مجله جنگل ایران
سال ششم شماره 3 (پاییز 1393)

Some growth characteristics of Casuarina equisetifolia seedlings affected by salinity-flooding stresses including 0 (freshwater), 50, 100, 150 mili-Molar NaCl and control (without flooding and salinity) treatments were studied in greenhouse as completely randomized design for 120 days. The results showed survival in all treatments was 100%, but in flooding treatment with 150 mM NaCl it decreased to 33.3%. Height growth and diameter growth decreased in various levels of flooding-salinity, and also with increasing salinity. Flooding-salinity stress resulted in decreasing dry biomass of seedlings and creation of adventitious roots in all flooding levels, but the biomass and number of adventitious roots decreased with increasing salinity. Biomass of adventitious roots in flooding levels with freshwater, and flooding with 150 mM NaCl were 6 and 3 times of main roots biomass, respectively. Based on the observations, in all flooding levels, one week after stress, hypertrophy pores were formed in part of the stem located in water. Generally, this research showed that in the studied period in flooding treatment, growth and biomass allocations of organs of C. equisetifolia seedlings decreased with increasing salinity. However, treatments lower than 100 mM NaCl did not display any decrease in survival, but in lower salinity concentrations survival was always 100%. Regarding to creation of abundant adventitious roots and hypertrophy pores showing different resistance aspects to flooding, accomplishment of such a study in next growing seasons can reveal more accurate resistance of C. equisetifoliaseedlings to salinity-flooding stress.

Root morphology is one of the significant factors in success of heavy metal remediation of soils using plants where pollutant absorption takes place. In the present study, effect of soil pollution with heavy metals on some root morphological characteristics of two tree species, Populus alba L. and Populus nigra L., were studied. Root length, root diameter, lateral and main root biomass of one-year old seedlings grown in lead-, cadmium- and chromium (VI)-contaminated and uncontaminated soil were compared. The results indicated that increased concentration of three metals in soil led to decrease of all morphological traits of studied species (P<0.01). Maximum and minimum decreases were related to Cd and lead, respectively. Cadmium pollution at 150 mg kg-1 led to 25% and 20% decrease in lateral root production in P. nigra and P. alba, respectively in comparison with control treatment. In most studied traits, P.nigra showed more tolerance than P. alba in presence of pollutants. It seems that the strategy used by two species at the increased pollution levels defined by greater focus on main root production rather than lateral root production, could be a fundamental solution for higher tolerance.

Field maple is a native tree species scattered in high altitudes of northern forests. Seedling production of this species is taken into consideration for forest development programs. Lack of knowledge about possibility and storage conditions of field maple seeds due to intervals are main problems for seedling production of most forest tree species. For this reason, full ripened seeds of this species collected in November 2009 in Leher Forest at 1800 m above sea level were subjected to two different storage temperatures (room temperature ~20° C, cold store 2-4° C) at two moisture content levels (primary 12.2%, reduced ~6%). Results showed that field maple seeds at both levels of moistures can safely be stored at room temperature for one and two seasons. However, seeds maintained in cold store, at both level of moistures preserved their viability for 18 months. Based on the results, seeds of field maple can resist low moisture content and at such a condition can be safely kept in cold store. Furthermore, on the basis of seed storage behavior it can be categorized as orthodox.

Drought stress is one of the most important environmental factors limiting plant growth and development so finding the new techniques to evaluate the drought tolerance in plants, would be valuable. The purpose of this study was the application of chlorophyll fluorescence technique as a reliable method for rapid assessment of drought stress in hackberry seedlings (Celtis caucasica L.). An experiment was designed as completely randomized block with one factor (irrigation), at five levels (1, 3, 5, 7 and 9 days) with five replicates. Chlorophyll fluorescence parameters (Fv/Fm, Fm & F0), and the proline content of leaves in one-year-old seedlings of Celtis caucasica were measured. The results indicated that maximum fluorescence (Fm) had a significant reduction in the 9 days treatment. Also maximum photochemical efficiency of photosystem II (Fv/Fm) showed a significant downward trend since the 5 days treatment, while the minimum fluorescence (F0) was not significantly affected by drought. Increasing the intensity of drought was resulted in proline accumulation in leaves from 1.7 (µmol/gfw) in the 1 day treatment to 72.95 in the 9 days treatment. In afforestations and urban green spaces, measurement of chlorophyll fluorescence is a reliable method for identification of well-adapted species to environmental stress.

The objective of this study was to evaluate the diversity of soil invertebrates at Brutain pine (Pinus brutia Ten.) and Cypress (Cupressus sempervirens var. horizontalis) afforestations in Kordkoy region (Mazandaran-Iran). Tending operations have not been performed in these afforestations. For this purpose, invertebrates were sampled in mid-summer, using 20 core soil samples (81 cm2 cross section) to a depth of 10 cm. The fourteen groups of soil invertebrates in each sample were extracted by Berlese funnel and counted by Binocular. Also 20 soil pits of 100×100 cm2 with 10 cm and 20 cm depth were taken and adult earthworms were collected by hand counting. The results of this research showed that the diversity of soil invertebrates (Shanon and Simpson index) with species richness (Margalef index) and species equitability (Heip index) in the Brutain Pine afforestation was greater than Cypress afforestation. Of course it must be mentioned that these differences were not statistically significant. Overall, this study showed Brutain pine has provided a more favorable environment for the presence of soil invertebrates than cypress plantation.

The accuracy assessment of canopy cover density in a Persian oak (Quercus brantiiLindl) stand, using vertical sighting from terrestrial points toward canopy of treesto determine the presence or absence of canopy cover in grids with 195, 102, 49 and 23 points with a similarly made device of Cajanus tube were compared with together and with a line intersect sampling method. For this reason, in 0.49 ha sample plots, grids with mentioned number of points were laid out, and the method of 195 points was considered as control. Because of the nature of the data, Non-parametric Kruskal–Wallis statistical test was used to compare the ranked averages of methods. Moreover, accuracy values including RMSE (%) and Bias (%) were calculated for each of the methods. According to the results, there were no statistically significant differences between the used methods to estimate canopy cover. The least amount of Bias was related to grid with 102 points, line intersect sampling method, grid with 49 points and finally grid with 23 points, respectively.

In this study, the intra- and inter-population genetic diversities of 125 genotypes representing nine populations of Quercus brantii from North-Zagros forests were studied using leaf morphological characteristics, inter simple sequence repeats (ISSR) andinter retrotransposal amplified polymorphism (IRAP) markers. Cluster analysis based on morphological characteristics differentiated significantly the nine Q. brantii populations into six main groups. Eighteen ISSR and 10 IRAP primers amplified a total of 233 and 129 fragments of which 224 and 126 fragments were polymorphic, respectively. Both ISSR and IRAP marker systems revealed high genetic diversity at species level (ISSR: h= 0.24, PPL = 98.71%; IRAP: h= 0.21, PPL = 99.22%). Estimated coefficient of genetic differentiation (ΦST) based on ISSR and IRAP primers were 0.23 and 0.16, respectively indicating most of the total genetic variation distributed within populations than between populations for both marker systems that confirmed with molecular analysis of variance (AMOVA). The low level of genetic diversity between populations and high genetic differentiation among individuals within populations were probably due to extensive gene flow resulted from wind pollination of oaks. Cluster analysis for both molecular marker systems grouped these nine populations into distinct clusters within UPGMA dendrograms. There was no significant correlation between genetic distances of populations and geographic distribution distances with mantel test.

The aim of this research was to measure rainfall components (throughfall, interception, and stemflow) in needle-leaved (Pinus brutia, Cupressus arizonica) and broadleaved (Fraxinus rotundifolia and Platanus orientalis) plantations located in Broujerd Forest Park. The total amount of gross rainfall was measured using three rainfall collectors fixed on an open area neighboring to the chosen trees. In order to measure throughfall, five trees of each species were selected and four collectors were fixed underneath each tree. The amount of interception was calculated based on the difference between throughfall and gross rainfall. In a time-span of six months running from November 2012 to May 2013, 24 rainfall events with total amount of 131.8 mm was measured. The amount of interception was measured as follow: Pinus brutia 46.1%, Cupressus arizonica 50.7%, Fraxinus rotundifolia 49.6% and Platanus orientalis 38.1% of total gross rainfall. Strong positive correlations were observed between total rainfall and throughfall for each kind of species. It was found that throughfall in hardwoods species was more than conifer species and the amount of throughfall in aforesaid masses increased as total rainfall increased. The amount of stemflow for all species was less than one percent of total precipitation. Regarding to importance of rainfall regime in this area, interception and throughfall of each species should be considered with priority of broadleaved in plantation and hydrological modeling process in forest ecosystem.

The beginning and the ending of radial growth in trees depend on genetics and climatic factors and its intensity varies during a growing season. Studying wood formation dynamics in a growing season will increase our knowledge about xylogenesis of important species and the influencing parameters. For this reason and in order to have a better understanding of a radial growth in oak, four Quercus castaneifolia individual treeswere selected in the research forest of University of Tehran located in the Hyrcanian forest. In 2012, micro-core samples were extracted from trees by Tropher in monthly intervals. Cambial cell divisions and radial growth started approximately on mid-April and terminated at the end of September. The highest number of cambium cell (15-17) and the maximum daily growth rates of all trees were achieved around Mid-June. The results of this research showed that the majority of radial growth in oak occurs from May to mid- July and this fact should be considered in dendroclimatological studies.

The amounts of throughfall and interception loss are as significant as habitat suitability regarding to the tree selection for afforestation. Horizontal cypress (Cupressus horizontalis Mill.), Turkish pine (Pinus brutia Ten.), and chestnut-leaved oak (Quercus castaneifolia C.A. Mey.) have been mainly used in afforestation projects in the East of the Hyrcanian region. How these afforestations affect the precipitation components and water balance of the region, however, is obscure. The main objective of this study was to measure throughfall and interception loss of Horizontal cypress and Turkish pine afforestation as well as of a natural stand of chestnut-leaved oak, over a period of 12 months starting from May 2012. One rain gauge and four rain collectors were placed in an open area adjacent to the study area in order to measure precipitation. To measure throughfall, thirty five throughfall collectors were randomly installed under the canopy of each stand. The amount of gross precipitation was 1135 mm over the study period. Throughfall measurements for planted Horizontal cypress and Turkish pine, and for natural stand of chestnut-leaved oak, were 439.4, 642.7, and 614.7 mm, respectively. Interception loss estimated to be about 61%, 43%, and 46% of gross precipitation in the above mentioned species, respectively. The positive and statistically significant relationships were found between throughfall and gross precipitation for the investigated stands, and then were parameterized with the power regression model. The identical procedure was applied as well for interception loss and gross precipitation for the stands. The analysis showed that considerable amounts of gross precipitation were intercepted by the canopy cover of the study stands and subsequently evaporated into the atmosphere. Since the species used for afforestation has significant influences on the amount of water reached to the ground, throughfall and interception loss should be considered in the process of choosing the species.