نشریه علوم و فنون منابع طبیعی
سال هفتم شماره 4 (زمستان 1391)

Stand stability is considered as one of the most important issues in Naturalist sylviculture method which has been introduced in recent decades. This may cause increase in stand biodiversity and moving to its ideal state. The Present study was designed to assess physiographic and qualitative and quantitative characteristics of common ash (F. excelsior L.) as a native species in the Hyrcanian forests. To achieve these aims, 50 sample plots in a randomized design with 1000 m square (circular shape) at parcels #314 and 315 of Tarbiat Modares university research and educational woodlot’s, located in watershed #45, were selected. Results of physiographic parameters show that 68.17% and 43.00% of all species were distributed 800-900 m above sea level and northwest aspect, respectively, while only 72.60% of those were on the slope 10-40%. In addition, distribution pattern of ash trees in diameter class shows that its skewness is to the right. So the highest density of it was in 20-30 cm diameter class. Quantities results of common ash also shows that 86.00% of trees branching was extended in the height more than 10 m, 47.00% of them have polar crown, as well as more than 60.00% of them have less stem curves and healthy stem. Results showed that this species can be nominated as a unique species in yearly afforestation activities especially in enriching beech stands. Future studies may require completing current study on other aspects of affecting parameters like soil characteristics in other sections of Hyrcanian forests.

According to forest ecosystem condition in Hyrcanian forests, the fixed numbers can not be useful for determining forest roads width In addifion, these numbers are frequently ignored by the executives and road constructors in order to preserve valuable trees and avoid cutting these trees on sensitive points such as cut slopes and fill slopes. In some cases that roads width is considered based on standard numbers, the vegetative characteristics of edge stands is determined by resl forest roads width. In this study the status of resl width was evaluated based on land slope, earth working limit, vegetative characteristics of edge stands and different slope classes of hillside in shenrood- siyahkal forests. Results showed that the forest roads right-of-way increased with raising hillside gradient (p < 0.05). The mean width of real right-of-way in type A (Fagetoalnetum with 237 stem per hectare and crown cover 68 percent) and B (Fagetocarpinetum with 192 stem per hectare and crown cover 70 percent) were 28.6 and 30.4, respectively. The most overlapped area between real right-of-way and slope of roads was observed in slope classes of 30-40 and 40-50 percent in both types and the lowest overlapped area was seen in slope classes of 50-60 and 60- 70 percent.

The effect of seed Provenance on the rate of seed germination and some quantitative characteristics of Cappadocian Maple seedling were investigated in this study. To achieve this goal seeds from the two seed Provenances were collected from Pahne kola (250 m) and Lajym (900 m). These Seeds were planted in the form of a completely randomized block design in nursery in Mazandaran pulp and paper company. then, after eight months of planting, percent age of seed survival, diameter and height growth, leaf number, stem on root ratio and root, stem and leaf biomass were measured. The results showed that the two source parameters studied were %99 significantly different and seedlings of seeds from Lajym source showed more favorable conditions.

This research is to study quantitative and qualitative characteristics of a 20 years stand of Cedrus deodara on Forest, Rangeland & Watershed Organization (F.R.W.O.) yard (Chaloos) with 1.8 ha area, in which full callipering method was used. Results showed the survival of Cedrus deodara was 91%, the mean diameter of Deodar cedar was 32.4cm and the mean annual diameter increment was 16.1mm. The mean height and mean annual height increment were 16.2 and 0.81m respectively. The volume of trees was 202.1m3he-1 and the mean annual volume increment was 10.1m3he-1. Relative frequency of one-branched stem was 85.3% and other trees forked. About 4.1% of cedar trees have weak vitality which were possible to be eliminated in the future. In general, the increment of quantitative parameters of Cedrus deodara and the status of qualitative parameters of trees have a good condition that make it possible for the region to be selected as a seed collection area.

In this study, CMP pulp yield and refining energy consumption of treated pulp affected by the fungus Phanerochaete chrysosporium BKM - 1767 were evaluated and compared with control samples. After preparing fungal specimens, hornbeam chips were treated at three levels 1, 2 and 4 weeks under temperature 39oC with relative humidity 65%. For preparing CMP pulp from treated chips, Production conditions were as follows: cooking temperature 165oC, cooking time (80 and 90 minutes), the percentage of sodium sulfite chemicals: 14%, 18%, 22% in comparison to the cooking liquid to chips which was 7 to 1. The results showed that treated wood, rate of output has decreased. In comparison to the control group. The reduction for treatments for the weeks 1, 2 and 4 was about 1.64, 2.84, and 6.20 percent respectively. Furthermore, increasing the consumption of chemicals has increased the yield, which actually increased the severity of reactions compression yield after cooking. The results of refining showed increasing the fungal treatment period caused easier refining and less consumed energy so that the week 4 treatment caused 40% reduction in refining energy.

In order to evaluate the performance (aggregative, technical and scale), a number of forest harvesting projects providing wood for demanding industries, were randomly selected. Input and output variables were determined using field surveying while applying the Delphi method. The actual value of input and output variables were extracted from forest harvesting projects. The input oriented models of CCR and BCC based on slacks variable were used for the evaluation of performances of fifty one projects at the end of their first and second 10-year periods for this research. Fifty one wood-producing projects were studied in three north Iranian provinces using Data Envelopment Analysis (DEA) The performance of wood-producing projects were calculated using two forms; constant returns to scale (technical efficiency) and variable returns to scale (scale efficiency). The results indicated that few projects were efficient reaching to the average aggregative, technical and scale efficiency of 40.38, 55.46 and 70.10% at the end of first 10 year projects and 40.72, 54.70 and 71.10 at the second 10 year projects. The results showed the score of scale efficiency is higher than technical efficiency at all times but the value of it for the first 10 years projects is lower than the second 10 years projects.

This study investigated the effect of temperature (120, 150 and 180 oc) and time (half an hour and 2 hours) in the hydrothermal treatment on physical properties, mechanical and natural durability of wood against White rot fungi (Coriolus versicolor). For this purpose, laboratory standard specimens were prepared and heat treated. Oven dried density, shrinkage and swelling and antiswelling efficiency as physical properties; stiffness on tangential surface and impact as mechanical properties and weight loss, willeitner scale (apparent damage) and surface covered by fungus as durability, were measured and statistically compared with control samples. The results show that the hydrothermal treatment lead to a reduction in oven dried density, darkening of color, and reducing the swelling in tangential, radial and volume of hornbeam wood. Increasing heat treatment temperature and time caused enhancement of anti-swelling effect in dimensions and volume of wood. The results also showed that heat treatment in general leads to toughness decrease, and rising temperature and time caused Increase the toughness degradation of wood. About impact, applying the more intense heat treatment, reduced the wood impact resistance. The results of the heat treated and control wood samples exposed to White rot fungi in laboratory conditions showed that thermal treatment, partly, lead to the improvement of durability of wood. However, checking the samples mold cover percent and willeitner scale indicated that heat treated samples with the characteristics of this study can only be considered as weak wood.

Riparian forests are forests which grow adjacent to streams, lakes, and other surface waters. Intensive activities in riparian areas can lead to serious losses of stream habitat and water quality. Sedimentation rates increase, and stream channels are altered. Examples of this situation is riparian zones of “Aras river” that include the removal of streamside vegetation, removing woody debris and boulders from streams for navigation, stream channelization, damming. This study measured the relationship between density of Populus deltoids and some soil characteritics on riparian zones of aras river, located on the north of Ardabil, Iran. For this purpose, by using systematic-random sampling method, 31 quadrats were set up in key area and density of Populus deltoids were measured, and for soil characteristics, 16 profile was dug. Determined factors for each soil sample were important factors of soil. Results indicated that, among the soil factors, the most density were observed on the sandy- loam texture, and salinity had no significant influence on density, but T.N.V, pH and SP had significantly affected the density of this species. Correlation coefficients of evaluated parameters showed that density of Populus deltoids with determined factors of soil and stepwise regression between soil and density of Populus deltoids were differently correlated and determined the important soil factors affecting this property.