فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیستم شماره 1 (پیاپی 47، بهار 1391)

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 490 °C 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 150 ˚C، respectively. Also، maximum available phosphorus was measured 14. 99 (mg/kg) in soil depth 0-5 cm burned at 350 ˚C. 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.