مسعود طبری کوچکسرایی

Biochar, a porous carbon-rich substance, is considered a soil amendment with the ability to preserve food and water and increase drought tolerance in plants. The present study aimed to investigate the effects of biochar (derived from hornbeam wood and produced at a pyrolysis temperature of 450 °C) on the survival, growth, and physiological traits of Arizona cypress (Cupressus arizonica Green) seedlings under rainfed and irrigation conditions in a mountainous degraded forest (Do-Ab in Savadkouh region, north of Iran).

The experiment was conducted as a completely randomized design for five months during the dry months of spring and summer. The treatment combinations included: 1) control soil-irrigation, 2) control soil-rainfed, 3) soil treated with biochar-irrigation, and 4) soil treated with biochar-rainfed. Two-way analysis of variance (AOVA) was used to determine the significant effect of the treatments, and a paired t-test was used to compare the means.

The results showed that, regardless of the effect of soil treatment, irrigated seedlings had greater survival (90%) compared to rainfed seedlings (56%). However, under rainfed conditions, the survival rate in the biochar treatment was 75%, almost twice that of the control soil. In both rainfed and irrigation conditions, the seedlings grown with biochar had larger sizes than those in the control soil. Regardless of the effect of soil treatment, the rates of photosynthesis and transpiration decreased under rainfed conditions. Similar to the irrigation treatment, the biochar treatment caused an increase in gas exchanges (20-60%) compared to those in the control soil. Mesophyll conductance, relative water content, and photosynthetic pigments were higher in the irrigation treatment than in the rainfed condition.

To restore the degraded forests of the semi-arid mountainous regions of northern Iran with Arizona cypress seedlings, it is recommended that in the early years, the seedlings be managed by irrigation without applying biochar. However, under rainfed conditions, it is recommended to use biochar to enhance seedling survival and growth.

Afforestation has been growing worldwide in recent decades and is expected to continue in this trend due to the increased use of wood. Therefore, the mass planting of pine trees and other fast-growing species for industrial wood production has intensified since the beginning of the 20th century. In Iran, with a low forest per capita (0.17 ha), per capita plans to create a forest and rehabilitate degraded forests to increase green space have been implemented with non-native species. For this reason, many non-native conifer species have been introduced to the country, which has not been successful in some areas. Therefore, for the success of afforestation with non-native species, it is necessary to select those that are suitable for the habitat conditions, adapt the ecological needs to the environment, and consider the effect of afforestation on the soil, understory plants, and living organisms. Ensuring sustainable management depends on knowing the effects of planted tree species on species diversity, structure, and ecosystem function. Since different tree species have different effects on soil characteristics in ecosystems, they can change soil properties with different mechanisms. In other words, the differences in litter quality, the state of nutrients, the performance of roots in nutrient uptake, the leaf structure, the crown of the tree, the microclimate under the crown, and finally the biological communities in different tree populations change the soil physicochemical properties. In general, the restoration of degraded forest lands through afforestation has a significant effect on the variability of soil characteristics, in which a major difference is observed between native and non-native species as well as broadleaf and coniferous species. Since broad-leaved tree species can positively affect the soil quality of conifer stands, this research aims to compare some soil physicochemical characteristics under the influence of pure and mixed Norway spruce (Picea abies L.) afforestation.

The studied area is in the southeast of section 101 of the Makarood series, watershed 36 (Kazemroud) in Kalardasht city and at an approximate height of 1200 m. It includes the afforested areas of pure Norway spruce (PS) (2 ha), mixed Norway spruce (MS) (2.5 ha) forestry areas, and barren land (BL) (3 ha). Three transects in each area were planned due to the smallness of the areas and the need to adopt a method that best describes the condition of the soil in each area. Then, on the 10, 50, and 90 m points of the transects, soil samples were taken in layers of 0-10 and 10-30 cm (in each area, nine soil samples for each layer). The texture, saturation percentage (SP), electrical conductivity (EC), pH, neutralizing substances or lime (T.N.V), organic carbon (O.C), nitrogen (N), phosphorus (P), potassium (K), and bulk density (BD) was examined in the laboratory.

The bulk density was lower in the 0-10 cm layer in the MS stand (2.28 g/cm3) than in the other two areas. The soil saturation was higher in the upper layer in the PS stand (85.77%) than in the MS stand (59.83%) and BL (51.07%). On the contrary, it was greater in the lower layer of the BL (94.40%) than in the two forest stands. EC values were lower in both upper (0.40 ds/m) and lower (0.38 ds/m) layers in the BL than that in PS and MS stands. The pH was significantly lower in the 0-10 cm layer in the PS (4.84) and MS (4.88) stands than in the BL (5.75). In each of the three areas, the amount of lime was zero in the upper and lower layers. O.C. in the upper layer was significantly higher in the PS (2.57%) and the MS (2.96%) stands than in the BL (1.45%), and the highest value was measured in the MS stand (0.94%) in the lower layer. Nitrogen was higher in the upper layer of PS (0.197%) and MS (0.270%) stands than that in the BL (0.143%). It was higher in the lower layer of the MS stand (0.09%) than the PS (0.02%) and BL (0.03%) stands. The C/N was highest in the upper layer in the PS stand (12.97), but this ratio was not significantly different in the lower layer of the three areas (10.82-11.50). The amount of P was highest in the upper layer in the MS stand (8.4 ppm), but no significant difference in P was detected in the lower layer among the three areas (3.57-5.60 ppm). K content was higher in the upper layer of the PS stand (203.43 ppm), but it was higher in the BL (193.50 ppm) in the lower layer than in the two forest stands. 

In the upper soil layer (0-10 cm), pH, C, and N values did not differ between MS and PS stands, but BD and C/N were lower in the MS stand; on the contrary, soil porosity and P and K contents were higher than those in the PS stand. From this research, it is generally concluded that afforestation with MS has a better effect on the optimization of physical and chemical characteristics in the soil layers than PS, which can provide the basis for more suitable growth of trees and a better balance of the forest.

Despite the potential of the Hyrcanian forests to maintain of Quercus castaneifolia, the abundance of this species has decreased drastically and most of the young stands of this species are seriously threatened. This research, using an integrated perspective, shows the distribution Q. castaneifolia species in the Hyrcanian forest with the aim of determining the optimal areas for reforestation using five different modeling methods including GAM, GLM, RF, CTA, and GBM. Rainfall and temperature maps are based on data collected from a network of weather stations, as well as soil data from Soil Grade database maps. Then, the most important independent variables affecting the distribution Q. castaneifolia were identified. The results obtained from the evaluation of the relative importance of the variables indicate that the amount of organic carbon, pH, changes in seasonal rainfall and rainfall in the coldest season of the year have the greatest relative importance in determining and developing the habitat of this species and the area has a favorable potential of 14.1 The percentage is for this species. The produced habitat suitability map is suggested as a basis for future forest restoration plans, especially in areas that are more affected by destruction.

Accumulation of cadmium (Cd) as one of the most toxic pollutants in the soil can lead to the reduction of microbial activities and soil fertility and as a result the death of plants; This issue has always caused global concerns. The present study was conducted with the aim of investigating the resistance to Cd of male (62-167) and female (62-149) individuals of black poplar (Populus nigra L.) based on vegetative and physiological characteristics.

For this purpose, a greenhouse experiment was conducted in the form of a randomized complete block design with factors of cadmium (concentrations of 0, 50, 150 and 200 mg/kg soil) and gender (male and female bases of poplar) for a 120-day period. Physiological variables of seedlings including net photosynthesis rate, transpiration rate, stomatal conductance, water use efficiency, water potential, mesophilic conductance, intracellular CO2 concentration, and vegetative characteristics including root collar diameter growth and height growth, total biomass and leaf area were investigated. The stress treatment was done in late May through irrigation with cadmium salt solution on a weekly basis for the first five weeks. After that, the seedlings were irrigated with rainwater, respecting the soil capacity, at intervals of three days until the end of the period (late September).

Regardless of the root species, with the increase of Cd concentration, the leaf area and height growth of seedlings decreased. The highest height growth (30.4 cm) and leaf area (51.8 cm2) were observed in the control, and the highest total biomass of seedling (59.2 g) was observed at the concentration of 50 mg/kg of Cd. Regardless of the concentration of Cd, the size of collar diameter growth (male 2.1, female 2 mm), seedling height growth (male 21.5, female 19.9 cm), leaf area (male 43.08, female 43.64 cm2), total seedling mass (male 46.48, female 44.19 g), water use efficiency (male 0.31, female 0.26 μmol mmol-1), mesophilic conductance (male 0.003, female 0.002 mol m-2 s-1) and stomatal conductance (male 0.45, female 0.39 mol m-2 s-1) was higher in males than females and only, the amount of transpiration (male 3.31, female 4.01 mol m-2 s-1) was higher in females than in males. Although, with the increase of Cd concentration, the size of most of the physiological and growth characteristics including photosynthesis, water potential, water use efficiency, diameter, height, leaf surface, and biomass decreased in general, the seedlings of both clones maintained their physiological and growth activities to some extent in high Cd concentrations.

It can be concluded that both clones can tolerate high concentrations of Cd; nevertheless, for afforestation development with Populus nigra in Cd-contaminated soils, the use of male individual (clone 62-167) can be more successful than female one (clone 62-149).

Forest hazelnut (Corylus avellana L.) is a hardy rooting plant and therefore its propagation by conventional asexual methods is almost impossible. The aim of this study was to determine the effect of auxin and inoculation of mycorrhizal fungi on callus, rooting and vegetative traits of hazelnut cuttings.

semi hardwood cuttings were collected on July from Arasbaran forests (Makidi site). Cuttings were firstly treated with concentrations of 0, 500, 1000, 2000 and 3000 mg L−1 IBA and then were inoculated individually with Glomus intraradices and Trichoderma harzianum fungi. Cuttings were cultured in perlite - sand medium and then they were kept in a mist system equipped greenhouse. After 70 days from planting, the percentage of callusing, rooting, root number, root dry weight, total plant dry weight, length cuttings, leaf area and Colonization were recorded.

The highest callusing (34.3 %), rooting (27.2 %), root number (2.6 n), root dry weight (0.35 g), total plant dry weight (3.39 g), length cutting (12.32 cm), leaf area (29.13 cm2) and Colonization (28.77%) was observed in cuttings that treated with IBA 2000 mg. L−1 and then inoculated with G. intraradices. Overall, it was confirmed that the hazelnut is difficult rooted via cuttings and application of IBA growth regulator is necessary for rooting of semi-hardwood cuttings plants.  

The best form its vegetative propagation is collecting cuttings from 1-year old cutting off shoots in June and treating by IBA growth regulator (2000 mg L-1) in combination with Glomus intraradices.

Changes in flooding regime have resulted in widespread declines in ecosystem functioning Flooding affects soils by altering soil structure, depleting O2, accumulating CO2, inducing anaerobic condition in soil, development of root rot, loss of mycorrhizae, and reductions in root metabolism, leads anaerobic decomposition of organic matter, and changing macro and micro elements of soil and leaf. In this experiment, the variations of macro and micro nutrient concentration in soil and leaf of Alnus subcordata (L.) seedlings under soil flooding stress were investigated during a 120-day outdoor experiment. Seedlings were subjected to three fixed treatments: 1) unflooded; 2) flooded to 3 cm depth and 3) flooded to 15 cm depth and their macro and micro nutrient concentration in leaf and soil were measured at the end of the experiment. Results indicated flooding had no effect on the concentration of Mg, Ca, Zn and organic C soil, while the concentration of P, N and K decreased and the concentration of Fe and Mn increased in the soil by flooding, although did not result in toxicity of elements of soil. In leaves of flooded seedlings, the concentrations of N, P, K, Zn, Ca, Mg and organic C decreased, but the concentrations of Mn and Fe increased to a detrimental level. In addition, there was a significant positive correlation between most of elements in soil and leaf. Generally, the results indicated that flooding changed the concentration of much elements in leaf and soil seedlings of A. subcordata that it is a current phenomenon in anaerobic condition of soil caused by flooding.

Indigenous knowledge refers to a set of skills, values, beliefs and methods of a social group that has been inherited in various areas of life through the experiences and approval of generations of generations. A great number of villagers have been living on the outskirts of the valuable Hircanian forests of northern Iran for hundreds of years. This research was carried out with the aim of the role of indigenous knowledge in employment, income of local people and conservation of forests of Vaz, city of Noor. The research was a survey and information gathering method in this documentary-field study and data gathering tool was questionnaire and interview. To determine the validity of the research, expertschr('39') opinions were used and to determine its reliability was applied the Cronbachchr('39')s alpha (0.8) and SPSS software. The statistical population consisted of residents of the area of ​​Vaz (800 people) and the sample size (260) was randomized using Cochran sampling method. In order to prove the hypotheses, inferential statistics such as Spearman Correlation Coefficient (for quantitative data), chi-square’s test, one-variable regression and one-sample t-test were used. The results showed that there was a significant correlation between the educations, the duration of the presence in the area, the employment, monthly income and the type of income earned by the individuals in the area with native knowledge (p≤0.05). This is while there was not a significant relation between of gender, age, place of residence, and the time of employment and income of individuals with indigenous knowledge. The results also revealed that familiarity with native knowledge creates employment and income and improves the protection of forests in the region.

In the present study, physical, chemical, and biological soil properties in pure plantation stands (21 years old) of Alnus subcordata, Populus deltoides, Cupressus sempervirens, and a mixed stand of Alnus subcordata-Populus caspica at Zaghmarz area, Neka city (north of Iran), were studied. In each stand, 10 plots of 400 m2 were selected and in each plot five samples were taken from 10 cm-depth of soil. The highest values of soil water content, pH, total nitrogen (N), phosphorus (P), potassium (K) and magnesium available (Mg), basal microbial respiration (BMR), soil microbial biomass nitrogen (MBN) allocated to stands of A. subcordata–P. caspica and A. subcordata, while the highest amounts of organic carbon (C), C:N ratio, microbial biomass carbon (MBC), and MBC/MBN ratio was observed in Cupressus stand. Analysis of PCA showed that Cupressus plantation has a positive correlation with the amount of C, CN, silt, clay, MBC, and MBC/MBN. But the pure and mixed stands of Alnus are positively correlated with total N, K, Ca, Mg, P available, water content, BMR, and MBN, showing the soil fertility of these stands and encouraging users to cultivate this species in the form of afforestation or agroforestry.

The aim of this study was to investigate the effect of seed maturation on germination, growth and seedling quality index of common ash (Fraxinus excelsior L.) in Kelardasht forest nursery. In 2017, the seeds of immature in late August and the seeds of mature in late November were collected and following stratification in moist sand were sown in nursery bed in mid-Feberaury each with three 100-replications . From the mature seeds, some of them germinated in 2nd year (April 2018) and the seed germination, biomass and quality indices of their seedlings were statistically (paired t-test) compared with the results of immature seeds germinated in spring 2017. The highest percentage of cumulative germination allocated to the immature seeds, followed by mature seeds germinated in 2nd year. Due to the lack of germination of most of the mature seeds in spring 2017, showed the seed dormancy, their germination traits were not considered in the statistical test. Germination percentage, mean germination time and germination speed and also, dry biomass, root biomass, root length and seedling quality index in immature seeds were greater than those in mature seeds germinated in second year. Generally, it is best to collect the seedlings of immature seed in order to achieve the optimum germination and growth, because the mature seeds are often dormant and unable to germinate during the first growing season. If mature seeds are supplied, it is advisable that these seeds to be stratified until spring of the second year.

Persian honey locust(Gleditsia caspica Desf.) is an endemic tree in the northern forests of Iran and southeastern Azerbaijan, which has low seed germination because of water impermeability of seed. In this research, effects of hot water at 70 °C and 100 °C (5, 10, 15 and 20 minutes), dry heat at 60 °C, 80 °C and 100°C (15, 30 and 60 minutes) and sulphuric acid treatment at two concentrations of 70% and 98% (at immersions of 5, 20, 40 and 60 minutes) were studied on the characteristics of seed germination of this species. Experiment was carried out based on completely randomized design in three replicates. No germination was observed in the seeds treated with hot water (100 °C), dry heat and control, while the seeds treated with semi-hot water (70 °C), sulphuric acids of 70% (60 minutes) and 98% (20 and 40 minutes) obtained 20, 84 and 100 percent of germination, respectively. In general, hot water, warm water and dry heat are not good treatments for seed germination of Persian honey locust seed. It suggests that for seed dormancy breaking as well as seedling production of Persian honey locust,sulfuric acid 98% (with immersion of 20 or 40 m.) to be used.

This study aimed to investigate the antioxidant enzyme activities such as catalase, superoxide dismutase, ascorbate peroxidase in Calotrope seedlings (Calotropis procera Ait) inoculated with mycorrhizal and Rhizobacterial microorganisms affected by drought stress under greenhouse conditions during a six-month period. Experiment in three inoculation levels (non-inoculated or control, Rhizophagus irregularis mycorrhizal fungi and Pseudomonas putida Rhizobacterial) and with three levels of drought durations (3, 6, and 12 days irrigation) in a completely randomized design with three replications was conducted. Results revealed that inoculation of mycorrhiza and Pseudomonas Rhizobacterial under drought stress significantly increased the activity of antioxidant enzymes. Maximum activity of catalase (1.57 units of enzyme per mg of fresh weight), superoxide dismutase (17.43 units of enzyme per mg of fresh weight) and ascorbate peroxidase (4.56 units of enzyme per mg of fresh weight) in mycorrhizal seedlings under drought stress for 12 days and also highest amount of peroxidase activity in mycorrhizal (11.96 units of enzyme per mg of fresh weight) and Rhizobacterial (12.9 units of enzyme per mg of fresh weight) seedlings under drought conditions for 12 days were observed.

The present study was carried out to investigate the effect of two mycorrhizal fungi and two growth-promoting rhizobacteria on survival and growth traits of Myrtus communis L. in water deficit conditions, as a completely randomized factorial design. Drought stress in three levels: 100% field capacity (without stress), 60% field capacity (mild stress) and 30% field capacity (severe stress) and biofertilizer in seven levels: control (without inoculation); inoculation with mycorrhizals of Funneliformis mosseae, Rhizophagus intraradices, and combination of these two fungi; inoculation with rhizobacterias of Pseudomonas fluorescens, P. putida, and combination of these two bacteria was considered in three replicates. Drought stress reduced and biofertilizers (in particular, composition of fungus, and combination of bacterias) increased the studied traits. In severe water deficit, combined treatments of fungal or bacterial improved height increment by 28-31%, leaf biomass by 51-52%, root biomass by 36-42%, total biomass by 37-41% and survival by 50% compared with the control (non-inoculation) ones. In severe drought stress, almost 50% of the seedlings survived without inoculation and 90-100% of them with inoculation, indicating the high tolerance of this species to drought. Due to the reduction of the destructive effect of water stress on M. communis seedling traits using biofertilizers, the use of these treatments, especially the combination of two fungi of Funneliformis mosseae and Rhizophagus intraradices or two rhizobacteria of Pseudomonas fluorescens and P. putida can be useful to improve seedling's growth characteristics.

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.

Cold tolerance is one of the important factors in the distribution of plant species. The aim of this study was to investigate the survival and gas exchange responses of olive (Olea europaea L.) seedlings to low temperature and freezing stress. For this purpose, 144 two-years-old potted seedlings of olive (cultivar yellow) with averaged height of 30 cm were examined as factorial in a completely random design (CRD) with 3 replications. Seedlings were exposed to six temperature levels (+2, -5, -7, -10, -16, and -20° C) for 1 and 3 hours. Gas exchange parameters such as net photosynthesis rate, transpiration, and stomatal conductance were measured for each treatment in three steps: before stress, immediately after stress, and 12 days after stress. Results showed that in each temperature level net photosynthesis rates, stomatal conductance, and transpiration reduced in both 1 and 3 hours chilling and this reduction was higher in seedlings subjected to 3 hours chilling. Olive seedlings exposed to -10, -16 and -20 °C temperatures were dead while in seedlings subjected to -7 °C and higher temperature (under both 1 and 3 hours chilling) gas exchange variables were recovered on day 12 after the stress. In general, this research revealed that olive seedlings (cultivar yellow) are able to tolerate low temperature up to -7°C for 3 hours.

 Biochar is known as a widely-use amendment in improving phytoremediation efficiency through the increase of plant growth; whereas its influence (either individually or in combination with bacteria) on the reduction of heavy metals (HMs) bioavailability of soil is an important advantage. This study was planned to assess the effects of separately and combined of biochar produced by forest wood wastes of hornbeam at three levels of 0, 2.5 and 5% of soil dry weight and Pseudomonas fluorescens bacteria on growth properties of potted white willow (Salix alba L.) seedling in a HM contaminated soil (Pb, Cu, and Cd). The variation of bioavailability (BA) and removal efficiency (RE) indexes, and bioaccumulation (BCF) and translocation (TF) factors also were analyzed in the treatments. The experiment was conducted under greenhouse condition for a 160 days’ period. The results showed that the variation in most growth components of seedlings was significant in the separate and combined treatments. The combined treatment of bacteria-biochar (at 5% level) increased the dry weight of leaf, shoot, root and total plant about 59, 36, 142, and 85% in comparison to the control (without the biochar and bacteria). In the biochar treatments, the BA, RE (except Pb), BCF, and TF (only in 2.5% of biochar) for Pb, Cu, and Cd were 13-57, 4-47, 29-60, and 16-33% lower than those in control, respectively. These indexes were improved by up to 191, 79, 84, and 13% in the bacteria-biochar treatment in compared to the individual application of biochar. In overall, according to our findings, the combination of biochar-bacteria led to the HMs bioavailability and improving the white willow function to eliminate soil HMs. So that, co-application of biochar and bacteria as soil amendments can increase growth parameters in white willow seedling and improve HMs bioavailability of plant in phytoremediation process.

Taxus baccata is an indigenous and valuable species of Hyrcanian Forests. According to recent studies, the presence of this species in the areas where distribution is declining; therefore, preserving and restoring this valuable species is essential. One of the most strategies for conservation and rehabilitation of valuable species is identification of its potential distribution and prioritization of areas with potential of presence of species using species distribution models. The purpose of this study was to prioritize desirable habitats for preservation and restoration of yew in Hyrcanian forest. In this study, the Boosted Regression Tree (BRT) algorithm was used to model the distribution of yew species in relation to climatic, edaphic, and topographic variables and identification of the most important variables affecting the distribution of yew. The results showed that the model constructed with climate variables in terms of model evaluation criteria by average of TSS (0.83) and AUC (0.97), has better performance in comparison to edaphic and topographic models. Also, among the climate variables, mean temperature of driest quarter and precipitation of warmest quarter has the most effect on the distribution of yew species. Soil organic carbon, sand percent, cation exchange capacity, altitude, and slope percent were also other important factors affecting the distribution of yew species. Finally, by combining the suitability maps of climatic, topographic, and edaphic models, a map of the priority of conservation and restoration of yew species was prepared, which is very valuable in planning for restoration of this species in Hyrcanian Forests.

In this study, using four commonly used modeling methods for assessing the potential habitat of yew species (generalized linear and additive models, classification and regression tree and random forest) and maps of the bioclimatic and topographic, the suitability map of the yew species in Hyrcanian forests was prepared. The evaluation of models by using AUC criterion (GLM=0.863, GAM=0.871, CTA=0.781, and RF=0.922) showed that the random forest model has the best performance in which slope percentage and solar radiation index are the most and least important variables, respectively. The present study showed that the presence probability of yew species in relation to slope percentage in the study area increases from 30% and then levels off. In the current conditions, the area of suitable habitats for yew species is about 10.5% of the studied area. The results of this research indicated that in the current climatic conditions, the suitable areas for presence of yew species are in east and center of the study area that will help to manage, protect and restore the habitats of this invaluable species.

Queues castanifoliais one of the most demanded species for reforestation in Golestan province. It is necessary to produce appropriate seedlings in nurseries.  This study was carried out to determine the effect of perlite on soil on growth and physiological responses of Queues castanifolia seedlings under water deficit stress. A factorial experiment was conducted as randomized complete block design in greenhouse condition of agricultural and natural resources research Center in Gorgan, 2015. Perlite treatments in 4 levels (0, 15, 25 and 35% (V/V)) was added in soil and water stress in 3 levels (40, 70 and 100% irrigation at field capacity) for 5 months were applied in the pot experiment. Some parameters including gas exchange (photosynthesis, stomatal conduction and transpiration) and leaf water potential of seedlings, diameter and height growth and dry weight of root, stem, leaf, and seedlings were measured in different treatments at the end of the experiment period. The results showed that all parameters were affected by different levels of irrigation and perlite. Water deficit to 40% FC reduced 51% and 68% of photosynthesis and stomatal conductance respectively. The highest diameter and height growth and dry weight of the seedlings were observed in 25% and 35% (V/V) perlite application under normal and stress conditions, respectively. The use of perlite alleviated the negative effects of water deficit and ameliorated seedling growth. It could be suggested that perlite application in soil is suitable for the production of desirable seedlings under water deficit condition.

The aim of this study was to evaluate the impacts of dust on the morpho-physiologial traits of Fraxinus rotundifolia Mill. seedling, a useful species in urban green space. In a greenhouse, a dust stress was applied using dust simulator with concentrations of 0, 750 and 1500 μg m-3. Experiment was conducted by a completely randomized design with 5 replicates (9 seedlings in each replicate) within 45 days with one-week interval.) . Dust deposition with 1500 µg m-3 concentration caused the appearance of symptoms of chlorosis and necrosis on leaves. This concentration decreased the amount of survival (29%), increment diameter (38%) and height (33%), average leaf area (19%), photosynthesis rate (45%), transpiration (60%), stomatal conductance (46%), mesophyll conductance (55%), spad index (23%), Fm (22%), Fv/Fm (22%), T1/2 (14%)increased intercellular CO2 concentration (22%), water use efficiency (40%), leaf temperature (2.34 oC) and Fo (30%).  For afforestation and tree planting initiatives in dust-polluted areas of urban and suburban regions of Iran,  F. rotundifolia seedling can be usefully used in areas where dust concentration is less than 750 μg m-3.

Common myrtle (Myrtus communis L.) spread in arid and semi-arid regions of Iran which it has many uses in different ways.  In order to investigation of microbial inoculation influence on the physiological changes of M. communis seedlings under water deficit conditions a greenhouse experiment as a factorial in a completely randomized design with three replications was conducted.  Water deficit consisted of 30% field capacity (FC) (severe stress), 60% FC (mild stress) and 100% FC (without stress), and microbial inoculations were including of Funneliformis  mosseae, Rhizophagus intraradices, combination of these two fungal, Pseudomonas fluorescens, P. putida, combination of these two bacteria, and also control (without inoculation). According to the results, in each water regime the highest root colonization was observed in the combination of two fungal. This treatment promoted root colonization by 17.8, 11.3 and 7.75 times in 30% and 60% and 100% of FC treatments respectively compared to the control. Microbial inoculation improved plant yield efficiency in water deficit conditions. In severe water deficit treatment, combined treatments of fungal or bacterial increased photosynthesis (47-48%), stomatal conductance (39-41%), transpiration (62-65%), mesophyll conductance (57-64%), water potential (20-21%), and relative water content (1.4 times), and decreased intracellular CO2 concentration (28-31%) and electrolyte leakage (1.4 times) compared to the control. It can be suggested that microbial inoculation can encourage drought resistance of M. communis seedlings to water deficit.

Cupressus sempervirens var. horizontalis, an ornamental tree, is suitable for wind break, soil conservation, wood production and forms a large part of seedling production in nurseries of Iran. Considering the expected limitations of water resources, the target of this investigation was to study the effect of rhizobacteria Pseudomonas fluorescens on the growth and survival of C. sempervirens seedlings under water deficit. The experiment was carried out with four irrigation periods and two rhizobacteria levels (inoculation and non-inoculation) in a randomized complete block design with three replications. To determine the amount of irrigation water, the field capacity was calculated and the water deficit was given to the plant to the desired moisture content after weighing of the pots. The seedlings in severe water deficit (irrigation period of 12 days) had a survival rate of 95% and higher. Shoot growth and diameter growth were, respectively, reduced by 52.6% and 49.6% in 12-day irrigation compared to 3-day irrigation, but inoculation increased by 14.7% and 14.3% in them, respectively. Regardless of water deficit, root biomass in inoculated seedlings increased by 23.2% compared to the non-inoculated seedlings. Shoot biomass, total biomass and seedling quality index in the period of 9 and 12 days and root volume during the 12-day period decreased, but by inoculation, these variables increased 13.9, 16.8, 20.1 and 25.3, respectively. Overall, although water deficit decreased growth characteristics of C. sempervirens seedlings but it can be concluded that root inoculation with P. fluorescens can be used as a biologic fertilizer to suit the growth and morphological quality of seedlings, even under severe water deficit conditions. This strategy can be useful for producing proper seedlings of C. sempervirens in nurseries facing water constraints.

This research was carried out with the aim of dormancy breakage and seed germination improvement in mature and immature seeds of T. rubra subsp. caucasica form angulata. The seeds were collected from middle altitude (500 a.s.l.) forests of Chamestan, north of Iran. Mature and immature seeds with pericarp were treated as 1) cold stratification (without pretreatment), 2) imbibed with NaOH (30%)+cold stratification. Also, mature and immature seeds without pericarp were treated as 1) imbibed with gibberelic acid (500 mg/l)+cold stratification, 2) imbibed with kinetin acid (1 mg/l)+cold stratification. The examination was performed as completely randomized design with three replications. The highest amount of seed germination belonged to mature seeds without pericarp-imbibed with pretreatments of acid (giberelic or kinetin) and also immature seeds with pericarp-without pretreatment. The highest germination speed allocated to immature seeds with pericarp-without pretreatment, and the maximum mean germination time to mature seeds without pericarp-imbibed with giberelic acid. The results of this research showed that for optimizing seed germination of this species with above mentioned provenance, the best conditions for seed germination is, immature seeds with pericarp, subjected to cold stratification (without any pretreatment).

This experiment was conducted to survey the effect of desiccation and storage temperature on Balkan maple (Acer hyrcanum Fisch & Meyer) seed viability. The seeds were hermetically stored at three moisture content levels (12%, 8% and 4%) and stored in three storage temperatures including -20 °C (freezer), 4 °C (refrigerator) and 25 °C (room) up to 48 weeks in order to record the loss variability in viability. Results showed that effect of seed moisture content, storage temperature and their interaction on seed viability was significant. Seeds were viable (98%) at refrigerator until week 48. Viability at freezer reduced to 80% on week 8 and was constant till week 48. At room temperature, viability sharply reduced from week 24, so that on week 48 all of the seeds (12% and 8% moisture content) were found dead, but the seeds with 4% moisture content had weak viable (18%). This research revealed that Balkan maple seed with 4-12% moisture content can be successfully stored up to 6 months at room temperature and up to a year at refrigerator and freezer. Continuing the experiment in refrigerator and freezer will reveal the storage capability of this seed for longer periods.This research revealed that Balkan maple seed with 4-12% moisture content can be successfully stored up to 6 months at room temperature and up to a year at refrigerator and freezer. Continuing the experiment in refrigerator and freezer will reveal the storage capability of this seed for longer periods.

In order to compare the quantitative and qualitative characteristics of eastern cottonwood (Populus deltoides Bartr. ex Marsh) trees that are the most common ones for wood culture in north of Iran, four P. deltoides stands with clone of 69/55 were selected in lowlands of Gilan (Davoodmazar and Haftdaghanan) and Mazandaran (Shirkola and Chamestan) provinces. In each stand, with method of random – systematic, samples of 400 m² were designed to measure the trees and soils. Likewise, the mean annual volume increment with highest coefficient of variation (CV) was considered as Comparison Index for determining the main affecting factors on growth and yield in four Populus stands. The mean diameter of trees in Shirkola (42.9 cm) and Chamestan (39.1 cm) was greater than that in Davoodmazar (27.9 cm) and Haftdaghanan (28.7 cm). The mean volume increment of tree in two province was significantly different, whereas in areas of Chamestan (34.4 m³/ha) and Shirkola (22.5 m³/ha) was greater than that in Davoodmazar (17.17 m³/ha) and Haftdaghanan (17.03 m³/ha). The mean annual volume increment of each tree was bigger in Shirkola (0.089 m³) and Chamestan (0.074 m³) compared to Haftdaghanan (0.036 m³) and Davoodmazar (0.031 m³). It can be deduced that in areas with very humid to humid climates of Gilan and Mazandaran which have favorable conditions for growth of Populus trees, soil texture is light to moderate with a silt content of more than 47% and pH higher than neutral, Populus deltoides growth is higher. The similar investigations with other clones of Populus in northern provinces of Iran with different climates are recommended.

One of the problems of propagation of lindens (Tilia spp.) is low seed germination. In this research, different treatments for stimulating the germination in immature seeds of Tilia rubra subsp. caucasica form angulata collected from middle altitude (500 m a.s.l.) and high altitude (1500 m a.s.l.) of Chamestan forests (northern Iran) were examined. In both altitudinal seed sources, immature seeds with pericarp were subjected to 1) cold stratification, and 2) imbibed with NaOH (30%)+cold stratification. Also, immature seeds without pericarp were examined as 1) imbibed with GA3 (500 mg/l)+cold stratification, and 2) kinetin acid (1 mg/l)+cold stratification. The most germination percentage (87%) allocated to non-pericarp seeds of higher altitude, treated respectively, with 1) GA3+cold stratification, and 2) kinetin acid+cold stratification. The most germination speed (6 seeds/week) belonged to seeds of with pericarp collected from middle altitude, treated respectively with 1) cold stratification, and 2) imbibed with GA3+cold stratification. The lowest mean germination time (20 days) allocated to seeds with pericarp of middle altitude (only cold stratified). Generally, even though, non-pericarp immature seeds of higher altitude, imbibed with GA3 (and kinetin acid)+cold stratification had favorable germination percentage, the immature seeds with pericarp of lower altitude (only cold stratified) represented satisfaction germination percentage along the shorter period. However, in future investigations, effect of treatments on seed vigor index and growth of Tilia seedling in order to employ the proper method for seed propagation and seedling production of this species in nursery are advised