Iranian Journal of Forest and Poplar Research
Year:2020 | Volume:28 | Issue:2 (80)|Papers Count:8

This research was done to quantify the effects of human interventions on the quantitative and qualitative status of natural regeneration of species with emphasize on oak (Quercus macranthera Fisch. & C. A. Mey. ex Hohen. ) species in Arasbaran forest region. Data were collected by transect method in 90 circular sample plots with an area of 3. 14 square meters. In each sample plot, the frequency of species, seedling height, growth form, vitality, and regeneration origin were recorded. Results showed that there was natural regeneration of 11 species. Dog rose (Rosa canina L. ) and medlar (Mespilus germanica L. ) had the highest and lowest frequency, respectively. About 53% of total seedlings had decurrent growth form and 54% of oak seedlings had excurrent from. About 63% of total seedlings belongs to high vitality classes and 45% of oak seedlings were in high vitality class. Seventy-six percent and 70% of total seedlings and oak had seed origin, receptively. Correlation analysis showed that with increasing the intensity of human interventions, frequency of high vitality seedlings have decreased significantly, but forked-spilt form and low vital seedlings have significantly increased. Based on the results, the increase of human interventions has led to decrease of total regeneration. Accordingly, to protect the Arasbaran forests and guarantee the survival of the forest, reducing the severity of human interventions such as grazing livestock and harvesting trees should be a priority.

This study aimed at evaluating the physical, chemical and biological properties of soil in the developmental stages of oriental beech (Fagus orientalis Lipsky) forest in Asalem-Guilan region. Three 1-hectare plots (100 ×100 m 2 ) with different stages of development including initial, optimal and decay were selected. Soil sampling was carried out at a depth of 0-20 cm in the four corners of the five sub-plots of 400 m 2 each, and the samples (n = 60) were analyzed in the laboratory. The results showed significant difference of soil texture amongst the three developmental stages of beech forest. The developmental stages of beech forest were significantly different in terms of available potassium, organic carbon content, C/N, iron, manganese, copper and zinc. The highest mean respiration rate, microbial biomass carbon and phosphorus, MBC/MBN ratio and MBP/MBN ratio were observed in the decay stage. These results indicated that decay stage is more favorable in terms of microorganism activity. The results also showed that biological and microbial properties are more appropriate indices for revealing differences in developmental stages. The results generally revealed that developmental stages of beech stand with respect to age and structural conditions cause changes in soil physical, chemical and biological characteristics. The results in the control compartment could be used as a basis in other forest stands for silvicultural and rehabilitation measures.

Silicon plays an important role in increasing plant resistance to drought-stress. In this study, the effect of silicon on drought-stress in seedlings of gall oak (Quercus infectoria Oliv. ) was investigated. The seedlings were transferred from forest nursery of Marivan Natural Resources Office to Urmia University and were subject to an experiment as a factorial design based on complete randomized blocks in three replications. Seedlings were irrigated by two types of silicon (coarse and nanoparticles) in different concentrations (0, 50, 100 and 150 mg L-1 ) pre-treatment during a 30-day period based on field capacity. Then, drought stress was imposed on three levels, which consisted of control (based on field capacity), moderate stress (based on 50% field capacity) and severe stress (water withholding) for 21 days. The results showed significant and main effects of silicon type on the amount of silica, drought stress on proline and silicon concentration on proline and silica. However, the interaction effects of drought stress with silicon type and drought stress with silicon concentration were significant only on the proline. None of independent and interaction effects of the fixed factors on growth parameters and the amount of carbohydrate were significant. Generally, silicone application had only a significant effect on severe drought stress in reducing proline content, but there no difference was observed between coarse and nanoparticles. The absorption of silica was obviously higher in the nanoparticle type. Finally, the application of silicon at a concentration of 50 mg L-1 in severe drought stress conditions was concluded to enable increasing the tolerance of Q. infectoria seedlings against drought stress.

The analysis of changes in mangrove forests production capacity and its relation to the drought periods can provide valuable information on the vulnerability of these ecosystems to the adverse effects of climate change. This study investigates the effect of long-term drought occurrences on the production capacity of the mangrove forests in the Gwatr Port in the Sistan and Baluchestan province. To do this, by recording the diameter at breast height and calculating the above and below ground biomass in the sample plots and analyzing the relationship between these characteristics with the Landsat satellite images, 34-year time series (1986-2019) mangrove biomass were mapped and the relationship between biomass variations and changes in meteorological drought (measured using SPI) and hydrological drought (measured using SSFI) was analyzed. The results showed that the above and below ground biomasses follows the trends of change in the severity of meteorological and hydrological droughts during the 34-year period such that in the wet season before 1998, mangrove biodiversity increased, and then with long-term droughts after 1998, the decline in biomass continued until the end of the period. The coincidence between biomass changes and SPI and SSFI variations resulted in a high correlation between mangrove biomass variations with changes in the severity of meteorological and hydrological droughts (correlation coefficients greater than 0. 82). The results of this study can be used for developing climate change adaptation programs and for the restoration and development of mangrove forests in the Sistan and Baluchestan province.

Having knowledge on stand structure and application of appropriate silvicultural interventions based on ecosystem approach and close to nature forest management is essential for sustainability of forest. This research started from 2009 in intact oriental beech (Fagus orientalis Lipsky) stands in four regions of the Hyrcanian forests. Twelve sample plots, each one ha, have been established in three development stages of initial, optimal and decay and 100% survey has been applied within the plots. A transect of 1000 m 2 has been laid out on the middle of the plot and diameter at breast height, tree height and coordination have been registered. Vertical and horizontal structure and the stand structure have been illustrated by SVS software and structure triangle. Results indicated that stem number varied between 188 in the decay and 475 ha-1 in the initial stages. Number of deadwood varied between 7 and 30 ha-1, among them 3 mature deadwoods with diameter more than 60cm. Mean basal area, total volume and deadwood volume was calculated to 40. 65 m 2-1 ha, 592. 6 and 55. 8 m 3-1 ha, respectively. The stands in the optimal stage showed two layers while the other stages were three storied stands. The high proportion of volume in large and extra-large timbers indicated that the studied intact stands were old growth and the structure was far from the theoretical irregular structure. Hence, different silivicultural interventions could be introduced in different development stages.

Non-implementing of forestry plans across Hyrcanian region in Iran has been one of the one of the important major decisions of forest management sector in recent years. This study was carried out to investigate implementing or non-implementing of forestry plan in the Babol Roud, Mazandaran province. Furthermore, Cochran's relationship was used to determine the number of respondents, whereas Delphi technique was used to adjust questionnaires, which were distributed among 32 people (16 local communities and 16 forestry plan’ s staff) for subsequent SWOT analysis. The SWOT analysis was used to analyze the opinions of stakeholders, the process of receiving feedback was purposefully performed. Then, their comments were tested and analyzed. The results of the SWOT evaluation matrix showed that the statistical community demands an aggressive strategy to implement the forestry plan and a defensive strategy in case of its non-implementation. The most important strength of implementing the forestry plan were identified as survival guarantee of the tree stands, whereas non-implementation was assessed to be associated with non-intensive harvest beyond forest capacity. In contrast, the most significant weaknesses were identified as soil and existing hydrological system degradation as well as intense forest invasion (wood smuggling, land use change), respectively. Overall, results generally indicated that in both methods the most majority of the statistical community in the study opposed stopping forestry plans which resulted in ongoing and upcoming economic and environmental problems. Likewise, the major revision of forestry plans’ current condition along with their codification and using alternative management strategies were suggested in order to comprehensively meet the beneficiary needs.

Intra and interspecific interactions of plants is one of the important processes in establishing spatial structure of plant communities in semi-arid regions. Additionally, the interactions can be applied in management and rehabilitation of vegetation in these regions. This study was aimed to investigate the spatial pattern of wild pistachio (WP) (Pistacia atlantica Desf. ) and wild almond (WA) (Amygdalus spp. ) in Baneh Research Forest of Fars province to identify their interactions. In two 150 m × 150 m sample plots, the spatial positions of 798 individuals of two species and their crown diameters were measured. Uni-and bivariate g(r), Oring, D(r) and kmm(r) were applied to explore the spatial patterns of species. The results showed the heterogeneity of spatial patterns of two species individuals, as well as lower density and higher mean crown area of WP. Moreover, WP and WA individuals were located in mixed clusters, although the positive interaction of conspecifics was stronger than heterospecifics. In small scales, density of conspecifics was almost two times more than heterospecifics. Furthermore, the positive interactions of conspecifics resulted in intense intraspecific competition that negatively influenced their crown areas (p < 0. 05) and was more in WA (in 3 m distance between conspecifics, crown areas of WA and WP were 60% and 20% less than mean, respectively). In general, it was concluded that a mutualistic relationship exists between WP and WA in the study area as a result of their facilitative effects. The quantitative results of this study can be used in silvicultural treatments such as plantation.

This study was carried out to derive biomass of wild pistachio (Pistacia atlantica Desf. ) and carbon stock based on non-destructive method in the Lordegan forests of Chaharmahal-oBakhtiari province. Initially 18 samples (with 1000 m 2 area) and 18 trees including six diameter classes were randomly selected, for which a number of quantitative characteristics were measured for all trees. Moreover, leaf and fruit biomasses were measured using direct method. The biomass estimation of the crown and trunk was conducted by measuring the actual volume and the specific gravity of the crown and trunk. In addition, litterfall biomass was estimated by 0. 5 m 2 samples. The results showed the amount of above-ground carbon stock of pistachio to be 5. 48 tons per hectare in the study area. Moreover, the smallest and largest amounts of carbon sequestration were found for fruits tree trunks, respectively. Litterfall carbon stock was also estimated at ca. 0. 63 tons per hectare. Therefore, 112118 tons of CO2 were absorbed by the wild pistachio trees in the study area. Based on the economic and ecological importance of wild pistachio trees in reducing atmospheric carbon and by additional emphasize on the valuable role of pistachio trees in the natural ecosystem of the Zagros, the results of this study can play an important role in the management of conservation and restoration.