Iranian Journal of Forest and Poplar Research
Year:2017 | Volume:25 | Issue:2|Papers Count:20

Agroforestry is one of the most important forms of utilization in Zagros forests. In the present study, Gandoman, Mirhesam, and Kokh-e Mamo allotments located in Armardeh region, in Baneh city of Kurdistan province, were selected. Strengths, weaknesses, opportunities, and threats (SWOT) were applied to provide the policy and planning of forest functions and services. SWOT was performed in internal system (strengths and weaknesses) and external system (opportunities and threats). Statistical population included 12 individuals of local people and 18 individuals of experts.According to the results of SWOT and Space Matrix, the appropriate strategy (aggressive, competitive, defensive or conservative) was identified and determined for non-wood products. The results of agroforestry systems indicated that local communities emphasized on long time reliance on forest (the most important weakness) and lack of compatibility with formal management programs (the most important threat), while experts (non-local communities) emphasized on reduction of high forest reproduction (the most important weakness), and decrease of biodiversity (the most important threat). In addition, local communities stated that the most important strength and opportunity of agroforestry systems were acceptance of local communities and reduction of rural-urban migration, respectively. Based on all stakeholders’ opinions, conservative management strategy was proposed for agrosilviculture, silvopastoral and agrosilvopastoral. To practice conservative management strategy, the opportunities should be applied and the weaknesses should be vanished.

Investigation on spatial distribution of tree growth characteristics in different forest stands, has a fundamental role in assessing possible harvest planning considering potential of the stands. The aim of this study is mapping the spatial distribution of forest characteristics such as stand volume growth, diameter, growth, ingrowth) and determining the amount of tree mortality in the district three of Sangdeh region within a period of 5 years. Two methods of Ordinary Kriging (OK) and weighted Inverse Distance (IDW) interpolation were applied for mapping. For this purpose, we calculated the increment using direct measurement in 130 permanent sample plots.The results of this study showed that the mean volume increment, diameter increment, ingrowth and annual mortality were 5.65 cubic meters per hectare per year, 0.48 cm, 3.5 and 4.2 stems per hectare per year, respectively. For volume increment, the IDW method by power one and with a root mean square error 0.29 cubic meters per hectare per year, for diameter increment, ingrowth and annual mortality the ordinary Kriging method with a root mean square error 0.219 cm per year, 1.4 and 2.8 nha-1y-1 showed better results, respectively. Overall the results showed that geostatistical methods are efficient methods for mapping forest growth characteristics.

Appropriate management of forest requires indices that can provide adequate information about forest structure condition and its changes with the least cost and time. In this research, the effect of tree marking on natural stand structure was evaluated in Gorazbon district of Kheirud forest using indices of spatial and non-spatial distribution. For this purpose, 682 structural groups (trees) were studied from the lower up to the upper boundary of compartment in two rectangular plots. The results showed that the changes of some indices, including mingling, Uniform Angle Index, DBH dominance, DBH differentiation, Pielou segregation, Clark and Evans aggregation, stem per hectare, basal area and diameter at breast height were not significant. Also, the paired t-test results showed non-significant differences for Uniform Angle Index and DBH dominance, whereas the Mingling and DBH differentiation indices showed significant differences, in the two studied sample plot before and after the tree marking. According to the results of this research, one can conclude that the applied indices are able to show the changes in the stand structure over different time studies and they are suitable for comparison of stands. These indices could be useful tools for forest management in close to nature silviculture.

Brant`s oak (Quercus brantii Lindl.) is one of the most important species of Zagros forest ecosystem that it’s natural regeneration has become a challenge. This study aimed to investigate the composition and species diversity component (alpha, beta and gamma) of indicator plant species in well and poorly seed-origin oak regenerated spots in north of Ilam city. In this study, ten 100-m2 plots were randomly selected from each of the spots. Four sample plots (1 ´ 1 m) were established in each spot for counting the number of plant species. The Monte Carlo test detected 23 and 13 indicator species from 109 and 58 species in well and poorly seed-origin oak regenerated spots, respectively. Based on Detrended Correspondence Analysis (DCA), two spots were different in terms of species composition. The dominant life forms in the two spots were therophytes and hemicryptophytes. The results showed that different components of species diversity i.e. alpha, beta, and gamma were higher in well seed-origin oak regenerated spots than in poorly regenerated spots. In both spots, diversity within the sample units (alpha) compared with diversity between sample units (beta) had a greater contribution in total diversity (gamma). In general, it can be concluded that the composition and diversity of plant species could be used as a bioindicator for monitoring the heterogeneity of oak regenerated spots.

This study investigates the capability of frequency ratio and an ensemble method of frequency ratio with Shannon’s entropy to produce a reliable map of wildfire susceptibility for Chaharmahal and Bakhtiari province, Iran. At first, the fire locations were identified in the study area from historical archives and field surveys. Ninety two cases (70%) out of 132 detected fire locations were randomly selected for modeling, and the remaining 40 (30 %) cases were used for the validation. Thirteen fire conditioning factors representing topography, climate, and human activities of the study area were extracted from the spatial database. Using the frequency ratio and the ensemble model, the relationship between the conditioning factors and fire locations were explored. The results were then used to produce distribution maps of wildfire hazard. The verification analysis using Receiver Operating Characteristic (ROC) curves and the Areas Under the Curve (AUC) revealed that the ensemble model with the capability of computing the weights of factors and their categories is more efficient than frequency ratio. The success and prediction rates for the frequency ratio and ensemble model were found to be 79.2 and 75.72%, and 85.16 and 82.92%, respectively. Further, the results suggest that more than one-third of the study area falls into the high and very high hazard classes, and the conditioning factors of land use, soil types, and distance from roads play major roles in fire occurrence and distribution in the study area.

This study was carried out to model the soil carbon sequestration changes regarding to soil physical and chemical properties in pure and mixed stands of Eldar pine (Pinus eldarica Medw.) and black locust (Robinia pseudo acacia L.) planted in Semnan Sokan forest park. Four different treatments including pure Eldar pine, pure black locust, mixed of these species and control (without any plant cover) were considered. Soil samples were taken from different soil depth (0-5, 5-10, 10-20, and 20-30 cm) in the treatments and transported to laboratory for further analysis. The results showed that the Eldar pine trees decreased soil acidity and increased aggregates stability of soil. Black locust increased organic matter content, phosphorus, potassium, and nitrogen content of soil which can improve the quality of poor soils of this area. The mixed treatments affect soil properties partly between two above mentioned treatments. The carbon sequestration for Robinia, Pine, mixed and control treatments were 28.67, 18.74, 24.05 and 1.73 tons per hectare, respectively. The modeling of carbon sequestration with physical and chemical properties of soil, the nitrogen and phosphorus were determined as the most important effecting factors on the soil carbon sequestration. Therefore, increasing soil nitrogen in such regions via biological methods (planting nitrogen fixing plants) can play important role in success of afforestion and carbon sequestration projects in such regions.

Mount Atlas mastic (Pistacia atlantica Desf.) is one of the most important species in the Zagros forests. This research was conducted in order to investigate the quantitative and qualitative characteristics of pistachio forests in Chaharmahal and Bakhtiari province.At first, all of the forest regions were investigated and typology map of forests was made on 1: 50000 map. Then the digital map of forest types was made. Sampling grid was established on the map, so that at least 30 plots were selected on the biggest type of pistachio. Using the same method, number of sample plots was calculated for other forest types. A total of 39 circle plots, each 1000 m2, were selected. The results indicated that Pistachio was present in 6 forests types.Quercus-Pistacia covering 84801 ha area was the largest type, whileAcer- Pistacia was the smallest type that covered 537 ha. Pistachio type with 90 trees per hectare was the most dense forest type, while Amygdalus-Pistaciatype with 20 trees per ha was the less dense type. The thickest and tiniest pistachio trees were recorded in the Acer-Pistacia and Amygdalus-Pistacia types, respectively. Considering the presence of pistachio in the vast and widest forest type of Quercus-Pistacia, we can plant this species in pure and dominant oak stands of the province.

The spatial distribution analysis of trees in arid and semi-arid regions presents valuable information about their interactions and impacts on one another. This study was aimed to investigate how biometric characteristics of mount Atlas mastic (Pistacia atlantica Desf.) are influenced by their clustered spatial distribution in Zagros vegetation zone.For this purpose, a part of Wild Pistachio Research Site, Fars province, was selected and in addition to registering the position of all trees with>2.5 cm diameter at breast height (DBH), DBH, height, and crown area of each tree were measured. Wild pistachio trees with DBH>10 cm and<10 cm were classified as adult and sapling, respectively. To achieve the aims of study, univariate and bivariate forms of mark variogram and mark correlation function (g(r), kmm (r), gm1m2 (r) and km1m2 (r), respectively) were applied. The observed pattern of wild pistachio trees showed significant spatial heterogeneity as compared to homogeneous Poisson process (a=0.05). This heterogeneity was caused by unfavorable environmental conditions of study area. The results of univariate and bivariate g(r) and kmm (r) showed that DBH, height, and crown area of wild pistachio trees located at three meter distance from each other were less than overall average.Moreover, the results showed that investigated biometric characteristics of wild pistachio saplings that wild pistachio adults were located up to three meter distance from them were less than overall average. In general, it was concluded that aggregation of wild pistachio trees because of environmental heterogeneity negatively influenced their biometric characteristics and prevented their increase.

In this study, six canopy gaps with medium (200-500 m2) and large (>500m2) sizes were selected in Shastkolate forest. In each gap, micro sample plots (6´6 m) were established at the center and north, east, south and west directions of each gap. Within each micro plot, 12 seedlings of chestnut-leaved oak (Quercus castaneifolia C. A.Mey.), Cappadocian maple (Acer cappadocicum Gled.) and Caucasian alder (Alnus subcordataC. A. Mey.) were planted in spacing of 1´1 m. Height growth and photosynthetic rate of seedlings were studied during the growth season, while the survival rate was calculated in the end of season. Data were analyzed using spilt split plot plan and SNK test. Results showed that survival rate of seedlings of all three species decreased with increasing gap size. Oak seedlings showed the highest survival rate in both large and medium sized gaps. The maple seedlings showed the lowest survival rate in the large gaps. The maximum height growth of seedlings was measured in the center of gaps; this was decreased in north, west, south and east edges of the gaps, respectively. The larger the gap size the higher was the height growth of alder and oak and seedlings, while that of maple was higher in the medium gaps. Therefore one can conclude that planting of oak and alder seedlings in the center of large gaps could bring more promising results, while planting of maple in the center of medium and edges of large gaps would be more effective.

Soil organic carbon (SOC) is a major component of global carbon cycle, hence forest soil as one of the major carbon sinks has a key role in the control of atmospheric Co2 concentrations. Consequently, changes of carbon release or uptake by forest ecosystems due to disturbance or management in an unsuitable period can have a considerable impact on atmospheric Co2 concentrations and global warming. In this study, the effect of selection systems were investigated on seasonal changes of soil organic carbon pool (SOCP) in the mixed beech-hornbeam stand in district one of Shastkolate forest, Golestan province. For this purpose, SOCP was determined in depth of 0-20 cm from February of 2014 to February of 2015 in four stands with one hectare area (one in compartment 32 of virgin forest) and three in compartments 30, 33 and 31 in managed forest, in which the last interventions date back to 10, 7 and 1 years ago). Soil temperature and moisture changes were measured through one year as effective factors on SOCP. One-way ANOVA were used to determine soil moisture and temperature variability in each treatment through one year, and seasonal dynamics of SOCP were comprised using repeated measures design (General linear model). The SOCP relationship with soil moisture and temperature were analyzed using Pearson correlation coefficient. Results showed that the monthly changes of soil moisture and temperature had a significant difference in each treatment. SOCP was also significantly correlated with soil moisture and temperature. SOCP difference in different seasons was also significant, which was more obvious in the managed treatments. SOCP showed severe decrease in the managed stands compared to the unmanaged stand in the summer.

Among positive effects of vegetation in erosion control, reinforcement of soil by roots is very important. The quantity of reinforcement depends on root biotechnical characteristics such as root density and tensile strength. The aim of current study is to assess the effect of traditional pollarding on root biotechnical characteristics, soil reinforcement and slope stability. To estimate the Root Area Ratio (RAR/Root density index) core sampling with cylinder cores was used. For this purpose, core samples were taken from four sides around each tree in three different soil depths. In each core, number of roots and total root length was determined for each diameter class. Root samples were collected from both up and down slope and their strength was measured with a standard Instron. The results showed that root distribution in relation to depth had a wide variation. The results of ANOVA revealed that pollarding had a significant negative effect on RAR. Also the results of Wald chi square showed that pollarding had a significant negative effect on tensile strength of roots. Mean RAR values of fine roots in control and pollarding samples were 47.0 and 28.0%. Mean tensile resistance in control and pollarding samples were 40.31 and 19.94 MPa, respectively. The average reinforcement of fine roots in control and pollarding samples were 2.29 kPa and 1.12 kPa. The results of this study confirmed that traditional pollarding not only have negative effect on aboveground biomass of oak trees but also significantly reduce the positive effect of vegetation on soil reinforcement.

Different plant covers have various effects on ecosystem litter and soil characters. This research aims to study the effect of different forest covers (Alnus subcordata C. A. Mey., Quercus castaneifolia C. A. Mey. and Cupressus sempervirens L. var. horizontalis(Mill.) Gord.) on litter, soil and CO2 emission characters in the forest management plan of Nowshahr Neirang-Khanikan. Soil samples were taken from the organic (litter) and mineral (0-15cm) layers using randomly systematic method. Litter quality characters (carbon and nitrogen), soil bulk density, texture, water content, pH, organic carbon, total nitrogen and CO2 emission (in different water content and temperature regimes) were measured in the laboratory. Results showed that the highest values of litter nitrogen, silt, pH were found in alder plantation, whereas greater amounts of C/N of litter, water content, organic carbon, C/N of soil and CO2 emission were found under cypress stand. The highest amount of sand was detected under oak stand. The maximum of CO2 emission were occurred in field capacity moisture regime and higher temperature in whole of studied plantations. The results of this research indicate that afforestation with needle-leaved species, Cupressus sempervirens var. horizontalis, can be effective on the increasing CO2 emission from soil that must be considered in ecosystem management from the global warming point of view.

Using remote sensing data is an applied method to estimate above ground biomass. In this study, satellite radar data of ALOS-2, with the full polarization and the optical data of Sentinel-2, has been used to estimate the aboveground biomass in the Nav-e Asalem forests, Gilan province. The backscattering coefficients at different polarization, the texture measures and target decomposition features of SAR images, obtained original and synthetic bands from optical images in three different combinations of radar images, optical images and the composition of radar and optical images, as inputs to the Artificial Neural Network (ANN) and Multiple Linear Regression (MLR) models were used. In order to measure aboveground biomass, 149 sample plots were laid out. Evaluation of ANN and MLR models using R2 and RMSE statistics showed that in all cases the ANN was better performance to estimate the aboveground biomass than MLR. The best results showed that the ANN from combined optical and radar data with R2 and RMSE, 0.86 and 31.62 Mg/ha (15.34%), respectively, can be the best applied method to estimate the aboveground biomass. The results of radar images and optical separately, with the R2 and RMSE for the modeling of aboveground biomass have been shown, respectively, 0.57 and 49.17 Mg/ha (23.85%) by radar images and 0.7 and 39.53 Mg/ha (19.17%) by the optical images, superior modeling to estimate aboveground biomass represents by optical imaging. The overall and more accurate results to estimate of aboveground biomass have been shown when we used combined radar and optical images with the ANN model.

This investigation was carried out in Albroz research station complex (Karaj, Iran) during 2014 summer. Mount Atlas mustic (Pistacia atlantica Desf.) seedlings were treated by drought (moderate, sever and without drought stress) and shading (low, moderate and without shade) factors in a split plot experiment based on a randomized complete block design. After one month, physiological characteristics of leaves including RWC, soluble sugars, proline and pigments content, catalase enzyme activity and ion leakage were studied. Drought stress caused severe decrease in RWC and a, b and total chlorophyll contents. In contrast, shade by ameliorating drought stress significantly increased these parameters. Drought induced tolerance mechanisms in saplings and increased proline and carotenoid content while shade decreased these parameters significantly as well as a to b chlorophyll ratio. Interaction of drought and shade was significant for a chlorophyll and catalase activity, suggested that, drought treatments showed different responses to shade. Overall, results revealed positive effect of shade on drought induced saplings.

Beekeeping is one of the most important rural activities and honey is one of the most valuable by-products obtained from rangelands and some forest areas in Arasbaran region. The aim of this research was to compare the pollen grain composition and quality of honeys obtained from Vinaq (rangeland habitat) and Tazekand (forest habitat). Ten hives (10 per habitat) was established at the beginning of the flowering season in 2013. After three months, honey produced in the habitats were taken in August and was transferred to the laboratory for physico-chemical analysis and pollen identification. Pollen studies showed that the pollen grains of common hornbeam (Carpinus betulus L.) and Montpellier maple (Acer monspessulanum L.) was dominant pollen in Vinaq and Tazekand, respectively. Futhermore, the pollen grains of Lonicera iberica M. B. and Montpellier maple in Vinaq and pollen grains of wild cherry (Cerasus avium (L.) Moench) in Tazekand were identified as companion species. According to the results of physico-chemical properties of honey samples, and particularly humidity, HMF, revival sugar, total sugar and sucrose, quality of honey obtained from forest was better than rangeland. These observations indicate that bees prefer to use of trees and shrubs pollen in compare to herbs.

Soil is one of the important components of the forest ecosystem and getting knowledge about the chemical properties of soil can be a good guide for analyzing of forest ecosystem health. In this research, soil samples were taken during a year over four times at intervals of three months (March, June, September and December) in order to evaluate the effect of seasonal changes on chemical properties of topsoil in Marivan forests. Five composite soil samples in each season were collected and altogether 20 samples were taken. Soil organic carbon, nitrogen, phosphorus, pH, electrical conductivity, potassium, calcium and magnesium were analyzed in the Lab. Data analysis was conducted using one-way ANOVA and Duncan's multiple range tests. The result of this study showed that the maximum amount of organic carbon, total nitrogen and phosphorous were observed in the summer that was 10.7%, 0.59% and 44.7 ppm, respectively while the least amount were observed in the winter which was 8.01%, 0.2% and 39.05 ppm, respectively. There were no significant differences in organic carbon and phosphorus during year and over seasons, but total soil nitrogen showed statistically significant (p<01) differences over time. Also pH (p<0.01), EC (p<0.05), Ca (p< 0.05) and Mg (p<0.01) showed statistically significant differences over time while changes in the amount of potassium were very low and showed no statistically significant differences over a year.