Iranian Journal of Forest and Poplar Research
Year:2018 | Volume:26 | Issue:3 (73) |Papers Count:12

Ectomycorrhizal symbiosis is essential for the establishment and functioning of trees in forest ecosystems. Despite widespread recognition of important roles of ectomycorrhizal fungi in improving plant nutrition, increasing the resistance of host plants to drought stress and suppressing of root pathogens, little studies have been carried out on the diversity of the fungal symbionts, especially in ectomycorrhizal symbiosis in Iran. Identification of ectomycorrhizal fungi is the first step in all studies related to this symbiosis and is essential to exploit its maximum potential in forest management. The aim of this study was to identify the ECM fungal associating with oak trees (Quercus castaneifolia C. A. Mey., Q. macranthera Fisch. & C. A. Mey. ex Hohen. and Q. petraea L. ) in the 6 locations of north forests of Iran. The ectomycorrhizal root tips of oak trees were collected for molecular identifications. Molecular analysis involved sequencing of the Internal Transcribed Spacer (ITS) region and Bayesian phylogenetic analysis with other sequences on website databases. A total of 207 root systems were sampled and documented high ectomycorrhizal diversity with a total of 49 taxa by Blast algorithm. These taxa belonging to 13 genus, including Amanita, Boletus, Cortinarius, Hebeloma, Hydnum, Hygrophorus, Inocybe, Laccaria, Lactarius, Lycoperdon, Russula, Scleroderma and Tricholoma. Species of Lactarius, Russula and Inocybe were diverse and dominant. Bayesian analysis confirmed the species-level and genius-level identification of 17 and 32 ectomycorrhizal fungi, respectively. This study documented high ectomycorrhizal diversity in Hyrcanian forests with oak trees.

Biodiversity and forest stand structure play important roles in the sustainability and dynamics of forest ecosystems, but grazing of livestocks can affect on the sustainability. In order to study the effects of grazing on forest diversity and structure, this research was carried out in Dalab region of Ilam province. Based on the number of livestock, three areas including enclosure, medium grazing and heavy grazing were identified. In each area, three transects which located on each of them ten plots, were considered. In each plot, quantitative characters and number of seedlings were measured. Indices of diversity, richness, evenness and dominance were calculated using PAST 3. 04 program. The results showed that the values of dominance and evenness indices in the enclosure condition status were less than two other conditions However, diversity and enrichment indices in livestock grazing conditions were less than the enclosure status. The study of structure shows that the grazing intensity has reduced the percentage of species in samples in comparison to the protected area. The intensity grazing effected on the parameters of DBH, trunk height, crown length, mean of crown diameter, number of branches and regeneration of Quercus brantii Lindl., Pistacia atlantica Desf., Acer monsopessulanum L., Amygdalus orientalis Duh., Crataegus pontica C. Koch, Cerasus microcarpa (C. A. Mey. ) Boiss., and Daphne mucronata Royle. Most of this parameters studied on these trees are different from the grazing situations than the enclosure status. Because intensity grazing cause restriction the growth or deployment of young seedlings in recent years or indirectly causing soil compaction to reduce fertility and permeability of the soil and cause changes in the structure of the forest. There was no significant difference between the moderate and severe grazing conditions, and in general it can be said that grazing of livestock with any intensity would disrupt forest ecosystem performance so, it is necessary to determine the grazing capacity of livestocks and prevention of overgrazing capacity in the forests.

Today, the use of the biological stabilizers of soil such as ashes and nano-particles has been concerned to accelerate and improve the stabilizing process of the swelling soil of road bed. In this study the swell soil was brought from the routes of recommended forest road in district two of Bahramnia forest management plan in Golestan province according to the appearance and performance properties of soil. At first, for preparing the soil stabilization treatments the mixtures of 0. 5% montmorillonite nano clay and 2% reed ash (Phragmites australis (Cav. ) Trin. ex Steud. ), 1% nano clay and 4% ash, 1. 5% nano clay and 6% ash and 2% nano clay and 8% ash were added to soil and then mixed for 5 minute to access homogenous mixture without lump. After the curing time of 7, 14 and 28 days from the stabilization time, the Atterberg limit, standard proctor, unconfined compressive strength and Californian bearing ratio tests were done for 4 replications on mixtures of soil and control sample. Results showed that adding reed ash and nano clay increased the plastic limit and decreased the liquid limit and plastic index. Moreover, with increasing the amount of additive materials in the soil, the maximum dry density of the mixture decreased and optimum moisture content increased. The CBR and unconfined compressive strength of the mixture increased considerably until adding 1. 5% nano clay and 6% ash and then adding more additive materials didn’ t change the soil strength. In this study increasing the curing time, caused that the maximum dry density and soil strength to increase, whereas the plastic index of the mixture decrease. So, the optimal treatment of 1. 5% nano clay and 6% ash and curing time of 28 day is recommended for stabilization of clay soil in study area.

In order to maintain biodiversity in the integrated management of forest ecosystems, there is a need for basic information on habitat trees. Regarding the challenges in assessing the level of animal diversity in forest ecosystems, the status of habitat trees can indicate the level of species diversity. This research was conducted to evaluate the abundance of different forms of habitat and dead trees within oriental beech (Fagus orientalis Lipsky) stands in eastern Gilan. Three one-hectare study area were selected in the Shirgalayeh forest management plan area and in each area the characteristics of all living, dead and habitat trees were measured. The mean of dead volume was 43 cubic meters per hectare. More than half of the dead volume were recorded log form and advanced stages of decay. A total of 81 trees with a sign of microhabitat equal to 15. 4 percent of the total trees were recorded. Beech trees with cavities (n = 29, 35. 8%) was the most frequent habitat trees after that Cracks and Fruitbodies of saproxylic fungi were the most frequent habitat tree, respectively. The minimum diameter and perimeter for habitat trees were 35 and 110 cm, respectively. Based on the results of this research, it is recommended that at least 15% of the total trees with a diameter of at least 40 cm (especially trees larger than 150 cm) should be selected and maintained in the forests stands. According to this fact that some types of habitat trees, such as hollow trees or trees with outgrowth (Burr) created in the long term, need to be given sufficient attention to keep them in compare with renewable habitats such as cavities.

The effects of some soil properties on growth of three-year poplars (Populus nigra L. ) were investigated in two poplar stands in south of Tehran. For this purpose, at the end of growth period, in each poplar stand, three sample plots (3×4 m) were chosen using technique of systematic random sampling. Diameter at breast height and height parameters of trees were measured and then basal area and volume computed. In order to study soil properties (texture, organic matter, pH, EC and NPK), in each plot, three soil samples were taken in depths of 15-30 and 30-60 cm. Results demonstrated that some soil properties (sand, silt and clay percent, K content and EC) of two poplar stands had significant differences, as a consequence growth parameters of two poplar stands also showed significant differences. So that, in stand 1 volume of three-year poplar tree was 3 times volume in stand 2. In general, loamy-clay soil with higher absorbable K (415/16 mg/kg) and lower EC (1/36 ds/m) (stand 1) provided better growth conditions for poplar trees compared with loamy-silty soil with medium absorbable K (219/43 mg/kg) and higher EC (4/43 ds/m) (stand 2). Also, positive correlation between growth parameters of poplar trees with sand and clay percent and K content and negative correlation with silt percent and EC were observed. The results of current study demonstrated that attention to soil properties before poplar plantation is necessary to achieve maximum wood production.

Analysis of the structure of tree species provides a complete information on species diversity, composition, spatial distribution in mixed natural forests. It helps to better understanding of many ecological and silvicultural issues in order to optimal management of the ecosystem. The main objective of this research is to investigate the differences and similarities of sites with different conservation history (Kalale and Vaygan Sites with a long-term conservation history and Kuran Sites with a short-term conservation history) in terms of diversity and composition of the tree structure in Arasbaran forests. For this purpose, nine hectares with one-hectare sample plot were inventoried with full-callipering method. The measured characteristics were type of species, distance and azimuth of each tree from the last tree, diameter at breast height (DBH), tree height. The spatial pattern of trees was determined by the modified K-Ripley function. Based on the results, 14 species were observed in the three study areas. Four species of hornbeam (68 %), maple (8 %), yew (7 %) and persian oak (2. 5 %) composed of about 88% of the total density of trees. Kalale site (15. 29 m2) and Kuran (0. 26 m2) had the highest and lowest basal-area per hectare, respectively. Kalale and Vaygan sites had a wide range of diameter classes in comparison with the Kuran site. L function showed that almost all species had cluster distribution and only hornbeam had a random distribution in Kuran site. Therefore, every intervention in order to tending reclamation andenrichment of the studied stands should be based on making species mixture and keeping clustered spatial pattern and also it should be avoided pure species reforestation to ensureboth biodiversity and sustainability of stands.

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.

Traditional animal husbandry within the Hyrcanian forest area and its impact on this individual ecosystem is one of the main challenges for Iranian natural resources management. The current study was carried out to investigate the presence of livestock on biodiversity, physical and chemical characteristics of soil in district 5 of Neka Zalemroud forest in Mazandaran province. In this research, after a pre study of the area, the four cattle (livestock) campuses was selected, then in total 72 plot of 400 m2 (20 × 20 m) in the campuses and in control forest area, were used to measure the type and percentage of ground vegetation in the center and four geographical directions of the campuses. Soil samples were taken from 0-10 and 10-20 cm depth. In order to compare vegetation and soil properties, neighboring forest stands were selected with similar conditions as control areas. In each plot biodiversity, heterogeneity, richness and uniformity indices were calculated. Non-paired T-test (Mean Comparison test for two groups) was used to compare properties in the campus and control forest area. The results showed that there is a significant difference between the two areas in the variability index (Hill and Shannon) and in the uniformity index (Smith-Wilson and Simpson indices). In the current study of soil characteristics, there was no significant difference for the sand percentage and moisture content between the direct affected areas and the control areas, but there was a significant difference between the other physical and chemical characteristics in the two areas. Our findings indicated a significant impact of livestock presence on forest soil.

Zagros forests as the most extensive forests in Iran have a special place for living and livelihood of local communities. Therefore, planning to prevent further degradation and proper management in order to preserve and restore these forests is necessary. Therefore, in this study, the effective factors on participation of local beneficiaries in management, preservation and reclamation of oak forests of Lorestan are identified and ranked. The statistical population of this research consisted of experts in natural resources and environment and collecting data using field Scrolling and completing 20 questionnaires. Analytical Hierarchy Process (AHP) has been used to analyze the data. The results show that economic factors relative to social, environmental and infrastructure factors most weight in participation of foresters in management, preservation and restoration of oak forests of Lorestan ranked first. By creating a variety of jobs for forest residents, their income will increase, and as a result, the dependence of local people on the forest will be reduced, resulting in increased participation and protection.

In this research, capability of Landsat 8 OLI was studied for estimation of aboveground biomass in pure stands of the common hornbeam (Carpinus betulus L. ) in Hyrcanian forests of Iran. In order to obtain in situ aboveground biomass, diameters at breast height (DBH) of all trees greater than 7. 5 cm were measured in 55 sample plots. Then, in situ aboveground biomass was calculated using local volume table and specific gravity in each plot. About 70 percentages of in situ measurements (40 sample plots) were used for modeling aboveground biomass based on Landsat 8 OLI data using different methods of stepwise regression, backward regression, artificial neural network, k-nearest neighbor and random forest. Validation of the models was done using 30 percentages of in situ measurements (15 sample plots). Based on the Pearson correlation coefficient, near-infrared band showed the highest correlation with aboveground biomass (0. 52). Backward regression with adjusted R2 of 0. 295 and RMSE% of 28. 63%, and artificial neural network with RMSE% of 23. 45% showed the best performance among parametric and non-parametric methods, respectively. Based on the results, Landsat 8 OLI data seems suitable for aboveground biomass estimation in pure stands of the common hornbeam only over large areas and small scale. Although more investigations are required to verify and generalize the results to the entire Hyrcanian forests of Iran.