مجله پژوهش و توسعه جنگل
سال هشتم شماره 3 (پاییز 1401)

The aim of this study was to study the effects of altitude and slope factors on beech natural regeneration around dead trees in Siahroud forests of Guilan province. In order to conduct this research, 45 dead trees were selected using selective sampling method. Then, around the standing dead trees, a circular plot with a radius of 5meters and around the fallen dead trees, a rectangular plot with 4meters width (2meters from two sides of each log) were measured. Inside each plot, regeneration frequency, slope (in three classes of <30, 30-30 and > 50%) and altitude (in three classes of <700, 700-1500 and >1500 m) were measured. In order to compare regeneration in 50m distance from dead tree, the measured variables were collected in samples with the center of healthy trees with the same DBH. The results showed that the regeneration frequency of all tree species around dead trees was higher than around of healthy trees. The ANOVA test showed that there is a significant difference between the regeneration frequency in different classes of altitude and slope. Also, with increasing altitude and slope, the regeneration frequency of around healthy and dead trees was decreased. The results showed that physiographic factors have an important effect on the tree regeneration around of dead trees.

In this study, the effect of different cluster sampling schemes based on nonparametric algorithms to estimate the characteristics per hectare and canopy cover of customary Olad Ghobad forests located in Koohdasht city in the west of Lorestan province, were modeled using data Ground and satellite images of the Sentinel-2 To estimate the characteristics, 150 clusters in the form of six designs were implemented in a regular-random manner in the region. Then, six cluster sampling designs were collected inside the subplots, density characteristics, and canopy. Each cluster consisted of four sub-plots with an area of ​​700 square meters. After pre-processing the images and appropriate processing, the numerical values ​​corresponding to the ground sample parts were extracted from the spectral bands and considered as independent variables. Modeling was performed with 75% of the data and the results were evaluated with the remaining 25%. For both density characteristics (number per hectare) and canopy, artificial neural network method with squared percent mean square error and BIAS of 10.53, 2.48, 9.38% and 0.33% respectively in modeling have more accurate results than other methods used. In general, the use of different cluster sampling schemes, nonparametric modeling methods, and Sentinel-2 satellite images have good results in estimating the number of per hectare and canopy.

Parasitoid wasps are one of the natural enemies and major causes of mortality of Oak gall wasps (Cynipidae). This study was conducted during 2018-2019 in Rabat and Vavan regions (Sardasht –West-Azerbaijan) in order to identify the sexual generation of oak gall wasp’s species on the Persian oak Quercus brantii and their natural enemies. The galls were reared to collect gall wasps and parasitoids in laboratory. Then, Species diversity, evenness and species richness (with Rarefaction method) were calculated with Ecological Mothology 3.0 software. 14 parasitoid wasps belonged to six families of Hymenoptera were identified. Bootaniomyia dorsalis had the highest frequency among collected parasitoid wasps from Rabat and Vavan in two years. The mean of diversity and evenness indexes in 2018 and 2019 in two studied regions showed that the mean of diversity between Rabat and Vavan had a significant difference in both years. The Shannon diversity index in Rabat was more than Vavan. The highest richness of parasitoids was recorded in Rabat in 2019.

The effect of physiographic factors on biodiversity and trees biomass is done in series 4 of Golband (watershed No:45) in Nowshahr by sampling and application of six north-south sample lines (1000-1600 m) and conducting 48 square sample pieces of 4 r on sample lines with 200 m intervals. In each one of sample plots, number and percentage of tree and shrub cover, physiographic factors of slope (three class), direction (three class) and altitude (eight class) were collected. Grass cover was investigated using five 25-square-meter sample plots (four sub-plot plots in the corners and one in the center) inside each plot. Then Simpson diversity indices, Margalef richness and Sheldon uniformity were used to study diversity and biomass estimation is done using allometric equations. The results showed that the differences between all biodiversity indices and biomass were significant in different physiographic conditions. By increasing slope, the average of biodiversity indices increased. The highest value of Simpson diversity indices was observed in the north direction (0.78). By increasing altitude (200-1600 m), the average indicators decreased. Also, the highest amount of biomass was related to the slope class of 30-60%, east direction (220 tons per hectare) and altitude class 1400 meters (268 tons per hectare). Based on the general results of this study, due to the higher humidity, the north direction has the greatest effect on plant diversity and the highest surface vegetation can be seen in the altitude range of beech presence and in the middle slope.Keywords: Elevation above sea level, Simpson, Margalef, Mazandaran, allometric equations.

The purpose of this study is to investigate the effectiveness of the early warning system of the Canadian Forest Fire weather Index in the Golestan Province. To estimate the weather index of Canadian forest fires, the input variables to the system were four climatic variables including temperature, humidity, wind speed at a height of ten meters, and rainfall for a period of 24 years (1997-2021) during the fire season (April to January) were collected from synoptic and evaporative stations in the province. First, the Canadian forest fire climate index system was calculated daily during the study period at each climate station. Then, the obtained 24-year average of fire risk potential rate for each station was estimated using the conventional kriging interpolation method with high accuracy and a continuous raster map of the fire risk potential of the Golestan province was prepared. Then, the continuous climatic potential of fire risk was zoned into three categories of medium, high risk, and dangerous using the Canadian Climate Index system classification. 1452 occurred fire points in the past years were used to evaluate the performance of the Canadian forest fire weather index system in the Golestan Province. The results showed that 68% of the fire points, which cover 80% of the burned area, are in the high-risk category. Based on obtained results, it could be concluded that the Canadian Forest Fire Climate Indicator Early Warning System can predict fires in susceptible areas in the Golestan Province with higher accuracy.

To conduct this research, 100% Inventory was performed in each stand by dividing whole study area into mosaics with dimension 40 × 40 meters. In each mosaic, all trees, shrubs and their vegetative origin were determined and also DBH, height of crown beginning, total height, height and diameter (large and small diameter) of crown were measured. To show the structure of the stands, sample plots with dimension 100 × 100 m were placed in each stand and the structural information of the forest was measured and recorded. The measured data in each stand were analyzed via statistical software and forest structure was plotted using SVS software. Comparison of the means of structural characteristics showed a significant difference at the level of 5% between the stands. The results showed that the elevation variation and stratification is greater in natural stand and the Quercus infectoria species occupies the dominant story. Also, the natural habitat has the highest crown density and developed crown and enjoys more favorable condition. Therefore, it is suggested that by modeling the natural stands and protecting and supporting the stands under traditional exploitation and implementing of enclosing and restoration operation in the exploited habitat, the condition of these stands be improved and led to a more stable situation.

The aim of this study was to investigate the changes in the amount of dead wood carbon storage of Quercus brantii Lindl in relation to physiographic factors in Qalajeh forest of Kermanshah province. For this purpose, an area of ​​Qalajeh forest with an altitude range of 1400-2100 meters above sea level was selected, and the area was divided into seven elevation classes with a difference of 100 meters. Then, at the level of each elevation class, one-hectare sample plots with three replications were implemented to estimate the amount of standing and fallen dead wood carbon storage. In each sample plot, while specifying the slope and direction, in addition to quantitative measurements in line with the research goal in relation to standing dead wood, the sample line in parallel and at a suitable distance from each other to check and measure the fallen dead wood whose diameter was greater than or equal to 2 cm for Necessary measurements were implemented. The results of Pearson correlation test showed that there is a significant negative correlation between the amount of standing and fallen dead wood carbon storage with the altitude factor. Also, the results of analysis of variance showed that the changes in dead wood carbon storage of Quercus brantii Lindl in different physiographic units did not have a significant difference, which shows that the changes in dead wood carbon storage of Quercus brantii Lindl trees in the study area are independent of the Physiographic factors effects.