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The present study aimed to assess the effect of canopy combination of beech trees and mixed species (beech-hornbeam-maple, beech-hornbeam, beech-maple and pure beech) on microbial indices and soil nutrient stockscharacteristics in Mazandaran Province, north of Iran. Leaf litter sampling was done by using litter traps and soil samples (30 × 30 × 30 cm) were taken in each of the stands with five replicaties under the canopy of beech trees. Characteristics of litter (organic carbon, total nitrogen, carbon to nitrogen ratio, phosphorus, potassium, calcium and magnesium) were measured. The physical, chemical, biochemical and microbial properties of soil (bulk density, Sand, silt, clay, pH, EC, organic carbon, total nitrogen, carbon to nitrogen ratio, sequestration of organic carbon, total nitrogen, phosphorus, potassium, calcium and magnesium, ammonium, nitrate, microbial respiration, metabolic and microbial quotient) were also investigated. The results showed that beech-hornbeam-maple stand had the highest pH, nitrogen sequestration, phosphorus, potassium, magnesium, microbial biomass of carbon and nitrogen, and microbial respiration. Also, the highest amount of soil carbon, carbon to nitrogen ratio, carbon sequestration, metabolic and microbial quotients were allocated to pur beech stands. In addition, the highest ammonium and nitrate levels were also observed in beech- maple and beech-hornbeam stands. According to the present study, beech-hornbeam- maple stand improved the litter quality, nutrient storageand microbial indicators of the soil, followed by beech-hornbeam, beech- maple and pure beech stands. The practical results of this research indicate the positive effects of tree species diversity on improvement of soil qualitaty and health.

One of the most important factors for determining the volume of trees is selection of an appropriate form factor. This study determined the most appropriate form factor formula and modeling the actual form factor in the Caspian region of northern Iran, Guilan’s forests. Totally, 150 beech (Fagus orientalis) trees were measured. Three coefficients of natural, artificial, and Hohenadel were compared with the actual form factor using pair-wise comparison test. Several nonlinear equations including logistics, Chapman-Richard, and exponential functions were used for modeling the form factor of beech trees. These functions were evaluated in terms of coefficient of determination (R2), paired t test, and accuracy statistics of ME, Root Mean Square Error (RMSE), MEr and RMSEr. The result showed that there were significant differences between the actual form factor and the each mentioned coefficients. None of the models presented high R2 values. Accuracy statistics showed that exponential and logistic models can be usefully applied for estimation of the actual form factor coefficient. Also the results of t-test showed that there was no significant difference between of actual and estimated means of form factor derived from the logistic model. Therefore, logistic model was selected as the best for the estimating form factor of beech trees in Guilan’s forests of the Caspian region.

The present study aimed to assess four forest stands, Fagus orientalis Lipsky-Carpinus betulus L.-Acer velutinum Boiss. (FO-CB-AV), Fagus orientalis Lipsky-Carpinus betulus L. (FO-CB), Fagus orientalis Lipsky-Acer velutinum Boiss. (FO-AV), and Pure Fagus orientalis Lipsky (FO) on basis of some soil quality indices in Mazandaran Province, northern Iran. Five samples per stand were taken (0-30 cm), the physical, chemical, and biological characteristics of soil were determined. Nine criteria were selected according to Principal Component Analysis as Minimum Data Set. According to the results, the highest value of litter Ca, density and biomass of earthworm, and C microbial biomass were found in FO-CB-AV. After applying the analytical hierarchy process, the calculated overall priority based on nine criteria showed that the FO-CB-AV stand had a higher ecological potential compared to the other stands. Therefore, the FO-CB-AV stand had more of appropriate conditions for improving soil quality in degraded forest regions compared to the other stands under current conditions.

Mixed beech (Fagus orientalis Lipsky) forests are very important to the Hyrcanian region of Iran because of their high degree of naturalness and as a source of wood production. Determination of tree spatial patterns over development stages is a first step in understanding underlying processes driving regeneration and forest dynamics. Spatial patterns of trees from three development stages (initial, optimal and decay) of an untouched mixed beech forest were quantified within three 1-ha plots. To prepare the stem maps, we measured each tree with a DBH larger than 7.5 cm using the azimuth-distance method. Spatial patterns were then analysed using Ripley's K-function. Results indicated that the number of trees decreased from the initial stage to the decay stage, with tree spatial patterns being aggregated, slightly aggregated and highly randomized for initial, optimal and decay stages, respectively. Differences in spatial patterns among the development stages are not unexpected considering that such unmanaged forests are driven by gap dynamics which results in interactions between gap filling individuals.

Associations between plant coverage and environmental parameters help to understand the natural habitats, as well as the effective functions on growth and establishment of plant species. The Marsdenia erecta (L.) R. Br. ex DC.is one of shrub species which occurs in forests of Chaharmahal and Bakhtiari province, about which almost no report on ecological characteristics and regional distribution has been published so far. In this study, growth regions of Marsdenia erecta were initially identified following site visits and preliminary checks, based on which two habitats of Chahartagh and Dorak Anari were selected. Field sampling was accomplished by means of 35 circular plots of 1000 m2 each. In each plot, quantitative characteristics of species, including number of standing trees, average crown diameter and height were measured. In addition, a mixture soil samples were collected from the surface soil horizon, which were then analyzed in terms of chemical and physical properties such as electrical conductivity, organic carbon, lime, phosphorus, potassium, nitrogen, sand, silt and clay contents. The properties were statistically analyses on species level. Furthermore, the relationship between Marsdenia erecta distribution and soil characteristics was surveyed by principal component analysis. The results showed maximum diameter, height and canopy of Marsdenia erecta across Dorak Anari test site, whereas Chahartagh test site revealed the highest density. Quantitative results also revealed a significant difference between the measured heights of Marsdenia erecta individuals across the two test sites. However, no significant difference was observed by comparing the mean values of soil variables (acidity, organic carbon, lime, phosphorus, potassium, nitrogen, sand, silt and clay). Based upon the applied principal component analysis, soil texture was the most influential factor on distribution of Marsdenia erecta in Dorak Anari, whereas chemical variables of soil such as organic carbon, phosphorus, potassium and nitrogen were the major determinants in Chahartaghtest site.

Despite superior medicinal properties of Birch, there aren’t any studies reported on its morphological diversity. For the first time, leaf samples were collected from four different sites, each site 10 trees and each tree 30 fertile and sterile shoots and leaves (totally 2400). In analyzing the mean values, the Siahmarz kuh showd the maximum and the Marmishoo minimum size mean. Angle of leaf base and number of veins had minimum and fluctuating asymmetry and distance border had a maximum coefficient of variation, minimum and maximum morphological diversity respectively. Average size of sterile leaf traits was larger than average size of fertile leaf traits. It seemed that Siahmarz Kuh is had the most interapopulation diversity and could apply a transition source to sink. The slightest change in the veins of the population in birch was more strongly controlled by genes. Multivariate analyses of variance indicated high statistical significance of all factors: leaf type, population, type population, tree nested population and type × tree nested population. The cluster analysis identified three clusters, the first cluster contained only Marmishoo trees. Because the majority of the population, geographic distribution of genotypes was not consistent with the grouping that could be due to the influence of environmental factors on morphological traits, so it is recommended to use molecular markers. Canonical discriminant analysis showed that petiole length ratio and fluctuating asymmetry could be used in future research on morphological diversity among populations of B. pendula.

The expanding phenomenon of dieback is caused by the reaction of trees against the harmful biotic and a biotic factor that lead to dying of shoots and branches of trees from upper crown to lower crown. This phenomenon spreads throughout the leaves and branches and all parts of the plant and may finally lead to the death of the plant. This study aimed to identify species dieback especially Carpinus betulus and to study the spread of dieback in this species using topography factors in series one of shastkalate forest. In the studied area, a statistical network with dimensions of 600*800 m was randomly and systematically designed (network of plots) and cluster sampling with six trees was applied (in every plot). Topographical factors (altitude, slope direction and percentage) in each plot were taken. Analyzing the data indicated that 28% of the total stands suffer from different degrees of dieback among which 22% belong to the carpinus betulus species. The percentage of dieback stands of this species in different classes of height had no meaningful difference, but it was more in western slope and gradient of less than 20%.

Norway spruce (Piceae abies L. Karst.) has been planted on a wide range of world. It is generally pyramidal in shape and can grow to 40 m in height and to 1-1.5 m in diameter. Norway spruce has apoor reputation for wind firmness. It is a shallow rooting species on sites with a high fluctuating ground water table or on soils where the effective rooting depth is limited. This study was carried out during 2001-2002 in four sites of Guilan Forests. These sites were Aroston, Rec, Picehson and Shenrud. The primary distance between the trees was 2×2 m. The stands age in Shenrud and the other sites was 17 and 27 years, respectively. The investigated growth parameters were; Survival %, mean height, mean D.B.H., density per hectar, basal area per hectar, annual growth rate of diameter, annual growth rate of height, dominant height, number of diameter classes per hectar, annual growth rate of tree volume, stand volume per hectar, volume table (tarif), form factor (f), relationship between quantitative parameters (diameter to height and diameter to volume) and stand qualitative parameters (natural pruning, stem condition and branch angle). The wood mechanical characteristics (density and fibre length) and the stand pests and diseases were investigated as well. In order to study the effects of Picea plantation on soil characteristics, soil samples were tested physicaly and chemicaly and the data of the two sites were compared. The results showed that Aroston site was the best one due to its greatest survival (70%), growth rate (basal area: 37 m2, Volume: 301.25 m3/ha, annual volume growth; 11.1 m3/ha) and wood quality (tracheid length: 2.89 mm and specific gravity: 0.36 g/cm')

The present study aimed to assess four forest stands, Fagus orientalis Lipsky-Carpinus betulus L.-Acer velutinum Boiss. (FO-CB-AV), Fagus orientalis Lipsky-Carpinus betulus L. (FO-CB), Fagus orientalis Lipsky-Acer velutinum Boiss. (FO-AV), and Pure Fagus orientalis Lipsky (FO) on basis of some soil quality indices in Mazandaran Province, northern Iran. Five samples per stand were taken (0-30 cm), the physical, chemical, and biological characteristics of soil were determined. Nine criteria were selected according to Principal Component Analysis as Minimum Data Set. According to the results, the highest value of litter Ca, density and biomass of earthworm, and C microbial biomass were found in FO-CB-AV. After applying the analytical hierarchy process, the calculated overall priority based on nine criteria showed that the FO-CB-AV stand had a higher ecological potential compared to the other stands. Therefore, the FO-CB-AV stand had more of appropriate conditions for improving soil quality in degraded forest regions compared to the other stands under current conditions. [ABSTRACT FROM AUTHOR]

Mixed beech (Fagus orientalis Lipsky) forests are very important to the Hyrcanian region of Iran because of their high degree of naturalness and as a source of wood production. Determination of tree spatial patterns over development stages is a first step in understanding underlying processes driving regeneration and forest dynamics. Spatial patterns of trees from three development stages (initial, optimal and decay) of an untouched mixed beech forest were quantified within three 1-ha plots. To prepare the stem maps, we measured each tree with a DBH larger than 7.5 cm using the azimuth-distance method. Spatial patterns were then analysed using Ripley's K-function. Results indicated that the number of trees decreased from the initial stage to the decay stage, with tree spatial patterns being aggregated, slightly aggregated and highly randomized for initial, optimal and decay stages, respectively. Differences in spatial patterns among the development stages are not unexpected considering that such unmanaged forests are driven by gap dynamics which results in interactions between gap filling individuals. [ABSTRACT FROM AUTHOR]

Quercus macranthera is extended in forest areas of the upper elevations in the north of Iran and plays an effective role in conserving soil and water infiltration. The biggest problem in the region is livestock grazing and forest dwellers. The aim of this study was to study the distribution of plant species and their relation to soil properties in protected and degraded stands of Quercus macranthera. This study included both protected and degraded areas. Within each of the study areas, we used a random systematic 100 m × 100 m sampling grid to locate 20 circular plots (1000 m2 plot for tree and shrub species and 8m2 for herbaceous species) in each area. Also, in each plot, soil samples were collected from 0 to 30 cm depth. The result showed that the distribution pattern of species in both areas was different. Shrub species and invasive herbaceous species were more abundant in the degraded area. Diversity, richness and evenness in the protected area were significantly higher than the degraded area. The soil nutrient factors were significantly more in the protected area. Soil texture was no different between the two areas. It seems that conservation programs such as prevention of livestock need to be carried out in order to protect Quercus macranthera. [ABSTRACT FROM AUTHOR]

Despite superior medicinal properties of Birch, there aren't any studies reported on its morphological diversity. For the first time, leaf samples were collected from four different sites, each site 10 trees and each tree 30 fertile and sterile shoots and leaves (totally 2400). In analyzing the mean values, the Siahmarz kuh showd the maximum and the Marmishoo minimum size mean. Angle of leaf base and number of veins had minimum and fluctuating asymmetry and distance border had a maximum coefficient of variation, minimum and maximum morphological diversity respectively. Average size of sterile leaf traits was larger than average size of fertile leaf traits. It seemed that Siahmarz Kuh is had the most interapopulation diversity and could apply a transition source to sink. The slightest change in the veins of the population in birch was more strongly controlled by genes. Multivariate analyses of variance indicated high statistical significance of all factors: leaf type, population, type population, tree nested population and type x tree nested population. The cluster analysis identified three clusters, the first cluster contained only Marmishoo trees. Because the majority of the population, geographic distribution of genotypes was not consistent with the grouping that could be due to the influence of environmental factors on morphological traits, so it is recommended to use molecular markers. Canonical discriminant analysis showed that petiole length ratio and fluctuating asymmetry could be used in future research on morphological diversity among populations of B. pendula. [ABSTRACT FROM AUTHOR]