Iranian Journal of Forest and Poplar Research
Year:2012 | Volume:20 | Issue:1 (47)|Papers Count:19

The aim of the study was to investigate the survival and growth of the grey mangrove seedlings (Avecennia marina Forsk) at different planting treatments on tidal zone of a natural mangrove forest at northern coasts of Qeshm Island (Pesian Gulf). The trial was conducted at two sites separately, one on lower tidal zone and the other one on upper tidal zone. At each site the trial was conducted under the statistical design of split plots and randomizaed complete blocks at tree replicates. The treatments consisted of two planting distance as main plots (1×1 and 0.5×0.5 m) and two seedling sources (coastal and non-coastalnurseries or irrigated with saline and sweet water). For this purpose, 720 mangrove seedlings of Avicennia marina Forsk were selected from the coastal and non-coastal nurseries and were transported to the plantation sites and were planted on the two upper and lower -tidal zones. the seedlings survival and growth characteristics were recorded during 18 months. ANOVA analysis and Duncan test was applied for data analysis, using SAS computer program. The results showed that 82.9 percent of the planted grey mangrove seedlings survived 18 months after planting. The survival rate of the saline water irrigated seedlings planted on lower tidal zone with planting distance of 1×1 m, was the highest (92%) whereas the survival rate of the sweet water irrigated seedlings, planted at upper tidal zone with planting distance of 1×1 m and was the lowest (74%). Overall, it might be concluded that the seedlings planted under the protection of natural grey mangrove stands, with planting distanceof 1×1 m on the lower tidal zone, obtained the greatest survival and growth records.

This research was conducted in 40000 ha of Mazandaran Central Forest (south of Caspian sea) in order to determine the distribution and some silvicultural characteristics of wild service tree (Sorbus torminalis L. Crantz). The forests were evaluated in four altitudinal profiles, stretched from northeast (NE) to southwest (SW), from lowland to upland (top of Alborz mountain). Wherever a Sorbus torminalis had been found, a circular 0.1 ha sample plot lied down. In 65 sample plots, habitat characteristics such as soil condition, slop, aspect and altitude was recorded. Some studied silvicultural characteristics of 185 individuals of wild service tree, includes: collar diameter, diameter at breast height (dbh), length of main trunk and total height. Moreover crown cover were evaluated in each plot. Climatic data of three climatological stations within the research area were used to determine the relationship between wild service tree distribution and climatic traits. The results showed that dbh, main trunk length and total height of wild service trees were 46.96 cm, 10.52 m and 19.96 m respectively. Majority of the studied wild service trees (42%) were on west exposed mixed stands of Fageto-Carpinetum or Fageto-Carpinetum, with Quercus types, 28% of these were on north exposed pure young beech stands. Frequency of wild servis trees with diameter more than 50 cm was greater than those with diameter lower than 20 cm. Correlation between soil depth and sorbus frequency was negatively significant (p<0.01) and with both d.b.h and total height was positively significant (p<0.05).

Fire is natural feature of most of ecosystems, including Mediterranean region and the site study in this research. In order to evaluate effect of fire intensity on dynamic of organic carbon, nitrogen and phosphorus of soil, 56 samples were selected from two depths (0-5 and 5-15 cm) in two areas of burned and unburned. Then, some unburned soil samples were burned in the laboratory by furnace at five temperature levels including of 95, 150, 220, 350 and 490oC for 30 minutes. The amount of organic carbon, total nitrogen and available phosphorus were measured by Walkley-Black method, Kjeltec method and Olsen method, respectively. Maximum organic carbon and total nitrogen were measured 4.44% and 0.89% in soil depth 0-5 cm burned at 150oC, respectively. Also, maximum available phosphorus was measured 14.99 (mg/kg) in soil depth 0-5 cm burned at 350oC. Overall it might be concluded that although increase in fire intensity, decreased total amount of organic carbon and total nitrogen, but increased amount of available phosphorus.

This research was carried out to investigate the effect of soil physical properties and ground water level on growth performance of poplar plantation. Two parcels of poplar plantations at west Guilan province of Iran (Guisum area) were selected due to their differences in growth performance. The random systematic method was applied to allocate the sample plots at each parcel. Soil sampling and poplar growth performance measurement were made at each plot. Soil sampling was made at two depth levels (0-20, 20-40 cm). In addition, a soil profile was dug at each parcel to study the soil morphology and seven holes were made by auger to study the water table level variation at different months. According to statistical analysis, the results showed that there was significant difference between the two parcels with respect to poplar quantitative and qualitative characteristics and some of the soil physical properties. Water table level at parcel No. 203 was higher than parcel No. 213 most of the year period. For this reason poplar performance in parcel 213 was significantly greater than parcel 203. It might be concluded that poplar growth performance on light textured soils with low water table level and high level of porosity and aeration is greater than the heavy textured soils with high level of water table and low soil porosity and aeration. According to economic value of poplar plantation and the effect of soil on growth and quality of them, it is necessary to study soil properties for choosing of suitable areas for the plantation.

Wildfires as one of the natural events influence forest ecosystems. Global warming and it’s effect on lengthening of dry season along with accumulation of senesced litter may couple the effects of fire in forest ecosystems. Hyrcanian forests of Iran are often bothered from the natural and also manmade fires severely. The present study was conducted to investigate the spread rate of surface fire and the effective factors which influence on it in natural mixed forest of Chalmardi- Mazandaran, Northern Iran. The spread rate of fire was measured under different conditions which were simulated with different wind speed (1-16 m s-1), slope classes (% 0-90), species (Parrotia persica C.A.M., Acer velutinum L., Fagus orientalis L., Carpinus betulus L., Quercus castaneifolia L.) and thicknesses of leaf litter (1-8 cm). Results showed that the surface fire distributed intensively with increasing wind speed. This was also accelerated in greater slope degrees. Our findings revealed that the spread rate of fire increased with increasing litter thicknesses up to 4 cm and then decreased. The types of leaf litter influence the spread rate of fire, as leaves with small thickness (Fagus orientalis L.) and large width (Acer velutinum L.), facilitate the fire transmission to neighbor litter by bending itself and increase the spread rate of fire, and leaves with greater (Quercus castaneifolia L.) and smaller (Carpinus betulus L.) thickness reduce the spread rate of fire due to the lack of rapid transmission of fire to the neighbor litter.

Spatial pattern as one of the primary ecological concepts is an important criterion to understand changes in forest communities and monitor them. The applied methods in this respect are based upon two main strategies, full callipering and sampling. Using point map of trees obtained by full callipering method gives the opportunity to determine the true spatial pattern of trees in a community. The methods of true spatial pattern determination are classified as Quadrat, Nearest Neighbor and K-function and its derivatives (L- and g functions). The aim of this research was to compare these methods in similar conditions and to study their advantages and disadvantages and also to utilize suitable statistical methods to evaluate the accuracy of the results. A 45 ha wild pistachio stand was chosen and the spatial positions of all trees were recorded by Differential GPS. The results showed that the spatial pattern of trees is aggregated. The outcomes of the methods and their statistical tests proved their ability to determine the true spatial pattern of trees in the study area. Also the comparison of the methods showed that each one can be applied, regarding the goal and available circumstances of future studies.

Manna oak (Quercus brantii) is the most important tree species in Zagross region of Iran that faces lack of natural regeneration by seed. Forest managers suggest reforestation by seeds or seedlings as the main silvicultural practice, in order to rehabilitate these sites. In spite of the importance of shade tolerance in reforestation or seedling production in nurseries, some species such as Mana oak have not been well characterized. A completely random experimental design with light factor at four levels (20%, 40%, 60%, and 100% of sunlight) was used to study morphological and growth response of Manna oak seedlings in the first growing year. There were two samplings i) 100 days after germination and ii) 190 days after germination, using 20 seedlings for each treatment. The results showed that at the lowest light radiation level (20% of full sunlight) height growth, slenderness coefficient, root/shoot biomass ratio, and mean of leaf area increased whreas collar diameter, shoot biomass, net assimilation rate, and relative growth rate decreased. Since, high relative growth rate implies high survival rate, so Manna oak can be considered as shade intolerant species that in nurseries with no humidity limitations has the most efficiency in full sunlight.

Vegetation has a major impact on carbon sequestration and soil quality. In order to assess the effect of vegetation type on soil attributes, two different plantation of pure Bald Cypress (Taxodium distichum) and mixed Alder (Alnus subcordata) with Poplar (Populus deltoides) were selected in Safrabasteh Poplar Research Station, Guilan province. In each site morphological, physical and chemical soil properties were studied and compared with each other. The results showed that wet aggregate stability measured as mean weight diameter, bulk density and saturated hydraulic conductivity were significantly different between the two sites. The wet aggregate stability and soil hydraulic conductivity were significantly higher in soil of bald cypress stand compared to soil of alder and poplar stand. The soil with bald cypress stand had more organic carbon and lower bulk density compared to the soil with alder and poplar stand. The organic carbon content had a positive correlation with size of aggregates and a negative correlation with CaCO3 content of soils. The highest concentration of carbon was measured for aggregates with diameter greater than 6 mm. In contrast, aggregates with diameter of 0.25-0.6 mm had the highest concentration of CaCO3. The organic carbon contents of organic and mineral layers for soil with poplar and alder stand were 112.5 and 85.73 ton/ha and for soil with bald cypress stand were 123.08 and 102.97 ton/ha, respectively. The findings of this research indicate that vegetation cover has major impact on carbon sequestration and thereby controls quality indicators of soils. Bald cypress accumulated significantly more organic carbon in soil compared to the mixed alder and poplar stand.

Forest canopy rainfall interception loss (I) and canopy water storage capacity (S) are important components of the water balance in arid and semi-arid climate zones. The goal of this research was to quantify S and free throughfall (p) in a mature Pinus eldarica Medw. afforestation planted in the Chitgar Forest plantation near Tehran, Iran. Measurements of gross precipitation (GR (n=6)) and throughfall (TF (n=45)) were recorded on an event basis from September 2009 to April 2010. I was calculated as the difference between GR and TF. For the measurement period, GR totaled 164.8 mm and rainfall interception loss (I) was 61.2 mm. In this study S was estimated as 1.7 mm, 1.4 mm and 1.8 mm by methods of Leyton, Gash and Morton, and Pypker- Jackson, respectively. Free throughfall (p) was estimated 0.1422. I was estimated 44% and 91.3% of total GR for rainfall events sufficient to saturate the canopy (GR>1.6 mm) and insufficient to saturate the canopy (GR>1.6 mm), respectively. The results demonstrate that canopy storage capacity represents a considerable portion of intercepted rainfall from GR in P. eldarica plantation regions of the semi-arid climate zone of Iran where soil moisture is a limiting factor on plant growth and productivity.

Ziziphus genus, belongs to Rhamnaceae family wich contains several species and varieties, and is a most important drought and heat resistant plant and covers an area of about 450000 ha in Fars province. Phenological stages of the two main species: Ziziphus spina-christi and Z. nummularia, were studied. Three regions in Fars province including Khonj, Farrashband, and Mamassani were chosen and these habitats were visited at 2-3 week intervals annually from 2000 to 2007 and tree’s phenological events and characteristics were recorded. These characteristics included: the time of bud break, flowering, fruiting, ripening, and fruit and leaf shedding. Climatic and the vegetation composition data of the areas were also gathered and studied. The results showed that there are significant differences between the three regions in terms of the initiation of all phenological stages as well as between the two species in the three regions with regard to time of flowering, fruit ripening and tree shedding. However, the interaction of region and species was not significant. The results also indicated that growth patterns of the of Ziziphus species may alter with drought and heat variation in different seasons of the year and as the result, they usually have two distinctive growth and seed production seasons, annually. Z. spina-christi is an evergreen tree in its natural habitats, while Z. nummularia is a deciduous small tree. The flowering and seed production of this species happen two times annually as well. The result of this research helps the farmers to plan their utilization of the species such as grazing, fruit and leaf collection as well as bee keeping according to the phenological events and guarantee a sustainable yield production and utilization.

This study investigated the response of three prosopis species to drought stress at different life cycles. In order to investigate the effects of drought stress on seed germination, an experiment carried out based on completely randomized design with 3 replicates and different water potentials (0, -1, -3, -5 bar). Germination rate, germination percentage, root and shoot length in seeds and proline and sugar in seedlings were measured. At field, the species seasonal changes of proline, sugar, Na and K content of leaves, were measured. The Results showed that germination rate and germination percentage decreased in all species with increase in drought stress. The effects of drought on root and shoot length were the same as their effects on seed germination, except for prosopis juliflora. Compared to other species, P. juliflora showed the highest germination in all treatments. The results of field study showed that the highest accumulation of proline and sugar happened in summer in all plants. Drought stress caused proline and sugar accumulation in Prosopis Juliflora and P. koelziana. Drought increased only proline in P. cineraria and Na, K in Prosopis Juliflora. The response of the Prosopis species to drought at two life cycles (seedling and maturity), showed that amount of these solutes maybe accounted as a mechanism to tolerate drought stress. On the other hands, P. juliflora did better performance compared to the two other species in all measurements due to its better adaptation to drought stress. P. koelziana also made better performance compared to P. cineraria. It might be concluded that P. juliflora made a greatest resistance to drought stress compared to the two other species and can easily occupy the endemic habitats in south Iran.

The aim of this study was to investigate the ecological condition of Cerasus mahaleb, in Khouzestan province of Iran. For this 72 square plots (50×50 m) were used. At first 20 lines were allocated between valley and mountain tip at 100 m interval. Then the plots were allocated on each line by random-systematic method at 150 m interval. At each plot the associated plant cover, number of seedlings (natural regeneration of C. maheleb), soil physical and chemical properties, including pH, EC and soil particle distribution (texture) and topographical characteristics, including altitude, aspect and gradient, were studied and recorded. The collected data were analysied by PC-ORD (Nonmetric multidimensional scaling) and SPSS softwares. The results showed that the most frequency of Cerasus mahaleb was between 1950-2450 m above sea level on dry aspects (most in south-west aspect) with 50-70% and 30-50% gradient. The mean value of pH and EC were 7.84 and 13/08 ds⁄m, respectively. Soil texture was clay, clay-loam and sandy-clay-loam. The results of this study also showed that the ecological condictions of Cerasus mahaleb were similar o those of Fraxinus rotundifolia, Amygdalus scoparia, Ficus carica, Salix persica, Celtis caucasica, Acer monspessulanum, Crataegus aronia, Lonicera nummularifolia and Juniperus polycarpus and there was least ecological similarity with Daphne mucronata, Quercus persica, Pistacia mutica and Pistacia khinjuk.

Nowadays the investigation and identification of natural process such as succession and gaps existence in forest ecosystems have been considered extently in forests management programs. This study examined the regeneration of tree species in relation to size, shape, slope gradient and direction of gaps in a Fagetum community in Gorazbon district of Kheyrud Forest, northern Iran. Three sample area, each 25 ha, were selected and after field study, all gaps within the compartments 317, 318 and 319 were identified. Regeneration of all tree species were record in the gaps, using 100% inventory. Beech, maple, hornbeam and elm tree, were observed in all of the studied gaps, but no significant differences were observed between regeneration frequencies of the species in different gap sizes. The most frequent species were observed in elliptical-shaped gaps. The most frequency of regenerations of beech and maple were observed in slop classes of 11-20%. Also, regeneration of beech, maple, hornbeam and elm showed more frequency in southwest-facing gaps rather than the other directions. According to total number of regeneration in gaps located on the slopes, beech regeneration showed the best establishment rather than another species. Maple and hornbeam followed beech in next ranks.

Considering the light as one of the important ecological factors in silviculture and forest ecology, this paper aims to present some information about light regime at different forest stands. Sample plots were laid out in natural forest types, including: Ironwood (Parrotia persica)-Hornbeam (Carpinus betulus), Chestnut leaved Oak (Quercus castaneifolia)-Hornbeam, pure and mixed Beech (Fagus orientalis), Hornbeam-Beech and mixed broadleaves stands as well as in some pure and man made stands including chestnut leaved oak, Maple (Acer velutinum), Alder (Alnus subcordata) and Cypress (Cupressus sempervirens). Quantitative characteristics of the trees were assessed and one hemispherical photo was taken with fisheye camera within the plots. The photos were analyzed with GLA. Results showed that the canopy openness varied from 9.6% to 29.4% in the natural stands and from 0.9% to 17.2% in the plantations. Relative light intensity varied between 11.8% (pure beech) and 35.9% (hornbeam-beech) in the natural stands and between 1.4% (pure cypress) and 25.1% (pure alder) in the plantations. The minimum Leaf Area Index (LAI=1.4) was computed in the hornbeam-beech stand, whereas the maximum (LAI=5.8) was found in the pure cypress plantation. A various range of sun flecks was observed within the studied stands from 20 sun flecks with 200 minutes of direct sun light per day in the ironwood-hornbeam stand up to 2100 sun flecks with receiving of 2 minutes direct sunlight per day in the pure alder plantation. The maximum energy received in the studied stand of the Caspian forests was 43 MJm-2 in June. Knowledge of light climate in the forest stands can be applied in silvicultural tendings, to improve tree quality.