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Iran, situated in Southwest Asia, showcases a diverse landscape, including three phytogeographical regions and two global biodiversity hotspots. This diversity is attributed to its intricate geology, mountainous terrain, wide altitudinal range, and heterogeneous climate, fostering a rich flora characterized by a significant proportion of endemism. We present an updated version of the Vegetation Database of Iran (IranVeg) (GIVD ID AS-IR-001), comprising 13,411 plots spanning six major habitat types. These encompass deciduous forests (18.0%), woodlands and shrublands (5.6%), steppes and other grasslands (52.0%), saline depressions (9.3%), wetlands (12.2%), and anthropogenic habitats (2.9%), derived from 100 published and unpublished resources, comprising 3,919 plant species, belonging to 961 genera and 147 families. The vegetation data of Iran have been assigned to 31 valid and invalid phytosociological classes. The oldest plots were recorded in 1936 in the Alborz Mountains in northern Iran, while more than 60% of all plots were collected after 2010. Plot sizes vary from less than 1 m2 to 10,000 m2 with the highest species richness of 101 species recorded in a 25 m2 montane grassland plot. IranVeg stands as the first national vegetation database in Iran, promising valuable insights into biodiversity patterns and facilitating the assessment of future environmental and anthropogenic changes. It remains open to further development through a collaborative network of vegetation scientists. This comprehensive database holds significant potential for advancing vegetation classification and survey efforts in Iran and beyond. Taxonomic reference: World Flora Online (WFO 2024).

Iran’s Hyrcanian forests are part of the temperate forests and have survived since Tertiary. These forests have experienced severe damages in recent decades because of socio-economic issues such as overgrazing. This study aimed at investigating the Nurse-protégé interaction and the impact of understory shrub species on the regeneration of the Hyrcanian main tree species in Kheyrud Forests. Filed sampling was carried out using the random-systematic method. Regeneration and their features under and outside of the canopy of shrub species, as well as some environmental variables were recorded in strip plots. According to the results, the canopy cover percentage of 25-50% provides the best regeneration protection efficiency for the six nurse shrub species. Overall, regeneration density was found to be higher outside the canopy area of the shrub species than beneath their canopy area; however, regeneration under the shrub species caused higher mean height and age. Moreover, the mean cover and the depth of the litter under the shrub canopy were significantly higher than that of outside the canopy area. Although the shrub species allow more durable and complete development of seedlings by providing protection against grazing, suitable conditions for seed germination and seedling growth may not be provided because of high litter depth and insufficient sunlight due to the massive canopy of trees as well as nurse shrubs’ dense foliage (especially, evergreen understory species).

Introduction: Species distribution modeling is a common method for understanding the relationships between a species and its environment and is used to predict the changes in distribution due to environmental changes. A lot of research has been done around the world based on these models. In this study, the optimal habitat of Juniperus excelsa, an indicator species, and the most important tree species in Irano-Turanian forests in the Alborz Mountains have been investigated using 38 environmental parameters and domain and logistic regression models. Material and methods: The study area consists of parts of the Alborz Mountains located in the north of Iran with an area of 14656 km2. In the present study, a stratified random sampling method was used to determine the sampling sites. Finally, 390 occurrence sites (240 presence sites and 150 absentee sites) of J. excelsa at a 30-second scale (approximately 1 km×1 km) as the input model was studied. Also, 38 environmental parameters were considered as predictive variables for implementing two models of the domain and logistic regression. Results and discussion: The results showed that the domain model had a high performance for predicting the habitat of J. excelsa with AUC =0.97, Kappa =0.730, and TSS = 0.91. Based on the results, the areas with the lowest potential for the presence of J. excelsa were 5665.95 km2, the moderate potential was 2033.1 km2, the good potential was 3076.38 km2, the very good potential was 3063.42 km2, and the high potential was 817.29 km2. The results obtained from the implementation of the logistic regression model indicated that 5084.37 km2 of the studied area was in the class of least potential, 2539.35 km2 had moderate potential, 1410.21 km2 had good potential, 1104. 84 km2 had very good potential, and 4517.37 km2 had high potential. Also, the results showed that the suitable habitats for J. excelsa were regions with a mean diurnal range of 13 °C and 15.5 °C, annual precipitation of 120-220 mm, precipitation of 64-90 mm, precipitation of coldest quarter of 35-60 mm, the altitude from the sea level of 3100-1800 m, and a slope of 30-10% in the southern, southeast, and east directions. Also, the probability of species occurrence was more in areas near the snow and water line as well as on calcic rocks. Also, in the habitat of J. excelsa the NDVI index varied between 0.38 and 0.20. The results of the performance evaluation of the models showed that the domain model had higher performance in predicting the suitable habitat of J. excelsa than the logistic regression model in the study area. Conclusion: Species distribution models can provide a suitable management plan for different parts of the habitat. Areas with low potential of suitable habitat are usually partial habitats and populations in these areas are more vulnerable than the others, whereas areas with very good potential are excellent for a protected area. Areas with good to the excellent potential that do not have significant tree cover are suitable for forestry and native ecosystem restoration. The present study showed that the domain model, despite using only presence data, can be a useful method for predicting the suitable habitat of J. excelsa in the Alborz Mountains. Therefore, it can be stated that species distribution models, with acceptable accuracy, have enough performance in the evaluation of species distribution and can be used to execute conservation strategies.

Fire affects vegetation and changes plant succession. In this paper, the vegetation of Sirachal Research Station, which burned in the summer of 2014, was studied and compared with the unburnt areas, based on biodiversity indices. The research was implemented as a factorial experiment in a completely randomized design. First, on the basis of physiognomy, the area was divided into three parts: shrubland, shrubland-rangeland, and rangeland. Each part was, then, divided into two sections, including a burnt area and an adjacent unburnt area (control area). In each area (burnt and unburnt), three sampling units were randomly assigned using PNP method, and vegetation measurements were subsequently performed. Based on data analysis, a total of 141 taxa were identified, belonging to 28 families and 95 genera, including one species of Gymnosperm, 19 monocotyledons and 121 dicotyledons in two burnt and unburnt areas of Sirachal Station. Based on the statistical analysis, using Past3 and SPSS softwares, there was no significant difference in the number of taxa between the vegetation of the burnt and unburnt areas. Of the indicators analyzed in Past3, the number of individual, the index of Menhinick's richness and the Shannon diversity index were significantly different in the treatments sampled from the burnt and unburnt areas. According to the Duncan test average, the number of individuals in the unburnt area, with a canopy cover below 25%, was greater than that in the burnt area, with the same canopy cover, however, no significant difference was observed between the individuals in the burnt area and unburnt area, with the same canopy cover of more than 25%. Also, the richness of the burnt area with a canopy of less than 5% is significantly higher than that in the unburnt area with the same canopy cover.

Tourism in natural areas can affect the biodiversity, density and structure of stands and plants health. The present research aims at studying the effects of tourism on vegetation structure and species diversity in Noor Forest Park, Mazandaran province. To do so, the study area was divided into three main zones: without pressure, moderate, and high tourism pressures. Then, sampling was done with 20 sample plots of 20 × 20 m sample with random-systematic distribution in each zone (60 plots in total). Within each sample plot, trees, shrubs, herbs and regenerations were counted and quantitative and qualitative characteristics of all woody species were measured. The species richness, evenness and diversity indices were then calculated and the calculated indices and forest structural features were compared amongst the mentioned zones. Based on the results, diversity of forest floor flora in high tourism pressure zone was higher than other zones and there was no significant difference in woody species diversity among three zones, nevertheless a considerable reduction was seen in density of both woody and floor species. The lowest regeneration abundance was observed in high tourism pressure zone and the most, in medium tourism pressure zone. In zone without tourism pressure, average height and canopy of trees were more compared with the high tourism pressure zone. Also, most snags, the highest ratio of broken trees to total trees and the highest number of diseased and damaged trees were observed in high tourism pressure zone. In this zone, Alnus glutinosa, Populus caspica and Parrotia persica had the lowest vitality.

The genus Carpinus is considered as a common taxon in the temperate forests of the northern hemisphere, of which three species (Carpinus betulus, C. orientalis and C.× schuschaensis) were reported from the Hyrcanian forests of Iran. These are the main species of a number of Hyrcanian plant associations and usually appear with a high frequency. In this research, vegetation and the environmental conditions of C. betulus and C.× schuschaensis habitats were studied at the protected areas of Naghibdeh and Mazdeh forests. Data was collected using 46 relevés. Data collection and analysis were performed according to the Braun-Blanquet method. TWINSPAN was used to classify and analyze the vegetation data, and CCA ordination was used for the species-environment analysis. Based on the results, the vegetation was classified into four groups belonging to two associations: Querco castaneifolia-Carpinetum betuli Djazirei 1964 and Zelkovo carpinifoliae-Carpinetum schuschaensis ass. nov. in which the characteristic species of the new association were Carpinus× schuschaensis, Zelkova carpinifolia and Pyrus boissieriana. The topographic and soil texture variables were significantly different between the two communities. The first association was distributed on fairly low-gradient slopes (41% in average) with southwest aspect and in the soils with a higher percentage of silt, whereas the second one was established on steeper slopes (74% in average) with southeastern aspect and in the soils with more sand. The canopy percentage of the second association was significantly higher than that of the first one. These two associations are placed in the Parrotio-Carpinion Djazirei 1964.

The climate is determinative of the soil and flora and fauna of a region and in wide scale causes variation in ecosystem and the species combination. In this study, distribution of Juniperus excelsa were studied on the current and future climate condition(2050, 2070) under two climate change scenarios of Rcp2.6 and RCP8.5 with the GCM dataof HadGEM2-ES by using of MaxEnt model. 22 variables of climate and topography in 160 sites were employed . The resultsshowed that in addition to height above sea level, precipitation in coldest season and annual mean temperature are the next important variables on Juniperus excelsa distribution. Also the results show that if the current trend of climate change continues, habitat area of species under the scenario of RCP2.6 till 2070, increases in middle habitat class (82.4%), in good and very good habitat classes, 31.3, 67.3 percent, respectively, and will be reduced and under the scenario of RCP8.5, faces with too much decreasing the area (in middle, good and very good habitat classes, 76.5, 98 and 100 percent, respectively). According to the results , the models like MaxEnt, with acceptable accuracy have enough performance in evaluation of species distribution and can be used for strategies of conservation by the experts.