Species diversity is one of the most important indices used for evaluating the sustainability of forest communities. This study aims to characterize the forest communities and to identify and compare the plant species diversity in the study area. For this purpose, 152 relevés were sampled by a randomized-systematic method, using the Braun-Blanquet scale. Classification of the vegetation was conducted by the twinspan algorithm. Four communities, including Querco-Carpinetum betulii, Carpineto-Fagetum Oriental, Rusco-Fagetum Oriental and Fagetum Oriental were recognized. Species richness, Shannon, and Simpson indices were applied to quantify diversity of the different communities. Turkey test was used to investigate the differences in the species richness, diversity and evenness indices among the different communities. The results illustrate that Querco-Carpinetum betulii and Carpineto-Fagetum Oriental communities are significantly more diverse than Rusco-Fagetum Oriental and Fagetum Oriental communities. The spatial structure of the releves becomes more 'homogenous' and the dominance structure changes: the proportion of beech-forest species is gradually increasing. At the same time, the number of species per unit area decreases constantly, reaching eventually the value comparable to that recorded for hornbeam forest. Generally, species diversity is inversely correlated with the dominance of shade tolerant climax species.

Three sites including “less disturbed”, “moderately disturbed” and “severely disturbed” were selected in Zagros forests in Kurdistan province (Iran). Three forest stands with similar physiographic conditions of each site were selected and three 400 m2 plots were assessed in each stand to record the floristic information and soil sample (0–30 cm). Different diversity indices were calculated for each sample. Cluster analysis and to collect soil samples detrended correspondence analysis were applied to categorize and investigate the vegetation trend. Indicator species analysis was used to determine the characteristic species. Tukey test was used to compare the variables amongst sites. The results showed that 47, 25, 15 species were exclusively observed in less disturbed, moderately disturbed and severely disturbed sites, respectively. Furthermore, cluster analysis illustrated the distinction amongst sites and detrended correspondence analysis result showed that the vegetation of the regions was ordinated by disturbance gradient. 21, 5, 7 characteristic species were respectively indicated in less disturbed, moderately disturbed and severely disturbed sites. In general, plant composition, plant diversity and soil quality were decreased dramatically along the disturbance gradient.

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Questions Which clustering algorithms are most effective according to different cluster validity evaluators? Which distance or dissimilarity measure is most suitable for clustering algorithms? Location Hyrcanian forest, Iran (Asia), Virginia region forest, United States (North America), beech forests, Ukraine (Europe). Methods We tested 25 clustering algorithms with nine vegetation data sets comprised of three real data sets and six simulated data sets exhibiting different cluster separation values. The clustering algorithms included both hierarchical and non‐hierarchical partitioning. Five evaluators were employed on each cluster solution to evaluate different clustering algorithms. Algorithms were ranked from best to worst on each clustering evaluator for each data set. Results The comparison revealed that the OPTSIL initiated from a Flexible‐β (−0.25) solution achieved particularly good performance. We also found that Ward's method and Flexible‐β (−0.1) implementations were accurate. K‐means with Hellinger distance was superior to Partitioning Around Medoids (PAM) algorithms. Accordance between distance measures and clustering algorithms was also observed. Bray–Curtis dissimilarity combined with a range of clustering algorithms was successful in most cases. Bray–Curtis dissimilarity proved superior to other distance measures for heterogeneous data sets. Conclusions All in all, the results demonstrate that choosing the most suitable method before clustering is critical for achieving maximally interpretable clusters. The complexity of vegetation data sets makes this issue even more important. The choice of distance measure had more effect than the choice of clustering method on the quality of results. Our results illustrate that OPTSIL Flexible‐β (−0.1) and OPTPART could prove superior to alternative conventional clustering algorithms when internal evaluation criteria are used to optimize clustering.

& Key message On the selected sites in the investigated Oriental beech (Fagus orientalis L.) dominated forests in Iran with an extensive individual tree selection system, tree microhabitats (MH) are more influenced by tree level factors such as tree species and DBH than by plot level factors such as plot basal area or size and species diversity. & Context Despite the ecological importance of tree microhabitats for biodiversity, there is a lack of information about the occurrence of microhabitat features in Hyrcanian forests in Northern Iran. & Aims The aims of this study were to assess selected MH types on living trees in forests managed with an individual tree selection system and forests unmanaged since at least 30 years and to study the effect of tree and plot level factors on their occurrence. & Methods A total of 120 circular sample plots were used to collect tree level microhabitat information at six different sites in Oriental beech forests in Iran. Pairs of managed and recently unmanaged forests were located at six sites. Generalized linear mixed models were employed to analyze (i) the effect of management on microhabitat occurrence, and (ii) to explain the occurrence of microhabitats at tree level. & Results There was no significant difference in total number of assessed microhabitats per ha in forests managed with a lowintensity management regime with individual tree selection versus recently unmanaged forests (no management intervention for at least 30 years). Stem cavity with decay was by far the most frequent microhabitat type in managed (16.5 per ha) as well as in recently unmanaged forests (14.2 per ha). Hornbeam and oak trees have a higher probability to host microhabitats (bark loss, woodpecker cavity, and stem cavities) than the dominant oriental beech. Suppressed trees indicated by basal area of larger trees have a lower probability to show bark loss and conks of fungi. & Conclusion Models of microhabitat occurrence on trees have potential to support the development of management guidelines to foster biodiversity.

Eshaghi Rad, J., Valadi, G., Zargaran, M.R., 2017. Effect of man-made disturbances on understory plant richness of oak forests in Iran. Folia Oecologica, 44: 61-68.The purpose of this study was to investigate the impacts of disturbance degree on the species richness and species diversity of oak forests in the Kurdistan Province (Iran). The study ran on three treatments: undisturbed, moderately disturbed, and highly disturbed. For each treatment, there were selected three forest patches with similar physiographic conditions and on each patch there were specified three 400 m 2 plots for recording floristic data. The species' name and the abundance of herbaceous species were recorded on 5 micro plots sized 1.5 × 1.5 m for each sample. Menhinick, Margalef, the number of species indices and also rarefaction, jackknife methods and species abundance distribution models were used to estimate the herbaceous species richness for the three treatments. The results showed that all the richness indices had the highest values for the undisturbed forests and the lowest values for the highly disturbed ones. Based on all models, undisturbed forests were showed more diverse than highly disturbed area. Generally the negative impact of human activities (wood cutting and grazing) on the herbaceous species richness was found much stronger in the highly disturbed forests and in moderately disturbed forests compared the undisturbed ones. With increasing destruction intensity, the herbaceous species richness in the oak forests decreased dramatically.

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Species of Paulownia are fast-growing trees that are planted in many countries in green spaces and agroforestry systems. We studied the influence of irrigation on the diameter growth of 2-year-old Paulownia tomentosa saplings planted in 3 m 9 3 m grids at Nazlou Campus of Urmia University, Iran. Completely randomized experimental design was used with four irrigation amount, viz. 10, 15, 20 and 25 L, and three irrigation intervals, viz. 3-and 6-days, in 8 replications. During the growth season, we measured collar diameters of all saplings at the end of each month. Diameter growth declined with reduced irrigation amount and increased irrigation interval. The lowest average diameter growth (9 mm) was recorded for 10 L water at 6-day intervals and maximum average diameter growth (28.7 mm) was recorded for 25 L volume at 3-day intervals. The latter treatment resulted in significantly greater diameter growth than any other treatment (except 20 L at 3-day intervals). More than 80 % of diameter growth was achieved in the first 3 months. Therefore, it is essential to irrigate with 25 L of water at 3-day intervals during the first three growth months to achieve maximum diameter growth for 2-year-old P. tomentosa saplings.