Iranian journal of Forest
Year:2011 | Volume:3 | Issue:1|Papers Count:10

National Botanical Garden of Iran (N.B.G.I) consists of different native and exotic collections. Pistacia atlanticais one of the main species which has remarkable density in native collections. Woody species existed in national botanical gardens throughout the world have effective role to absorb CO2 from atmosphere. In this research, leaf biomass and leaf carbon sequestration ofPistacia atlantica was studied in N.B.G.I. At first, 30 trees were selected using stratified random sampling method and quantitative parameters were measured. All leaves of 1/4 crown area were gathered, weighted and dried. Enough quantity of leaves was burned in electrical kiln to calculate the Carbon storage. Finally, amount of atmosphere CO2 absorption was determined and allometric regressions were calculated. Based on results, mean of leaf biomass, mean of leaf Carbon sequestration and mean of atmosphere CO2 absorption were 69.4, 26.2 and 96.3 kg per hectare, respectively. Diameter difference had no effect on leaf biomass and leaf Carbon sequestration. There was good relationship between mean diameter of crown with leaf biomass and leaf Carbon sequestration.

Emission of carbon dioxide via human activities is known as the main cause of global warming. Appropriate forest management practices can have effective role to mitigate carbon emission as well as adsorb atmospheric carbon. The present research was carried out to investigate the effect of 35 years old Common ash (Fraxinus excelsior L.), Chestnut-leaved Oak (Quercus castaneifolia C.A.Mey), Norway spruce (Picea abiesL. Krast) and Black pine (Pinus nigra Arn.) plantations on soil carbon sequestration in Dehmian plantation. Systematic soil sampling was done randomly. Totally 54 soil samples were taken from the top soil layers (0-10 and 10-20cm depths) in four plantations. Soil texture, pH, bulk density, electrical conductivity, organic carbon and total nitrogen were measured in the laboratory. Analysis of variance indicated that the amount of soil carbon sequestration of softwood plantations stands increased in comparison with hardwood ones. Results showed that the amount of soil carbon sequestration in Norway spruce stand (124.27 ton/ha) was significantly (P<0.05) higher than Black pine (94.67 ton/ha), Common ash (87.58 ton/ha) and oak (78.11 ton/ha). Results of stepwise regression showed that nitrogen percentage and C/N ratio were the most important factors affecting soil organic carbon content.

Understanding "what kind of damage, where it occurs during the timber harvesting process, and how serious it is" can help the wood products industry to make proper decisions and take the necessary precautions to promote better utilization of forest resources. The objectives of this study are to determine which processes cause damage, the type of damage, where and how they occur, to focus on whether the volume and value of hardwood logs harvested in this region are affected by harvest operations, to determine what actions can be taken to minimize the effects of damage throughout the tree felling process. This study was carried out in compartments 208 and 211 in Namkhaneh district in Kheyrud forest. In order to calculate the wood value loss following tree felling, 206 trees consisting of beech and hornbeam species were measured. There were five types of damage recorded: split damage, gouge damage, slab damage, scrape damage & no damage. The total volume of damaged logs was 46.87 cubic meters (5.2 %) for all trees. The majority of woody tissue damage is caused by splits and slabs. Gouges and scrapes caused a small amount of volume loss. Finally, wood value losses for each group were measured.

Digital images which have been acquired by UltraCamD advanced aerial camera from Northern forests of Iran have potentially valuable data for obtaining useful information. In this study a pan-sharpened imagery (in 4 bands with 16 bit spectral and 7 cm spatial resolution) collected in 2008 from a forestation area near the town of Nur, was analyzed for tree identification. On-board GPS/IMU parameters along with ground control points using DGPS were applied to ortho-rectify the image precisely. Appropriate enhancement methods were accomplished and different band sets were utilized based on original and derivative images. The same training sets were utilized for both pixel-based and object-based classification methods. Reference map was produced through fieldwork for assessment of the accuracy of resulted maps. In pixel-based method supervised maximum likelihood classification was carried out. For object-based classification, segmentation was conducted stepwise at two levels in order to construct a hierarchical image object network. Initially various alternatives of segmentation with different color, shape, compactness, smoothness and scale parameters were tried. The classification hierarchy was developed and Nearest Neighbor classifier based on Fuzzy logic, using integration of different object features was performed. By examination of different features and band sets along with the revising training areas, the optimum classification framework was established based on Class separability, Best classification results, Class stability and Accuracy assessment.The comparison of the resulted maps with reference data showed that object-based approach produced significantly higher overall accuracy and Kappa index. Meanwhile the resulted maps indicated the nonexistence of "salt and pepper" effect, like pixel-based results. Furthermore object-based method separate properly the species mixed spectrally, considering spatial information. The accuracy of detailed vegetation classification with very high-resolution imagery is highly dependent upon the type and separability of the classes, segmentation quality, sample size, sampling quality, classification framework and ground vegetation distribution and mixture.

Timber marking is one of the most important silvicultural intervention which affects directly on forest stand. This research investigates the impact of timber marking on qualitative and quantitative characteristics of forest stand in Shourab district (compartment No.149). Comparing the condition of managed forest with control forest as well as proposes new approaches in timber marking were also envisaged. For this purpose, all of the marked trees in the studied area were tailed in the fall of 2007 before harvesting and their spatial coordinates were recorded, as well. Results showed that the most marked and harvested trees have been in high diameter classes while tree densities in this classes are fairly low. The mean rate of harvesting volume was 63.5 m3/ha in which the most part of them belonged to high quality of beech (Fagus orientalis Lipsky) trees. On the other hand, the spatial pattern of marked trees investigated using Ripley' sK function was highly aggregated. The important point in timber marking is the change of forest harvesting conception from timber production to silvicultural tending. At the same time, the correct information according to forest stands is important for proper forest management.

Studying the soil and eucalypt relationships is essential for eucalypts plantation and avoidance of their negative effects on soil productivity. For this purpose, eucalypt species trial consisting of six species (E. camaldulensis, E. macarthurii, E. maidenii, E. rubida, E. saligna, and E. viminalis) planted in 1983 was conducted. Randomized Complete Blocks with four replicates at 2 x 2 m spacing and total number of 100 seedlings at each plot was used for this research. At each plot, three trees were randomly selected and leaf sampling was done for each tree at 1/3 of upper height at the end of summer. The aim of the study was to investigate the nutrients of six eucalypt species planted at Guilan province, Iran. The results showed that there was not significant difference among the replicates regarding the amount of N, P and K, but there was significant difference between the eucalypt species in respect to amount of N. There was significant correlation between K% and P% of eucalypt leaves and some soil characteristics.

This study is aimed to access the impact of land use change (from forest areas to forest parks) on vegetation and soil inParisan's park (Ilam Provience). For this purpose, three zones including non-recreation, extensive recreation and intensive recreation were chosen. In each area 20 sample plots in a systematic random design (100 m´150 m) were established. Herbaceous species type and their coverage were recorded using 4 microplots (1.5 m2) within each sample plot. In each plot, three soil samples were taken from 0-30 cm depth and a mixed sample was transferred to soil laboratory. Cluster Analysis and Detrended Correspondence Analysis were used for better understanding of the vegetation structure, to avoid subjective classification and to indicate the major gradient of variation within the vegetation structure of three areas. Canonical Correspondence analysis was applied to determine important soil variables of three areas. Results showed that the vegetation in intensive recreation area was completely different from non- and extensive recreation areas and was classified as distinctive group. Total nitrogen, organic carbon, phosphorus and exchangeable potassium and litter depth were decreased in the intensive recreation area, but pH and bulk density were increased.

Long term sustainability of forest ecosystems is dependent on preserving soil quality. Therefore, knowing the forest soil conditions and studying the different action effects on status of soils are very important and it can be effective in forest management. This study investigated the effect of cutting and delimbing of trees, as one of the most important damaging factors, on soil properties in Zagross forest. For this purpose, two selected forest stands including highly-damaged (as a usual damaging area) and less-damaged area (because of its low accessibility) were selected. The most important physical and chemical soil properties and quantitative characteristic of trees including canopy percentage, density, basal area and height were analyzed. The results showed that soil factors were affected by trees and damaging factors. All of physical and chemical soil properties and quantitative characteristics of trees showed significant differences between two areas. The results of correlation analyses between physical and chemical soil factors and quantitative characteristics of trees in less-damaged area showed that there is a positive correlation between percentage of canopy, basal area and height of trees with C, P and N. On the other hand, these tree characteristics showed negative correlation with C/N and bulk density. Existence of trees and lack of delimbing in less-damaged area have created suitable conditions for forest soil.