مجله پژوهش و توسعه جنگل
سال هشتم شماره 2 (تابستان 1401)

Understanding the dynamics and spatial distribution of plant species is an important strategy to conserve biodiversity. Modeling the distribution of plant species is one of the important methods in this field, which uses appropriate indicators to identify the relationships of different environmental variables and evaluate the habitat suitability for a species. In this study, in order to identify suitable areas for the presence of Iranian oak, which is one of the most important tree species in the Zagros forests in Iran, the model of maximum entropy (MaxEnt) was used. 16 environmental variables including topographic, climatic, and soil variables were used as independent variables and occurrences of Iranian oak were used as response variables. In order to evaluate the model, the area under the curve (AUC) was used. Jackknife method was used to determine and evaluate the importance of environmental variables. The results of this study showed that the MaxEnt model had a high efficiency with AUC: 0.98 and the mean annual temperature, elevation, and precipitation in the wettest quarter are more important. In addition, aspect and NDVI were the least important in model construction. In this study, the suitability map of Iranian oak in the study area was prepared, which can be a reliable source for managers in planning to protect and rehabilitate deforested forests in the study area.

The present study was conducted for investigation the trend of soil carbon, total nitrogen and soil aggregate stability changes with increasing depth under different land uses in Alandan area–Sari. The soil samples were taken from soil depths 0-10, 10-20, 20-30, 30-40, 40-50 cm using coring (8 cm diameter) and auger method in each site systematic randomly (n=6). The soil texture, soil pH, the percentage of CaCO3, organic carbon, total nitrogen and geometric mean diameter (soil aggregate stability index) was measured in the laboratory. The result showed that, soil carbon and nitrogen were significantly (p<0.05) affected by soil depth and land use change. However, the geometric mean diameter was only affected by soil depth. The compared means showed that, the amount of carbon, nitrogen and soil aggregate stability index is significantly reduced with increasing soil depth. In the surface soil layers, the highest carbon (4.6%) and nitrogen (0.31%) were found in ash plantation and theirs lowest (2.5 % and 0.15% respectively) were observed in pine plantation. Also, soil organic carbon is significantly (p<0.05) increased with increasing geometric mean diameter.

The aim of this study was to identify the composition and diversity of plants in the Persian ironwood habitat in the Chefrood forest in western Guilan province. For this purpose, five one-hectare sample plots were randomly selected in less disturbed Parrotia persica stands. All tree and shrubs species were identified in each sample plot. Also, 16 micro-sample plots of four-square meters in each sample plot were executed by randomized systematic method and all herbaceous species were identified and recorded. The life form of species was determined using the Rankier method, geographical distribution of species was classified using Zohari method and total biodiversity was determined using Simpson heterogeneity, Menhenick richness and Smith-Wilson evenness. The results of the study of habitat vegetation showed 71 plant species belonging to 59 genera and 43 families. The family of Rosaceae with eight species and Cyperaceae and Poaceae each with four species were the richest plant families in this habitat. Phanrophytes with 44% and hemicryptophytes with 25% had the highest percentage of biological form. In terms of geographical distribution, the highest frequency was obtained with 52% related to Siberian European elements. Also, richness diversity and total element uniformity were calculated to be 0.86, 1.08 and 0.65, respectively. According to the results of the present study, the Persian Iron-wood habitat of West Guilan is one of the various Hyrcanian habitats.

One of the consequences of destruction and fragmentation of forest ecosystems in the north of Iran is the creation of an edge effects and changes in the composition and biodiversity of the understory cover. Therefore, the purpose of this study was to investigate the edge effects due to rural roads, forest roads, rural development and recreational areas on the composition and biodiversity of understory cover in the Zarin Abad forests of Sari City. In order to conduct this research, in each of the four mentioned areas, three transects were considered in parallel with a distance of 100 meters. On each transect at intervals of zero, 50, 100 and 150 meters, sample-parts of 400 square meters were landed and in each sample plot, a list of all plant species and their abundance (percentage of canopy cover) were recorded. The results showed that the sample plots in the distances of 50,100 and 150,100 had higher Jaccard index and the 0,150 sample plots had lower Jaccard index. DCA analysis indicates that the sample plots at zero and 150 m distance from the road were different from other distances. The results of the present study showed that all the studied edge effects had significant effect on the richness, diversity and composition of vegetation, which these effects increased with the distance from the edges. Among the studied edge effects, the forest road had the least effect and the recreation area had the most effect.

Reddish black berry fruit has a high antioxidant capacity and Iran is one of the most important centers of valuable plant diversity of this fruit. Therefore, in a study, the potential of this valuable medicinal plant in breeding, morphological, phytochemical and genetic diversity in Arasbaran region was investigated. The measured parameters included fruit morphological characteristics including fruit length, fruit weight and phytochemical properties of fruit such as soluble solids, phenolic compounds, flavonoids, anthocyanins, vitamin C, DPPH and peroxidase activity. The results of cluster analysis showed that the collected genotypes were divided into four main groups. In the first group, 9 genotypes (R 1; 18; 6; 9; 15; 7; 8; 13; 12) were present. The genotypes of this group had many similarities in terms of weight, fruit length and solids. In the second group, there were 3 genotypes (R 10; 3; 2) that were very similar in traits such as peroxidase and antioxidants. In the third group, 4 genotypes (R 14; 4; 17; 16) were present. The genotypes of this group were similar in phenol and anthocyanin traits. In the fourth group are 3 genotypes (R5; 11; 19), which are very similar in traits such as soluble solids and antioxidants, cluster analysis confirms the results.

One of the assumptions raised about the phenomenon of forest decline is the change of climatic indicators. In this study, in order to detect the occurrence of climate change in the ecosystem of Zagros forests of Chaharmahal and Bakhtiari province, cold temperature indicators indicating climate change have been used. Daily climatic data including precipitation, maximum temperature and minimum temperature for the statistical period 1991-2019 were extracted at the nearest synoptic stations to the Chego, Ghalesama, Rahimaabad, and Gelsefid deterioration monitoring sites. Before calculating the indicators, daily input data were examined for quality and homogeneity and prepared in the desired format to enter ClimPACT software. Among the global standard indicators detecting the occurrence of climate change, cold temperature indicators; Two days and two nights consecutive cold, number of frosty days, number of icy days, percentage of cold nights frequency, percentage of cold days frequency, two-day cold period and 6-day cold period were extracted and analyzed. The results showed that all cold indicators of climate change had a significant and decreasing trend and experienced the largest decrease in the last decade, especially in 2017 and 2018. The percentage of decrease in cold night temperature indices is more than daily cold temperature indices. Some indicators in all deterioration monitoring sites, especially in the last decade, have been severely reduced to some extent and will probably be unrepeatable in the future due to the continued increase in temperature. Awareness and recognition of climate change in the Zagros Forest ecosystem based on standard indicators can help manage forest conservation and restoration through climate change adaptation methods.

The main purpose of this study is to evaluate the effects of single-tree selection method on some quantitative and qualitative characteristics of Shafarood forest ecosystems and compare these indicators with control forest area in that area. Data collection was performed from four series (5, 8, 17 and 18) in four elevations of less than 600, 600 to 1000, 1000 to 1500 and more than 1500 meters. In each series, one managed parcel and one control parcel were selected and, in each parcel, 15 sample plots with an area of ​​1000 m2 were conducted. Five samples from each parcel were randomly selected and soil samples were taken. The results showed that the mean of both indices of diameter at breast height and basal area in the control area (32.11 cm, 1158.05 cm2) was higher than the managed area (25.93 cm, 724.94 cm2) and the density of trees in the management area (391/66) is more than the control area (317/50). Also, the average diameter at breast height in the altitude above 1500 is higher than the lower classes. It was observed that forest management by single selection method did not have a significant effect on any of the studied soil indices but elevation factor has a significant effect on all soil characteristics. The present study showed that conducting single-tree selection method improved quantitative and qualitative characteristics of the forest stands.