فهرست مطالب omid esmailzadeh

In this study, the impact of boxwood moth pest defoliation on the dynamics of leaf litter and soil nutrients in the Cheshmebolbel boxwood (Buxus hyrcana) reserve was evaluated. A random sampling technique was employed to collect litter layer samples (using a 400 cm2 frame) and soil samples (using a metal cylinder with an 8 cm diameter and a 10 cm depth) from 32 sites in unpolluted and polluted boxwood stands. The results revealed that only soil moisture percentage differed significantly among the soil physical variables, whereas all chemical soil variables showed significant differences between the two polluted and unpolluted boxwood sites. Furthermore, basal respiration (0.14, 0.12), metabolic rate, microbial ratio, and carbon availability index were significantly higher in the polluted sites compared to the unpolluted site, while no significant difference was observed based on the microbial-carbon respiration index. The principal component analysis (PCA) results demonstrated a distinct separation of the two sites, both polluted and unpolluted, along the first axis, based on both litter and soil variables. In this context, nitrogen, metabolic rate, moisture, nitrate, ammonium, and stimulated respiration (0.30, 0.39) exhibited a positive correlation with the first axis, representing the concentration of the unpolluted stand. On the other hand, C/N ratio, potassium, magnesium, calcium, and microbial biomass carbon displayed a negative correlation with the first axis, representing the concentration of unpolluted sites. In general, the findings of this research underscore the substantial influence of defoliation induced by pest outbreaks on an important aspect of forest ecosystem health, performance, and nutrient cycling.

In this study, the efficiency of the two nearest neighbor (KNN) and weighted average (WA) methods was evaluated for indirect estimation of environmental variables in plant communities. For this purpose, vegetation composition data of 324 relevés with an area 400 m2 of the Hyrcanian yew forests database were used. Then, environmental variables in each relevés were indirectly estimated by using KNN and WA methods based on two kind of vegetation data (incidence based and abundance based of floristic data) as well as the initial values of that environmental variables.Validation of the models were evaluated using determinant coefficient of linear regression analysis, which done based on the initial values and followed by estimated one of each environmental variables as the predictor and response variables. Results showed that using KNN method based on abundance data due to having the highest determination coefficient value has the priority in comparison to another three algorithms. The main reason of the differences between KNN and WA was influenced by different approaches of interpolation (KNN) and extrapolation (WA) in the process of environmental variables point estimation. The better performance of the KNN compared with WA in the point estimating of environmental variables is due to using the environmental data of the only adjacent plot data with the most similarly floristically features to each points in the KNN, while the results of the WA are globally affected by the range of each environmental variables at the whole of the dataset.

Hyrcanian forests in northern Iran are one of the world's precious deciduous broadleaved forest ecosystemsbut are subjected to increasing disturbances mostly of anthropogenic origin.In this context, it is necessary to assessthe existing vegetation and its relation toenvironmental factors in order to establish a scientific reference for conservation measures.The purpose of this research is to evaluate the quality of the modified and classical TWINSPAN (Two-way indicator species analysis) classification based on the environmental factors toidentify the plant communities of Taxus baccataL. forests of Golestan Province (Northern Iran). Fifty400-m2 plots were systematically selected along an elevation gradient in the Taxus baccataforests. In each plot, the soil was sampled usinga compositesample of threereplicates taken to a depth of 20 cm.All vascular species were recorded on each plot according to Braun-Blanquet’s method. In total,56 plant species belongingto 48 genera and 34 families were recordedin spring 2018. The comparison of the results of modified and classicalTWINSPAN showed that the modified TWINSPAN did not change the classification logic, but introduced moreflexibility in the hierarchy of the division.It was also found that the compliance rate of the results provided by the classical TWINSPAN method was lower than the modified method. Usingmodified TWINSPAN, Detrended correspondence analysis (DCA), and Redundancy analysis (RDA),we determined four floristic groups in the Taxus baccatahabitat.The first(Carpinus betulus) and second (Taxus baccata) groups were located at low altitudes and soil contents in silt and clay were higherthan in the other groups. In contrast, the third (Quercus castaneifolia) and the fourth (Juniperus communis) groups were located next to each otherat higher altitudes and southwestern aspects, on steeper slopesand soils that exhibited a highpH and a high sand content.We foundclose relationshipsbetween the distribution of vegetation groups of Taxus baccatahabitat withedaphic and physiographic factorsusing the RDA method.To conclude, the modified TWINSPAN offers a more efficient and flexible method to identify vegetation communities. This is thefirst step to implementingfuture management and ecological restoration measuresin habitats of high ecological value such as yew forests

Identification of plant species in different habitats of the country, specially protected areas, is of special importance .In the present research, the flora of the Qalajeh protected area in the south of Kermanshah province was studied during the period from 1393 to 1395 (2015 to 2017). A total of 326 species (258 species of dicotyledons and 68 species of monocotyledons) belonging to 58 families and 225 genera were identified in this area. The largest families were Fabaceae with 13 genera and 43 species, Asteraceae with 29 genera and 39 species, Poaceae with 27 genera and 38 species, Apiaceae with 17 genera and 23 species, Lamiaceae with 13 genera and 21 species, Brassicaceae with 16 genera and 20 species, Boraginaceae with 10 genera and 13 species and Caryophyllaceae with 9 genera and 11 species. The life forms of the studied plant species included phanerophytes (5.2%), chamaephytes (7.7%), Hemicryptophytes (32.5%), Geophytes (11.4%), Therophytes (42.0%), Hydrophytes (0.9%), and Epiphytes (0.3%). From the chorological point of view, 26.3% of the total species were Irano-Turanian elements from which 4% were Iranian endemic species. The other species belong to two, three, or more phytogeographical regions.

The distribution pattern and the association of trees of different species have a direct correlation with the dynamics and tree species relationships in the forest ecosystems. The purpose of the present study was to determine the spatial pattern of Yew, Hornbeam and Oriental Hornbeam trees and also to analyze the competition between Yew trees with two other species in Afratakhteh yew reserve of Aliabad katul city. After the circling forest, intended stand selected and the location of the species was recorded using the TP360 Laser Rangefinder machine by distance and azimuth method. Overall of 366 yews, 47 hornbeams and 71 Oriental Hornbeams were measured. The results of Single variable pair correlation function showed that spatial distribution of three species follows a random pattern. Investigating the competition between species using a bivariate pair correlation function showed that there was no or no significant difference between yew trees and hornbeam trees and Oriental Hornbeams. Middle aged stand, Intra-specific competition and reaching the stage of puberty are important factors for the formation of a random pattern for three species of Yew, Hornbeam and Oriental Hornbeam. The optical nature of forest trees, the existence of different nutrition of different species trees and the growth of trees in steep and sloping arenas with different soil beds can be a reason for the absence of negative competition between species. Therefore, in order to revive this valuable species, must be tried The yew will be established in low-slope areas with great soil depth.

This study was conducted with the aim of classifying the Box tree forests of the plant communities in Bandar Gaz Golestan. For this purpose, Vegetation releves, 97 numbers, were made at peak vegetation cover by systematic-selective method in 200 meter grid dimensions with an area of 400 square meters by using Braun-Blanquet and consideration indicator stands concept. In each releves, all vascular plant species were recorded, and their percentage cover was visually assessed using a modification of the ordinal van der Maarel cover-abundance scale. The classification of plant communities was done using the combined results of two modified TWINSPAN methods and a Braun-Blanquet table synthesis method. Determination of diagnostic types was also done using the qualitative index of correlation coefficient. The results showed that in the area of the region, there are five plant communities in the form of two communities: Danae racemocii Buxetum hyrcanae and Parrotia persicae-Buxetum hyrcany and five subspecies of Quercos castaneifolia, Acer cappadocicum, Cornus australis, Ficus carica and Zelkova carpinifolia. The results of this study, while introducing Box tree Syntaxons in the eastern part of Hyrcany, indicate the high sociality of the Box tree species in the formation of distinct herbaceous communities with high denominability of the forests due to the absence of herbaceous species in the foraminous.

The aim of this study was to investigate the effect of environmental factors and stand properties on changes of humus forms in the managed and old growth forest of Gorgan. First we superimposed geological, soil, topography and tree type maps to producing homogeneous units. In each unit, three sample plots (20 × 20 meters) were selected and five humus profiles were described in each plot. Main and secondary humus forms were identified based on new European classification. Environmental factors and stand characteristics were investigated in each sample as factors influencing the changes in the humus form. Kruskal-Wallis test and random forest algorithm were used based on the Gini index for analysis. Three main humus forms and eleven secondary forms were identified in the research area, so that the main humus of the MULL (49%) and the secondary humus of the Oligomul (26%) were the most abundant humus forms. There was a significant difference between the main (p<0.01) and secondary (p<0.001) humus forms between the managed and old growth forest. The effect of most environmental variables and stand characteristics were significant on the changes of humus forms. The effective important variables in the main and secondary humus forms classification were thickness of H horizon, altitude from sea level, geographic direction and tree basal area.

The Increase in studies of beta diversity has led to several measures and methods. The variety of theses indicators cause their use in confusion. The aim of this study was to evaluate and determine the relationships between 18 different beta diversity indices based on presence and absense data. For this purpose, Buxus hyrcana database in Golestan and Mazandaran provinces was used. Clustering results showed that these 18 indices classified into 4 distinct groups with similar performance. Evaluation of clustering results by Detrended correspondence analysis (DCA) analysis showed that the indices of the four groups of cluster analysis can be separated into three distinct groups. From basis of combined results of discriminant analysis and Braun-Blanquet method, three vegetation units were recognized, which had 64.1 percent coincide with phytosoicilogical plant communities in Braun- Blanquet method. Also, among of 18 beta diversity indices included in the discriminant analysis, only Bm, Bc, B-2, Brlb, Bco, BI and Be were added in three functions. Among these 7 indices, them, Bm, Bc, BI and Be had a high canonical correlation with the three discriminant analysis functions. totally, the results of this study showed that many beta diversity indices based on presence and absense data have similar performance, and the numerical values of beta biodiversity indices are a good criterion for identifying Buxus hyrcana plant communities, provided that species turnover in these plant communities being high.

Zarde-Kija mushroom(Cantharellus alborufescens) is one of the edible mushrooms belong to the Cantharellaceae family. It is widely distributed in the northern forests of Iran and is desirable for local residents in these areas. Despite the economic importance of this genus, litthe is known about their habitat requirements. This study was conducted to identify the environmental factors affecting the distribution of this mushroom in a plain forest of Noor city (Mazandaran province, northern Iran) with 120 ha area. For this purpose, 20 pair plots (20 m × 20 m) with at least 100 m distance were established (20 plots with Cantharellus and 20 non-Cantarellus plots). To analyze the species-environment relationship (soil characteristics), three groups of plant species were identified by the TWINSPAN method. The results showed this mushroom presents in oak-hornbeam stands with following conditions: clay-loam soils, pH value 5.7-7.2, soil C content 2.2-3.7%, total N 0.16-0.27%, C:N ratio 10.8-18.9, water content 29.4-46.2% and litter thickness 4.8-19 mm. In this regard, soil C content, C/N ratio, amount of sand and clay in plots with Cantharellus was 36, 71, 30 and 18 percent greater than those in plots without Cantharellus. Also, Nitrogen concentration (N), ammonium (NH4+), nitrate (NO3–), litter thickness and amount of silt in non-Cantarellus plots were respectively 30, 20, 19, 48 and 28 percent lesser than those in plots containing Cantharellus. Overall, our findings showed that C content, C:N ratio, sand (%) and clay (%) were the most important factors influencing the presence of C. alborufescens.

In the present study, the response curve of box tree to some edaphic characteristics (texture, nitrogen content, carbon content and pH) and physiographic factors (slope, aspect, and altitude) were analyzed in the Hyrcanian forests using random forest algorithm. For this purpose, 857 sample plots (400 m2) were established in the large habitats of B. hyrcana as selective method. The response curve of B. hyrcana Pojark showed that acidity and altitude are the most important and aspect and silt content are the least important variables. Also, based on the ecological optimum values for each variable showed that the Buxus tree is lime- and moisture-demanding species, which is present in low altitudes, steep slopes and light soils with high nitrogen content that can be used for the management decisions. The results and methods presented in the paper can also be applied to conserve and restore the other rare and endangered species.

In this research, the application of Artificial Neural Network or MLP method in the process Assignment of relevé-groups/ plant communities allocation was evaluated using Buxus hyrcana forests database. For this purpose, firstly, the ecological and sociological groups of B. hyrcana were determined using TWINSPAN and Braun-Blanquet method, respectively. The results of both numerical and expert based classification dendrogram of the B. hyrcana communities, which included seven levels of classification as primary groups/plant communities, were introduced to MLP. Then, with assignments in three sets of training (70%), test (15%) and validation (15%), the MLP classification was performed on each level of the two dendrogram. The results showed that by increasing the level of classification, the degree of adaptation of the MLP result to primary results of TWINSPAN (99% to 60%) and Braun-Blanquet (98% to 68%) from the cutoff level of 1 to 7. Results of sensitivity and kappa cross tab coefficients, except in 7 cut level, imply that the quality of MLP groups based on TWINSPAN primary ecological group is upper than primary Braun-Blanquet groups.Appropriate adaptation of the MLP results in Buxus hyrcana plant communities classification with the TWINSPAN and Braun-Blanquet ecological/syntaxa groups at the fifth cut level of both dendrograms indicate that application of MLP aim at a reliable results in plant community classification. So our result reiterate that MLP could be introduced as a suitable method in the assignment of releves to plant communities.

In this study, the Qalajeh protected area in the Kermanshah Province (Iran) was investigated for its plant associations. Based on the map of the region, areas of natural and semi-natural habitats were initially separated from inhabited, farms and disturbed areas, in which 98 releves were stablished. Vegetation data were collected using the Braun-Blanquet method and soil samples were collected to analyze soil characteristics. The vegetation analysis was carried out by the Braun Blanquet tabular synthesis using the JUICE software, while classification of releves was carried out using TWINSPAN. Results showed that  19 associations including Aveno barbatae-Trifolietum scabri, Aegilopetum triuncialis-umbellulatae, Sanguisorbetum minoris, Astragalo flexilipedis-Acanthophylletum caespitosi, Trifolio echinati-Anemonetum coronariae, Scirpoidetum holoschoeni, Daphno mucronatae-Quercetum brantii, Pistacio eurycarpae-Quercetum brantii, Pruno orientalis-Quercetum brantii, Fico caricae-Quercetum brantii, Pistacio khinjuk-Quercetum brantii, Crataego ponticae-Quercetum brantii, Festuco ovinae-Astragaletum veri, Pruno microcarpae-Quercetum brantii, Ferulago carduchori-Quercetum brantii, Pyro oxyprii-Quercetum brantii, Aceri cinerascentis-Quercetum brantii, Juncetum inflexi and Typhetum grossheimii in the area. Furthermore, their distribution was found to be mainly due to climatic factors of temperature and precipitation, which are resulted from difference in elevation levels, aspect and soil factors including texture, lime, available potassium (K), available phosphorus (P), organic carbon and electrical conductivity.

Understanding the underlying mechanisms for tree species regeneration, as well as the positive and negative interaction between tree species and regeneration can improve the effectiveness of forest management and restoration activities. English yew, as one of the rare and valuable native species in Hyrcanian forests, Iran, has declined over the past several decades for many reasons such as lack of regeneration in existing populations. This research aims at studying the spatial pattern of English yew regeneration and its interaction with adult trees. For this purpose, the location of all English yew trees and its regeneration was recorded using TP360 device and distance-azimuth method in the Afratakhteh Forest Reserve, Golestan province. Totally, 417 English yew trees and 59 regenerations were recorded in the research area. The minimum and maximum diameter of the English yew trees was 6 and 124 cm, respectively. The results of the univariate analysis O-ring function showed that the spatial pattern of English yew trees is completely random and spatial pattern of regeneration were clustered in < 5 m, and then it is random. The results of the bivariate O-ring function showed that there is strong competition and negative interaction between the yew tree and its regeneration. It seems the density of the mother trees in the forest and a large shadow over the length of the year by yew trees is linked directly to the absence of regeneration in this forest reserve. Also allelopathic influence of parent yew trees could negatively impact on seedling density beneath a conspecific canopy. The areas out of existing English yew canopies are most likely to represent optimal sites for regeneration. Therefore, in order to protect the existing English yew stands, management activities on regeneration should focus on these areas.

One of the most commonly used methods for estimating environmental conditions using plants is the use of Elenberg Indicator values. However, due to objections to the Elenberger system (including caution in its use outside Central Europe), in this study, inaddition to EIVs, three calibration methods (weighted averaging, species response curves by using HOF models, adjusting the original EIVs with respect to a measured gradient using the HOF models) were used to calculate indicator values (IVs) of species in a Hyrcanian forest for two environmental factors (soil reaction or acidity (R) and nitrogen (N)). Also, two bioindication methods WA1 (cover-weighted average) and WA2 (cover-weighted average based on reciprocal squared tolerance values) were used to predict mean R and N values using EIVs, IVs and cover of species for each releve. Then, the regression of the mean values of environmental factors against the measured environmental values in each releve was performed. In general the performance of bioindication methods for soil acidity and nitrogen varied from 1.35- 32.5% and 3.6- 36.7% of the explained variance, respectively. In addition, calibration methods (especially the weighted average method) resulted in better results compared to Elenberg values.

In this paper we described variations of plant biodiversity indices in the plant communities of Salaheddinkola forests, Nowshahr. For this purpose, plant species floristically data with some environmental properties have been recorded in 76 plots (400 m2) along two altitudinal gradients (200–2300 m a.s.l.). Five ecological species groups were distinguished by using the results of TWINSPAN which were done based on floristic cover data. The comparison of diversity indices between ecological groups were done by ANOVA test and DCA Analysis. Results showed that biodiversity indices had significant differences between plant communities. The plant communities I and II, which represents Carpinus betulus-Parrotia persica forests and located in lower elevations had the largest values of Simpson’s Diversiry index, shannon’s Diversiry index and Shannon Evenness index. As well as, Simpson Dominance was maximum in the III, IV and V plant communities, which represents the beech forests at the higher altitudinal ranges. Result also showed that there was no clear trend in Richness index’s along the altitudinal gradient. Finally, we concluded that altitude was a basic factor in variations of plant biodiversity indices and distribution of plant communities in this area.

This study was investigated the above-ground vegetation and soil seed bank flora in three site of Albizia julibrissin Durazz. In Hyrcanian Lowland Forests (including Haloomsar, Anjilisra forests and Sisangan Box tree (Buxus hyrcanus Pojark) reserve). Aboveground vegetation was sampled by 68 plots of 400 m2 during late June and seed bank flora was studied by seedling emergence method. The result showed that there were 66 plant taxa belonging to 59 genera and 38 families in the extant vegetation of the studied eareas, while a total of 93 species, 82 genera and 48 families were represented in the soil seed bank.Lamiaceae, Poaceae and Rosaceae with 5 species (7.6%) were the most frequent families in the above-ground vegetation while in soil seed bank Asteraceae with 12 species (12.9%), Lamiaceae with 6 species (6.5%) followed by Cyperaceae, Fabaceae and Poaceae with 5 species (5.4%) were the most important families. Results also showed phanerophytes with 37.9% (25 species) and Euro-Siberian with 42.4% (28 species) in the Above-ground Vegetation floras and Hemicryptophytes 32.3% (30 species) and pluriregional regions elements 28% (26 species) were the most important biological spectrum and phytochorion in the seed bank floras, respectivly.From total of 118 plant species, the proportion of species that presented only in the above-ground vegetation, only in soil seed bank and in both of them were 25, 52 and 41, respectively. This condition not only explains low similarity between soil seed bank and above-ground vegetation and it also showed the importance of soil seed bank study for introducing more accurate capacity of plant biodiversity. our result also showed that Albizia julibrissin Durazz with the average seed density of 270 seeds/m2 are attending in 61% of total seed bank samples which it emphesizes the role of its seed bank as a suitable source for natural restoration of Albizia julibrissin in the Hyrcanian Forests

This study intends to assess the application of Cocktail method in the classification of large vegetation databases. For this purpose, Buxus hyrcana dataset consisted of 442 relevés with 89 species were used and by the modified TWINSPAN. For running the Cocktail method, first primarily classification was done by modified TWINSPAN, and by performing phi analysis in the groups resulted five species were selected which had the highest fidelity value. Then sociological species groups were formed by examining co-occurrence of these 5 species with other species in the database. 21 plant communities belongs to 6 variant, 17 sub associations, 11 associations, 4 alliance, 1 order and 1 class were recognized by assigning 379 releves to the sociological species groups by using logical formulas. Also, 63 releves by the logical formula were not assigned to any sociological species groups, by FPFI index were assigned to the sociological species groups which had the most index value. According to 91% classification agreement with Brown-Blanquet classification and Cocktail classification, we suggest Cocktail method to vegetation scientists as an efficient alternative of Braun-Blanquet method to classify large vegetation databases.

This research aims at ecological classification and identifying diagnostic species of box tree (Buxus hyrcana Pojark) sites in Farim forests, Sari, Iran. The data were collected from 60- 400m2 sample releves in systematic- selective design (200 × 400 meter) by considering the indicator stand concept. Floristic data were analyzed using modified TWINSPAN and consequently, six ecological groups were classified. The results of diagnostic species analysis based on Phi fidelity index revealed that of the 77 species recorded, only 47 species had positive fidelity to presented groups (P

There are several available indices to assess the group associations between species and sites in order to identify diagnostic species. In this study, we introduced 11 indices of species-site groups and evaluated their quality by means of a TFVI model and four numerical criteria, including average positive fidelity, sharpness, uniqueness and crispness based on of 168 releve of Buxus hyrcana habitats. We used a modified TWINSPAN classification of 168 releve (Nine vegetation community/site groups) to determine the species fidelity value. The results showed that new classification obtained from assigning releve using TFVI model based on IndVal, UbinB and Ochiai indices returned the highest values of the fourfold criteria in evaluating classification quality. Moreover, they achieved higher qualities compared to other indices. Also results of cluster analysis and PCA diagram showed that 11 species-site groups’ association indices can be divided into four groups. The scatter plot of association indices along two first axes in PCA (eigenvalues 0.556 and 0.365, respectively) explained 92% of total variation, and species fidelity values based on IndVal and Ochiai indices were similar and noticeably different with other indices. Finally, the results of this study revealed that IndVal and Ochiai indices have the most priority in determining diagnostic species of vegetation communities compared to the other examined association indices.

Populus alba because of fast growing and relatively adapting to dry and semi-dry climate conditions and P.euphratica because of salt tolerating are important as native species. Cuttings of 18 clones (P.alba x P.euphratica), a single reciprocal crossed clone (P. euphratica x alba) and 2 other P. alba clones were planted, surveyed under a RCBD with 3 replications each of which including 10 individuals per plot in Kushkak research station during February 2010. Germination percentage (GP), collar diameter (CD) and height (H) were measured early and late 1st growing season, respectively. 9 morphometric characteristics of randomly collected 30 leaf samples were also measured in the middle of the 2nd growing season. ANOVA showed significant differences among all investigated traits except for GP. During the two-year experiment, P.euphratica x P.alba 44/9 with 6.75 m H and 6 cm CD, and P.alba 58/57 with 2.51 m H and 2.1 cm CD had maximum and minimum growth respectively. Furthermore, PCA showed P.euphratica x P.alba 44/9 was completely different from other hybrids because of correlating with 9 out of 14 investigated traits, therefore P.euphratica x P.alba 44/9 was evaluated the best poplar hybrid during the two-year study in climatic conditions of north of Khouzestan province.

The aim of this study is to propose a modification of TWINSPAN algorithm with introducing new stopping rules for TWINSPAN. Modified TWINSPAN combines the analysis of heterogeneity of the clusters prior to each division to prevent the imposed divisions of homogeneous clusters and it also solved the limitation of classical TWINSPAN in which the number of clusters increases power of two. For this purpose, ecological groups of Box tree stands in Farim forests were classified with using classical and modified TWINSPAN basis of plant species cover percentage of 60 plots with 400 m2 surface area which were made by releve method (by consideration of indicator stand concept). In this relation, five different heterogeneity measures including Whittaker’s beta diversity and total inertia, Sorensen, Jaccard and Orlo´ci dissimilarity indices which representing diversity and distance indices respectively were involved. Sample plots were also classified from basis of topographical properties using cluster analysis with emphasizing Euclidean distance coefficient and Wards clustering method. Results showed that using of two sets of heterogeneity indices lead to different classification dendrograms. In this relation, results of Whittaker’s beta with total inertia as diversity indices were similar and the other three dissimilarity indices have shown similar behavior. Finally, our results reiterated that modified TWINSPAN did not alter the logic of the TWINSPAN classification, but it increased the flexibility of TWINSPAN dendrogram with changing the hierarchy of divisions in the final classification of ecological groups of Box tree stands in Farim forests.

This study intends to present floristic-physiognomic investigation of Box trees (Buxus hyrcana) of the Farim area of Sari. All of species in the area were recorded by two methods field-walk and 60 releves with an area of 400 m2 in a systematic-selective design in two elevation classes, more and less than 1200 m above sea level implemented. Our results showed that the flora of this region includes 47 families, 67 genera, and 77 species. Phanerophytes (37.7%), Cryptophytes (32.5%) and Hemicryptophytes (24.7%) were the most important structure groups of the local biological spectrum according to Raunkiaer method, and also with increasing elevation, portions of Hemicryptophytes and Cryptophytes increased and decreased, respectively. Chorological studies showed that chorotype form Euro-Sibria was the most important phytochorion in two habitats. The correlation of environment variables with two first axes of DCA showed that elevation of sea level and dominance average (canopy percentage) of Box trees had decisive role on the vegetation composition and mean richness of species (Hill N0 index). Also, Jackknife estimation results confirmed that species richness in habitats with elevation more than 1200 m (75.8 species) had a higher level compared to habitats with elevation less than 1200 m (58.6 species) because of decreasing box trees dominance. Totally, the results of the present study not only confirmed the ecological capacity of Box trees in developing up to 1700 m in mountain forests of north Iran, but also the association of box trees with some plants of high regions with steep slope of north Hyrcanian forests such as: Acer mazandaranicum, Carpinus schuschaensis and Taxus baccata, can be introduced as two new syntaxa including Taxus baccata- Buxus hyrcana and Carpinus schuschaensis- Buxus hyrcana in Hyrcanian forests.

In order to investigate some silvicultural and soil physico-chemical characteristics of Christ's thorn (Ziziphus spina christi L. Desf.) natural stands, ten natural stands of the tree species which have similar climate and aspects were selected and altitude from sea level (ASL), the thickest sprout collar diameter (TSCD) and total tree height (TH) of the tree species were measured in 1000 m2 circular main plots. Seedling regenerations of the species were counted in 100 m2 circular microplots. We sampled soil from three depths of 0-30, 31-50 and 51-70 cm for studying on soil physico-chemical properties in each main plot. To compare means of tree quantitative characteristics, t-student, ANOVA and Duncan and for soil studying, CA and PCA were used. The results showed that TSCD and TH hadnt significant differences in two levels of ASL. Although there were an exclusive correlation between presence of the species and sand percent of all three layers of soil in around 60% of Christ's thorn sites, the minimum TSCD were recorded in the sites too. Christ's thorn had the maximum TSCD in sites correlated with N, OC and EC in shallow and percent of silt and clay in deep layers of soil. So for increasing success of Christ's thorn plantations we suggest such sites are selected.

The present study involves the soil seed bank flora of the Sisangan Box tree (Buxus hyrcanus Pojark) reserve by using seedling emergence method. 150 soil samples were collected during late June and early November by hammering a hollow metal frame 400 cm2 to a depth of 5 cm. Results showed 67 species، representing 63 genera and 38 families germinated from soil seed bank. 45 species belonging to 28 families and 59 species belonging to 32 families were recorded in June and November soil seed bank respectively. The largest families were Asteraceae (7 species، 10. 5%)، Lamiaceae (6 species، 9%)، Poaceae (5 species، 7. 5%) and Rosaceae (4 species، 6%) which compromised 32. 8% percent of the total species in the soil seed bank. Results also showed that Hemicrptophytes (28. 4%) and Euro-Sibria elements (23/9%) were the most important biological spectrum and phytochorion respectivly in the soil seed bank of Sisangan forest. From the total number of species recorded in seed bank، 30 species (44. 6 %) were found only in the seed bank and never observed in above-ground vegetation. In this regard، seeds of 10 woody species including Albizia julibrissin، Ficus carica، Morus alba، Diospyrus lotus، Celtis australis، Gleditsia caspica، Buxus hyrcana، Ulmus minor، Zelkova carpinifolia and Carpinus betulus were found in the soil seed bank، from which only 6 species were able to produce persistent soil seed bank. This condition confirmed low similarity between above-ground vegetation and persistent soil seed bank and it also reiterated the importance of soil seed bank study for introducing more accurate capacity of plant biodiversity.