فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیست و هفتم شماره 2 (پیاپی 76، تابستان 1398)

In spite of Greek Juniper´s (Juniperus excelsa M. B.) resistance to harsh environmental conditions, the area of its natural habitat is decreasing due to human activities and a low rate of natural regeneration. Therefore, the plantation is one solution to rehabilitate its natural habitats. Understanding the factors that affect the establishment, survival, and growth of seedlings are necessary to design and implement the rehabilitation programs. In this study, the effect of vegetative form and shading (only during the first year) was evaluated on the survival and growth parameters of J. excelsa in the Sirachal research station for a four-year period. Four hundred and fifty saplings that were produced from three different maternal vegetative forms (A, B and C) were planted in the Sirachal research station as complete random blocks in split plots. The shading treatment was applied only in the first year. Statistical analysis showed the positive significant effect of vegetative form on current height growth and crown in the first and second years, respectively. In addition, the significant effect of shading increased collar diameter in the first year but decreased height growth in the second year. Given the results and also the high costs, there is no advice to use shading in Juniper´s plantation programs. Following four years of surveys, our results showed that vegetative form is more influential in the establishment, survival, and growth of J. excelsa saplings. Due to the importance of genetic diversity, selection of seeds from C vegetative form (including both A and B vegetative forms) with high potential of seed production will increase the success chance of planting and rehabilitation programs of J. excelsa habitats.

Optimal forest management implies multiple uses in accordance with the principles of sustainability in natural ecosystems. Due to the ever-increasing demand for forest tourism in recent years, further research is required in terms of the environmental impact assessment. In this research, the environmental aspects of two implementation scenarios (two construction phases and exploitation) as well as non-implementation of the Arghavan forest park project were evaluated using an improved RIAM method in biological-ecological, physical-chemical, social-cultural and economic-functional aspects in the Ilam province within the Zagros region. Improving the RIAM method involves the use of fuzzy logic and network analysis (ANP) to prioritize evaluation criteria. The results showed that while the evaluation index in the conventional method was positive in both implementation and non-implementation of the project, its magnitude in the implementation option was almost doubled compared with the non-implementation option. The result of comparing the evaluation index of the improved method with that of the initial method showed a minor reduction (~6%) in the implementation and a significant decrease (~115%) in the non-implementation. Accordingly, assuming compliance with the implementation defaults, the evaluation revealed the most positive effects of the project implementation. Although the analysis of the results of the method requires complementary research, the use of fuzzy logic and ANP in improving the environmental impact assessment seems to be necessary due to the subjective nature of the evaluation, criteria measurement error, the uncertainty in predicting the aspects and the complex internal relations between the evaluation elements.

Tecomella undulata (Roxb.) Seem. is an important evergreen plant species from different points of view. This species has important characteristics including resistance to high drought and temperature, sand fixation, medicinal properties, and durable wood. The objective of this study was to investigate the genetic diversity among 30 genotypes of the species collected from Bushehr, Kerman and Hormozgan provinces using molecular data obtained from SSR primers. DNA samples were extracted and used in PCR tests by applying microsatellite primers. After agarose gel electrophoresis of DNA Fragments, a totally 29 alleles were distinguished. In831 primer generated most locus. Results of cluster analysis using the UPGMA algorithm based on the Jaccard similarity coefficient categorized the genotypes into eight groups, indicating a high level of genetic diversity among the genotypes. Furthermore, observed and expected heterozygosity were estimated to be 0.4 and 0.29, respectively. Furthermore, the effective number of alleles ranged between 1.2 in the In831 gene to 1.81 in the Tau16 gene with average values of 1.51. These results showed that SSR markers are highly effective in determining the amount of genetic diversity in the population of T. undulata. The observed high diversity among the genotypes of the species showed a rich source of germplasm which can be used in breeding programs.

Ash (Fraxinus excelsior L.) is a forest species with seeds consisting of hard woody skin and high dormancy that complicate the germination. This study was designed to facilitate the growth of ash seed using the in vitro culture of the embryo. Seeds from four regions of Kelardasht, Alandan-Kiyasar (in the Mazandaran province), Aliabad and Galikesh (in the Golestan province) were collected and sterilized using a sterilized scalpel to split tip of an embryo without any damage. Prior to being transferred to the culture medium, the embryo was washed by 70% of alcohol per minute as well as with sterile water under laminar hood. It was then placed in Monier, WPM and MS mediums in three replicates (with five ash seed per each petri dish). All indices studies here in the four geographical regions for the MS medium were significantly higher than the other two media, with the lowest amount observed in Monier culture media. In all four regions, all indices in Alandan and Galikesh were significantly higher than the other two regions, with the lowest amount observed in the Aliabad area. In addition, all indicators showed a significant and positive correlation with each other. Regressions between the length and weight index of vigor with other variables resulted in high R2 values that showed that changes in independent variables are influenced by dependent variables in a close fit. Therefore, it can be concluded that MS medium is more suitable for the in vitro propagation of the embryo plant of the ash.

Estimation of allometric tree attributes such as heights that are not directly observed on unmanned aerial vehicle (UAV) imagery is challenging. Therefore, this study aimed to introduce a method to estimate the height of wild pistachio (Pistacia atlantica Desf.) single trees in the Zagros region. Therefore, a 45-ha area in Baneh Research Forest of Fars province was captured by a Phantom IV UAV. An algorithm was then suggested to consider the difference between pixels of ground and crown top as tree height on the digital surface model (DSM) following automatic single tree detection. The heights of 100 trees were estimated on DSMs with spatial resolutions of 3.47, 10, 20, 40, 60, 80, and 100 cm. The results showed that the highest coefficient of determination of 0.89 and the lowest relative root mean square error of 11.8% were returned for heights estimated on DSM with 3.47 cm spatial resolution. Moreover, no significant difference was observed among measured and estimated height values on spatial resolutions of 3.47, 10, and 20 cm, respectively. The tree heights were overestimated on DSM with a spatial resolution of 3.47 cm (bias score 1.15), while they were close to the measured values on 10 cm spatial resolution (bias score 1.01) and were underestimated in other spatial resolutions. In general, the results showed the feasibility to estimate heights of wild pistachio trees on Phantom IV imagery, in particular on UAV imagery with a 10 cm spatial resolution.

Net primary production (NPP) is an important indicator of ecosystem production potential, which is heavily affected by climate change. The purpose of this study was to investigate the effect of climate change on-trend and sensitivity of NPP in the Hyrcanian region of northern Iran using long-term (31 years, 1987-2017) meteorological data recorded in Gorgan, Ghaemshahr, Babolsar, Nowshahr, Ramsar, Bandar Anzali, and Astara synoptic stations. The synthetic climate-based model was used to estimate NPP and Mann-Kendal test was employed to test the trends of NPP and other meteorological parameters. We observed that the trends of annual temperature were statistically significant in all stations, whereas the annual precipitation trends were not statistically significant. The average annual NPP in the Hyrcanian region was found to be 10.6 t. ha-1 per year on average (SD: ±1.91), in which the maximum and minimum NPPs were corresponded to Bandar Anzali (13.42 t. ha-1 per year; SD: ±1.38) and Gorgan (7.6 t. ha-1 per year: SD: ±1) stations, respectively. The amount of NPP showed an increasing trend from the eastern to the western Hyrcanian region up to Bandar Anzali. Furthermore, the sensitivity of the NPP coefficient was estimated at 0.5 throughout the Hyrcanian region in response to changing temperature. This indicated that a 0.6 °C increase in temperature could approximately increase annual NPP by 0.2 t. ha-1 per year. Conclusively, understanding the temporal change of NPP in response to changing climate is necessary for the utilization of ecosystem services and benefits.

Sexual regeneration is amongst the most important factors that affect the survival and sustainability of forests. It is controlled by the total resources and conditions representing the role of microhabitats in the establishment of the regeneration. Thus, identifying the role of microhabitats on the establishment and diversity of regeneration is of great significance. Therefore, the present study was conducted in a central part of the Zagros region in Baba-Yadegar forests of Dalahoo County, Kermanshah province. A total of 372 5 × 5  plots were established with respect to the tree microhabitats, including Quercus brantii Lindl., Q. infectoria Oliv., Crataegus pontica C. Koch., mixed and open spaces (with no trees) along 7 transects. In each plot, the biological characteristics of the trees were measured together with sexual regeneration and soil litter depth. The results showed that the mean value of DBH was significantly higher for Q. infectoria microhabitat compared to other microhabitats. In addition, the number of sprouts was significantly higher for mixed microhabitat compared to others. The highest species diversity of regeneration was observed in Q. brantii microhabitat. Furthermore, the result of multivariate analysis showed that the species diversity and abundance of trees in the microhabitat were the most important factors in the discrimination among microhabitats with over 83 percent of accuracy. It was concluded that the microhabitats and their characteristics play a major role in the establishment of tree species regeneration, diversity and consequently on the future forest structure that can contribute to the success of the restoration plans in the Zagros forests.

Vegetation classification is an essential tool to describe, understand, predict and manage ecosystems. The aim of this study was to compare different types of hierarchical clustering. Three forest patches with similar slope and altitude gradients located on the southern slopes of Chahar Zebar forests, Kermanshah province, were selected. Vegetation sampling in each patch was conducted at 0, 25, 50, 100 and 150-meter distances along three transects that were 200 m apart. Cluster analysis was used for the classification of samples. Amongst the applied methods, Gower’s distance (or similarity) initially computes distances between pairs of variables over data sets and then merges those distances with the nearest neighbor, complete neighbor, average neighbor, and Ward’s method. The optimal number and quality of clusters were evaluated with silhouette criteria. In addition, the Cophenetic correlation coefficient was computed for evaluating the correlation between the dendrogram and the distance matrix. Results showed that two was the optimal number of clustering for oak stands. Moreover, the Cophenetic correlation coefficient between the distance matrix and the nearest neighbor and average method was higher than that returned between complete neighbor and Ward’s method. Based on silhouette criteria, the nearest neighbor and average methods were associated with higher cluster quality compared with two other methods. However, the mean value of the silhouette index was low for the second cluster of the nearest neighbor method. Considering the disadvantages of the nearest neighbor, the average method is suggested for clustering categorical data.

Participation of local communities plays a significant role in preserving natural resources. The purpose of this study was to analyze the cultural and social patterns of local people´s cooperation in the preservation and management of renewable natural resources as well as the emphasis on internalization and findings on background conditions and causal factors affecting this. To this aim, the Grounded theory was used. The categories and theorems were constructed by means of three-step coding of the concepts. Sampling was used for a deep interview with the association of 32 subjects. Interviewees were composed of stakeholders and users of natural resources. The findings showed non-internalization is the hub of the study, which was due to focused decisions, the chaos of power structure in villages’ economy trading, the natural poverty of local people, the lack of social investment, social alienation, and tribal micro-cultures. Dominating endeavors of local communities in such conditions include asking for support and the development of subsidy-seeking spirit and ignorance. Each of these abovementioned procedures bears consequences, including non-cooperation of natural resources schemes, reducing sensitivity to declining natural resources and alienation to nature, excessive exploitation of natural resources, following individual interests in the face of natural resources. Based on the findings of this study, macro- and micro-scale factors in one interaction have resulted in the lack of organized participation of indigenous and local stakeholders in the conservation and management of renewable resources.

Since the long-term sustainability of the natural ecosystem depends on soil quality protection, knowledge about soil conditions in natural lands is effective for their correct management. The aim of this study was to investigate the impact of Christ's thorn (Ziziphus spina-christi L.) crown on soil physicochemical and biological characteristics in the Izeh region of Khuzestan province. Soil sampling was carried out from the soil surface (0-20 cm) under the crown and open area (control) by using random transects. In addition, several numbers of soil physical (bulk density, and saturation moisture), chemical (acidity, organic carbon, potassium, and phosphorous) and biological (carbon microbial biomass, basal respiration, and microbial quotient) properties were measured. According to the result, the organic carbon content under the crown was 1.90 percent, which was 23.5% higher than that of the soil outside the crown. The available soil potassium content (233.35 mg kg-1) under Christ's thorn crown was higher than that of open area. However, pH was not shown to be affected by trees, with no significant difference between measured values in free space and under the crown. The highest amounts of carbon and nitrogen microbial biomass (547 and 60.1 mg kg-1, respectively) were found under the canopy. In addition, the highest basal respiration rate was 19.29 mg of carbon dioxide per kg of soil under the tree crown. The microbial quotient of 1.68% was highest under the crown. Based on the results, the metabolic rate showed an inverse trend, with the highest amount was observed outside the tree shadow. Furthermore, the presence of Christ's thorn trees in the study area has resulted in increasing soil fertility and the improvement of soil microbial activities.