Iranian Journal of Forest and Poplar Research
Year:2018 | Volume:26 | Issue:2 (72) |Papers Count:16

Quantification of forest structure and its various components helps to better understand the forest ecosystem and supports its improved management. Here, the Gini index were used as a spatial distribution index for evaluating the structural diversity. The main objective was to analyse the stand structure and determine the necessary factors for the structural heterogeneity and homogeneity. This study was conducted in compartments 305, 306, 309, 310 and 311 in Gorazbon district, Kheyrud forest by means of a full calipering method. Then Gini index was calculated and finally the Lorenz curve was derived by using frequencies of stems, diameter class, as well as cumulative relative frequencies of trees and their basal area. The results showed Gini index values of 39. 5%, 66%, 44%, 82% and 74% for compartments 305, 306, 309, 310 and 311, respectively. In addiiton, the diameter structure for 305 and 309 compartments was shown to be close to homogeneity, whereas it was close to medium for compartment 306 and close to heterogeneity for compartments 310 and 311. Finally the use of Gini index and Lorenz curve was concluded to he helpful in reclecting the near-real structural diversity in natural beech stands.

Forest stand structural development occurs over time and is commonly studied based on initial, optimal and decay developmental stages. The purpose of this study was to evaluate the capability of non-spatial indices for differentiating among developmental stages of beechhornbeam stand in Haji-Kola-Tirankoli forest of Sari in Mazandaran province. Three sample plots were selected in each developmental stage (totally 9 sample plots). The characteristics of trees with a diameter > 7. 5 cm were measured in each plot, including species, diameter at breast height and total height. The results of analysis of variance revealed significant differences amongst the developmental stages for basal area, volume, density, density of large trees, standard deviation of diameter and height, diameter and height of overstory, leaf area index, relative light intensity, species richness of over story, basal area of large to mature trees, modified Frelich-Lorimer index. Nevertheless, other attributes including DBH, density of trees > 100 cm, deadwood diameter, and number of dead wood, Gini coefficient, Doliucort index, Structural Complexity index, and Cox index did not differentiate among the developmental stages. The structure triangle and the Frelich-Lorimer index were shown to properly determine the stage of stand development.

This research was started in 1995 in order to investigate the effect of thinning on the young plantations of velvet maple (Acer velutinum Boiss. ). The silvicultural interventions comprised three main treatments (medium and heavy thinning), two secondary treatments (3-year and 5-year rotations) in the fully randomized design with three replications. There were 9 sample plots in the experimental design with an area of 0. 3-0. 4 hectare each. A full calipering of the future trees was done after 20 years and 6 thinning operations. The results for DBH, total height, trunk height and trunk diameter showed significant differences between the control treatment and thinning intensities. However, no significant difference was observed between the secondary sub-treatment (circulation 3 years and 5 years) and the intersection between the main and sub plots treatments for DBH, total height, trunk height and trunk diameter. For the intensive thinning treatment, the largest value of 32. 95 cm was observed for the DBH, while the lowest value of 27. 39 cm was observed for the slight thinning. In addition, the largest height of 24. 42 m was observed for intensive thinning, whereas the lowest rate of 23. 63 m was observed for the control treatment.

Interspecific interaction of tree species is an important process in establishing spatial structure of species associations in ecosystems with low species diversity. This study was aimed to investigate the interspecific interactions of Montpellier maple (Acer monspessulanum L. ) and two accompanying species (i. e., Amygdalus scoparia and Astragalus gossypinus) in a site close to Firooz Abad, Fars province. A 200 m × 200 m sample plot was selected in a part of the site. The spatial locations of 629 individuals were measured together with their tree species, height and crown area. In addition to bivariate g(r), M(r) and P(r) were applied to explore more details about interspecific species interactions. The results showed that A. monspessulanum had the highest density, mean height and crown area compared to other species. The results indicated negative interspecific interactions of tree species, which was decreased with increasing distance. Negative interactions were observed between A. monspessulanum with A. scoparia and A. monspessulanum with A. gossypinus up to spatial scale of 3 m and 10 m, respectively. Moreover, A. monspessulanum and two other species showed repulsion up to 7 m distance. In general, it was concluded that A. monspessulanum showed negative interspecific interactions with A. scoparia and A. gossypinus in the study area. This might be caused by environmental heterogeneity and resource limitation. Furthermore, M(r) and P(r) explored more details about type and spatial scale of negative interspecific interactions of A. monspessulanum with two other species.

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 relevé s. 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 castaneifoliae-Carpinetum betuli Djazirei 1964 and Zelkovo carpinifoliae-Carpinetum schuschaensis ass. nov. in which the characteristic species of the new association were C. × schuschaensis, Z. 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.

A comprehensive study on breaking dormancy of mountain ash (Sorbus luristanica Bornm. ) endemic species is still lacking. Here, the high efficient potentials of multiwall carbon nanotubes were used to break seed dormancy and improve seed germination in mountain ash. First, the seeds were primed with different concentrations of the nano-material including 0, 75, 150, 250, 350 and 500 mg l-1 during 24 hours. Then warm (two weeks) and cold (three or four months) stratifications were performed. The results showed that the seeds require cold stratification for at least 3 months. After the cold stratification period, the seeds were transferred to petri dishes in germinator. Daily seed germinations were recorded during 22 days. Eventually seed germination parameters such as seed germination percent, germination speed as well as mean germination time were calculated and compared. To understand the effects of nanomaterials on the seedlings from different treatments, the subsequent growth of seeds was studied. The results revealed that all germination parameters were improved by 350 mg l-1 treatment. The microscopic seed observations showed that the nano-priming treatments led to seed endocarp abrasion and increased oxygen and moisture infiltration into seeds. Increasing root height growth was associated with the most considerable effects of treatments. Conclusively, it seems that increase in seedling moisture is one of the functional mechanisms of the MWCNT.

Brant`s oak (Quercus brantii Lindl. ) is one of the most important tree species of Zagros forests. The major objective of the study was to assess various populations of the species for identification of plus tree individuals and growth trend analysis of the sapling of the selected trees. Therefore, seeds were collected from twelve single trees of one Brant`s oak populations located in Lorestan province. The selected trees were progeny tested based on a nested statistical design with three replications. Morphological data were biometrically and genetically analyzed, followed by investigating the trend of growth changes during the two years of the study. The selected trees were significantly different in the studied attributes. In addition, one of the progeny families showed outstanding domination over the others. Second year growth trend of 340 studied progeny saplings of the twelve families was similar to that of the first year. Meanwhile, the families with higher rank for the first-year growth based on seedling height, collar diameter and leaf number obtained better growth rates during the second year of the experiment. In other words, selecting plus trees based on progeny test at early years of sapling growth may effectively be used for selecting plus trees for breeding purposes such as seed orchard establishment. Furthermore, heritability of the studied characteristics varied between 0. 48 to 0. 99 and correlation coefficients between most of the paired characters increased for the second year.

This study was conducted to protect the genetic properties and propagation of 4000-year-old Abarkooh horizontal cypress (Cupressus semprvirens L. var. horizontalis (Mill. ) Gord. ) by tissue culture technique. In the first experiment, the effect of preparation time of explant (four seasons), medium culture (MS and WPM) and concentrations of BA (0, 0. 1 and 1 mg/l) on proliferation of horizontal cypress explants was investigated. In second and third experiments the effect of culture media (MS and WPM), concentrations of BA (0, 0. 1, 0. 5 and 1 mg/l) was studied alone or in combination with 0. 01 mg/l IBA and type of explant (primary or secondary shoots) in a factorial experiment and completely randomized design with three replications. In first experiment, the maximum shoots number was obtained from spring and summer explants that were cultured in MS and WPM culture media, respectively. In second experiment, the maximum number and length of shoots was obtained in WPM culture medium and secondary shoots. The highest length of shoots was found in first shoots cultured in WPM medium containing 0. 1 and 0. 5 mg/l BA, followed by primary shoots cultured in MS medium culture without BA. In the third experiment, the maximum number of shoots (3) was observed in secondary shoots by using WPM medium containing 0 mg/l BA + 0. 01 mg/l IBA. Conclusively the best time of preparing explant, type of culture media and explant were found to be spring, WPM medium and secondary shoots, respectively.

This experiment was conducted to evaluate the establishment and adaptability of woody species under wastewater irrigation condition in arid climate. This experiment carried out in Yazd city wastewater treatment station with 11 tree species under randomized complete block design with three replications. The species included Eucalyptus camaldulensis E. microtheca, Elaeagnus angustifolia, Tamarix aphylla, Melia azedarach, Pinus eldarica, Populus euphratica, P. alba× P. euphratica, Morus alba, Cupresus simperverence and Ailanthus altissima. In each plot, trees were planted with 48 seedlings for each species. Immediately after planting, the seedlings were irrigated with wastewater for 15 days, followed by further irrigations in 20-30 days intervals after the establishment. After 4 years, the effects of wastewater on establishment and growth, including survival percentage, height growth, the average diameter of the crown, crown volume, collar diameter and diameter at breast height (DBH) were measured. The results showed that the P. eldarica had highest rates of deployment with 100% of establishment. However, no significant differences were observed with other species including M. azedarach, E. camaldulensis and, E. microtheca. For all growth indicators and yield traits, the T. aphylla tree showed better performance, although it did not significantly differ with many others species. The results of this study showed that woody species such as E. camaldulensis, E. microtheca, M. azedarach, E. angustifolia, P. euphratica and P. eldarica can be irrigated with wastewater under arid condition due to their better establishment, growth and slenderness coefficient compared to other species.

The purpose of this study was to investigate reforestation projects based on the principles of sustainable development in the Darabkola watershed in Mazandaran province. Therefore, a goal programming model was used for the consideration of multiple goals. A fuzzy hierarchical process was used to compute the weights of different criteria. The criteria and indicators were determined according to principles of the sustainable development, including those related to economy, environment, production, biodiversity conservation, forest health, and forest cover (e. g., various indicators such as net present value, carbon balance, annual increment of diameter, stem biomass, basal area, diameter variation, mass stability, and ecological productivity). The tree species comprised Acer velutinum, A. cappadocicum, Fraxinus excelsior, Juglans regia, Quercus castaneifolia, Alnus subcordata and Pinus brutia. The results of goal programming model showed that the areas of afforestation with different species were changed compared to the ecological capability assessments. The results showed a zero ha potential for maple, which was initially defined 590. 197 ha based on the assessment of ecological potential. In addition, the results revealed 120. 17 ha increase (547 vs. 667. 21) for F. excelsior, 470. 02 ha increase (535. 96 vs. 1005. 99) for A. cappadocicum and 89. 72 ha reduce (416. 30 vs. 326. 57) for Quercus castaneifolia. The reforested area was unchanged for the other species such as J. regia, A. subcordata and P. brutia. Therefore, a total area of 3091. 01 ha was suggested for the afforestation according to the results of goal programming model.

This research was carried out to study the adaptability and performance of four Eucalyptus spp. species in Bushehr province. For this purpose, one-year-old seedlings of four species, including Eucalyptus camaldulensis Dehnh, E. rubida H. Deane & Maiden, E. grandis W. Hill and E. saligna Sm. were planted under randomized complete blocks design, using 49 seedlings per plot at 5 × 5 m spacing at Shabankareh Research Station, Dashtestan, Bushehr province, in late February. All trees were irrigated, protected and enumerated each three months in the first year after plantation. Survived trees were counted and measured at the end of each year from second year on. Diameter at breast height (DBH), collar diameter, total height and crown diameter were measured to evaluate tree performance. Results showed that E. camaldulensis had the highest survival, height, DBH, crown area, standing stock volume and volume increment rates, followed by E. saligna. Application of Duncan test showed significant differences among species in terms of their survival and growth performance (α = 5%). Furthermore, E. rubida and E. grandis completely died at the end of first year of cultivation due to drought and high temperature stress in June and July. Based on these results, E. camaldulensis was suggested for plantation in similar sites in the south of Iran and further research was recommended.

Regarding the effects of climate change and the recent drought in Iran, it is necessary to assess the growth and producion of poplar varieties under drought stress. In this research, 14 clones of black poplar (Populus nigra L. ) were studied during 2001-2008 in Sanandaj, Kurdistan province. Cuttings were planted in early March of 2000, and the samplings were transplanted in early April of 2001 in 3m × 3m spacing and a Randomized Complete Block Design (RCBD) with 3 replications. The yearly field works included uniformly-applied irrigation, weeding and pruning. However, they were subjected to drought stress in 2007 due to the impossibility of providing water by the tenth of July (103 days). The results showed that drought caused leaf yellowing and fall, as well as mildew (Melanophylla picta) outbreak and finally drying of a number of trees. Moreover, simultaneous drought and increase the range of traits changes limited the growth of poplar clones, so that the trees could not show their potential growth rate. Responses to drought stress among poplar clones showed a significant variation, so that P. n. M and P. n. 42/53 showed zero percentage, while P. n. 63/135 showed about 50% damage caused by drought. The average loss of drought in the clones was 20. 49%. In addition, the P. n. 56/52 and P. n. 56/75 clones with 25. 61 and 24. 80 m3/ha per year wood yield and moderate (25-30%) damage caused by drought were defined as high-yield and relatively tolerant clones. The results of multivariate statistical analysis (correlation coefficients, cluster analysis, and principal component analysis-PCA) showed a negative effect of drought stress on the wood yield and its components. They also showed that smaller clones with fewer leaf sizes have higher drought tolerance by more water maintaining potential and lower evaporation levels. Finally, the presence of genetic diversity in terms of stress tolerance among poplar clones as well as their segregation pattern in cluster analysis and PCA biplot indicated the interference of genetic factors in its control and the availability of stable clones that can be compatible with dry conditions of the country via their hybridization.