Iranian journal of Forest
Year:2010 | Volume:1 | Issue:4|Papers Count:11

In this study, variations of woody species diversity were investigated in Beech, Beech-Hornbeam and Horn Beam stands of Janbesara district (located in the west of Guilan province) after the application of single selection method. Random-systematic sampling method was applied in the first and last year of the 10-year period (1993-2003) with 3.3% intensity and 200×150 grid size. Shrubs and trees species were recorded in 0.1 ha circle sample plots. Species richness, Shannon Wiener and Simpson diversity indices were used to evaluate plant diversity in each sampling plot. The means of different diversity indices were calculated and t-test was used to analysis all indices means differences in both sampling. The results showed that species richness, Simpson and Shannon diversity indices both in Horn Beam and Beech-Hornbeam types increased (with non-significant mean differences) after applying the single selection method. Therefore, single selection approach can be applied as an appropriate silvicultural method in northern natural forests for plant diversity conservation together with wood production.

This research was conducted on the status of growth, biomass, survival and performance of needle-leaved species of Brutia pine (Pinus brutia Ten.) and Aleppo pine (P. halepensis Mill.) with different combinations of organic matter in Koloudeh nursery located in Amol (north of Iran). Seeds in plastic pots were sown as randomized completely design (RCD) with four replications at different treatments of soil including: T1) nursery soil (control), T2) control soil: cattle manure (5:1), T3) control soil:decomposited litter (5:1), T4) control soil: cattle manure: decomposited litter (5:1:1). The results after one year showed that seedlings of T4 obtained better survival rate, shoot height, collar diameter, seedling Vigor Index, shoot dry weight, root dry weight, total dry weight and seedling Quality Index (QI) in both species. A highly positive significant correlation was detected between soil nutrition and characteristics of survival rate, shoot height, collar diameter, shoot dry weight and root dry weight in both species. There was a better response in most of characteristics for P. brutia compared to P. halepensis. It is concluded that higher soil organic matter, due to proper physical and nutritional properties of soil media, increases the seedling quantity and quality.

In order to investigate the qualitative and quantitative changes in forest stands of Janbe Sara district, some raw data collected in 1993 and 2003 were compared. Inventory in both years was carried out using systematic random sampling with network dimensions of 150×200 meter and 0.1 ha sample plot. In each sample plot, such factors as type of species, diameter at breast height in cm, height of two trees in each plot in meter, regeneration conditions and qualitative class of trees were measured. The results of comparison between 1993 and 2003 data show significant difference between mean of regeneration’s density, stand density, average diameter of basal area and Lorey height in this period. Standing volume per hectare was significantly reduced about 19.63 silve/ha in 1993 comparing to 2003 (p-value < 0.05). Based on results, the average diameter of basal area was reduced from 42.638 in 1993 to 37.64 in 2003. Also average Lorey height had 2.42 meters of reduction and there were significant differences (p-value < 0.05) between average diameter of basal area and Lorey height in 1993 and 2003. The number of regeneration per hectare regarding to all species including Fagus orientalis, Tilia begonifolia, Carpinus betulus, Acer velutinum, Alnus sp., Fraxinus excelsior and other species increased during the period. But, percentage of first class trees in 2003 has been reduced. Also the percentage of second, third and fourth class trees increased in 2003 and these changes are significant.

Heavy metals are high atomic weight elements which are harmful for living organisms. The main goal of this study is the investigation of the ability of Lead biofiltration by two important species in Zagros forests (Pistacia atlantica and Quercus brantii). In this study 90 seedlings were chosen from both species. Then different concentration of Lead (Lead Nitrate (Pb (No3)2): 0, 50, 250, 500, 1000, 2000 ppm was prepared as different treatments of pollutants. This study was carried out in a factorial design on the basis of random complete design with two factors: plant species and different levels of pollutant. Time of applying pollution was the late June that 100 ml of each treatment was sprayed on seedlings three times, with seven days interval. Using Atomic Absorption, amount of gathered pollutant was measured in taken samples of leaf, stem, root and soil. The results of this research are as follows; P. atlantica and Q. brantii were classified as super absorbent plants because of absorbing a high amount of Lead pollutant. According to the average absorption of organs for August and October leaves, P. atlantica had the most leaf absorption. Although the most root absorption was related to Q. brantii. Results showed that the amount of pollutant absorption in leaves, roots and soil depends on the type of species and the concentration level of pollutants. Significant difference of quantities of lead absorption between August and October leaves begins from the application of more than 250 ppm. This might be the result of not transferring of lead from leaves to stem in the lower concentrations.

The western forests of Iran are among the richest biological resources and their understory vegetation is the main source of forage for rural and nomadic livestock. So these forests are the focus of animal husbandry in Iran. Pasture yield and quality were compared between zones under trees and open areas near the trees. Trees affected pasture quality and yield. In this study, two species of trees were studied: Quercus brantii lindl and Acer monspesulanum. These trees influenced pasture yields grown under the trees. Pasture yields in open areas near the trees (without trees land) were greater than under trees but forage quality factors were higher under trees than in open areas. These results indicate that, while removing trees may enhance pasture productivity, this benefit may be offset by a reduction in pasture quality.

Poplar trees produce annually more than two million m3 woods in Iran and they have main role in decreasing the pressure on natural forests. Therefore, efforts should focus on improving quantitative and qualitative characteristics of wood production especially in short rotation systems. In this study in order to determine the growth characteristics of new clones compared to previous clones and study the height and diameter growth in a growing season, seven new exotic clones along with eight previous indigenous and exotic clones (27 cuttings of each clones) cultivated in a Randomized Complete Block Design with 3 replication at Elborz Research Station, Karaj/ Iran. Irrigation and weeding operation was done at suitable time during growing season. Height and diameter of all seedlings were measured every 10 and 30 days, respectively. Growths in periods for both attributes were computed. The data were analyzed using analysis of variance and mean comparisons for all traits. The results show significant differences between clones, periods and their interaction. The greatest height growth in a 10 days period belonged to 20th -30th June with 19 cm height growth and its lowest belonged to the end of September and October periods. P. deltoids 63.8 and P. deltoids 69.55 revealed 13 and 11.5 cm height growth in ten days periods, respectively, ranked as first and second clones. At the end of growing season, P. x alborz1 with more than 2 m height was the highest clone. Regarding the diameter growth, end of June until early July with 3.5 mm height growth mean was the best period, as well as, for diameter growth P. deltoids 63.8 with 3 mm was. As a final result, end of June until early July revealed highest height and diameter growth so this shows the importance of irrigation and weeding operation in the period in order to increase productivity.

High cohesion of ecological and human factors in Zagros biogeographic Region and its ancient institutional structure, emphasize the necessity of integrated natural resources policy-making and management with institution centrality in this region. This research was done in order to determine and analysis the policy-making  paths between institution (independent variable), forest (intermediate variable) and water (dependent variable) variables in Zagros biogeographic Region and investigate the relationship between these three variables and their changing processes during 1992 - 2008. Survey methods were used for data collection of public and state formal and informal institutions related to forest and water resources. The main steps of this research included variable determination and operation, questionnaire preparation and validity and reliability determination, data collection and statistical analysis through path analysis. The results showed forest and water resources have been degraded in this watershed in this period. Also, policies and managerial activities of institutions had the most direct and indirect affects on forest and water situations and are the beginning point of three policy paths between these three variables. So it is necessary for policy institutions to pay more attention to the relations between these variables and their changing effects to others and also avoid unilateral policy-making and management of forest and water resources.

The comparison of different methods for estimating the genetic diversity could define their usefulness in plant breeding and conservation programs. In this study, a total of 5 seed morphological traits, and 4 highly polymorphic simple sequence repeat (SSR) loci were used to study the morphological and genetic diversity and differentiation among 600 seeds from 6 beech (Fagus orientalis Lipsky) populations (each population 100 seeds from 10 forked and unforked beech trees). The analysis of variance of the morphological data revealed significant differences among seeds of each trees for all measured traits. Principal Component Analysis (PCA) and UPGMA clustering of studied populations or stem form groups in each population did not show any clinal trends in variation of seed and nut traits. A highly non significant correlation coefficient (R2=0.002, P=0.227) between morphology and geographical distance matrices was calculated by the marker systems using mantel's test. Nut and seed morphological traits suggest no ecotypes existence of F. orientalis along with Iranian beech forests. Genetic structures were studied based on the mean genetic distance between seeds of each tree. Population differentiation was moderate and differed significantly (Fst = 0.13-0.22) among forked and monopodial tree groups. A tendency of a strong family structure among seeds of forked and monopodial genotypes was obvious, indicating the observed phenotypic variation was at least partly caused by genetic factors. Besides, the correlation between morphology and geographical distance matrices was significant (R2=0.136, P=0.04), indicating the existence of a relatively clinal trends in variation of microsatellite loci. Low correlation coefficients (R2=0.028, P=0.140) between distance matrices of two marker systems shows contrary microsatellites, morphological traits are relatively less reliable and non-efficient for precise discrimination of closely related genotypes and analysis of their genetic relationships.