فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیست و نهم شماره 3 (پیاپی 85، پاییز 1400)

This study investigated the effects of reforestation by native broadleaf and exotic coniferous species on some soil properties at Rimaleh plantations, Khorramabad County, Iran. The experiment was performed by using a completely randomized design with Arizona cypress (Cupressus arizonica Greene), Turkish pine (Pinus brutia Ten.), wild almond (Amygdalus scoparia Spach) and control treatments in four replications. Each replication consisted of a 20  20 m2 plot. Diameter at breast height, canopy cover, and tree height were measured at each plot. Two combined soil specimens were sampled at the two distinct 0-10, and 10-20 cm depths in each treatment replication. The two-way ANOVA was used to compare the ratio of aggregate size and sand proportion, fractal dimension, the mean weight diameter (MWD) of aggregates, geometric mean diameter (GMD) of aggregates, and carbon sequestration among tree species and sampling depths. Results showed that wild almond and Turkish pine plantations play a major role in the development and sustainability of both coarse (more than 2000 µm) and fine (less than 53 µm) aggregates. The Arizona cypress plantations only led to increase of fine aggregates (53-250 and less than 53 µm). A significant increase also was observed in the MWD and GMD of aggregates, and the carbon sequestration in the wild almond plantation soil. In a short time, the wild almond and Turkish pine plantations added more organic carbon to the soil and improved both the soil properties and the stability of aggregates in comparison to the Arizona cypress and control treatment.

The aim of this study was to evaluate the efficiency of two expert systems in automatic classification of pre-defined yew (Taxus baccata L.) communities in the central and eastern of the Hyrcanian forests. Therefore, initial plant communities were recognized using Two-Way Indicator Species Analysis (TWINSPAN) based on floristic data of 408 relevés with 400 m2 areas each. To determine representative species, the integrative results of Phi-coefficient index, constancy ratio, and the ratio of average cover were used. Five plant communities were introduced after transferring the initial communities to the Braun-Blanquet synthesis table. The assignment of relevés into the fifth yew associations were done by functional and sociological species groups as two different automatic algorithms of expert system for vegetation classification. The results showed that all relevés in the expert system based on functional species groups were correctly assigned to the target groups. This method was in 100% agreement with the existing yew syntaxa. However, 87 relevés were not assigned to any of the five pre-defined yew associations, or they were assigned to more than one unit in the Cocktail method, which showed 78.7% agreement with the previously yew syntaxa. Finally, our results illustrate that application of expert system based on functional species groups is preferred to sociological species groups in automatically plant community classification due to the importance of consistency and flexibility of vegetation classifications and the correct assignment of relevés to the target units.

The effects of ecological factors and their interaction on quantitative changes of 10 physiological, 12 anatomical and two morphological traits of leaves in six different populations of Caucasian alder (Alnus subcordata C.A.Mey.) in the west (Guilan province) and east (Golestan province) of Hyrcanian forests were examined and statistically compared in three altitudinal ranges of lowlands, midlands and highlands. Two-way analysis of variance was used to investigate the effect of ecological factors in the region (temperature and precipitation) and their interaction on the studied variables. The principal component analysis (PCA) was used for the correlation between leaf traits and the relationship between environmental factors. The activity of catalase, peroxidase enzymes and proline were significantly different between the two provinces and showed an increasing trend from west to east. In addition, the amount of phenol in the site located in Golestan province was about 1.5 times that of Guilan province. There was no significant difference between the levels of superoxide dismutase activity and the amount of soluble sugar between the two provinces. Superoxide dismutase showed an increasing trend from lowlands to highlands, but the amount of soluble sugar increased from low altitudes to midlands and decreased in the highlands. There was no significant difference in the amount of chlorophylls a and b, total chlorophyll and carotenoids between the two provinces and at different altitudes, as well as the effects of the interaction of ecological factors on them. The most important morphological and anatomical adaptations to drought included increased leaf thickness, stomata density and length, abaxial cuticle thickness, epidermal cell thickness, thickness of palisade cells, thickness of spongy cells, middle vein thickness, thickness of vein abaxial parenchyma cells and number of abaxial parenchyma layers of vein. There was a correlation between most leaf physiological as well as morphological traits and ecological factors. The results of analysis of variance and the interaction of ecological factors on some anatomical features of Caucasian alder leaves were significant. It seems that the anatomical adaptations that are formed in plants over a long period of time are more appropriate indicators for measuring drought stress in plants.

Galazani (pollarding) is a traditional silvopastoral system, which comprises disbranching and defoliation of oak trees to provide livestock fodder. This affects forest stand structure, tree architecture and growth. This study aimed to compare diameter increment between households’ forests (conventional territories) in different diameter classes and analyzing the effect of Galazani on both diameter increment and its trends. To obtain the goals, 16 Lebanon oak (Quercus libani Oliv.) trees in the Armardeh forest in the Kurdistan Province, western Iran, distributed in five family territories (as an indicator of how local owners treat their own forest) from different diameters were cut. The width of annual rings of the cross-sectional discs, which were taken from the trees, were measured via a LINTAB table equipped by a binocular with a precision of 0.01 mm. Results showed that mean annual increment (1.78 mm) was not significantly different amongst various diameters nor amongst different owners. Mean comparisons of diameter increment in the years after Galazani indicated that the increment in the first year after Galazani (1.34 mm) was significantly less than the second (2.11 mm), third (2.76 mm) and fourth (3.19 mm) years. The trend of diameter increment enhances the tree stability and supports forest structure in order to improve the tree growth. Furthermore, it is necessary to both extend Galazani rotation to at least five years and to limit its maximum allowable diameter. Based on our findings, practicing Galazani in large diameter trees (30 to 35 cm) significantly reduces diameter increment.

The socioeconomic situation in the Zagros Forests has provided conditions for the overexploitation in this region, which has raised concerns about the intensified decline of ecosystem services in these forests. In this study, soil and water protection services (as the most important regulatory functions of the Zagros Forests) were economically estimated in the Sarvabad basin of Kurdistan province. Then, the trend of change in their values was examined in two scenarios of 1) reaching all the forests of the basin with 30-50% canopy (first scenario) and 2) conversion of forests to sparse forests with 5% canopy (second scenario). The results showed that the average annual value for soil protection, i.e. preventing land loss and sediment control is 27002.82 IRR per ha, while the average annual value for water protection is 790000 IRR per ha. We also estimated the changes in the total annual value of soil protection function by assuming the first scenario, which increased by 34.83%. In case of the second scenario, it decreased by 37.3%. Moreover, the first scenario was able to add 29.96% to the value of the water protection function of these forests, whereas 33.54% of the value of the water protection function decreased for the second scenario. Decrease in the value of ecosystem services due to the tree canopy reduction in this study emphasizes the importance of protection and restoration of the Zagros Forests ecosystem to maintain and provide valuable ecosystem services.

Dust storms are a major source of solid particles in the world that significantly impact air pollution and human and environmental health. Generally, trees and plants not only improve air quality by absorbing airborne particles on the surface of their leaves, but also they are affected by the accumulation of fine particles on their leaf surfaces. In this study, the uptake of fine dust by some dominant forest species of the Zagros region (Quercus Brantii Lindl., Q. libani Oliv., Q. infectoria Oliv. and Pistacia atlantica Desf.) was evaluated in the North Zagros Forests of Iran. For this purpose, soil, leaves and microdust on tree leaves were sampled by using a random systematic sampling network in the forests of Marivan County, Kurdistan province. The leaf ultrastructure of these species was examined by electron microscopy (SEM). Elements in the soil of the area and microdust deposited on the leaves of the trees were evaluated using the EDS (Energy Dispersive X-ray Spectroscopy) system and atomic absorption spectrometry. Finally, the ability of each hectare of forest to absorb fine dust was derived. Results showed that the leaves of all three oak species as well as wild pistachio are structurally different, which plays a distinct role in the deposition of microdust on tree leaves. The highest amount of microdust uptake by leaves was observed for Q. Brantii (0.012 g per leaf), followed by Q. infectoria (0.006 g per leaf) and Q. libani (0.005 g per leaf). In contrast, the lowest amount was observed for P. atlantica (0.0015 g per leaf). Based on the results, the amount of deposited dust in one hectare of forest in the study area with appropriate coverage (400 units per hectare) was estimated at 87.7 kg. The results of EDS test showed that the tested soil samples did not contain radioactive elements as well as heavy, toxic and dangerous elements. The results of the current study indicate the notable role of forest trees in the purification of air polluted by microdust as well as the the difference between species in their ability to absorb microdust.

Despite the implementation of forest protection programs during the last decade, the continued presence of livestock is one of the reasons for vegetation decline in Iran's forests. Therefore, livestock exclusion is an important necessity for forest conservation. This study was done with the aim of investigating the causes for rancher’s unwillingness to livestock exclusion from forest in Galikesh County in Golestan province of Iran. Using multistage random sampling method, 150 ranchers living in the bordering villages of the forest in Central and Loveh Districts in Galikesh County were selected as research samples. Data was collected using questionnaires with content and validity confirmed by experts. Cronbach's alpha coefficient was used to determine the validity of the questionnaire, which returned the value of 0.89. The results showed that 12 factors were responsible for the ranchers’ unwillingness to livestock exclusion from forest, which included dependence on ranching occupation, disbelief in the Plan for Organizing Livestock Exclusion from Forests, lack of a suitable place to keep livestock, weak financial strength, ancestor affiliations, legal rights to graze livestock, insufficiency of granted financial facilities, lack of participation, high cost of industrial livestock, lack of justification training, lack of proper cooperation of the banking system and belief in usefulness of livestock grazing in the forest, which explained 64.07% of the total variance of the factors related to the ranchers’ unwillingness to livestock exclusion from forest. Implementing empowerment training programs and creating diversity in ranchers' livelihoods resources is one of the suggestions of this study for increasing willingness for livestock exclusion from forest.

The Arasbaran Forests are the main habitat of Caucasian black grouse (Lyrurus mlokosiewiczi Taczanowski) as one of the most important endangered avian species in Iran. Quantitative analysis of the structure and composition of woodlands provides an appropriate basis for conservation programs in its habitat. This research was conducted to quantify the structural characteristics of woody communities in the Caucasian black grouse habitats in Iran. For this purpose, after determining the absence and presence regions, three one-hectare plots in each region were selected, in which all trees were inventoried. Results revealed that the greater amount of relatively large trees (DBH > 20 cm) and the vast range of tree diameter were observed in the presence area. The mean comparison showed that the mean of DBH (11.1±0.6 cm) in the bird's presence was significantly greater than that in the bird absences region (8.5±0.7 cm). The coefficient of variation of DBH, tree size diversity, tree species richness, tree height class richness, and tree heights in overstory were similar in both presence and absence areas. However, the tree and shrub heights in the understory were significantly greater in the presence area (1.5±0.06 m) compared with the absence area (1±0.02 m). Moreover, the abundance of dead trees was significantly different in those areas. In conclusion, the habitats with the relatively higher dominance of Quercus macranthera Fisch. & C.A.Mey. and the presence of dog rose (Rosa canina L.) and black currant (Ribes biebersteinii Berland.) are favorable for the black grouse. The relatively homogeneous structure with the presence of large diameter oak trees and the least amount of fallen dead trees provides suitable conditions for this species. This should be considered in the reconstruction of bird habitats and the restoration of previously manipulated habitats.