فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیست و نهم شماره 4 (پیاپی 86، زمستان 1400)

Clustering task is optimized and summarized high dimensional vegetation datasets that indicator of environmental change and gathering to interpreting pattern form ecosystem. Variety clustering methods is available and the issue is chosen proper methods. The aim of the research was compared two non-hierarchical clustering as K-means and K-medoids in forest ecosystems. For this purpose, two real datasets from Hyrcanian and Zagros forests of Iran and six simulated datasets were applied. The Hellinger transformation was employed before calculating dissimilarity matrices. Euclidean distance, Manhattan distance and Bray-Curtis dissimilarity indices were then calculated on the transformed data sets. And three evaluators including silhouette width, phi coefficient and ISAMIC were chosen. The results show that combination of Bray-Curtis dissimilarity matrices and K-means and K-medoids have first and second ranks among other clustering methods. K-means clustering is more effective in heterogenous dataset as Zagros and simulated datasets. The weakest clustering algorithm was combination between Manhattan distance and K-medoids. Also results show that Hellinger data transformation cause to improve Euclidean distance matrix. Our results indicated that combination of Bray-Curtis dissimilarity with K-means is more significant and recommended.

Somaclonal diversity is a genetical test that can be used to study the genetic variation and genetic stability of a propagated plant relative to the mother plant. The aim of this study was to investigate the genetic stability of Caspian honey locust (Gleditsia caspica Desf.) regenerated plants under the influence of BAP growth regulator and CPZ growth inhibitor. For this purpose, native and regenerated plants genotypes were compared in culture media containing growth regulator BAP (20 μmol) and CPZ (0.3, 3 and 15 μmol) used by molecular marker of ISSR. The highest percentage of shoot proliferation and number of shoots was observed in 20 μmol BAP treatment. The presence of CPZ in the culture medium greatly reduced the shoot proliferation percentage and with increasing CPZ concentration, the decreasing trend of the studied characteristics increased. The results showed that the use of 10 ISSR molecular markers produced a total of 107 DNA bands that had 87.9% polymorphism. Cluster analysis dendrogram based on Jaccard similarity matrix by UPGMA method showed that the studied genotypes were divided into two groups with similarity coefficient of 0.27. It seems that the presence of CPZ, despite the growth inhibitory effect on the plant, will increase diversity and reduce the genetic affinity between the regenerated plants and the mother plant.

The structure of Zagros forests in Iran is changing drastically due to human interventions and environmental factors. Only small parts of these forests, such as protected and inaccessible areas that are somewhat immune to human intervention, have the main structure of these forests and can be used as a model for the management of other Zagros forest stands. The aim of this study was to compare the structural characteristics of a protected stand with a history of 15 years of protection (Golzar) with a natural stand (Kohshour) in a part of the forests of Izeh city, Khuzestan province of Iran. In each area, a one-hectare square-shaped sample plot was implemented and the structural variables of all woody species were measured. Due to the non-normality of the data, Mann–Whitney U non-parametric test was used for statistical comparison. According to the results, in Kohshour stand, there were 273 woody species per hectare from three species of Quercus brantii Lindl., Acer monspessulanum L. and Crataegus aronica Bosc., but in the protected stand, 225 woody species per hectare were measured. In addition to the above three species, there were also two shrub species of Amygdalus orientalis Mill. (with significant frequency) and Pistacia khinjuk Stocks in protected stand. In Golzar, the ratio of coppice and seed-origin woody species was almost equal, but in Kohshour, 83.5% of the trees were coppice. Although in general, the mean of quantitative variables in natural stand was higher than protected stand, but the comparison of quantitative variables by species and origin between the two stands showed that in most cases the mean of the variables in Golzar stand was significantly higher than natural Kohshour stand. There was only no significant difference between the height of shoot-origin A. monspessulanum trees between the protected stand and natural stand. The results of this study showed that protection can have positive effects on the structural elements of the stands, especially species diversity, the remaining of shrub layer in the lower part of the forest and the improvement of diameter distribution. Therefore, it can be recommended to increase the protected areas in the Zagros forests.

Tecomella undulata (Sm.) Seem known as desert teak, a multipurpose woody species has fallen under the category of endangered plants mainly due to lack of an efficient natural reproduction system. Inherent low adventitious rooting of cuttings has been the principal cause of failure in its vegetative propagation. Hence, research was conducted to assess in vitro somatic embryogenesis potential in the species. Ovary explant was cultured in modified MS media fortified with various auxins and cytokinins. The results revealed that NAA was superior in the induction of embryogenic callus (EC). NAA at 0.5, 2, 3 and 4 mg L-1 induced the highest ECs exhibiting developing pro-embryogenic masses and globular somatic embryos. TDZ and BA, though induced good callogenesis at low concentrations but the formed calli were non-embryogenic. The proliferation of embryogenic calli was the best on a phytohormone-free medium. The media containing NAA at 7.5 and 10 mg L-1 NAA only, induced somatic embryos alongside callus proliferation. The media containing low concentrations of BA (0.2 and 1 mg L-1) resulted in recurrent embryogenesis. Application of BA and GA3, and elevating the sucrose concentration of the culture medium did not make advancement in the maturation of the somatic embryos formed during stages of callogenesis and callus proliferation. The findings achieved in this study in the field of induction of EC and somatic embryo can be a beneficial basis for future extensive studies on micropropagation of this recalcitrant species.

The present study was carried out in the nursery of Markazi Natural Resources and Watershed Administration of Iran in 2009 in order to select and introduce the most adaptable and productive poplar clones. For this reason, 10 clones of closed crown non-native black poplar for a period of 11 years were planted under the randomized complete blocks statistical design with three replications at 2×3 m2 spacing for adaptability studying. The characteristics of diameter at breast height (dbh), total height, total volume (stocking), mean increments of diameter, height and volume, crown area, survival percentage, trunk quality, branch density in the trunk and resistance to pests were measured and studied annually at the end of each growth period. The results of variance analysis showed that all the studied characteristics showed a statistically significant difference between different poplar clones, except for total height. According to the comparisons of means with Duncan’s test, the highest dbh, total volume and mean increments of height and volume were observed in P.n.62/154 clone whereas the lowest dbh, total volume, crown area, mean increments of diameter, volume and survival percentage were in P.n.56/32 clone. The highest bending and branch density in trunk and more susceptibility to pests were observed in P.n.56/33 clone than other studied clones. Clones of P.n.62/154, P.n.56/75 and P.n.62/172 with an annual volume increment of 80.63, 68.68 and 62.29 m3ha-1, respectively, were introduced as adaptable poplar clones with high wood production and suitable for planting in Markazi province.

In order to investigate the effect of plant growth in soil pollution conditions in hackberry plant (Celtis caucasica Willd.), a test was carried out as a factorial design in a completely random pattern in the research conservatory of the University of Zanjan, Iran. The treatments included three levels of lead (0, 50, 100 mg/kg) and bacterial treatments invcluing Pseudomonas putida and Bacillus subtilis with concentrations of 105 and 108 cfu/ml. The attributes of the evaluation include root fresh and dry weights, plant height, total chlorophyll, total phenol, flavonoids and enzyme activity including peroxidase and malon-di-aldehyde, lead value in root and leaf and phosphorus in leaf. The two-way analysis of variance and compare the comparison with Duncan's method were used in order to investigate the effects of the lead stress and bacteria. The findings of this study showed that the use of bacteria in lead stress improved the growth and function of hackberry plant including root fresh and dry weights, plant height, total chlorophyll and flavonoids. The maximum amount of peroxidase was obtained in the treatment of 100 mg/kg lead and Bacillus subtilis (105 cfu/ml). In this treatment, the amount of lead in the fresh roots was 26.53 mg/g, which was a significant difference compared to the other treatments. Also, the highest amount of lead uptake by leaves (16.8 mg/g Fw) was observed under the treatment of Bacillus subtilis with a concentration of 108 cfu/ml. While hackberry plant performed well in terms of phytoremediation under lead stress, its growth characteristics were significantly diminished, but with the presence of growth-promoting bacteria specially Bacillus subtilis that can prevent severe reduction.

Despite the initial need of seeds and seedlings of grey mangroves (Avicennia Marina (Forssk.) Vierh.) for semi-shade, they are very low under the canopy of trees of this species in Hormozgan province, Iran. For this purpose, in this study, the effects of possible inhibition of pneumatophores and leaves of mangrove trees on the vegetative characteristics of grey mangrove seedlings in greenhouse conditions have been investigated. After collection of propagules from healthy mother trees and cultivating them in September 2020, propagules were irrigated with concentrations of 0, 0.05, 1 and 2% of leaf and root extracts. After six months, the vegetative and biomass characteristics of mangrove seedlings were measured in different treatments and evaluated using two-way analysis of variance and Duncan test. The results showed that the diameter of growth (5.58 mm), height (29.27 cm), root length (27.73 cm), number of leaves (14.58) and root fresh weight (5.65 g) were the highest in the control treatment. Also in control and 2% treatment, root dry weight (1.02 and 0.77 g), stem fresh weight (12.77 and 10.59 g), stem dry weight (3.54 and 2.93 g), root water (4.62 and 3.29 g) and stem water (9.23 and 7.66 g) had the highest and lowest values, respectively. Investigation of organ × concentration interactions showed that leaf extract had a significant reduction effects on root fresh weight and root water in 2% treatment compared to those in the other treatments. According to the results, increasing of leaf and root extracts concentration of grey mangrove trees has a inhibitory role on the vegetative characteristics of seedlings of this species, so in reforestaion and afforestation of gery mangrove trees, the seedlings should be planted at a suitable distance from the trees.

Forest fires can have a significant impact on water quality, especially in basins that provide drinking water. To investigate the effects of low, medium and high intensities of prescribed fire on runoff quality, 12 runoff plots were established in Kheyrud educational and research forest, north of Iran. In the first rainfall event after fire, six and 12 months after the fire, runoff samples were collected and transferred to the laboratory. Qualitative characteristics of the runoff were pH, electrical conductivity (EC), total suspended solids (TSS), total soluble solids (TDS) and total hardness (TH). The results showed that all the quality characteristics of the runoff after the fire increased compared to the control plots, but the differences among them were not significant. Most of these characteristics were in the high fire intensity, but as time passed after the fire, they had had a declining trend. The time elapsed after the fire had a significant effect only on TSS and TH. TSS values after six months and pH values after one year at low and medium fire intensities reached the level of control plots. TDS values immediately in the first event of precipitation in control, low, medium and high intensities were 22, 46, 53 and 78 mg/l, respectively. After one year, the values were 25, 36, 41 and 44 mg, respectively. Fire causes changes in the quality characteristics of runoff, element loss and reduced soil fertility. In order to reduce soil degradation, forest soil management measures after fire are necessary.