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Afforestation is one of the most important tools in creating green cover and providing wood supply. The aim of current study was to investigate the growth and performance of 25-year-old afforestation's in the Radar-Poshteh region of ​​Guilan province. In this study, eight sample plots of 400 square meters in four 3.5-hectare stands of maple, black alder, chestnut leaved oak and loblolly pine were executed by randomized systematic method and within each sample plot, diameter, height, trunk length without branches, large and small diameter of the crown were measured. Litter depth was also measured at ten points in the sample plots with a ruler. Also, the quality of tree trunks was divided into three categories: grade 1, 2 and 3. Using the collected data, the most important quantitative and qualitative indicators of the four stands were extracted and statistically compared. Also, the biomass of the trees was estimated using the reported allometric equations for the studied species. Based on the results, the highest average diameter (33.42 cm), diameter growth (1.23 cm), highest basal area (78.43 m2/ha), volume (763.98 m3/ha), biomass (971.5 ton/ha), grade 1 trunks (92%), litter thickness (8.6 cm) and the lowest height form factor (0.78) were obtained for loblolly pine stand. Among the native broadleaf species, the highest volume and biomass were calculated with 458 m3 and 520.75 ton/ha for alder species, respectively. Therefore, loblolly pine due to its high production (Controlled in non-forest lands) and chestnut leaved oak due to its high yield along with the production of high quality timbers are recommended for afforestation in Guilan province.

The genus Alnus has two species in old references of the flora of Iran in which two varieties and one subspecies have been recorded. However, recently, five new taxa have been described and recorded for the flora of Iran. In this study, the herbarium samples were obtained during a widespread sampling from 25 stands, ranged from the most eastern limit of alder dispersion in Golestan to the west of Talish, across the plains and highlands of Hyrcanian forests. After sampling, 28 leaf and female cone morphological traits belonging to 140 alder individuals were measured and analyzed. The results of discriminant analysis showed 11 most important traits in differentiation of the taxa such as leaf angle in apex, blade shape at the base, type of serration, villosity intensity, presence of hairs on the upper surface of leaf and cone shape. In this analysis, 84.3% of recognized individuals were correctly grouped in the related taxon. The maximum disagreement between predicted and recognized groups corresponded to allocation of A. subcordata varieties to villosa and visc versa. Generally, the morphological traits of the two new species including A. dolichocarpa and A. djavanshirii were very similar to that of A. subcordata var. subcordata. While, three sub-species of A. glutinosa were distinguished by the same traits. Finally, the use of DNA barcoding techniques is suggested in order to verify the presence of new taxa in Iran.

In order to evaluate resistance of commercial wood species of alder and horn beech, logs were cut to lumbers. After caution of reduction moisture content, the lumbers were converted to special marine samples. The wood blocks were impregnated by CCA (Chrome- Cupper-Arsenic) and Betel method. Then treated and untreated wood samples were installed in one meter depth of water at seaside of Amirabad port, for 3, 6, 9 and 12 months. The result of observations showed that, the staining fungi and balanus were able to colonized surface of control samples. However, treated specimens were only occupied by balanus and with increasing time (3 to 12 months) balanus presence were major. The numerical result showed that untreated samples of alder were reduced in weight about 3.5% and treated samples not only had no weight losses but also increased in weight to12.21%. In the case of horn beech the result indicated that the weight loss of control was 2.7% and treated samples -7.9%. Also on surfaces of treated samples on both wood species were no sign of staining fungi. Finally could conclude the water of Caspian Sea is safe for using treated woods by many operations.

Effects of screw length (2, 2.5,3 inch), wood species (beech, alder, white spruce), and two screw interval (2, 2/5 cm) on bending strength of the T-type joints were investigated. In order to fabricate the T –shaped joints, dimensions of the parts were determined as 15*5/5*2/5 cm. From the above variables, 18 combinations were reached. Four replications, and a total of 72 specimens were made and the mechanical strength of the specimens were measured by mechanical testing machine. Results indicated that the beech joints with 3-inch length screws had the highest bending strength, while the lowest bending strength was observed in spruce wood with 2-inch length screws. The study revealed statistically significant differences between the wood species, while there were not any difference between screw interval and bending resistance.

Laminated veneer lumber (L. V. L) manufactured from Maple and Alder wood is investigated. Three levels of layer thicknesses of 2, 3 and 4mm. were investigated. Bending strength (MOR and MOE), CompressionThe results of this investigation indicated that laminated wood strength of samples produced from Alder layers are superior to Maple. Statistical analysis of the results showed that the effect of wood species on strength properties was significantly different at 99% level. Layer thicknesses also showed significant effect on strength increasing layer thicknesses from 2 to 4 mm. caused a reduction on MOE and improved impact properties.The results of this investigation also showed that Alder layers at 4 mm. Is superior to Maple layers in impact properties.

In this research solid wood properties of sound absorption coefficient in over frequency were investigated. Sound absorption at 2000, 4000 and 8000 in Hertz Frequencies was measured on the influence of effective factors in solid wood. Solid wood variable factors were species (Beech, Poplar and Alder), fiber direction (Longitudinal, Radial and Tangential) and Frequencies (2000, 4000 and 8000 in hertz). Data was analyzed using factorial experimental design at completely random blocks and DMRT test. The measurements were taken using the sound absorption with standing waves apparatus type 4002. The results of this research indicate that sound absorption at frequencies 2000, 4000 and 8000 in hertz were in maximum level for poplar wood. Longitudinal direction in solid wood had sound absorption maximum levels. Radial and Tangential direction have less sound absorption than Longitudinal direction respectively. Therefore this investigation showed that sound absorption with increasing frequency of 2000 to 8000 hertz, maximum level was considered.

The genus Alnus has two species in old references of the flora of Iran in which two varieties and one subspecies have been recorded. However, recently, five new taxa have been described and recorded for the flora of Iran. In this study, the herbarium samples were obtained during a widespread sampling from 25 stands, ranged from the most eastern limit of alder dispersion in Golestan to the west of Talish, across the plains and highlands of Hyrcanian forests. After sampling, 28 leaf and female cone morphological traits belonging to 140 alder individuals were measured and analyzed. The results of discriminant analysis showed 11 most important traits in differentiation of the taxa such as leaf angle in apex, blade shape at the base, type of serration, villosity intensity, presence of hairs on the upper surface of leaf and cone shape. In this analysis, 84.3% of recognized individuals were correctly grouped in the related taxon. The maximum disagreement between predicted and recognized groups corresponded to allocation of A. subcordata varieties to villosa and visc versa. Generally, the morphological traits of the two new species including A. dolichocarpa and A. djavanshirii were very similar to that of A. subcordata var. subcordata. While, three subspecies of A. glutinosa were distinguished by the same traits. Finally, the use of DNA barcoding techniques is suggested in order to verify the presence of new taxa in Iran. [ABSTRACT FROM AUTHOR]

The most important role of the litter invertebrates is leaf litter decomposition and helping of nutrient elements cycling. The objective of this study was to evaluate litter invertebrates dversity within 20 years old plantations of alder (Alnus subcordata C. A. Mey.), maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C. A. Mey.), cypress (Cupressus sempervirens var. horizontalis) and natural forest in Darabkola (Mazandaran-Iran). For this purpose, one sample plot, each 1 ha was selected in every plantation as well as in the natural stand. In each sample plot 10 micro plots, each 100 m2 were selected random-systematically. Litter invertebrates were sampled by removing, by hand, all leaf litter in 100×100 cm quadrats. Fifty samples were taken each time and during four seasons 200 samples were taken. Invertebrates were separated out visually in the lab and transferred to 95% alchol, after sorting and counting. More over, various parameters of the stands and soils were measured in each micro plot. For determination of soil invertebrates diversity in these treatments, Shannon and Simpson indices were used, while for determination of species richness and equatibility, Margalef and Heip indices were applied. The results of this research showed that although the differences between the annual means of litter invertebrates diversity was not statistically significant in studied sites (p=0.05), but the decreasing of diversity index in these treatments was respectively as reforestations of alder, maple, natural forest with cypress and oak reforestations. Also the analysis of PCA showed that the parameters of temperature, crown canopy, relative light intensity, moisture content of soil and litter and the amount of P and C/P of litter take an important role in seasonal differences of litter invertebrates diversity in treatments.

Poplars are fast-growing species that were planted pure in the past. Mixed plantations of poplar with nitrogen fixing species have been recommended recently to increase the soil fertility. In this study, American poplar (Populus deltoids 77/51) has been planted with different mixture ratios with Caucasian Alder (Alnus subcordata) in randomized complete blocks with four replications in Chamestan research station, Mazandaran province, northern Iran. For further comparisons, pure stands of poplar and alder were also added to the treatment design. The plantation spacing was 4×4m. Results after 7 years showed that survival rate of poplar were greater than alder, in general. The highest rate of poplar survival was observed in the treatment of 50% poplar + 50% alder. The differences among treatments were statistically significant. The highest diameter increment was measured within poplars in the treatment of 33% poplar + 67% alder and the least in the pure poplar stand. The highest total height was measured within poplars in the treatment of 67% poplar + 33% alder. The highest volume of individuals trees were measured within poplars in the mixture of 33% poplar + 67% alder, while the highest tree volume of alder was obtained within the alder pure stand. The amount of soil nitrogen was significantly higher in the pure alder stand and mixture of 33% poplar + 67% alder, than in the soil of other treatments.

Depletion of natural forest due to different reasons has made the forest plantation important for extending forest area and wood production. Therefore, evaluation of forest plantation can play an important role to establish the plantation for the future. The objective of this study is to evaluate three different reforestation which was planted by Acer velutinum, Alnus subcordata and Fraxinus excelsior species. Each planted area with 49 ha was established in 1985. For data collection, 90 plots of 400 m2 were selected randomly. Different variable such as diameter, total height, trunk length, forked tree and number of trees in different classes of diameter were assessed. The obtained results indicated that Alnus subcordata with 3.2 percent in 5 cm diameter class and 38.5 percent in 20 cm diameter class had the highest values in survival, while Fraxinus excelsior with 31.7 percent in 5 cm diameter class and 19.7 percent in 20 cm. diameter class had the lowest values in survival. Data analysis for stem quality showed that Fraxinus excelsior with 31.6 percent forked trees had the lowest value, while Alnus subcordata with 18.5 percent forked trees had the highest value in stem quality. Therefore, assuring seed quality for seedling production and protection after out planting could be resulted as a good quality of plantation.

Forest plantation at the degraded parts of the Caspian Forests is important for forest rehabilitation. Most of the plantations at the low and midlands of the Caspian Forests are made with the native broad - leaved species such as Maple, Alder, Ash and Oak. Availability of information in relation to forest plantation techniques is important for expenses reduction and plantation maintenance and density. The trail was Conducted in 1987 under experimental design of Randomized Complete Blocks, using five spacing treatments (1×1, 1×2, 2×2, 2×3, and 3×3 m.), two species (Acer velutinum Boiss. and Alnus subcordata C. A. M.) and four replicates. The measured tree characteristics were: survival%, collar diameter, d.b.h. and height. The methods of ANOVA and T - Test (Duncan) were used for statistical analysis. The trees parameters were measured in 2001. The results show that the treatments have not influenced the height in the both species, significantly. In Maple, the greatest survival% and diameter growth were achieved at spacing densities of 2×2, 2×3, and 2×3, 3×3 m., respectively, whereas in Alder were at 2×2, 2×3, 3×3 and 2×3, 3×3 m., respectively.