جستجوی مقالات مرتبط با کلیدواژه « ریشه » در نشریات گروه « جنگلداری »

Increasing industrial activity, followed by the entry of heavy metal pollutants into the aquatic ecosystems, are one of the biggest environmental challenges. Plants are good indicator of metals concentration in water and sediment of aquatic ecosystems. The aim of this study was to investigate the concentration of heavy metals in sediments, roots, stems and leaves of mangrove trees in Khorkhoran protected area as one of the most important mangrove habitats in the Persian Gulf. For this purpose, 9 samples of sediment, leaves, roots and stems were collected from this area and analyzed by ICP-OES to determine the concentration of heavy metals. Shapiro, Kruskal-Wallis, Tukey and bioaccumulation index and transfer coefficient were used for statistical analysis. The results showed that the highest concentrations of heavy metals in sediment samples were specific to nickel, zinc, copper and lead, respectively, and in the plant the highest concentrations were related to zinc, nickel, copper and lead. In general, the process of accumulation of metals in sediment and plant tissues indicates an increase in the concentration of metals in plant tissue with an increase in sediment. Bioaccumulation index showed that the highest and lowest concentrations of heavy metals were in roots and leaves, respectively, and mangrove root is a suitable indicator for measuring mangrove contaminants. The transfer coefficient of nickel metal in the stem and copper metal in the leaf showed the ability of these organs for phytoremediation of these two metals. The results showed mangroves are repelling species for other metals.

The root of trees is one of the most important living materials for stabilizing and reinforcing the cut and fill slopes of forest road. This study was conducted to investigate the tensile strength of tree species according to changes in lignin, cellulose and root extracts content.

Darabkola forest in the southeast of Sari-Iran was selected for this study. To determine the tensile strength of tree roots, root samples from tress including the beech, hornbeam, alder, Zelkova carpinifolia, Persian Ironwood and oak were collected by soil profile trenching method and then the test of tensile strength was performed. The amount of lignin, cellulose and ash for the roots of different tree species was also measured in the laboratory. One-way anova was used to compare the means of roots tensile strength and also multivariate analysis was used to classification of species based on cellulose, lignin, ash and other extracts content.

The results showed that in beech, alder and Persian Ironwood, the measured rates of lignin were higher than cellulose levels. While in the Zelkova carpinifolia, the amount of cellulose was higher than others parameters, in beech and alder species (with higher lignin rate) the means of tensile strength was recorded less than other species, and for oak and hornbeam with higher cellulose levels, tensile strength was recorded higher than other species. The results of multivariate analysis based on tensile strength and numerical values of root decomposition showed three groups with high adaptability percentage (alder-beech, hornbeam-Zelkova carpinifolia and Persian Ironwood-oak).

According to the results, investigating the amount of lignin and cellulose in roots of different species as well as discriminant analysis with consideration of different factors can be a scientific method to select best species for soil bioengineering projects.

Almond is one of the major shrub species with high ecological extent in Iran. Impact of climate change and drought stress on forest ecosystems، as well as the unsuitable conditions of Zagros forest ecosystem and importance of planting shrub species at such ecosystems، have brought the attentions to use the wild almond species in forest plantation programs. Awareness of the impact of habitat factors on tolerance to environmental stresses will guarantee success of most of the forest rehabilitation programs. For this reason، seeds of four wild almonds، including Amygdalus arabica، A. scoparia، A. haussknechtii and A. eleagnifolia، were collected from three altitude levels، including: 1600-1800، 1800-2000 and more than 2000 m. above sea level at Karebas site; (Chaharmahal and Bakhtiari province)، west of Iran. After cold stratification، the seeds were sown in nylon bags. Two months later، the seedlings were treated by four levels of drought stress (control، -0. 4، -0. 8 and -1. 2 MPa) induced by application of Polyethylene Glycol 6000 in irrigation water، using the factorial experiment under the completely randomized design with three replications (five seedlings per each replicate). Results showed that drought stress significantly reduced seedlings growth characteristics، including total height، shoot height and shoot wet and dry weight، except root wet weight which was increased. Furthermore it increased seedling''s nitrogen and calcium content، while the minimum levels belonged to control treatment. In addition، the seedlings from the lowest (1600-1800 m. a. s. l.) and the highest (above 2000 m a. s. l.) altitude origin، provided the highest and the lowest growth values، respectively. Overall، Amygdalus arabica showed the highest resistance to drought levels among the other species، due to its greatest growth values at these hard circumstances.