جستجوی مقالات مرتبط با کلیدواژه « regeneration » در نشریات گروه « جنگلداری »

Reproduction (regeneration) is a fundamental process that drives the dynamics of a forest, occurring continuously in a healthy and natural forest with a specific spatial and temporal pattern. Natural regeneration poses significant challenges in Zagros forests, Iran. This research was undertaken to examine and analyze the current state of reproduction of tree and shrub species in the monitoring sample plots of Zagros forests. This study, while scrutinizing the species composition, origin, distribution curves, and health of seedlings and saplings, explores the interrelationship between reproduction and nurse species. It will serve as the foundation for long-term studies that determine the temporal changes in reproduction and its characteristics in the Zagros forests.

This research was conducted in the permanent monitoring plots of Zagros, spanning from West Azerbaijan to Fars province. A total of 120 sample plots of 100 square meters were studied within these plots. Each province had 30 studied sites in the typical forests, with 10 of them located in the protected forests. The variables studied included reproduction density by species, origin and type of reproduction, nurse species, height of seedling, terminal bud, and health status of reproduction. A height of 0.5 meters was set as the criterion to distinguish reproduction. The t-test was used to compare parametric data in two groups, while the Kruskal Wallis and Mann-Whitney U tests were employed for non-parametric data.

In the studied area, the reproduction of 20 forest tree and shrub species was recorded, and the density of seedlings and saplings was calculated to be 366 plants per hectare. However, the reproduction was not uniformly distributed, with 37% of the sample plots lacking reproduction. The abundance distribution diagram in the height classes revealed a decrease in the number of oak (Quercus spp.) and hawthorn (Crataegus spp.) reproduction with a height of less than 5 cm. Of the total number of recorded reproduction, 72.5% originated from seeds and 25% were shoots. Overall, 66% of reproduction was dependent on nurses, with oak, hawthorn, stone, and rock playing the greatest roles as nurses. Stones and rocks played a more significant role in the revival of seedlings. Cerasus microcarpa (C.A.Mey.) Boiss., Q. infectoria Oliv., and Q. libani Oliv. had the highest dependence on the nurse, while Pyrus spp., Daphne mucronata Royle, and Crataegus spp. had the least dependence on nurse species. Reproduction sheltered by nurses was significantly healthier than those without nurses. Also, reproduction sheltered by stones and rocks had a higher health rate than reproduction sheltered by trees, although this difference was not significant. Lonicera nummulariifolia Jaub. & Spach, Fraxinus angustifolia Vahl, and Acer monspessulanum L. had the worst condition in terms of reproduction. Despite the presence of mature trees, they had no reproduction (L. nummulariifolia and F. angustifolia) or had very low reproduction (A. monspessulanum). The results showed that the number of reproduction in protected sites was higher than non-protected sites. Although this difference was not significant, the reproduction in the protected sites was significantly healthier.

The results indicated that the reproduction in the Zagros forests is not in a normal situation. However, given suitable spatial and temporal conditions, reproduction occurs and establishes. Although in conditions of disturbance and overgrazing, reproduction attempts to survive by taking shelter near stones, pits, or under thorny shrubs, the conservation of the forest stand by maintaining the tree canopy (oak, hawthorn, and other species) and the forest’s natural structure provides the best conditions for the establishment and survival of reproduction, thereby ensuring the sustainability of the ecosystem.

The regeneration of trees in forests with a long dry season such as Zagros has extreme difficulties. Predicting of water deficit tolerance in the progenies based on the geographic, vegetative and physiologic characteristics such as the performance of photosystem can conducted to increasing the efficiency of plantations.

In this study, the progenies of 40 Persian oak trees derived from 8 populations located in southern Zagros forests were assessed for water deficit tolerance based on their geographic, growth and physiological characteristics such as photosystem II under greenhouse conditions. Also, the percentage of seedling establishment for each mother tree were evaluated by field trial during two years. The corresponding data obtained from these experiments in accompanied by the morphological characteristics of leaves and seeds of mother trees were used to developing of the predictive models of seedling establishment in the field. In this research, greenhouse and forest field experiment was conducted to evaluate the response of Persian oak seedlings to drought stress based on some indicators of stress resistance from photosystem II. Persian oak seedlings from different mother trees were subjected to drought stress by stopping irrigation for one month in the greenhouse conditions. Then, the seedlings were irrigated for one month again and in all stages, the photosystem II, the percentage of leaf yellowing and the percentage of survival of the seedlings were recorded. Also, the establishment of the offspring of mother trees in the forest field was evaluated based on the percentage of survival and the height of the seedlings during two years, and their relationship with the leaf and seed morphological characteristics of the mother trees was investigated.  

The results showed that there is a positive relationship between the percentage of survival, and stress resistance indicators in greenhouse conditions with the percentage of survival and the height of seedlings in the forest field. Also, seedlings from drier seed origin, lower altitudes and latitudes, had higher drought resistance in greenhouse conditions. However, none of the growth and survival parameters in the field was related to the environmental characteristics of population. The relationship between the leaf and seed morphological characteristics of mother trees with stress resistance and the establishment of seedlings showed that the seedlings grown from wider and heavier seeds had better growth characteristics and survival only in the first year. Also, some leaf morphological characteristics of mother trees, such as petiole length, tooth width and number of veins were affecting traits to seedlings successful establishment in the forest field.

The results of this research showed that collecting of larger seeds from mother trees with suitable leaf traits could be effective for reforestation success. In addition, the use of physiological traits in the control condition in greenhouse can help for selecting the resistant progenies from superior populations or mother trees.

The aim of this study was to study the effects of altitude and slope factors on beech natural regeneration around dead trees in Siahroud forests of Guilan province. In order to conduct this research, 45 dead trees were selected using selective sampling method. Then, around the standing dead trees, a circular plot with a radius of 5meters and around the fallen dead trees, a rectangular plot with 4meters width (2meters from two sides of each log) were measured. Inside each plot, regeneration frequency, slope (in three classes of <30, 30-30 and > 50%) and altitude (in three classes of <700, 700-1500 and >1500 m) were measured. In order to compare regeneration in 50m distance from dead tree, the measured variables were collected in samples with the center of healthy trees with the same DBH. The results showed that the regeneration frequency of all tree species around dead trees was higher than around of healthy trees. The ANOVA test showed that there is a significant difference between the regeneration frequency in different classes of altitude and slope. Also, with increasing altitude and slope, the regeneration frequency of around healthy and dead trees was decreased. The results showed that physiographic factors have an important effect on the tree regeneration around of dead trees.

Quantifying the structure of forest stands by quantifying their different components helps to better understand for the management of different components of the forest ecosystem. One of the most important reasons for the structure quantification is that the forest structure is related to the habitat of many plant species, the modeling and reconstruction of the forest based on its structural characteristics, and the forest structure is an important source of information for forest dynamics, aesthetics and wood production. Therefore, in this research, the structural characteristics of two stands managed by single-selection and shelterwood methods were compared with the control stand.

In order to conduct this study, three plots including plot No. 3 with single-selection method, plot No.  13 with shelterwood method and plot No. 10 (control plot) were selected in Alandan forests, Mazandaran province. To study the structural features of forest stands, circular sample plots with an area of ​​1000 m2 were used (21, 14 and 25 sample plots in (In the plots of single-selection, shelterwood and control plot, respectively and a total of 60 sample plots). The inventory was conducted in a systematic-randomly method with a grid size of 200 × 150 m. To investigate the regeneration condition, a 1 m2 micro-plot in the center of the sample plot and its four main directions were used. In order to investigate the soil properties, sampling was performed by a combined method at a depth of 0-10 cm in the center of the large sample plot and the four main directions. Percentage of soil texture (including sand, silt and clay), moisture content, bulk density, pH, EC, percentage of organic carbon, percentage of organic matter, percentage of lime, total nitrogen, absorbable phosphorus and absorbable potassium were measured in the laboratory.

The results showed that the average number of trees per hectare was 206, 209 and 358 in the single-selection, control and shelterwood plots, respectively; which had a volume of 428.22, 477.14 and 373.3 sylve, respectively. The average percentage of moisture, percentage of organic carbon and percentage of organic matter in the single-selection was 49.4%, 4.7% and 8.2%, respectively; while, in the control and shelterwood plots they were 44.12 and 43.24%; 3.4 and3.28%; and 5.9 and 5.66%, respectively. The bulk density was 1.72 g/cm3 in the shelterwood plot; while, its amount in single-selection and control masses plots 1.22 and g/cm3, respectively.

In general, the results of this study showed that the implementation of different silvicultural methods such as the shelterwood and selection methods have different effects on the structure, regeneration, and physical and chemical properties of the soil.

 Biodiversity is one of the most important indicators of the sustainability of forest ecosystems, which is affected by stand mixture. Vegetation composition and diversity data are the most important basic information for recognizing the natural capacity and targeting for the principled management of forest habitats. On the other hand, the correct understanding of the regeneration status in the forest is the most important The components in predicting the future of the forest are in terms of structure and composition of tree elements. The aim of this study was to compare the diversity of herbaceous cover and regeneration in pure beech, pure hornbeam and mixed stands in Darbakola educational and research forest of Sari.

 For this purpose, the inventory was performed by randomized systematic method with grid dimensions of 75 × 100 meters and in each stand, 25 sample plots with an area of 400 square meters were implemented and the diameter and height characteristics of the trees were collected. To study biodiversity, names of herbaceous species and the type and number of regenerations were collected in 2×2 meter micro sample plots in four quarters and the center of the sample plots in two stages (May and September). Diversity indices of Shannon and Simpson richness indices of Margalf and Manhenick and evenness Owens and Burger Parker diversity indices were used to study the biodiversity of regenerations and grass cover. One-way analysis of variance was used to compare quantitative characteristics of biomass and biodiversity between habitats and to compare the means by SNK test in SAS software environment and to draw graphs using Excel-2010 software. Past software was used to study biodiversity.

 The results of the present study showed a higher density of beech regeneration in all three studied stands. The highest total number of regeneration was observed in mixed habitat (4040). The highest indices of diversity, richness and regeneration evenness were observed in pure hornbeam and the lowest in pure beech. Regarding herbaceous cover, no significant difference was observed between diversity indices among different stands, while the average of these indices was higher at the beginning of the growing season than at the end of the growing season. Therefore, stand mixture has more tangible effects on regeneration diversity than herbaceous cover, and herbaceous cover diversity is more affected by the during the growing season than type of stand mixture.

 Based on the results of the present study, the future composition of the studied populations will be affected by the dominant species of beech. Also, due to the species diversity in the mixed habitat, the highest total number of regeneration and forest density will be related to this stand. Regarding the grass cover, the higher average of diversity indices at the beginning of the growing season than at the end of the growth season, indicates that the environmental conditions are better in terms of temperature and soil moisture in this season. Therefore, mixing has more noticeable effects on regenerative diversity than grass cover and the difference in grass cover diversity is more affected by the time period of the growing season.

Forest health monitoring is essential to assess the changing state of forest resources and create awareness of forest health issues. This study was conducted to monitor forest health using two indicators of regeneration and deadwood in the Masouleh watershed,. To collect data in the study area, using Forest Health Monitoring method 5 clusters of plots including 20 plots in two different altitudes were considered. In each cluster, the regeneration status of species was determined based on the quality of seedlings and their division into two categories: healthy and unhealthy. The characteristics of the deadwood including diameter, and quality characteristics (species type, degree of decay) were measured and recorded. In the study area, 80% of the seedlings were healthy and 20% unhealthy. The results of the analysis of variance of the number of regenerations per hectare in the altitude classes showed that there is a significant difference between the number of healthy seedlings and unhealthy seedlings in the studied altitude classes. According to the results of the study, the volume of deadwood is 44 m3/ha, which is 34 and 10 m3/ha of down logs and standing deadwood, respectively. Analysis of variance showed that there was no significant difference between the volumes of deadwood per hectare in the two altitude classes in the study area. But there is a significant difference in the number of deadwood per hectare in the altitude classes. Study of the quality of deadwood showed that the highest percentage of deadwood belongs to the first-level decay (81%).

Studying and evaluating the canopy gaps structure provides an accurate understanding of the process of forest stands dynamics as well as natural disturbances that play an important role in the future management of the forest ecosystem. The purpose of this study was to investigate the relationship between gaps and quantitative and qualitative characteristics of regeneration in the natural forest of Haftkhal in Mazandaran province.

For this purpose, gaps in the area were identified and recorded. Then the characteristics of collar diameter, height, seedling abundance in growth stages were recorded. According to the smallest and largest gap area, gaps divided into three classes of small (less than 300 m2), medium (300 to 600 m2), and large (more than 600 m2).

The results showed that gaps area was 3.65% of the total study area. In terms of area, 85% of the gaps were in small and medium-sized classes, which could indicate small-scale disturbances. The relationship between the gap area and perimeter and the study of Miller's elongation index showed more elliptical shape in small gaps to a circular shape in large gaps. The value of the Miller elongation index in small, medium and large gap area classes was 0.42, 0.59 and 0.86, respectively. The results showed that 85% of the regenerations in the gaps were related to the beech species. The highest frequency of regenerations was in the pole stage with a diameter of less than 5 cm and a height of 4 to 8 meters, which is an essential factor in starting the competition for light. Comparisons also showed that the frequency, diameter growth, and height growth of regenerations decreased significantly with increasing canopy gap area due to ecological needs, especially shade-tolerant growth of beech species, which provided by small canopy gap area.

Finally, the results indicate that pathways smaller than 600 m2 have more suitable conditions and in forest management, the creation of gaps larger than 600 m2 should be avoided as much as possible.

Today, the use of modeling methods to predict and modeling of regeneration for different species in forest conservation and management plans is increasing. It is possible to predict the condition and density of forests in the future by forest regeneration modeling and based on that, adopted different management scenarios.

With regard to importance of the subject, in this study the regeneration rate of oak species in a part of oak forests of Manesht and Qalarang protected area-Illam province was estimated using artificial neural network (ANN) and environmental variables such as primary topographic properties, secondary topography, soil physical properties, soil chemical properties and forest structural characteristics as independent variables. For this purpose, various functions and models were evaluated. After sampling, 70% of the, oak regeneration samples was used as training samples to implement the ANN model and the remaining 30% of the data was used to evaluate the model results. Finally, the sensitivity of the oak regeneration model was analyzed.

The results showed that the artificial neural network with error standard error equal to 0.99 was able to estimate the oak regeneration in the study area. The results of sensitivity analysis showed that the highest R2 is related to the model with all input variables, which indicates the positive effect of all input parameters to the model, so that by removing each of the input variables, the accuracy of the model in predicting oak regeneration decreases. However, the results also showed that forest structural and soil chemical characteristics are the most important factors affecting oak regeneration in the study area. The least effect on oak regeneration in the prepared model are secondary topographic variables, which although had a positive role in predicting the regeneration. However, the effect of these variables was less than other variables. The results showed that about 21% of the study area has less than 100 regenerations per hectare. Also, more than 12% of the study area has more than 1200 regenerations per hectare.

In general, the simultaneous use of all primary and secondary topographic features, soil and forest structural characteristics increase the accuracy of regeneration modeling of Zagros oak forests. On the other hand, ANN due to its flexibility, allows the selection of the various variables according to the study area conditions and the available information, as a result, it increases the accuracy of modeling.

The aim of this study was to investigate the accuracy and precision of single microplot method in estimating the regeneration of wild cherry and introducing an alternative method. For this purpose, after a primary survey, three parcels in district-7 from Shafarood basin, which had mother trees and wild cherry regeneration, were selected. A total of fifty circular plots were taken randomly, in a 150×200 m grid, each 1000 m2 area. Four microplots were measured at a radius of 2 m and all the cherry seedlings were counted. A transect, 0.2 m wide and 10 m long was layed in each plot and all of the cherry seedlings under 1.3 m height were counted. In an area of 10,000 m2, including 10 randomly selected plots, all wild cherry seedlings were counted and calculated density was considered as control. Based on the results, the sampling error in the clustered-microplot method was minimal (18.69%) and in the transect method was maximum (45.62%). In terms of the accuracy, the clustered-microplot method had the highest accuracy (15.72%) and transect method had the least accuracy (111.74%) in density estimates. One-sample t-test showed that there is a significant difference between transect and single-microplot methods with the control in 5% confidence level, while the clustered-microplot was not statistically different. It can be said that the clustered-microplot method is more superior than single-miroplot method and is preferable for accurate and precise estimation of regeneration for rare specieses like wild cherry.

In this study, a habitat of wild cherry (111 ha) in Mamji-Darasii in the province of East Azerbaijan, the city of Kalibar, was fully inventoried and all wild cherry trees were then counted and measured. Frequency of cherry regenerations was also calculated by establishing 23 0.1 ha ample plots. The results showed that 86.6% of the cherry trees were healthy and vital and their mean height, diameter at breast height and volume were 9.3 m, 12.6 cm and 0.08 m3, respectively. The highest and lowest frequencies were 10 and 25 cm DBH classes, respectively . Density, basal area and volume of cherry trees in stand level were calculated as 2.14 individual.ha-1, 0.032 m2.ha-1 and 0.17 m3.ha-1, respectively. There was no significant correlation between the quantitative characteristics of trees and slope but diameter, height and basal area of the cherry trees decreased with increasing the altitude. Most of the trees (62%) were found on the northeast-facing slopes. The trees were taller in the northeast directions and in terms of diameter, basal area and volume, trees in the eastern aspects had higher dimensions. A total of 53 dead trees were counted, of which 43 were standing and 10 fallen. They constituted 18.2% of total cherry trees. The regeneration rate of cherries was 36.1 individual.ha-1. The highest abundance of trees belonged to the hornbeam followed by oak Wild cherry with 3% abundance was in fourth place. To enhance and increase the density of wild cherries, slight opening of the canopy is necessary using appropriate silvicultural operations.

Natural regeneration is responsible for the conservation of species and the protection of biodiversity in forest stands and an important step in forest dynamics towards sustainable management. In order to evaluate the effect of long-term exclosure on the density and diversity of natural regeneration, two forest habitats were selected including excluding stand and control stand, regenerations were measured and counted in six sample plots with an area of one hectare. Regenerations were divided based on height into four categories: seedlings, coppice large saplings, standard large saplings, and small saplings. the indices of richness, diversity, and evenness were calculated and statistical analysis was performed for each habitat. The results of the density showed that the exclosure area had a higher number of regeneration densities per hectare. The types of regeneration classes were more frequent in the exclosure area, except for coppice large seedlings, which were more abundant in the control area. Diversity and evenness indices were less in the control area than the exclosure habitat with a significant difference, but the richness index was not significantly different (p≤0.05). A successful stand recovery process is necessary to enhance regeneration and community sustainability in the future. Enhancing natural regeneration is a cost-effective way to improve the quality of forest stands. Based on the results, it is proposed to determine the optimal duration of exclosure in order to prevent the reduction of biodiversity and also to investigate the effect of exclosure on soil seed banks in the studied area.

The aim of this study was to evaluate the vegetation cover of alder and broadleaved coniferous forests of alder, maple and oak and compare it with natural forest in Ramsar Ridge. 96 sample plots of 400 square meters were collected by regular random sampling.The bio-spectrum of plants was determined based on the vegetative forms of Rankier and the geographical distribution of species based on the Zohary method. The results showed that 30 plant species belong to 23 families, most of which belonged to Fabaceae and Poaceae, Rosaceae. In terms of biological form, hemicryptophytes and cryptophytes were dominant with 68.73% of vegetative forms. The study of geographical distribution of plants in the region showed that the plant elements of Europe-Siberia constitute the most of the plant elements in the study area. Evaluation of plant biodiversity in forest stands showed that Simpson and Shannon Wiener diversity indices and Ghanaian Margalph index were not statistically significant and Kamenergo and Smith Wilson richness indices and homogeneity indices were not significantly different. Showed. Biodiversity of woody species regeneration in Simpson species diversity indices was highest in Alnus subcordata C.A. Mey and lowest in Cupressus Semprvienes L.Var. horizontails.

Process of natural regeneration in uneven-aged stands is one of basic issues for sustainability in close to nature silviculture approach. The present research started form 2009 in four intact oriental beech stands of the Hyrcanian forests. Twelve, one ha sample plots have been established in three development stages containing five micro sample plots of 4 m2. Three gap sizes (small, medium and large) with five micro sample plots of 4 m2 have been selected within the development stages and characteristics of saplings have been studied. Relative light intensity (RLI) and leaf area index (LAI) have been studied as well. Results showed that the stands in the initial and optimal stages were pure, while decay stage was mixed. The least RLI was observed in the optimal stage and small sized gap while the highest amount of RLI was in the decay stage and large gap. The lowest amount of LAI was calculated in the optimal stage and small gap size. The maximum mean height increment was measured in the initial stage and small gap, maximum length of uppermost internode and annual shoot in optimal stage and large gap and the widest crown width was calculated in the initial stage and small gap. The proportion of saplings with favored quality was highest in the optimal stage and medium gap size while the highest proportion of twig and broom shaped saplings was observed in the large gaps. Overall, small and large gaps can negatively affect the saplings, whereas medium sized gap creates better condition for saplings.

Tourism in natural areas can affect the biodiversity, density and structure of stands and plants health. The present research aims at studying the effects of tourism on vegetation structure and species diversity in Noor Forest Park, Mazandaran province. To do so, the study area was divided into three main zones: without pressure, moderate, and high tourism pressures. Then, sampling was done with 20 sample plots of 20 × 20 m sample with random-systematic distribution in each zone (60 plots in total). Within each sample plot, trees, shrubs, herbs and regenerations were counted and quantitative and qualitative characteristics of all woody species were measured. The species richness, evenness and diversity indices were then calculated and the calculated indices and forest structural features were compared amongst the mentioned zones. Based on the results, diversity of forest floor flora in high tourism pressure zone was higher than other zones and there was no significant difference in woody species diversity among three zones, nevertheless a considerable reduction was seen in density of both woody and floor species. The lowest regeneration abundance was observed in high tourism pressure zone and the most, in medium tourism pressure zone. In zone without tourism pressure, average height and canopy of trees were more compared with the high tourism pressure zone. Also, most snags, the highest ratio of broken trees to total trees and the highest number of diseased and damaged trees were observed in high tourism pressure zone. In this zone, Alnus glutinosa, Populus caspica and Parrotia persica had the lowest vitality.

PPoor regeneration has endangered the important and valuable species of wild pistachio (Pistacia atlantica Desf.) in the Zagros forests, which calls for finding an appropriate solution to its regeneration and establishment to protect it from extinction. For this purpose, in this research, the effect of different methods on germination and the establishment was reported after direct sowing of seeds in one of the wild pistachio’s habitats in Kermanshah province. Nine different sowing methods as main plots, four main directions as first sub-plots and shade and sun as second sub-plots were planted. During this time statistic data collected in four periods (before and after two growing seasons) and analyzing germination and establishment showed the significant effect of some approaches rather than others. Amongst the sowing methods, loosen the soil+humus (32.22%) and among the four main directions, northern plots (27.04%) had the maximum germination. There was a significant difference in the percentage of establishment only between shade and sun treatments and the plots in shadows had a maximum establishment at the end of the first growing season (43.8%), at the beginning of the second growing season (26.39%) and at the end of second growing season (22.8%). Based on these results, it has been concluded that the most appropriate method of direct sowing of the seeds is to sow them in northern micro plots that are created in the north, by loosening the soil to a depth of 30 cm + humus and under the shadows of other trees.

The aim of this study was to study effect of fire on vegetation and natural regeneration in Shanderman forests, Guilan province 7 years after burning. For this purpose, two burned and unburned areas were selected. Within each of the study areas, we used a random systematic 150 m × 150 m sampling grid to locate 40 circular plots of 1000 m2 for tree and shrub species (20 plots in burned area and 20 plot in control area). In each plot, density and DBH of tree species and density of shrub species were measured. Regeneration density was studied by 100m2 plots. Regeneration was studied in three classes as height < 1.3 m, DBH < 2.5 cm, and 2.5 cm < DBH < 7.5 cm. The results showed that density, the DBH and basal area of tree species and density of shrub species significantly deceased after burning. Also, density of regeneration significantly increased after burning. In tree layer, density of Quercus castaneifolia, Carpinus betulus, Zelkova carpinifolia and Parrotia persica significantly increased after burning. In shrub layer, density of Prunus divaricate, Mespilus germanica, Crataegus microphylla and Ruscus hyrcanus significantly decreased after burning. Forest structure was uneven-aged with a reverse J distribution in each two areas. Composition and pattern of dominance didn’t changed in tree, shrub and regeneration layers.

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.

The objectives of this study were to evaluate the soil physiochemical properties and regeneration of Prosopis cineraria in Bushehr and Hormozgan provinces, and to determine the most important soil factors effecting P. cineraria distribution and regeneration establishment. For this purpose, we selected four natural pure sites including Chah Mobarak, Nakhl Ghanem, Amani, and Bahdeh in Bushehr and Hormozgan provinces. In each site, five 25*25 m plots were randomly selected and soil samples were taken in each plot in two depths of 0-5 and 6-25 cm. Also, all of the regeneration in each plot, were counted and categorized based on their height (seedlings, <10, 11–25, 26–50, 51–75, 76–100, 101–130, 131–200 and >200 cm height). Collected soil physiochemical data and regeneration classes were subjected to one-way ANOVA. Result indicated that the highest and lowest amount of soil calcium carbonate belonged to the Amani (57.28%) and Bahdeh (80.6 %) sites, respectively. However, no calcium carbonate was observed in Chah Mobarak and Nakhl Ghanem sites. The maximum and minimum soil electrical conductivity belonged to the Chah Mobarak (5.58 ds/m) and Bahdeh (1.28 ds/m) sites at the depth 0-5 cm, respectively. Furthermore, the highest amount of calcium carbonate were recorded in Bahdeh (77.7 %) and Amani (55.4 %) at the depth of 6-20 cm. Soil Organic matter (1.24 %) and nitrogen (0.12 %) were greater in Nakhl Ghanem compared to other sites. Results of regeneration indicated that there are significant differences among the studied sites. Furthermore, Nakhl Ghanem, Amani, Bahdeh, and Chah Mobarak had 3814, 1491, 2813, and 3088 regeneration per ha. No regeneration was recorded in Amani and Bahdeh for >200 cm height class. Based on the results, the most important soil factor effecting P. cineraria distribution are silt followed by sand, potassium and clay. Moreover, nitrogen is an essential soil element in P. cineraria regeneration establishment. However, calcium carbonate and electrical conductivity had negative effects on P. cineraria regeneration and should be considered in plantation plans.

This study was carried out in managed and unmanaged Fagus orientalis L. (beech) stands in the Asalem beech forest in order to compare the composition and diversity of plant species. Three V-shaped catena landforms were selected for each stand. Then, large quadrats, 400 m2 area, with selective method and within each of them, small quadrats, 4 m2 area, were established along each catena and slope position (summit, shoulder, backslope, footslope, topeslope) to study the density and species diversity of trees, composition and species diversity of regeneration and herbaceous species, respectively. Simpson, Margalef and Camargo indices were employed for diversity, richness and evenness analysis. The result showed that beech had the highest crown cover and regeneration density. Slope position analysis showed that significant differences in Simpson diversity and Camargo's evenness indices in trees and Simpson diversity and Margalef richness in herbs. There was no significant difference between indices regarding to regeneration. Dryopteris filix-mass L. and Asperula odorata L. exposed the highest frequency in managed and unmanaged stands, respectively. Considering the dominant form of land in north forest habitats of Iran is catena landform; it is necessary to implement silviculture's plans (protection, restoration, development and utilization) with particular attention to catena management.

Natural regeneration is one of the key aspects of forest sustainability and a tool to decide on restoration programs in forest areas. The purpose of this study was to investigate the quantity of natural regeneration of Acer campestre L. as one of the most important tree species in Arasbaran forests and its relationship with elevation changes and structural characteristics in the natural stands. For this purpose, two habitats in two altitudes (less than 1500 meters and more than 1500 meters above sea level) were identified in the Kaleybarchay watershed of Arasbaran forests. In each elevation, three sample plots (one hectare area) were used to measure the structural characteristics (including density, basal area and canopy cover) by the whole trees inventory. The regenerations were classified in three classes: sapling (height greater than 1.30 m), large seedling (0.30-1.30 m height), and small seedling (height less than 0.30 m) per hectare in 10 circular micro-plots (100 m2) in each one hectare. The results showed that the saplings density was significantly higher (p≤0.05) only in the low elevation. The structural characteristics of the stands showed that only the difference between the basal areas of trees in different elevations was significant. Relationship between structural characteristics and regeneration density showed that there was a significant difference between the basal area and the density of saplings and regeneration density of the large seedling class and the canopy cover was significant. The findings of the present research let to better understand the ecological nature of this species in the early stages of life, will help to decide on environmental constraints for the establishment and continuation of the successful regeneration, and could help to more effective management for conservation and cultivation operations.