Iranian Journal of Forest and Poplar Research
Year:2010 | Volume:18 | Issue:3 (41)|Papers Count:17

The objective of this study was a comparative evaluation of 20-year old plantations of Alder (Alnus subcordata C.A. Mey.), Chestnut leaved Oak (Quercus castaneifolia C.A. Mey.), Maple (Acer velutinum Bioss.) and Cypress (Cupressus sempervirens var. horizontalis) with the adjacent mixed broad leaved stand from qualitative and quantitative point of view. The study area is located in Darabkola, east of Mazandaran province in the Caspian region. One sample plot, each 1 hectare was selected in every plantation as well as in the natural stand. A total of 5692 trees were measured by full callipering; the studied factores were diameter at breast height (dbh), height and qualitative characteristics of trees. Also the physico-chemical properties of soil were studied in all treatments. The differences of the studied factors between the treatments were significant, statistically (p>0.01). Analysis of quantitative characteristics showed that natural forest and plantation of Alder were the most promising followed by Maple and Chestnut leaved Oak. From the qualitative point of view, alder and maple plantations were the most promising stands, while the Cypress plantation showed the worst results.

Function of water retention and avoidance of its loss, is one of the most important functions and services of the forest ecosystems which has a major role in provision of human welfare. In this study, in order to estimate the effect of forest cover on water retention and surface runoff reduction, the runoff depth has been calculated using Curve Number method. Firstly, study area has been homogenized in the basis of land use/land cover and hydrologic soil groups' characteristics and the Curve Number of each homogeneous unit determined. Thus, the average weighted Curve Number for entire of the basin has been calculated. Lag time and time of concentration parameters of the basin were also calculated. Then, the input data were entered into the HEC-HMS model and the model was run using Curve Number (SCS) method for six observed rainfall-runoff events. Four hypothetical scenarios have been developed for the concept of water retention by forests and repeated the running of model for the developed scenarios. Results showed that in the case of scenario 1 which assumes that the entire of watershed area is covered by forests, the values of initial loss and lag time in the watershed has increased while Curve Number and flood peak discharge values decreased that indicates the role of forest cover on the prevention of water loss and its retention in the soil. Furthermore, the volume of infiltrated water in scenario 1 is about 2.7×106m3.

Fires have considerable effects on biogeochemical properties of forest soils. Fire could change soil nutrient elements which may affect forest soil fertility through the time. The aim of the study was to assess the effect of the fire that occurred in 1998 on chemical properties in some parts of Chelir’s district of Kheyroudkenar Educational and Research Forest. In this study, the effect of fire on some soil chemical properties including pH, EC, total nitrogen and carbon percent, available nitrogen and phosphorus and CEC has been evaluated after seven years of the event. After a brief survey, the studied forest was divided to four sections regarding to fire damage consisting of control, sever, moderate and low plots. At each plot, five profiles were dug and from three depths of each profile, soil samples were collected. Results showed that the soil depth had significant effect on all soil properties, excluding available nitrogen, but the fire severity and its interaction with soil depth, had significant effect just on pH, EC and CEC, which in turn increased fire severity, soil pH, EC and CEC and decreased the amount of the other properties. Furthermore, increasing fire severity increased the difference between the soil depths significantly, regarding to soil properties. In addition, the whole soil chemical properties in A horizon, except CEC, were significantly more influenced by fire than the other horizons.

Yew in Arasbaran forests is mixed with broad-leaved species like hornbeam, oak and maple that has been destroyed very much in the past years. This study is aimed to investigate the natural regeneration of yew in these forests. For this purpose, 111 sample plots, each 100m2, were established by a systematic-random grid of 100m×250m. The natural regeneration (saplings) of yew was investigated quantitatively and qualitatively in the sample plots. Results showed that the number of yew saplings per hectare were 520. Most of these saplings had seed origin and were classified in height class less than 30cm with high vitality and health condition. Regarding to the past history of the area, this results show that the protection of area was effective and successful, so a dense and fresh yew stand in the Arasbaran area is expected in the future, if the protection is continued.

Tree species distribution in different ecological zones depends on their ecological demands including the physical and chemical properties of soils as well as different aspects and altitudes. In this research, several ecological characteristics of Quercus brantii were studied. This species is distributed in three altitudes of:1000-1500, 1500-2000 and higher than 2000 m.a.s.l. Fifty two site samples, each covering 500m2, were selected in the basis of several parameters including aspect, land form and elevation classes. Different variables such as species, diameter at breast height (dbh), tree height, trunk height, crown cover, origin (standard or coppice), age class, number of sprouts, accompanying species and forest type were measured or recorded in each sample plot. Moreover, a soil profile was dug in each sample plot. Results showed that natural distribution of Quercus brantii varies from 1050 to 2550 m.a.s.l in all land forms. The pH of the studied sites varied between 7.5 and 8.1, and the soil texture varied from clay, clay-loam to loam. The most important limiting factors in the soil of the studied area were the texture and organic matter, whereas the soil moisture was an important factor for the presence of this species. The eastern slopes had the highest density, while the flat area showed the highest crown cover and dbh. The average crown area of each tree in seed origin and coppice origin plots were 16.61m2 and 15.71m2, respectively. The mean dbh was 20.2cm and the average number of sprouts per tree was 5.9. The mean total tree height was 6.1m in seed origin and 5.59m in the coppice origin plots.

In this research tentative model was determined by GIS for evaluation of the ecological capability in Zagros forests. The study was carried out in Masbei area [Oak (Quercus brantii Lindl.) forests] located in south aspects of Kabirkooh in Ilam province. This model was designed in five different classes and forest evaluation process was done in quantitative form using the model. In order to ecological evaluation in the study area, some factors including altitude, aspect, slope, climate, land form and soil depth were applied. The results obtained from this model showed that there are 425 different ecological situation in 7436 ecological final unit within the study site. Coefficient of determination (R2=0.56) between potency gradations of ecological potential and mean height of trees in 64 field plots (0.15 ha) showed that this model is fairly suitable efficient for ecological potency evaluation in Zagros forests.

Felling as the initiation of harvesting chain-work is the first step for preparing trees to market consumption which has severe effect on the subsequent work stages. The aim of this research is to assess the productivity of manual felling and costs of felling team as well as recognizing their effective factors. In this evaluation after identifying work elements of one felling turn, 72 felling turns were time studied. Furthermore independent variables such as tree diameter at cutting stump height, distance between trees, longitudinal and latitudinal slopes were time studied in each turn. Felling time regression model is a function of independent variables such as tree diameter and distance between trees. Amount of production including delay time and without delay time were 63.48 and 83.19 m3 per hour, respectively. The cost determination model which recommended by Forests, Rangelands and Watershed Organization project work agenda was used to determine felling costs. Therefore, felling costs with delay time and without delay time were 4017 Rials per m3 (26872 Rials per tree) and 3065 Rials per m3 (20516 Rial per tree), respectively. The under cut and back cut time and technical delays formed the greatest felling element time of chain saw felling. Examination of the variation effect of the variables on time due to the variation of felling cost showed that increasing in each of the variables causes an increase in time and therefore increases felling costs.

In order to investigate the reaction of biodiversity and richness of plant species in relation to physiography and physico-chemical properties of soil, Arasht catchment (approximately 500 ha) from Kabirkoh protected area in Ilam province was selected. After determining transects in different aspects, 67 sample plots (20m×20m) in a grid of 150m×150m were established (northern aspect 24 plots, western aspect 20 plots and southern aspect 23 plots). The environmental factors and vegetation in each sample plot were recorded. Results from correlation analysis showed that the biodiversity of herbaceous species in southern aspect has a negative relation with clay and sand and has a positive relation with silt and lime. The biodiversity of herbaceous species in northern aspect has a positive relation with soil saturation percentage, organic matter and nitrogen and has a negative relation with altitude. The biodiversity of herbaceous species in western aspect has a negative relation with EC and altitude and has a positive relation with lime. Based on the results, it can be stated that for ecological evaluations in Zagros region, physico-chemical factors are more suitable for herbaceous species and physiographic factors and land form are more suitable for shrub and tree species.

Plantation forests can influence both plant diversity and soil properties. This study mainly aims to determine and compare the status of plant diversity of ground flora and some physico-chemical properties of soil under influencing of plantation with conifer and broad leaved species. Three sites (conifer, broad leaved and non-planted site as control) were selected in Sanandaj (Dushan region). These sites were physiographically and climatically similar. Systematic random sampling was used as a method for data collection. To study quantitative characteristics of stands, 20 quadrate sample plots with 400m2 area were selected in each site (60 plots totally). In order to determine the herbal species and their coverage percent, each plot was divided into 4 sections and a microplot (1.5m×1.5m) was selected in each section. To study the physico-chemical properties of soil influenced by planted species, 3 soil samples were selected in the center of each plot in depth of 0 to 20cm and the soils were mixed with each other to obtain mixed soil samples. The data was analyzed using complete randomized design. Results showed that the plant diversity and frequency on ground flora under influence of plantation with broad leaved species was maximum, while the evenness index was minimum. There was significant difference among all sites regarding to porosity, however there was no difference among the sites from view point of other physical parameters. Moreover, there were significantly differences between most chemical parameters of soil in three studied sites.

This research has been carried out in twenty-years-old plantations with species of Cupressus sempervirens, Acer velutinum, Populus deltoides and Alnus glutinosa, located in Sourdar-Vatashan forestry plan which have been damaged due to the heavy snowfall in February 2008. The study aimed at evaluating and comparing of the damage intensity in studied species and determining the correlation between effective factors with damage rate. Damage rate was evaluated using 30 circle sample plots with an area of 314m² in a systematic-random grid (125m×125m) in 48 ha area. Results showed that damage rate was 84% in Cypress stand, 6.18% in Poplar and 18.28% in Alder, while Maple stand remained intact. There is significant relationship between damage percentage and diameter at breast height (P<0.05), also between percentage of damage with pruning height, crown length and H/D ratio (P<0.01). Trees with diameter less than 20cm (d1.3<20cm), crown length more than 6m, pruning height less than 6m and H/D ratio more than 70 had a damage rate of 52.46%, 50.93%, 57.71% and 39.80%, respectively. Trees with diameter more than 20cm (d1.3>20 cm), crown length less than 6m, pruning height more than 6m and H/D ratio less than 70, had a damage rate of 18.75%, 13.18%, 7.04% and 18.36%, respectively. Therefore, the probability of injury will increase due to increasing of H/D ratio and crown length and decreasing of pruning height and diameter at breast height. Considering the above mentioned criteria and ever green characteristic of cypress, the snow damage rate in this species is high. Hence, one can conclude that planting of native broad-leaved species such as maple could be more effective and promising in the region.

Thuja orientalis is one of the most important species due to its low ecological needs and tolerance against winter dry and summer heat, which is very current in forest plantation in degraded ecosystems and arid and semi-arid shrub lands of Iran. This experiment was performed at complete randomized block and factorial design with three treatments, sowing date (autumn and winter), irrigation periods (2 and 4–days) and weed mechanical control (7 and 14-days) with four replications and 15 vases (per replications) in Zaghe nursery in Khorramabad, Iran. At the end of the first growing season, measurements were including germination characteristics, height growth, collar diameter, root length and survival rate. Results showed that effect of sowing dates and irrigation periods on germination characteristics, height growth and collar diameter were significant. Maximum growth was in autumn sowing and 2-days irrigation periods. Effect of sowing dates on survival of Thuja orientalis seedlings indicated that maximum survival was at autumn. Effect of sowing date and weed control on root length was significant. Based on the results, maximum root length was at autumn sowing and 14-days weed control periods. Based on the obtained results, autumn season can be suggested for Thuja orientalis, also since there is no significant effect of weed control on height and collar diameter, we can use 14-days weed control operation instead of 7-days, for decreeing the cost of seedlings production in the nursery.

Eucalyptus camaldulensis is one of the most adaptable and suitable tree species in view point of wood and other productions in Khouzestan province. The aim of this study was to determine the most suitable cutting tools, cutting heights and coppice management in Eucalyptus camaldulensis Dehn. plantations. This study was carried out in Research Station of Abbasabad Dezful on Eucalyptus camaldulensis 9616 plantation (10 years old). The research was conducted in 2002 under statistical method of split-split plots and Randomized Complete Blocks Design, with three replicates. The main treatments consisted of two levels of cutting tools (axe and chainsaw), two stump heights (15cm and 30cm.) and two sprout management methods (reduced and control). Evaluations have been done on 90 trees of Eucalyptus at 3m×3m spacing. After five years, the data were analyzed using Duncan test and analysis of variance. Results showed that the sprouts appeared at the same time, after cutting the eucalypts in the all treatments. Cutting tools and stump height treatments affected wood production, significantly. The greatest wood yield was achieved at chainsaw and stump height of 15cm treatments. Sprout management treatments also affected sprouts wood production, height, diameter and foliage biomass, significantly. Sprout reduction (2-4 sprouts/stump) increased sprouts wood production and diameter, whereas the control treatment (without sprout management), increased sprouts height and foliage biomass. The results of interaction between the treatments showed that the highest amount of sprouts wood yield and diameter achieved by applying the treatments of chainsaw, stump height of 15cm and leaving two sprouts on each stump.

Palaeobotany is knowledge of composition of plant communities (occurrence) in geological time scale )Phanerozoic Eon). To reconsider the distribution of existing plants, we had to pay attention to past dominancy of the flora communities. The purpose of this research is study of a small part of Mesozoic flora in Iran. Based on the presence of several coal mines, abundant well-preserved plant macrofossils and samples of scattered wood fossils, Kalat area in Gheshlagh region, (midway Azadshahr to Shahroud) seams number 24 (K24) has been studied by this research. Collected plant remains systematically can be assigned to 3 genera of Mesozoic Gymnosperms. These 3 genera have been described by this research. Based on the prevailing presence of Bennetittlaes, the presence of Podozamites as a conifer genus, Rhaeto-Liassic time can be dated for the Kalat area or Shemshak group (Shemshak Formation). In the basis of palaeobotanical evidences and comparing recovered flora to the present plants, the weather conditions during depositional time can reconstructed to a warm and semi-moisturized condition, therefore middle elevation forests were dense and mixed of evergreen and deciduous trees were dominated in that time.