مجله جنگل ایران
سال پانزدهم شماره 1 (بهار 1402)

This study aimed to evaluate the performance and effect of time and concentration of xanthan gum and sugar beet molasses spraying in controlling forest road dust and the amount of dust settling on the leaves of roadside trees. Treatments of sugar beet molasses and xanthan gum with concentrations of 2%, 5%, and 10% were sprayed on 60-meter sections of the forest road by a device designed with a spray pump in the Arghavan-Shar forest roads of Ilam city. The study measured the amount of dust when passing the vehicle at a speed of 40 km/h using the HAZ-DUST EPAM-5000 device 3, 9, and 27 days after the implementation of the treatments. The results showed that all treatments were able to significantly reduce the amount of forest road dust. The amount of dust emission in the parts treated with sugar beet molasses (1.19 mg/m3) was significantly lower than the parts treated with xanthan gum (1.62 mg/m3). There was no significant difference between the concentrations of treatments in reducing the amount of dust on forest roads. The study also examined the durability of the treatments and observed that the highest effect of treatments with a significance level of 5% occurred in the first week, and the lowest amount of dust (0.63 mg/m3) was recorded during this period. The study suggests that the use of 2% concentration of sugar beet molasses can be used to control forest road dust due to its operational and economic efficiency.

This study investigated the influence of land-use change on soil quality in the Alandan area of Sari, with five different types of land-uses, namely pure beech stand and destructed forest stand, ash plantation, pine plantation, and arable land. Soil samples were taken from a soil depth of 0-10cm, using six plots (20×20m) in each site, which were selected by random systematic sampling network (50×100 m). The different physical, chemical, and biological characteristics of soil were measured in the laboratory. To calculate the soil quality index, characteristics such as field capacity, bulk density, geometric mean diameter, calcium, magnesium, and phosphorus availability, total nitrogen, ammonium, nitrogen microbial biomass and urease, acid phosphatase, and invertase enzyme were selected as the minimum data set by principal component analysis. In this study, additive and weighted indices were used to evaluate soil quality. The results showed that the higher amount of both additive and weighted index of soil quality were observed in ash plantation (0.76, 0.25), and their lowest amount was found in pine plantation (0.58, 0.16) and arable land (0.54, 0.15), respectively. It should be noted that the weighted index of soil quality in ash plantations was significantly higher than in different pine plantations and arable land. Also, the results of this study confirm that rehabilitation of degraded forests using coniferous species, which has led to a decrease in soil quality, such as soil condition in agricultural land, is not recommended.

The Hyrcanian or Caspian Forests in Northern Iran are facing critical forest degradation due to unauthorized harvesting and illegal logging (IL). This study investigates the causes and factors of IL in the Caspian Forest. Open interviews were conducted with 51 stakeholders to gather data, which was analyzed using the Grounded theory method. In the open coding, the text of the informants' interviews was broken into concept codes and then categorized. In the axial coding, the relationships between the extracted codes were specified, and in the selective coding, the connections between them were illustrated. In open coding, 22 codes relating to IL were obtained. Based on the paradigm model, the position and connections between the causes and factors around the central issue of IL are determined. Then, the codes were divided in to five components consisting of causal conditions (one), context conditions (seven), intervening conditions (11), action/interaction (three), and consequences (one). The study found that "the collapse of the forest management system and the lack of plans for forest resources conservation" is the fundamental causality for IL. Further, contextual conditions such as high unemployment, poverty, subsistence livelihood, and intervening conditions such as weakness and absence of a system for monitoring IL have significant roles in intensifying it. The result of these conditions has caused the actions/interactions in which some people's greed in earning money with little effort and enormous profits from IL; avoidance of wood industries from tariffs and taxes by IL and "conflict between violators and forest guards, and legal and social issues. The consequences of these actions/interactions include deforestation, biodiversity loss, floods, and landslides. To address these issues, the study suggests establishing forest management systems in the context of forest management plans and providing the essential equipment, facilities, and human capital. The forest management plans should be prepared with local communities' participation, and reduce their direct dependence on the forest resources. This point can moderately unravel infrastructural, managerial, and supervisory barriers toward IL.

The study of temperature fluctuations is essential for agricultural planning and environmental studies. With global warming affecting various regions, access to long-term temperature data is becoming increasingly important. Dendroclimatology is a useful tool for long-term climate study, and in this study, the average habitat temperature was reconstructed after developing the chronology of Juniperus polycarpus trees in Keygoran site (Aligodarz, Lorestan). The correlation of annual tree rings with climatic variables of meteorological stations was investigated to reconstruct the average temperature in January-March for the period 1910-2014 for this region. The findings show a positive and significant correlation between the average January-March temperature and the growth of annual tree rings. The results show the occurrence of cold years in the first years of the 1910s to the first half of the 1960s. Warm periods have occurred since the second half of the 1960s, and the temperature trend has generally been increasing in recent years. An examination of the positive and negative pointer years also shows that most of the positive pointer years occurred in the second half of the twentieth century.

The aim of this research was to identify the optimal habitat areas of ash species (Fraxinus excelsior L.) in Kheyrud Nowshahr forest, which covers an area of approximately 8,224 hectares. We recorded the geographical coordinates of 1004 ash individuals using a GPS device, along with environmental variables such as climate variables and primary and secondary topographic predictors extracted from DEM. We used the predictors with the least degree of correlation as input in the Generalized Linear Model, Generalized Additive Model, Random Forest, and maxent models. We prepared and analyzed the variables in ArcGIS, SAGA, and R software. To compare the performance of the four models, we considered the input variables in all models to be the same. We evaluated the models using kappa coefficient (K), Area Under Curve (AUC), and True Skill Statistic (TSS) measures. The RF model had the highest K (0.973), AUC (0.997), and TSS (0.973), indicating the best performance among the models. According to the RF model, the most important variables were valley depth, profile curvature, slope, and topographic position index. These variables indicate the areas with rich soil, sufficient moisture, proper drainage (non-stagnant water), slope less than 45%, and sufficient light (suitable for the vegetative stage). We identified the most suitable areas in the Baharbon, Chelir, and Menia-Sang districts due to optimal conditions for these effective variables.

Forest management involves resource management, natural disturbance, and wildlife habitat. To achieve a sustainable equilibrium, managers require explicit ecological information about the distribution of biodiversity hotspots in the matrix of the mountain-forest landscape. Cave-roosting bats are a keystone species in caves and an ecological indicator of forest quality that are sensitive to ecosystem changes caused by human activities. Spatial explicit models are appropriate tools to identify biologically sensitive areas in achieving key habitats of the forest. In this study, we used the geographical locations of caves in the study area for habitat suitability modeling of cave-dwelling bats. We used spatial explicit models with variables of agriculture, aspect, climate, forest, NDVI, precipitation, range, and water resources (a combination of rivers and streams) and six algorithms: Boosted Regression Tree, Multivariate Adaptive Regression Splines, Mixture Discriminant Analysis, Random Forest, Recursive Partitioning and Regression Trees, and Support Vector Machines in the sdm package. According to the AUC criterion, the best models were RF and BRT with a value of 0.87, and the RPART model with a value of 0.67 had the lowest value of this measure. In explaining the models, water resources and forest variables had the highest scores. We determined the suitable habitats predicted by the ensemble model as a unit of forest ecosystem management at the landscape level. An area of the management unit that has been disrupted by roads and other activities such as sand extraction and tourism development has been determined as a conservation unit.

The aim of this study was to determine the optimal rotation age of even-aged forests with respect to timber and non-timber values by developing the Faustmann model. We conducted the study in four regions of Populus deltoides Marshall. plantations located in the west (Hefz-Abad in Talesh), center (Choobar in Shaft), east (Chalesham in Siahkal), and coastal region (Chaf-chamkhaleh in Langeroud) of Gilan province. We determined the volume increment by the stem analysis method and carbon sequestration by combustion in an electric oven. Then, Net Present Value (NPV) of timber and carbon sequestration is calculated by using volume increment, carbon amount, discount rate, adjusted timber price by stationary autoregressive model, carbon price by non-stationary model, the marginal revenue and marginal cost at the finite series of identical. Results showed that when the economic value of timber is considered, optimal rotation ages are 6-9 years. Optimal rotation ages when carbon sequestration is considered increased to 11-15 years. Integration of carbon sequestration value into timber economic value increased the optimal rotation ages to 7-10 years.

This study investigates the use of seed priming with different materials to induce resistance to charcoal disease and drought in the first year of growth of brant's oak. The seeds were soaked in solutions of salicylic acid, indole butyric acid, and potassium nitrate with three different concentrations, and the seedlings were tested for resistance to oak charcoal and drought. Both water deficit treatment (25 percent field capacity) and inoculation with the pathogenic fungus (Biscogniauxia mediterranea) declined photosystem performance, chlorophyll index, water potential, transpiration, and stomatal conductance in brant’s oak seedlings. The results show that priming of seeds with 150 ppm salicylic acid had the greatest effect on limiting stem lesion in the resulting seedlings and maintained the root potential of the root and stem under conditions of moisture stress. Priming with 100 ppm indole butyric acid showed similar effects in limiting the lesion but showed weaker effects than salicylic acid on plant water relationships and the abundance of ray parenchyma cells. Potassium nitrate (0.5 percent) had no effect on disease resistance and did not alter plant water relations. Overall, the study suggests that seed priming with salicylic acid plays an effective role in inducing systemic resistance of seedlings to charcoal disease and drought in the first year. The findings of this study can offer new insights to achieve improved seedlings.