well as the thinning from below regime. At age 62-yr, the stand structure is unfavorable and statically unstable as the slenderness coefficient is increased compared to the condition at 37-yr. Thus, it can be concluded that the risk for achieving the productive and meliorative potentials of the stand is increased, primarily due to absence of adequate maintenance of the stand between age 38 and 62-yr.

Copyright of Bulletin of the Faculty of Forestry / Glasnik Šumarskog Fakulteta is the property of University of Belgrade, Faculty of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Agronomy Science is the property of University of Life Sciences in Lublin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research was started in 1995 in order to investigate the effect of thinning on the young plantations of velvet maple (Acer velutinum Boiss.). The silvicultural interventions comprised three main treatments (medium and heavy thinning), two secondary treatments (3-year and 5-year rotations) in the fully randomized design with three replications. There were 9 sample plots in the experimental design with an area of 0.3-0.4 hectare each. A full calipering of the future trees was done after 20 years and 6 thinning operations. The results for DBH, total height, trunk height and trunk diameter showed significant differences between the control treatment and thinning intensities. However, no significant difference was observed between the secondary sub- treatment (circulation 3 years and 5 years) and the intersection between the main and sub plots treatments for DBH, total height, trunk height and trunk diameter. For the intensive thinning treatment, the largest value of 32.95 cm was observed for the DBH, while the lowest value of 27.39 cm was observed for the slight thinning. In addition, the largest height of 24.42 m was observed for intensive thinning, whereas the lowest rate of 23.63 m was observed for the control treatment.

This experiment was conducted to evaluate the establishment and adaptability of woody species under wastewater irrigation condition in arid climate. This experiment carried out in Yazd city wastewater treatment station with 11 tree species under randomized complete block design with three replications. The species included Eucalyptus camaldulensis E. microtheca, Elaeagnus angustifolia, Tamarix aphylla, Melia azedarach, Pinus eldarica, Populus euphratica, P. alba × P. euphratica, Morus alba, Cupresus simperverence and Ailanthus altissima. In each plot, trees were planted with 48 seedlings for each species. Immediately after planting, the seedlings were irrigated with wastewater for 15 days, followed by further irrigations in 20-30 days intervals after the establishment. After 4 years, the effects of wastewater on establishment and growth, including survival percentage, height growth, the average diameter of the crown, crown volume, collar diameter and diameter at breast height (DBH) were measured. The results showed that the P. eldarica had highest rates of deployment with 100% of establishment. However, no significant differences were observed with other species including M. azedarach, E. camaldulensis and, E. microtheca. For all growth indicators and yield traits, the T. aphylla tree showed better performance, although it did not significantly differ with many others species. The results of this study showed that woody species such as E. camaldulensis, E. microtheca, M. azedarach, E. angustifolia, P. euphratica and P. eldarica can be irrigated with wastewater under arid condition due to their better establishment, growth and slenderness coefficient compared to other species.

Pilu (Salvadora oleoides Decne.) is a shrub or a small tree indigenous to southeast of Iran and is known as a multipurpose species for forage production, soil protection and medicinal value, which altogether reveal its importance in forestry and reforestation projects in warm and arid areas. The purpose of this study was to investigate the effects of runoff and moisture storage methods in the soil (Bankette arches, pan (control), plastic sheets, straw in the bottom of the pit, superabsorbent polymers and canopy) on the establishment, survival and growth of the pilu species in Southeast of Jazmurian in Sistan and Baluchestan province. The factors studied in this experiment included seedlings survival, seedling height, seedling crowns, seedling collar diameter and seedling vigor, which were measured in the middle of March, 2017. The results showed that the development of plastic layer improved the survival rate and seedlings cover. Creating a shadow increases the height growth and slenderness coefficient of seedlings and decreases the diameter growth of seedlings. In general, it can be concluded that planting plastic surfaces on the surface of the pit and planting canopies on seedlings are the most suitable treatments with respect to the percentage of seedlings' survival and seedling growth characteristics. It seems that combination of these two treatments could help to improve seedling establishment across similar areas.

Snow damage on natural stands is an important problem concerning mountainous forest management. In the present research, the frequency and intensity of heavy snow damage on natural stands and the relationship of damages with characteristics of trees, stand and topography were studied in mountainous forests of northern Iran. A systematic sampling design was applied to the study area (140 ha), with 122 circular plots. The grid dimension was 100 m and each plot area was 1000 m2. The four types of snow damage to trees include: crown damage (8.6%), stem breakage (5.4%), uprooting (3.2%), and bending (1.4%). The frequency of crown damage grew with an increase in the diameter at breast height (DBH), while the frequency of stem breakage, uprooting and bending decreased with an increase the DBH. The frequency of crown damage, stem breakage, and total damages was related to tree species (p < 0.01). Not all tree species were equally susceptible to snow damage. The amount of damage grew with increasing elevation and slope angle and decreased with increasing soil depth. Young trees (DBH < 25 cm) were more susceptible to snow damage than other trees. Snow damage decreased by as the trees in the stand became more mixed in age. The susceptibility of trees to snow damage increased by height and slenderness coefficient. With adequate silvicultural operation, snow damage can be reduced to a minimum level in these natural forests. [ABSTRACT FROM AUTHOR]

Forest management has a decisive role in decreasing or increasing snow damages on trees due to effects on stands structure. In this research snow damages on trees were investigated and compared in managed and natural stands with selection silvicultural system in Nav-Asalem Forests, Guilan province. Circular 0.1 ha sample plots were established using random-systematic method for studying the effects of snow on different species with various ages. The distance between sample plots were set to 100 m. The results showed that the frequency of snow-damaged trees in managed stand (10.2%) was significantly higher (P < 0.01) than natural stand (7.2%). The occurred changes in the age structure and tree species composition in the managed stand during selection cuts was the main cause of most snow damage in this stand compared to natural stand. The most frequency of damages was observed on young trees with high slenderness coefficient. For fortifying the studied forests against risk of snow damage the following recommendations can be mentioned: increasing the selection cutting period from 10 to 20 years, reducing the removed volume in each logging period, reducing the areas of regeneration gaps, increasing the number of large trees, avoiding the cutting trees in forest edges, implementing the thinning operation in the stands in which previous cuttings caused homogenous, even aged, young stands with high slenderness coefficient, and avoiding tree cutting in the areas that are sensitive to snow damage such as ridges, steep slopes with low depth of soil.

Management of mountainous forests implies detailed information on the extent and intensity of snow damages. Furthermore, such information is required for improved conservation of natural stands. In this study, snow damages on six dominant tree species including Beech (Fagus orientalis Lipsky), Hornbeam (Carpinus betulus L.), Velvet Maple (Acer velutinum Boiss.), Cappadocian Maple (Acer cappadocicum Gled.), Caucasian Alder (Alnus subcordata C. A. Mey) and Chestnut-leaved Oak (Quercus castaneifolia C. A. Mey.) were investigated across a portion of the Nav forest in the east of Guilan province. Circular 0.1-ha plots were systematically sampled in a grid with 100m sampling distance. Four types of tree damage were detected including crown damage (8.6%), stem breakage (5.5%), uprooting (3.2%) and bending (1.4%). The six studied tree species have different resistance to snow damage. The highest rates of uprooting and stem breakages were observed in Alder trees. The Oak trees were mostly influenced by crown damages. Furthermore, the Beech trees showed the lowest rate of crown damage and stem breakage. Based on the results, the tree species of Alder, Oak and Cappadocian Maple were categorized as being more vulnerable to snow risk, whereas Beech, Hornbeam and Velvet Maple proved to be less vulnerable. In addition, the slenderness coefficients were calculated for bended trees (76.7), stem broken trees (64.5), uprooted trees (64.0), crown damaged trees (60.1) and intact trees (50.2). This study also showed that trees of higher slenderness coefficient are more vulnerable to the snow risk.

Oriental Beech forests have economic and ecological important roles in northern forests of Iran. Therefore qualitative and quantitative controls of their stands are essential in management of these forests. This study is aimed at determining the stem taper, form factor, and slenderness coefficient of Beech species in four growth stages; (small pole, pole, saw-timber, mature) in natural forests of Lomir area located in Asalem, Guilan Province, Iran. In this study, 159 Beech trees were selected and analyzed based on diameter classes (5 cm). Analysis of Variance and Tukey test showed the factors of stem taper and tree natural form were significantly different at small pole stage compared to other stages (p < 0. 05). Beech species had the highest value of stem reduction factor and the lowest value of tree artificial form factor in stages of small pole (the class with a diameter 10 to 30 centimeter) and mature (the class with a diameter over 80 centimeter). These results indicate that Beech form is affected by growth stages in natural forests. So, the separate management and cultivation planning during various growth stages is necessary in order to obtain the maximum benefit of the Beech natural stands.

The present paper deals with derivation of target stocking in forests of Norway spruce vegetation zone. Target stocking in forests with prevailing ecological and social functions is the stocking when the forest fulfils demanded functions in the best way. For forests in the Norway spruce vegetation zone target stocking was derived by original procedures as an optimum stocking in harmonization of demands on the fulfilment of ecological functions (especially erosion control, hydrological and water protection ones), securing static stability and preconditions for the formation and growth of natural regeneration. We investigated the relations between stocking and indicators of static stability (slenderness coefficient and ratio of crown length to tree height), natural regeneration phases, ground and non-wood vegetation coverage and natural regeneration coverage. The most favourable status of these indicators was found out in stocking 0.7 and in the upper forest limit 0.6.

A static stand density management diagram was constructed for Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) plantations in Spain on the basis of 3 equations that were fitted simultaneously by the full information maximum likelihood procedure to data derived from 172 plots measured across the Cantabrian and pre-Pyrenean ranges. The first equation relates quadratic mean diameter to the number of stems per hectare and dominant height. The other 2 equations relate stand volume and stand aboveground biomass to quadratic mean diameter, number of stems per hectare, and dominant height. An estimation of the average slenderness coefficient for the 250 largest trees per hectare and the canopy bulk density were included. The stand density management diagram outlined here enables rapid, straightforward comparisons among different thinning schedules for forest plantations in mountain regions, in which timber production, risk of crown fire, and the risk of damage from wind or snow are considered. [ABSTRACT FROM AUTHOR]

Variable retention harvesting (VRH) has been proposed as a silvicultural practice to maintain biodiversity and ecosystem integrity. No previous study has examined tree carbon isotope discrimination to provide insights into water stress that could lead to dieback and mortality of trees following VRH. We measured and compared the carbon isotope ratios (δ13C) in stem wood of trembling aspen (Populus tremuloides Michx.) before and after VRH. Eight trees were sampled from isolated residual, edge and control (interior of unharvested stand) positions from each of seven plots in three regions (Calling Lake and Drayton Valley, Alberta and Lac Duparquet, Québec). After VRH, the general trend in mean δ13C was residual > edge > control trees. Although this trend is indicative of water stress in residual trees, it also suggests that edge trees received some sheltering effect, reducing their stress compared with that of residuals. A strong inverse relationship was found between the δ13C values and the mean annual precipitation in each region. The trend in mean δ13C signaturewas Calling Lake > Drayton Valley > Lac Duparquet trees. These results suggest that residual or edge trees in drier regions are more likely to suffer water stress following VRH.We also observed a trend of greater δ13C in stout trees compared with slender trees, both before and after VRH. The evidence of greater water stress in stout trees likely occurred because of a positive relationship between stem diameter and crown volume per basal area. Our results provide evidence that water stress could be the driving mechanism leading to dieback and mortality of residual trees shortly after VRH. Additionally, the results from edge trees indicate that leaving hardwood residuals in larger patches or more sheltered landscape positions could reduce the water stress to which these trees are subjected, thereby reducing dieback and mortality. [ABSTRACT FROM AUTHOR]

Oriental Beech (Fagus orientalis Lipsky) is one of the most important forest tree species in the north of Iran. This study aimed to investigate the morphological and quantitative characteristics of mature beech trees (d.b.h.>1 m) in two forest regions, located at Kheiroud district in Mazandaran province and at Sistan district in Guilan province. In each region, 33 trees were selected and some morphological and quantitative characteristics were studied. Results showed that frequency of forked crown shape has significant difference (α= 0.01) in two regions and in Kheiroud was more than Sistan. Frequency of spiral growth and Chinese beard node didn’t show significant difference in two regions. The differences of crown height, tree height (α= 0.05) and trunk length (α= 0.01) were significant in the two regions. Crown height and tree height in Kheiroud were higher than in Sistan, but trunk height in Sistan was higher than in Kheiroud. Slenderness coefficient didn’t show any significant difference in two regions.

Slenderness coefficient of trees, defined as the ratio of total height to diameter at breast height (DBH), is frequently used as resistance index of trees to wind throw. By measuring DBH and total height of 1379 trees, the relationships between slenderness coefficients and trees DBH were investigated for five major tree species in a broadleaved Hyrcanian forests of Iran, Kheyroudkenar-Noshahr, including beech (Fagus orientalis Lipsky), hornbeam (Carpinus betulus L.), maple (Acer velutinum Boiss.), alder (Alnus subcordata C.A.M.) and oak (Qercus castaneifolia C.A.M.). Tree slenderness coefficients were found to be negatively correlated with DBH. The graphical results indicated that about 75% of the sampled trees had a slenderness coefficient lower than 80 and the range of variation is between 20 to 173. The most of difference among the slenderness coefficients of tree species were found in diameter class below 30 cm. Maximum slenderness coefficients observed in the valleys and northern aspects, while minimum in karstic phenomenons and southern aspects. No correlation was found between tree slenderness coefficients and stand density.