مجله جنگل ایران
سال چهاردهم شماره 2 (تابستان 1401)

Sustainable development and sustainability will be achieved if there is a balance between the human dimension and ecosystem. The purpose of this study is to evaluate the sustainability and resilience of forest ecosystems in the Totshami watershed, which seeks to maintain a balance between the human and ecosystem dimensions. Implementation of this model includes assessing the sustainability and determining the resilience of the basin. ArcGIS software was used to analyze and measure the sustainability of the IUCN method and after the final combination of indicators and criteria to produce the map. Identification of functions of the basin with 54 types of functions and was classified into four major services: provider, regulator, habitat and culture. Based on the research results, the final score was 35 for ecosystem dimensions and 50 for human dimensions. The two main objectives including maximizing the water production and minimizing the annual soil losses, along with responding to local demand, have been achieved in the process of optimizing the functions in this study. According to the projected watershed management operations in the basin, it is expected that the ecosystem sector will reach the desired level of sustainability, and in order for the basin to remain sustainable, the economic and social sections must also be considered, and it can be achieved by taking steps to improve people's living standards. Evaluation of the results of Totshami watershed resilience measurement during indicates low tolerance threshold and flexibility of Zagros forests and the result is a reduction in the resilience of these ecosystems to potential threats and disruptions.

In this study, the effect of irrigation with municipal effluent on performance of two clones of Populus alba after one year growth was investigated. The test was done in a completely randomized design with two factors: 1) soil in two levels and 2) poplar clones in two levels. After one year growth, in both poplar clones, significant increase (P ≤ 0.01) in growth and biomass parameters of plants treated by soil irrigated with municipal effluent was observed with the highest values in P. alba 44/13 clone. Also, in both poplar clones, treatment of plants with soil affected by municipal effluent resulted in significant increase  (P ≤ 0.01) of nutrient and heavy metal concentration in plant organs compared to control plants. In both poplar clones, the highest uptake and accumulation of Fe, Cu, Ni, Cr and Pb were in the roots and Zn and Mn in the leaves. The effect of clone on the uptake and accumulation of most micronutrients and heavy metals was significant (P ≤ 0.05). In general, the plants of P. alba 20/45 accumulated higher amounts of micronutrients  and heavy metals in plant organs. The results of the present study showed that after one year growth, P. alba 44/13 clone had better growth performance and biomass production and P. alba 20/45 clone demonstrated higher uptake and accumulation potential of most micronutrients and heavy metals in plant organs. In general, due to good performance of two studied poplar clones, both poplar clones can be considered for wood farming in lands affected by municipal effluent.

Canopy gap delineation is essential for achieving a better comprehension of forest structure. This study aims to (a) extract canopy gaps using UAV data and (b) compare the performance of different canopy gap extraction methods in a managed stand in the northeast of Iran. A canopy height model (CHM) was produced by subtracting LIDAR digital terrain model from the UAV digital surface model. CHM classification performs to extract gaps by thresholding CHM (fixed height and CHM slope and relative height thresholds) and object-based classification on the UAV CHM and orthophoto. Ground truth is produced in the point and polygon forms through field measurements and visual interpretation of the UAV orthophoto. The geometry of the canopy gaps (Area, perimeter, and shape complexity) was calculated. Finally, the point and polygon base accuracy of delineated gaps assess for each of the methods. Point accuracy assessment suggests that 60% CHM slope produces the highest overall accuracy and Kappa coefficient of 91.7% and 0.874, respectively. About area accuracy assessment, the best match between delineated gaps and ground truth polygons was achieved by using relative height and 60% CHM slope thresholds. The lowest mean errors of GSCI produced by 70% CHM slope (0.15). Moreover, object-based classification showed the lowest mean error of area (33.76 m2) and perimeter (16.80 m). In conclusion, while area accuracy is considered the best fit of the delineated gap's geometry is gained by the object-based classification.

The mechanical behavior of vegetation roots significantly affects the mechanism of soil reinforcement and slope stability. The aim of the present study was to determine the mechanical properties of seedling roots of some tree species in the second district of Kheyrud forest. Ten samples of each species (beech (Fagus orientalis Lipsky.), hornbeam (Carpinus betulus L.) and, maple (Acer velutinum Boiss.)) completely extracted from soil and all roots were collected, then their mechanical properties were measured in the labratory. The results showed that in all species, the relation between root diameter and tensile force, was positive power law whereas the relation was negative power law for root diameter and tensile strength and also Young’s modulus. Results of ANCOVA showed that tensile force, tensile strength, and Young’s modulus were significantly different among species. Accordingly, the average tensile force and tensile strength for hornbeam species were 48 and 40% higher than beech and maple species, respectively and the average Young's modulus of beech species was 38% higher than hornbeam and maple species. The findings of this work show that the mechanical properties of the roots can be used as an indicator in selecting species for soil bioengineering purposes. Therefore, it is recommended that these properties be considered in soil reinforcement modeling.

Spatial distribution and size of canopy gaps have important implications for light regime and regeneration, and affect species diversity. In this regard, the present study was conducted with the aim of investigating the spatial pattern and structure of harvesting canopy gaps and comparing with natural canopy gaps in mixed beech forests in the Sordar-Anarestan forestry plan located in Chamestan-Noor, Mazandaran. All natural and harvesting canopy gaps were surveyed by a full inventory and gaps area were measured by using of triangles method. In order to spatial analysis, O-ring statistics, variogram analysis and mark correlation function (MCF) were used. The results showed that the most frequency of gaps was related to canopy gaps with area less than 200 m2. The spatial pattern of natural and harvesting gaps was similar and up to a maximum distance of 35 m was clustered and then random. Only the harvesting gaps indicated a spatial structure up to a distance of 168 m. Natural canopy gaps did not have spatial structure and revealed that the gaps are independent of each other in terms of area. Thus, in silvicultural management, disturbance should be created with different areas that unfortunately have been less considered in the study area.

Vascular characteristics of the xylem determine the efficiency of the hydraulic system in broadleaved trees. To investigate the effects of elevation and longitude (temperature and precipitation gradient) on radial growth and vascular properties of common ash (Fraxinus excelsior) xylem, samples were taken from trees located in two wet sites in Ramsar (300 and 1300 m.a.s.l) and a semi-dry site in Sari (1260 m.a.s.l) of Hyrcanian forests. Tree-ring width (TRW), as well as early- and latewood width, average size (AVLA) and the number of vessels per area (VF), tree-ring porosity, relative specific hydraulic conductivity (RSC), and fiber length were measured and compared in the last ten growth rings of selected trees. According to the results, variations in vessel size were independent of other features and were affected by a different component. Compared with the highland of Ramsar, trees at low altitudes had wider annual rings while having lower RSC, VF, and porosity. Surprisingly, with a decrease in altitude (increasing temperature), the size of vessels shrank, which can be attributed to the inverse effect of over-threshold temperature on tree physiology. Despite the differences in AVLA and VF in the two highland sites of Ramsar and Sari, the combination of two features was in a way that the porosity, RSC, and TRW of trees in the two sites became comparable. In general, it can be concluded that in the western and central Hyrcanian forests, the effect of altitude – manifested in a decrease in temperature - on the radial growth and vascular system of ash trees is more pronounced than the effect of precipitation gradient (longitude).

The study of heavy metals in plants is done with two objectives of studying food safety and application in biological monitoring and elimination of heavy metals from the environment. The aim of this study was to investigate the concentration of heavy metals zinc, copper and lead in the bark of poplar and walnut trees and surrounding soil samples from road of Heidareh Balashahr village in Hamadan. A total of 40 topsoils and tree barks samples were collected from this area. After initial preparation, the samples were prepared using wet digestion method to analyze the heavy metals and the concentration of heavy metals were determined by using an atomic absorption spectrometer (ASS). In order to data analysis, statistical methods, pollution indices and ratio of indices were used. According to the results the Degree of Contamination (CD), Modified Degree of Contamination (mCD), Potential Ecological Risk (PER), Potential acute Toxicity (∑TU) and Integrated Pollution Index (IPI) indices showed low pollution and Pollution Load Index (PLI) and PINemerow indices showed moderate pollution and precautionary zone, respectively. The highest contribution to potential toxicity was 43.8 and 38.05 percent in the soil around walnut and poplar was related to copper. Also, the highest potential environmental risk was related to lead with 52.3 and 58.08 percent, respectively for the surrounding soil of walnut and poplar. Based on these results, there was only a statistically significant difference between zinc concentrations in the two species (p <0.05). Also, significant positive correlations were observed between the Pb contents in soils and those of poplar bark (p<0.05) that indicated Pb in plant increased with increasing Pb in soil and, so poplar is a more suitable species as a biomonitor and lead accumulator. Despite the contaminants caused by road traffic, food safety of the region's agricultural products should be checked in spatial and temporal monitoring, especially for lead and copper.

The purpose of this study was to measure the relative efficiency of forest harvesting processing companies in Guilan province by considering pollution as an undesirable output. For this purpose, data envelopment analysis (DEA) method was used to evaluate the efficiency. In order to conduct this research, data from 12 forest harvesting companies in Guilan province were collected during 10-year period (2007-2016). First, the variable reduction method was used to reduce the indicators and then the units were ranked using the super-efficiency method. The results show that due to the importance of undesirable output, a number of companies have good ranks in terms of efficiency despite their high adverse undesirable output (air pollution) are in a good position in terms of efficiency (Iran Wood Coating Company and Layl Forest Cooperative). Due to the existence of undesirable output (air pollution) in forest exploitation companies, it is possible to improve the performance of companies with high efficiency along with undesirable output by reducing the amount of pollution.