Iranian Journal of Forest and Poplar Research
Year:2012 | Volume:20 | Issue:2 (48)|Papers Count:19

Despite the cost of forest roads, they are essential infrastructure to provide access for resource management. The quality of roads pavement depends largely on the material used, particularly type of pavement that sometimes includes up to 70% of total cost. The purpose of this study was to use the DCP for CBR assessment of a newly completed road segment. Therefore, a DCP and a penetrometer were used to assess penetration resistance. Then penetration index of DCP was converted to field CBR. The results showed that bearing ratio of sections with clay material (which treated with Ionic stabilizer) was significantly lower than sections with clay and gravel material. There is a significant positive correlation between values of DCP and penetrometer. CBR values of the investigated road were less than expected and improper for passing traffic, which road destruction and wheel rut caused by traffic pass at the end of summer, confirms the achieved result. Regarding the lack of CBR tests in forest road projects due to its cost-time consuming and road surface destruction, using DCP as a simple, efficient and non destructive tool is suggested for estimating field CBR.

In order to investigate and determine an appropriate inventory method for Yasuj Oak forests, considering inventory precision (confidence limit) and accuracy for canopy cover parameter per hectare, four methods consisting of: systematic-random (rectangular plots), transect, strip and stratification were selected and their efficiency in the forest was evaluated. For this purpose, at first 100% inventory was applied in 100 hectare area of Yasuj Mehrian Forests, then geographical characteristics of the total trees were recorded, using GPS apparatus. The geographical data were transmitted to computer and the trees positions were identified on the area’s digital map. The data which had been recorded at 30 replicates by the four inventory methods, were analyzes by AutoCAD, Arc View and Arc Info software's and the outputs were compared with the results of 100% inventory method. The results showed that the real average canopy cover (recorded from 100% inventory) was equal to 2257 m2/ha whereas for the inventory methods of: systematic-random, transect, strip and stratification, was equal to 2390, 2220, 1995 and 2341 m2/ha respectively. The statistical errors for systematic-random, transect and stratification inventory methods were 18, 4 and 14 percent, respectively. Although the strip method is lack of statistical basis, and calculation of sampling error and confidence limit is impossible, but comparing the average canopy cover of this method with the other inventory methods was possible. Overall, the greatest and the lowest accuracy rate belonged to transect and strip methods, respectively. It can be concluded that the transect is the most appropriate inventory method for these forests.

The aim of this study was to determine the most impotent Criteria and Indicators (C&I) in Tange Solak watershed of Kohgiloye va Boyerahmad province, for sustainable forest management. Determining the most important C&I, simplifies the forest control process. For this purpose, using the judgmental sampling method and questioner based on Likert scale, at first step the most important criteria and at second step the preference of key indicators were determined. At third step, using the Pressure-State-Response (PSR) framework, led to determine the most important responses for sustainable management indicators. The results showed that the extent of forest resources, law-organization framework and role of conservation are the most impotent criteria for sustainable management at the studied site. Total forest area, the area under conservation management, eroded area and national forest policy are the key indicators for sustainable management in the proposed site. The results of PSR analysis shows that developing national forest policy, applying integrated management and reinvestment are the most important responses for key indicators.

In this research, the adaptation and establishment of several industrial provenances of Eucalyptus was studied during a five year period. Climatic, edaphic and floristic data were primarily collected. In this trial, 15 species and provenances of Eucalyptus were planted under Complete Randomized Blocks design with 3×3m spacing. Factors including survival, height, diameter and crown cover of the rees were assessed annually. Based on Duncan’s test, E. camaldulensis 15195, E. camaldulensis15272, E. camaldulensis 20709, E. camaldulensis 15023 and E. maidenii 300-sh ranked in the higher class in terms of survival, but they achieved the middle class with regard to height and diameter parameters. E. globulus ssp. bicostata 16731 and E. camaldulensis 41-ch were classified in the lowest class in terms of survival, despite exhibiting excellent height and diameter growth.

Production and secretion of alkaline and acid phosphatase by microorganisms and plants has a very important role in mineralization of organic phosphate and availability of it for plants. Acid and alkaline phosphatase activity was assayed in two hazel natural habitats including Agh-e-velar in Gilan province and Arpatappeh in Ardebil province and compared with their activity in artificial habitat in Alborz research center in Alborz province. Soil sampling was made in spring and summer. Available phosphorus and acid and alkaline phosphatase activity was assayed by spectrophotometer. The results showed that available phosphor was 23.21, 32.42 and 56.8 ppm in Arpatappeh, Alborz and Agh-e-velar habitats, respectively. Acid phosphatase (678.02(±29.52) µg ρNP g-1 h-1) and alkaline phosphatase (520.35(±21.38) µg ρNP g-1 h-1) activity in Arpatappeh was more than the those in other habitats at both spring and summer seasons. In addition, acid phosphatase activity in summer was almost 2.5 times more than that one in summer at the three locations, which indicates root growth through growth season. Alkaline phosphates showed opposite pattern. Alkaline phosphatase activity in summer samples was two times more than its samples in spring at the three locations, which indicates a decrease in microbial activity at summer

This research was conducted for the first time in Iran on Northern Zagros Forests close to Halou village located 40 km far west of Baneh City at Kurdistan province. 120 sample trees of Gall oak (Quercus infectoria) were selected, using stratified random sampling method and their seed amount was measured, using different methods of visual surveys (Whitehead, Christisen-Kearby and Modified Graves), then the achieved data were correlated with the crown counting data. Stem diameter at breast height and big and small diameters of crown of the trees were measured. In early September, just prior to acorn fall, each tree was surveyed; using the visual survey methods and its acorn density (acorns number/m2 crown area) was calculated, using crown counting method. The results showed that 24 of the sampled trees had no acorn and average acorn density was 7.2. Overall, weak acorn production of Q. infectoria was observed, based on the estimated visual survey indexes and the best visual estimation method was Whitehead (r2=0.87). Finally, usefulness of the visual survey methods was confirmed due to their simple application, acceptable accuracy and low labor costs.

This research was performed in Chamestan Forest and Rangeland Experimental Station since 1994. In this research chestnut leaved oak (Quercus castaneifolia) was planted at pure and mixed plantation, including Siberian elm (Zelkova carpinifolia), maple (Acer velutinum), hackberry (Celtis australis) and hornbeam (Carpinus betulus). The aims of this research were as follows: 1. investigation on nutritional elements of the leaves and their return by senescent leaves at both pure and mixed plantations, 2. litter production of the species and nutrient fluxes in the two plantation types. For these reasons, sampling was made from the fresh leaves in August and for the senescent leaves in November, and the elements were measured in laboratory. Litter traps were located within the treatment's plots for litter collection and litter dry weight was measured and recorded. The results showed that the mixed plantations produced more amounts of nutritional elements than the pure plantations. Dry litter production was 5.02 to 6.14 ton per hectare per year, which was more than the European temperate broadleaved forests production. The concentration of elements in the mixed oak- maple plantation was more than the pure oak and the other mixed plantations. It can be concluded that investigation on nutritional behavior of forest trees is very important for sustainable forest management.

The importance of land-use/ land-cover (LULC) as a dynamic factor and effective on environmental conditions, makes it necessary to get precise quantitative and qualitative information from it and to identify its changes through short time periods. Modeling LULC changes provides useful information for better understanding of the changes process, determining driving forces and predicting areas under change conditions. In this study, the integrated CA-Markov model was used to simulate forest cover changes in the Chehelchay Water catchment at minodasht area of Golestan province of Iran. CA-Markov is a combined Cellular Automata/Markov chain land cover prediction procedure that adds an element of spatial contiguity to the stochastic Markov chain analysis. Landsat images of 1987 and 2009 and land-use map of 2001 were used to derive forest extent maps of the Chehelchay Water catchment and characterize changes through time. To investigate the relationships between forest extent changes and some environmental and human-related factors and to produce transition suitability maps, a logistic regression analysis was applied between forest extent changes as response variable and the deriving factors as explanatory variables. Future LULC types for 2009 were then predicted using CA–Markov model, based on the land-cover changes between 1987 and 2001. In order to evaluate the modeling results, prediction for 2009 was compared with the observed 2009 land cover map. The computed accuracy coefficient indicated high efficiency of CA-Markov for simulating forest extent changes in the Chehelchay Water catchment (Kappa=0.92). Finally, assuming current trends in LULC changes continue, forest cover map for the year 2020 was developed. The results indicate that there will be a notable decrease in forest area.

Plant litter decomposition plays an important role in forest soil fertility due to nutrient cycling and soil organic matter formation. Litter decomposition, results in return of leaves nutrient to soil and supply of necessary elements for plant growth. In fact, nutrient availability is highly related to litter nutrient dynamic in soil. In this study the nutrient dynamic of Norway spruce litter was investigated in both pure and mixed condition to determine whether its nutrient dynamic is affected by its composition with broad-leaved litters or not. For this reason, Norway spruce litters were treated for 400 days at pure and mixed conditions with Beech (Fagus orientalis lipsky), Alder (Alnus subcordata C.A.Meyer) and Maple (Acer velutinum Boiss.) litters in pure Norway spruce plantation at Lajim site, using litter bag method. The results showed that the non-additive effect of litter composition on dynamic of lignin and manganese was neutral, but on dynamic of nitrogen, potassium and magnesium was positive, whereas on dynamic of calcium was negative. The finding of this study showed that litter mineralization rate of nitrogen in the three treatments of litter composition was higher than the its rate in the pure Norway spruce litter, whereas the mineralization rate of manganese was negative at the end of the study time in all the combinations, except for Norway spruce mixed with beech.

The significance of biodiversity maintenance in sustainable forest management has been indicated at many scientific studies. The present study was conducted to investigate the impact of Pine (Pinus nigra Arnold.) and Ash (Fraxinus excelsior L.) plantations on diversity of herbaceous vegetation cover and soil properties in Alandan site of Sari Forest area of the Iranian Caspian Forests. herbaceous vegetation cover percentage and natural regeneration number of woody species were measured, using six plots (20×20 m.) at each stand, which have been selected by random systemic statistical method. Soil sampling was made at center of each plot up to 30 cm depth at 10 cm intervals, using coring method (8 cm diameter). Soil tested propertirs consisted of: C, N, pH, EC, particle density and bulk density. Biodiversity indices (Shannon, Simpson), richness indices (Menhinick, Margalef) and uniformity indices (Equitability, Evenness) were estimated, using PAST software. The results showed that the biodiversity richness and evenness indices for herbaceous species cover and woody species regeneration at pine stand were greater than at the ash stand (p<0.05). There were significant differences in some of the soil properties between the both investigated stands (p<0.05). Despite the common believe about unfavorable biological conditions in coniferous stands, findings of this investigation suggested that the conditions under the pine canopy might be suitable for presence of some herbaceous and woody species with similar ecological needs, 25 years after plantation.

The rock proportion of the subsoil directly influences on the cost of embankment in forest road construction. Therefore, developing a reliable framework for rock ratio estimation prior the road planning may lead to more light excavation and less cost operation. According to the ordinal nature of hardness classes of the soil in executive branches, the purpose of present research is to model the ratio of rocks in the subsoil as a function of terrain slope and geology information using Ordinal Logistic Regression Model. To do so, first, the geological units were weighted using the Analytical Hierarchy Process (AHP). The obtained priorities and terrain slope data were feed to the model. To evaluate effects of change in link functions, five types of link functions were adapted. The results showed that the Probit function gives the best determination coefficient and parallel lines test for our model. To show the applicability of the proposed approach, the optimum model was applied to a mountainous forest in where additional forest road network should be constructed in the next periods.

Population Increase and cities expansion caused increase in energy consumption and negative effects on climate temperature changes and on physical and mental health of cities residents as well. One of the effective solutions is preservation and development of urban forestry (green space) which can retrieve partly, these negative effects. In order to investigate the urban forestry economy effects (green space), 384 questionnaires were distributed among people and the data were analyzed, using SPSS software. The results indicate that urban forestry has useful effects on energy consumption. Based on calculated coefficient of determination (R2), 56% of variation of depended variable (Urban forestry or green space) can be predicted and determined by tree variables (turn on air conditioner time, maximum of energy consumption and energy cost in hot season). Finally, a mathematical correlation between urban forestry and economical factors was developed. The correlation showed that development of urban forestry (green space) decreased the various costs.

Biological property is a best indicator for soil quality identification due to its relationships with soil nutrient cycle, respiration, microbial biomass and enzymes activity. The aim of the research was to study the influence of two even-aged and adjacent stands of loblolly pine (Alnus glutinosa L. (Gaertn.) and alder (Pinus taeda L.) on activity of dehydrogenase and urease enzymes, microbial biomass and some of the soil chemical and physical properties at west of Guilan province. Soil sampling was made up to 20 cm depth of soil surface (0-10 and 10-20cm). Dehydrogenase and urease enzymes activities and microbial biomass were measured, using the substrate reaction method and application of spectrophotometer device. The tested soil properties consisted of: texture, bulk density, mean particle density, moisture content, pH, organic carbon, total nitrogen, phosphorus and potassium. The results showed that there were significant differences between the two stands in respect to amounts of dehydrogenase and urease enzymes, microbial biomass, carbon, nitrogen and potassium. The amount of urease and dehydrogenase enzymes, microbial biomass, organic carbon and nitrogen in alder stand was more than in the loblooly Pine stand. There were significant correlations between the enzymes density and microbial biomass, organic carbon, nitrogen, pH, potassium, soil texture and soil porosity. Overall, it might be concluded that the alder stand provided better condition for organic matter and microbial production and microbial biomass development and activity.

The aim of the study was to investigate the effects of economical-social factors on poplar plantation development at Somesara city. The statistical society consisted of 200 poplar planter households in 2009 to 2010 at Somesara city at minimum acrage of three hectars. The field study was conducted, using questionnaires. Simple random sampling was applied to colloct data. The data was analyzed, using SPSS software and multivariate linear regression. The results showed that 17.5 % of the variance of poplar cultivation and development related to four variables, including: first year of poplar cultivation, attending training courses, amount of governmental loans and support and first acrage of poplar cultivation.