مجله پژوهش و توسعه جنگل
سال سوم شماره 3 (پاییز 1396)

The goal of study is to explore the impact of selection system on the variability of microbiological indices and characterization of their influencing factors in mixed beech stand of northern temperate forest. For this purpose, 18 sample plots were selected in the control and managed compartments of mixed beech (Fagus orientalis- Carpinus betulus). The plot size was 3×3 m within a gap area about 400 square meters. We measured some physical, chemical and biological soil properties in the depth of 10 cm. The soil respiration (average ± standard deviation) in understory (3.30±0.64 µmol.m2.s-1) was significantly greater than canopy gaps (2.50±0.62 µmol.m2.s-1) while soil organic carbon wasnt significantly different. We found that microbial respiration, microbial biomass carbon and microbial quotient were significant higher at increasing soil moisture and temperature in canopy gaps than understory, which reflected disturbance of canopy gap could change soil characteristics. Whereas, selection system as Silvicultural practices has no significant effect on above mentioned characteristics that could indicate similarities of ecosystems function between the two stands.

Knowledge of canopy and trunk ecohydrological parameters is a decision support tool for forest managers to choose suitable species for plantations, tree spacing, irrigation treatments, and silvicultural treatments including thinning, lighting, and pruning. The purpose was to estimate the canopy and trunk ecohydrological parameters of eldar pine (Pinus eldarica) in Chitgar Forest Park, near Tehran (Iran) during two years measurements. To measure gross rainfall, ten rain-gauges were installed in an open area adjacent to the trees, and throughfall were measured using 60 rain-gauges installed beneath of canopy, and stemflow was measured using the spiral type stemflow collectors installed at six trees. The results showed that estimated canopy saturation point, canopy storage capacity, the ratio of mean evaporation rate from to the mean rainfall intensity, and free throughfall coefficient were 2.07 mm, 0.97 mm, 0.27, and 0.30, respectively. Trunk storage capacity, stemflow partitioning coefficient, trunk saturation point, funneling ratio coefficient were estimated 0.36 mm, 0.17, 2.12 mm, and 8.54, respectively. This study was the first step for understanding the trunk and canopy ecohydrological parameters simultaneously. However, we recommend to consider all these parameters in longer periods collectively.

The high-altitude Lake Neor along with its southern and southwestern marginal peatlands in northwestern Iran (Ardebil province) are unique in terms of floral and vegetation diversity. This floristic study presents the floral composition of different vegetational belts of the southern part of the lake and its marginal peatlands along a humidity gradient. Four vegetation zones were defined based on vegetation composition and water availability. A total number of 84 plant taxa belonging to 45 genera and 27 families were identified. The most abundant families included Poaceae (10 species), Cyperaceae (9 species), Asteraceae and Fabaceae (6 species each) as well as Polygonaceae and Santalaceae (4 species each). The life form analysis revealed that hydrophytes (8 species, 61%) and helophytes (10 species, 47%) predominated in the first (shallow margins of the lake) and second (lake-peatland transition) zones. Whereas hemicryptophyte was the main life form in the third (peatland) and fourth (wet meadows) vegetation belts, with 23 (70%) and 15 species (80%), respectively. From a chorological viewpoint, the vast majority of the flora under consideration belonged to pluriregional and/or Irano-Turanian origins. The Neor montane wetland is one of the few ecosystems in Iran, which inhabit a number of rare plant species such as Sparganium emersum and Utricularia minor. Strict conservation of such unique vulnerable ecosystems may guarantee the long-term preservation of the genetic diversity of the country.

In this research two forest plantations (Picea abies and Fraxinus excelsior) with similar site conditions were selected in the near vicinity of each other. Three trees of each species were randomly selected for later analysis. Profile trenching method was then used to analyze and compare their root distribution. Root samples of each species were collected to test their tensile strength using a standard Instron. The results showed that, RAR values and additional root cohesion tend to decrease with soil depth following a logarithmic function for both forest species. Also for both studied species, root tensile strength tend to decrease with increasing root diameter following a power function. According to the results, over 80 percent of roots were found to be within the top 20 cm of soil profile, indicating the highest reinforcing contribution within this layer. The results revealed that the root tensile strength of Picea abies (19.31 ± 2.64 MPa) with roots diameter ranging from 0.32 to 4.93 mm were greater than that of Fraxinus excelsior (16.98 ± 1.01 MPa) with roots diameter ranging from 0.42 to 4.91. Also, the additional root cohesion from Picea abies (0.03 ± 0.008 kPa) was found to be significantly greater than that from Fraxinus excelsior (0.02 ± 0.005 kPa). The results of this work may help us when applying an efficient bioengineering technique.

To investigate effect of seed source on germination and seed and seedlings morphological traits of Quercus brantii lindl., a factorial experiment in a completely randomized design was considered. Seeds were selected of six populations including: Sardasht in West Azarbayejan, Selin in Kordestan, Chele in Kermanshah, Nojhian in Lorestan, Kabirkoh in Ilam and Dorag-Anari in Chaharmahalo Bakhtiari. At First, seed length and seed weight of 25 sample seeds from each population were measured. Then seeds were planted in three replications in germinator. After 5 days, to investigate germination characteristics, every day, number of germinated seeds were counted during 18 days. Then 3 to 5 seedlings of each seed sources was planted in peat and perlite. After 30 days, growth parameters such as height shoot, collar diameter, leaf number, shoot and root weights were measured. The analysis of variance results showed that the effect of seed source on seed length, seed weight, germination speed, germination time and root weight were significant.Generally, in the condition of present study, seeds and seedlings of Nojhian in Lorestan and Selin in Kurdistan were more suitable.

In close to nature silviculture system knowing the amount of forest stocking is critical issue to management, optimal and sustainable utilization of forest and its production. This research was done in compartments of 305, 306, and 309 with total area of 88 ha. Volume increment calculated using direct method by full calipering inventory. Current stocking volumes (2014) were acquired 431.6, 457.6, 455.7 m3ha-1 for 305, 306 and 309, respectively. The volume growth results showed that the gross annual volume increments were 3.3, 4.6, and 3.8 m3ha-1 for 305, 306 and 309, respectively. Furthermore, the percentage of the annual volume growth rate compared to beginning of period (2004) for small, intermediate and large diameter trees were 2.54, 2.03 and 0.96 in compartment 305 respectively. Moreover, the percentage of the annual volume growth rate compared to beginning of period (2004) for small, intermediate and large diameter trees were 2.58, 3.1 and 1.55 in compartment 306, respectively. The percentage of the annual volume growth rate compared to beginning of period (2004) for small, intermediate and large diameter trees were 7.08, 3 and 1 in compartment 309 respectively. The maximum amount of volume growth was occurred in 35 and 40 cm diameter classes while the growth rate was gradually reduced diameter classes greater than 75 cm.

On May 31, 2003 the Scan Line Corrector (SLC) in the ETM instrument on Landsat 7 failed. Until now, a wide variety of gap-filling methods have been developed to recover missing pixels in the Landsat 7 SLC-off images. In present study, a newly-developed approach known as the Weighted Linear Regression (WLR) method was evaluated on the simulated SLC-off TM image acquired on 18 June 2011 when plants and vegetated lands are growing. The statistical measures of the RMSE (