مجله جنگل ایران
سال چهاردهم شماره 1 (بهار 1401)

The uprooting of large trees leads to the formation of depressions in the root area and plate-like features next to it, which are referred to as pit and mound microtopography. For studying the plant species diversity in these positions, Deldareh forests, Nowshahr was selected. For this purpose, all pits and mounds were identified in 70 ha of the study area. The presence and frequency of plant species were recorded on these positions and each pit and mound was compared with a plot 2×4m located 25m far from these positions. Firs, to analyze the plant species, biodiversity indices were computed. Then, to study SIV in each position, relative frequency, relative density, and relative dominance were also calculated. The results indicated all indices of diversity and richness had significant difference between positions, except the Simpson one. Accordingly, in the comparison between the pit and control positions, the control position, and between the control and mound positions, the mound position had higher values of the indices. Also, neither of both evenness indices showed a significant difference between different positions. The study of the SIV also showed that in all positions, there is a normal logarithmic curve. The findings of the present study show the high ability of pit and mound effects on increasing the species richness in forest stands. Therefore, the design of silviculture methods should be such that by maintaining and increasing the thickn trees, a certain number of pit and mound microtopography remains per unit area.

Afforestation is one of the most important tools in creating green cover and providing wood supply. The aim of current study was to investigate the growth and performance of 25-year-old afforestation's in the Radar-Poshteh region of ​​Guilan province. In this study, eight sample plots of 400 square meters in four 3.5-hectare stands of maple, black alder, chestnut leaved oak and loblolly pine were executed by randomized systematic method and within each sample plot, diameter, height, trunk length without branches, large and small diameter of the crown were measured. Litter depth was also measured at ten points in the sample plots with a ruler. Also, the quality of tree trunks was divided into three categories: grade 1, 2 and 3. Using the collected data, the most important quantitative and qualitative indicators of the four stands were extracted and statistically compared. Also, the biomass of the trees was estimated using the reported allometric equations for the studied species. Based on the results, the highest average diameter (33.42 cm), diameter growth (1.23 cm), highest basal area (78.43 m2/ha), volume (763.98 m3/ha), biomass (971.5 ton/ha), grade 1 trunks (92%), litter thickness (8.6 cm) and the lowest height form factor (0.78) were obtained for loblolly pine stand. Among the native broadleaf species, the highest volume and biomass were calculated with 458 m3 and 520.75 ton/ha for alder species, respectively. Therefore, loblolly pine due to its high production (Controlled in non-forest lands) and chestnut leaved oak due to its high yield along with the production of high quality timbers are recommended for afforestation in Guilan province.

Calculating the amount of canopy ecohydrological parameters is the main step in rainfall partitioning modeling, and by calculating the amount of ecohydrological parameters, it is possible to predict the amount of throughfall, stemflow, and rainfall interception per rain storm. Therefore, this study aimed to evaluate the canopy echohydrological parameters of three oriental beech (Fagus orientalis Lipsky) stands and three chestnut-leaved oak (Quercus castaneifolia C. A. Mey.) located in the Hyrcanian vegetation region in the annual-based time scale. The ecohydrological parameters studied included canopy saturation point, canopy water storage capacity, free throughfall coefficient, and the ratio of mean evaporation rate from canopy to the mean rainfall intensity. On average, the canopy saturation point was 5.37 mm in the chestnut-leaved oak and 6.29 mm in the oriental beech. Also, on average, the canopy water storage capacity of the oriental beech (2.08 mm) was higher than that of the chestnut-leaved oak (1.15 mm). The mean rainfall magnitudes in the chestnut-leaved oak and oriental beech stands were 20.0 and 16.2 mm, respectively. The average relative interception in the oriental beech (36.9%) was slightly higher than the chestnut-leaved oak (33.5%). The average free throughfall coefficient and the ratio of mean evaporation rate from canopy to the mean rainfall intensity were calculated to be 0.50 and 0.25 for the oriental beech and 0.71 and 0.36 for the chestnut-leaved oak. By knowing the values of canopy ecohydrological parameters, thinning and pruning silvicultural treatments can be applied in stands with high water storage capacity and low free throughfall coefficient to reduce rainfall interception.

Protection and conservation of forests require access to information and awareness of structural features such as number per hectare and canopy cover of trees. This study aimed to select the optimal cluster sampling design in estimating the quantitative characteristics of the forest according to the three measures including accuracy, precision, and time required for the sampling. For this purpose, 30 hectares of watershed Olad Ghobad forests in the west of Lorestan province were selected. The Cartesian coordinates of all the trees in them were determined. In Matlab2014 software environment, the position of all trees was simulated. Then different cluster sampling designs (triangular, square, star 1, linear, L-shaped, star 2) were  defined in the research  by taking into account the number of samples (30, 60, and 90) and three distances (10, 20, and 30 meters). These processes repeated 10,000 times. The results showed that there was no significant difference between the estimated mean of different designs of cluster sampling methods of the study area. Based on the number of samples and the distance studied, it was found that sampling error for linear design has the highest accuracy compared to other designs. The results of estimating the E%2× T index for the characteristic number of trees per hectare and canopy cover showed the lowest values for the square (770.99) and linear (2347) designs, respectively. The results of accuracy estimation for both mentioned characteristics of Star 2 Design showed the lowest values (18.83) and (-5.54), respectively. The results of accuracy estimation for both mentioned characteristics of Star 2 Design showed the lowest values (18.83) and (-5.54), respectively.

Eucalyptus species are one of the most suitable tree species in terms of wood production for pulp and paper industry and leaves for pharmaceutical industry. This study aims to determine the wood and foliage production in coppiced Eucalyptus species. This study carried out on four Eucalypts species including Eucalyptus camaldulensis 9616, E. melliodora, E. stricklandii and E. Salubris with 4 treatments (1, 2, 3 shoots per stumps and control) and were planted at 1.5×  2 m spacing as statistical split plot design with 3 replications at Shooshtar Research Station, Khuzistan province.  At the end of first year, seedlings were cut 10 cm above the ground and coppice shoots treatment was applied. Survival percentages, diameter at breasts height (dbh), and height were measured yearly during dormancy on all trees. After four years of growth, all shoots were cut and stems and branches were weighed separately, and finally the biomass was recorded. The growth results of four years after the shoot treatment showed that the highest average wood yield was in the E. camaldulensis species and in the control and 3-shoot treatments with 45.4 and 38.9 tons per hectare per year, respectively. The average foliage biomass under different shoot treatments showed that in the 3-shoot treatment of  E. camaldulensis species with 10.3 ton/ha/yr. had the highest value  and was placed in the first group. Also, total of wood and foliage yield of E. camaldulensis in control and 3-shoot treatments with 50.8 and 49.9 tons per hectare per year respectively, were placed in the first group.

Increasing industrial activity, followed by the entry of heavy metal pollutants into the aquatic ecosystems, are one of the biggest environmental challenges. Plants are good indicator of metals concentration in water and sediment of aquatic ecosystems. The aim of this study was to investigate the concentration of heavy metals in sediments, roots, stems and leaves of mangrove trees in Khorkhoran protected area as one of the most important mangrove habitats in the Persian Gulf. For this purpose, 9 samples of sediment, leaves, roots and stems were collected from this area and analyzed by ICP-OES to determine the concentration of heavy metals. Shapiro, Kruskal-Wallis, Tukey and bioaccumulation index and transfer coefficient were used for statistical analysis. The results showed that the highest concentrations of heavy metals in sediment samples were specific to nickel, zinc, copper and lead, respectively, and in the plant the highest concentrations were related to zinc, nickel, copper and lead. In general, the process of accumulation of metals in sediment and plant tissues indicates an increase in the concentration of metals in plant tissue with an increase in sediment. Bioaccumulation index showed that the highest and lowest concentrations of heavy metals were in roots and leaves, respectively, and mangrove root is a suitable indicator for measuring mangrove contaminants. The transfer coefficient of nickel metal in the stem and copper metal in the leaf showed the ability of these organs for phytoremediation of these two metals. The results showed mangroves are repelling species for other metals.

Among different methods for classification, clustering is commonly used methods. Flexible-Beta clustering is successful hierarchical agglomerative clustering which is employed by ecologists as effective clustering method. The aim of the research was to detect the suitable value of beta for flexible-clustering methods. For this purpose, two different forest regions from Hyrcanian and Zagros Oak regions were selected. The clustering algorithms included Flexible-beta algorithms with five value of beta (-0.1, -0.25-, -0.4, -0.6 and -0.8). Five evaluators (Silhouette, MRPP, PARATNA, Phi coefficient) were employed on each cluster solution to evaluate different clustering algorithms. Algorithms were ranked from best to worst on each clustering evaluator for each data set. The results showed that Flexible-beta clustering with beta value -0.1 had best performance and Flexible-beta clustering with beta value -0.25 and -0.4 were proper performance in Hyrcanian regions. Flexible-beta clustering with beta value -0.25 was superior to others and Flexible-beta clustering with beta value -0.1 had the second rank. Since, choosing the most suitable clustering method is critical for achieving maximally ecological interpretable results, therefore, we suggested using flexible beta clustering with beta value equal to -0.1 and -0.25 in the studies area.

The dynamics of nutrients and their return to the soil through the litter is one of the most important pathways of the nutrient cycle in forest ecosystems. The aim of this study was to evaluate the dynamics of nutrients in pure beech, pure hornbeam and beech-hornbeam stands in Darabkola educational-research forest of Sari. For this purpose, in each stand, 10 sample plots with 1000m2 area were randomly established and by measuring the diameter and height of the trees, descriptive statistics of the studied stands were calculated. Then, litter traps with dimensions of 50 × 50 cm to measure the amount of litter fall per unit area and litter bags with dimensions of 20 × 20 cm (with a pore of 2 mm) with 10 replicated were installed in the studied stands for 360 days and at intervals of 60, 120, 180, 240, 300 and 360 days, the concentrations of nitrogen, carbon, phosphorus and potassium in the litter of the bags were measured. According to the results, the highest rate of litter falls with 1817 kg/ha was related to November and December in beech stands. In addition, the highest input of the studied elements was related to the pure hornbeam stand. The resultas also indicatedthe dynamics of phosphorus, potassium and carbon elements in pure and mixed stands are decreasing with a slight increase at the end of the period and increasing in the case of nitrogen and decreasing at the end of the period. The dynamics of the elements in the mixed stand showed more fluctuation than the pure stands. Also, the results of this study showed that the 200th to 300th days after litter fall is an important time range in the fundamental changes in the dynamics of litter nutrients.