Iranian Journal of Forest and Poplar Research
Year:2010 | Volume:18 | Issue:2 (40)|Papers Count:17

In order to study the spatial structure of oriental beech (Fagus orientalis Lipsky) stand at optimal stage, this research was carried out in the Caspian forests of Iran. The studied site consisted of a natural stand located at Sangdeh district (Mers-e-se) with three hectare area. It is located between 1900 and1950 m.a.s.l. Six sample plots each with 0.36 ha area, were systematically selected and all trees (1244 stem) within the plots were measured and recorded. Using increment borer, the mean age of the stand was estimated as 137 years; the age difference of trees was 40 years. Results showed that the stand has a closed canopy cover and distribution of stem number per diameter class was more or less homogenous (Bell shape) with a semi even-aged structure. Using Ripley's K function, the distribution of trees within the stand was random.

The project of investigation on characteristics of poplar saplings (1/1) was carried out to select the best poplar clones in Chalaki research nursery of Golestan province during 2001 to 2004. For this purpose, 4 clones of Native poplars were collected from different areas of the province and planted beside 31 exotic clones provided from research center of Alborz Karaj. In the first year‚ cuttings were prepared from all clones and planted in 20 cm spacing within rows with 1.3m distance. Parameters including survival rate, diameter and height growth of saplings were recorded. Analysis of variance and Duncan multiple range test were applied using SAS software. Results indicated significant statistical differences between studied poplar clones. Populus deltoids and P. euramericana showed higher diameter and height growth compared to the other clones.

Since the economic problems are the most important factors in degrading of Zagros forests in Iran, plantation of species with economical values in rural areas can be useful. In order to investigate the success of different genotypes of Almond (Prunus dulcis), this research was conducted in Kermanshah province. At first, 12 Almond genotypes which were resistant to cold and drought conditions were collected and then planted in a nursery. Six genotypes with high performance were selected for the trial.This research was conducted under Factorial Experimental design in the base of Complete Randomized Blocks design with two factors: six genotypes and three water catchments methods, including linear banquet, crescent banquet, and common method as control. Some variables including survival, pest resistance, stem base diameter and height were measured every year after the growing season. In survival point of view, results showed that there was a significant difference between water catchments methods and the planted genotypes. The linear banquets and crescent banquet had more vitality than those planted in common method (p<0.01). The stability analysis for water catchments methods at the research period showed that the seedlings planted in the crescent banquet had the most stability in survival and establishment.

Most of soil physical, chemical, mineral and biological attributes are changed by forest fires. Fire is one of the most important factors of forests destruction in Marivan region and considerable area of the region are annually exposed to fire. Depend on environmental conditions and also fire intensity, different effects will impose on ecological conditions of the environment. Whereas soil is considered as a base for forest’s growth and regeneration, study of fire effects on it’s properties takes an important place. The study area is located in 2 km far from Marivan. The study was carried out in autumn 2006 and the objective of this research was to compare the effect of fire on some soil chemical properties in surface soil (0-5 cm depth) and subsurface soil (5-20 cm depth) in a forest stand that was burned in 2002 in an area of 1.3 ha. A control stand with similar conditions was selected beside of the burned area. Five holes were dug in each site and soil samples were collected from the above mentioned depths and analyzed. Results showed significant effects of fire on most chemical attributes of surface soil including: pH, available phosphorous, electrical conductivity and available potassium increasing. The fire caused increasing of total nitrogen and cation exchangeable capacity in surface soil. All of chemical properties of subsurface soil were measured higher in burned area than control however; these differences were not significant, statistically.

In order to study the effect of canopy and stand density on natural regeneration, 460 ha from oak forests of southern aspect of Manesht mountain in north of Ilam province was selected. Forty six sample plots, each 2000 m2 for recording stands characteristics and 46 micro plots, each 400 m2 for recording regeneration characteristics were established by random systematic sampling method. Variables in macroplots included dbh, maximum and minimum crown diameter of all tree species. Number, height and quality of seedlings were studied in the micro-plots. The collected data were analyzed by Excel and Spss softwares (ANOVA test) and then compared using of Dancan test and correlation. Results showed that the abundance of seedlings in this area were low. The number of Quercus brantii and Pistacia atlantica seedlings has a positive correlation with canopy density, whereas Lonicera nummularifolia and Amygdalus orientalis had negative correlation. The maximum height of Quercus brantii seedlings (160 cm) found in denser canopy, while it was 88 cm in stands with open canopy. The maximum seedling height (154 cm) of Lonicera nummularifolia and Amygdalus orientalis were measured in the stands with open canopy. The mean height of seedling, the ratio of tall seedlings to whole seedlings and their vitality in denser canopy (located in northern aspect and medium elevation) were more than those in the stands with open canopy (located in southern aspect and higher elevation). These results indicate the best growth condition in northern aspect and medium elevation due to the richer canopy.

In order to achieve a sustainable management of land resources and to improve land quality, quantitative assessment of effective factors and environmental indicators are required. Environmental capability evaluation regulates the relationship between socio-economic impacts and land use changes to monitor the sustainable development. The aim of this study was to evaluate environmental capability of the Saman-e-Orfie-Cham-Haji of Kakareza forest in Lorestan province for ecotourism management. Digital topographic map, classified tree crown cover density map, some soil properties and socio-economic data have been prepared to appropriate different management practices such as recreational and conservational zoning using GIS application. Results indicated that 6%, 68% and 26% of total areas in the study site were specified as appropriate zone for intensive recreation, extensive recreation and conservation, respectively. The evaluation of environmental capability and the ranking of the suitable zones for intensive recreation (in order to choose the best zone for physical development planning) were performed by considering the socio-economic criteria such as recreational demand, distance from rivers, accessibility and the present land use. The results showed that the most important factors affecting the process of environmental capability evaluation in the study site for ecotourism zoning are altitude, land use and recreational demand.

Regarding to the importance of forest in carbon sequestration, this study attempted to investigate the carbon storage potential and CO2 uptake in a coppice oak stand. An area of 278 ha of Khalkhal forest located in Ardebil province, north of Iran was selected as the study area. After combining slope, aspect and hypsometric maps, 63 land units (polygons) as well as their area were determined. Then 60 sample trees were selected in such a way that all environmental and typological conditions were taken into account. After determining the fresh weight of different parts of trees in the field, their dry weight and biomass was determined after drying in the kiln. The humus was collected and weighted from an area of 400 cm2 under canopy of each tree. To determine the organic carbon content of the biomass, ash content was deduced from dry biomass. To determine the amount of stored carbon in soil, samples were collected from 0-10 and 10-30 cm soil depths. The amount of annual sequestrated carbon in biomass and soil was estimated as 1.51 and 0.1 tons per hectare, respectively. The annual carbon dioxide uptake was 5.94 tons per ha.

Juniperus-Cotoneaster reserve of Ooshan located in central Alborz (north of Iran), is one of the Irano- Turanian forest stands which shows the characteristics of a semi-virgin ecosystem. Although the stand has registered as a "forest reserve" by Forest and Rangeland organization of Iran, some evidences of deforestation and changing the landuse are obvious. The aim of this research was identification and study of biologic and ecologic characteristics of the stand to provide the situation of subsequent studies as a first step for further investigations. Data obtained using stratification method by one strip transect in each stratum. After analysis of the data, structural and ecological characteristics and healthiness of the stand were considered. In this stand, Cotoneaster kotschyi is the dominant species with a frequency of 51%.Juniperus excelsa with a frequency of 10% and 6.5 meter height is the dominant species of the tree layer.According to the abundance of species, two forest types were distinguished in this stand: Cotoneaster kotschyi-Juniperus excelsa and Cotoneaster kotschyi-Cerasus microcarpa. Species in the tree storey were Juniperus excelsa, Lonicera nummularifolia, Pistacia atlantica and Celtis caucasica while species in shrub storey were Cotoneaster kotschyi, Cotoneaster nummularioides, Cerasus microcarpa, Rosa spp., Rhamnus pallasii, Colutea persica and Berberis spp. The structure of the stand is uneven-aged and irregular. Regeneration in the areas with closed canopy is 7 times more than the areas with sparse canopy.The healthiness of stand was considered by ranking to main 7 species.

Evaluation of toxic metal concentration in soil and plants are the most important subject according to the health of ecosystem. This study was carried out to investigate on the lead content absorption in different parts (leaf, root and branch) of Eldar pine (Pinus eldarica Medw.) trees in Tehran city. For this aim in polluted sites (Azadi, Bahman and Bazar) and controlled site (Aghdasiyeh), in defferent seasons (January, March, July and September) and in different distance of air pollution measurment station (0, 500m and 1000m), 432 samples from leaves, branches and top root were collected and lead content density in each samples determined by atomic absorption instrument model Varian 220. Result indicated that lead content absorption in root of pine was higher than aerial parts (leaf and branch). Lead absorption in parts of tree in Azadi site was higher than other sites and the lowest content of lead was measured in Aghdasiyeh site.However, the highest lead content in parts of trees was observed in September and the lowest in March.The results also showed that by increasing of distance from air pollution measurment station, lead content absorption in parts of trees decreased.

Poplar trees are appropriate species for plantation and forest rehabilitation because of fast growing and high wood yield, as well as adaptability to unfavorable climate. Salinization of soil and high temperature are the inhibitory factors in Khuzestan province. Populus euphratica is a tree species that tolerates soil salinity and high temperature. Acclimatization of cut seedling of three Populus genotypes including P. euphratica, gametoclonal of P. euphratica and hybrids of P. euphratica with P. alba were studied in Dezful botanical garden of Khuzestan province in southwest of Iran. Heterosis effect was observed for hybrid trees and they had higher yield than the Khuzestan's endemic P. euphratica during the experiment.Maximum values of height and diameter were measured in the hybrid genotype. Because of morphological properties of the hybrid trees such as straight trunk and high diameter, they could be exploited in wood production among these three genotypes. Moreover, the survival rate of hybrid of P. euphratica with P.alba was higher than other poplar genotypes. Therefore, these hybrids could be introduced as promising genotypes for forest rehabilitation and wood farming projects.

Root distribution of three-year-aged Eucalypt (Eucalyptus camaldulensis Dehnh.) seedlings was determined under different soil moisture regimes in Yazd, Shahid Sadoge Desert Research Station. The seedlings were grown in lysimeters which subjected to three soil moisture regimes including; 100% (well watered), 70% (medium drought stress) and 40% (high drought stress) of field capacity (FC). Soil moisture was restored by adding the required volume of water in the basis of time domain reflectometry (TDR) reading taken from tubes installed in each lysimeters. The roots were harvested at 0-30, 30-60, 60- 90 and 90-120 cm depth of the soil at the end of the experiment. Results showed that root dry weight and length decreased significantly when soil water content reduced (P<0.001). The effects of various soil moisture content treatments on root dry weight and length distribution at different depths of soil were significant (P<0.001). Therefore, deep root development of E. camaldulensis was related to soil moisture content and intensive soil drought stress inhibited root growth in high depth of soil.

Because of several radiometric errors, precise estimation of forest stand volume based on spectral indices is not achievable. In contrast to spectral indices, textural indices are more consistent dealing with these errors. In this research, estimation of forest stand volume based on textural indices was studied. For this aim, 150 plots were collected using systematic random design. Green, red and near infra-red bands were used. Textural indices included second moment, contrast and homogeneity extract by different window size. Appropriate band, index and window size were chosen by stepwise regression. Based on this analysis, near infra-red band, homogeneity index and 31×31 pixel window size were selected. RMSE and bias of estimation was 43 and 2 percent, respectively. Although, estimation accuracy of forest stand volume by textual indices was suitable for mapping purposes, however, its application in forestry operations needs more researches.

Effects of provenance and seed moisture content (SMC) on viability, germination and vigor of chestnut leaved oak (Quercus castaneifolia) acorns were investigated in laboratory. For this purpose, 1500 sound and mature acorns were selected from three different provenances in Loveh forest, north eastern of Iran, located in elevations of 400, 1000 and 1600 meter above sea level, with initial moisture content of 47.0%, 43.0% and 42.8%, respectively. In order to set up 5 different SMC levels (including control, 39.4%, 35.1%, 30.1% and 25.9%) in each seed provenance, acorns were dried for 7 days close to silica gel in 27°C. All dried acorns imbibed in tap water for 24h and incubated under optimum growth condition (8h light in 30°C, and 16h dark in 20°C) for 30 days using a complete randomized factorial design, with 4 replications. At the mentioned period, number of germinant, and characteristics of emerged seedlings were recorded every other day. Results showed that acorn quality decreased with seed MC reduction. So that, in all studied provenances, reduction of SMC lead to reduce seed viability, germination percent, germination speed, germination value, germination energy, and vigor index. Accordingly, it can be said that Q. castaneifolia seed apart from provenance has recalcitrant seed storage behavior. In this study, we found that threshold water content (TWC), critical water content (CWC), and lethal water content (LWC) of chestnut-leaved oak seed are %35.5, %30.1 and %24.3, respectively. Incidentally, aforesaid limits changed slightly in different provenances. Totally, in order to retain chestnut-leaved oak seed quality, the results suggest that seed technologists should retain SMC above %35.5 (TWC). Because in lower SMC, seed viability decreases gradually. So that until CWC (%30.1) half of seeds lost their viability.Furthermore, because rehydration of seeds with SMC bellow %24.3 (LWC) cannot restore their viability, silviculturists and forest nursery managers should avoid sowing acorns with SMC bellow %24.0.

Determination of trees spatial patterns in each development stage illustrates the dynamic of stands during the time and can provide valuable information on the underlying processes, particularly in case of uneven-aged forests. For this purpose, three one- hectare (100m×100m) plots were closely selected at three development stages of initial, optimal and decay in an untouched, unmanaged and uneven-aged beech (Fagus orientalis Lipsky) dominated forest in the Kelardasht region. Diameter of all trees with dbh greater than 7.5cm together with their coordinates, using azimuth-distance method, were recorded and fully mapped. Spatial point pattern analyses by Ripley's K- function showed that, while the number of stems decreases from initial stage toward decay stage, the spatial pattern of trees in initial, optimal and decay stages are highly aggregated, random and slightly aggregated, respectively. This research emphasizes the application of spatial statistics for investigating tree spatial patterns. It's believed that forest managers for any insight of natural processes, need to such information from untouched stands as a key reference for any close to nature intervention in under managing forests and for sustainable management of forest ecosystems, as well.