فهرست مطالب iraj hassanzad navroodi

The distribution of canopy classes is the most important structural characteristics of Zagros forest stands. Determining the fitting pattern of canopy classes in Zagros forests shows that, the overall status of these forests from the destruction process and ecological sequence points of view at different times. The aim of this research was to evaluate of probability-statistical functions in order to fit canopy classes of trees in Chartagh forests of Ardal city, Chaharmahal ve Bakhtiari, Iran.

For this purpose, an area of 50 hectares in Ardal forests was selected (3157 trees) were fully callipered and statistically analyzed. Exponential, Gamma, Normal, Beta, Weibull and Log-normal probability distribution patterns were fitted to crown canopy classes. Characteristics of distribution patterns were estimated using maximum likelihood method. Kolmogorov-Smirnov, Anderson-Darling and Chi-square tests were used for comparing of actual probability and probability which derived from functions.

The results of fitting tests showed that log-normal probability distribution was suitable for canopy classes modelling in Chartagh forests.  

Log-normal probability distributions can be used for those who want to simulate changes of forests

The tree crown component is one of the decisions making tools in units of forest management and commonly used in growth and yield models. One of the indices in related to tree crown in crown ratio which is the ratio of live crown length to the total height of the tree. The purpose of this study was to crown ratio modeling of poplar trees (Populus deltoides) using linear and nonlinear regressions (exponential, logistic and Chapman-Richard) in plantations of Guilan province.

For this purpose, the data related to 660 poplar trees including DBH, collar diameter, total height, crown length, crown width, crown area, crown diameter, basal area, tree slenderness coefficient, stem height and crown ratio were measured and recorded. To evaluate and compare different models were used coefficient of determination (R2), paired-samples t-test and four accuracy statistics including ME, RMSE, MEr and RMSEr.

The coefficient of determination of linear and nonlinear models showed that all models have acceptable coefficient of determination. Also, the results of accuracy statistics showed that the exponential and linear models were more accurate than the other models. But the results of mean comparison test indicated there was no significant difference between of measured mean with estimated mean of crown ratio derived from exponential model. While there was significant difference between of measured mean of crown ratio with estimated mean of linear, logistic and Chapman-Richard models. Regarding to the results of precision and accuracy of studied models, exponential model was selected as the more suitable model for estimation of crown ratio of poplar trees in plantations of Guilan province.

Based on the obtained results, it can be suggested to use the crown ratio index in order to select a suitable species for wood cultivation.

Recreation use assessment is considered as an important tool for sustainable tourism development and also ecotourism management development causes local economic growth and biodiversity conservation‎.The main objective of this study is to identify and prioritize the potential ecotourism site in Hassanabad forest park.

Analysis system Makhdoom and Analytic Hierarchy Process (AHP) combined with Geographic Information System (GIS) was used.
In AHP method after identification effective factors on recreational potential, a matrix is formed and factors were compared by the experts in the form of questionnaire. Next factors were weighed and ranked the regions for recreational potential. In Makhdoom method after identifying ecological sources, the data were collected and analyzed to ecological homogenous units. Finally the map of final resorting capacity was provided by comparing ecological traits of each unit with Makhdoom tourism ecological model. Eventually maps obtained by the two methods in GIS were overlapped.

Results of AHP model showed that the total area of the park (434/6 ha) has recreational potential of medium to high class. This area has no zone with very low recreational potential. In makhdoom method, this area includes all of recreational classes except concentrated recreational potential zone of first class.  

In both methods, the recreational potential classes have 50% overlapping. Since after applying two methods, the park has no inappropriate zones for tourism, this area is suitable for the development of ecotourism plans.

In this research, modeling tree height distributions of beech in natural forests of Masal that is located in Guilan province; was investigated. Inventory was carried out using systematic random sampling with network dimensions of 150×200 m and area sample plot of 0.1 ha. DBH and heights of 630 beech trees in 30 sample plots were measured. Beta, Gamma, Normal, Log-normal and Weibull probability distribution function were surveyed. Characteristics of distribution functions were estimated by using of maximum likelihood method. Actual probability and probability which derived from functions was compared using Kolmogorov-Smirnov and Anderson-Darling tests. Results of Kolmogorov-Smirnov test showed that only Beta probability distribution function was suitable for modeling height distribution of beech; while results of Anderson-Darling tests demonstrated probability distribution functions of Beta, Normal, and Weibull were fitted to the height distribution of trees. Therefore probability distribution function of Beta was selected for modeling height distribution of beech.

The present study aimed to investigate the accuracy and precision estimation of the number, basal area and volume of the standing trees by methods of random and systematic random sampling in the forests of West Guilan. The cost or inventory time was determined using the criteria (E%2 × T). Inventory was carried out by complete sampling (census) in an area of 52 hectares. The study area (section 11, district 2, Nav forests, Asalem) was divided into 520 rectangular plots (50m×20m) and each plot was measured separately. Measured characteristics were the kind of tree species, diameter at breast height and height. After inventory operation, the study area was stratified based on forest density. In each stratum, sampling was carried out by simple random sampling and systematic random sampling. The results showed that implementation of stratified sampling has reduced the sampling error and increased the sampling time for estimating the characteristics of abundance, basal area and standing volume of trees per ha in the study area. Amount of criterion (E%2 × T) in stratified sampling was less than sampling without stratification and between stratified samplings; stratified random systematic sampling had the lowest value. Therefore, among the studied methods, stratified random systematic sampling, due to high precision and minimum criteria of (E%2 × T), was a suitable method for evaluation of the number, Basal area and volume of standing trees in the study area.

To evaluate the quantitative and composition status of the trees regeneration in natural forest stands of Astara region, were studied the less disturbed areas in Astara (watershed 1). After selecting the study areaو sampling was done by systematic random method. Sample plots were circle shape with area of 0.1 ha. The relevant data were analyzed in the total altitude classes. The results demonstrated that sapling density of total species and the number of tree regeneration per hectare increased with increasing of altitude from sea level. The results also showed that there are significant correlation between the number of beech, hornbeam and mean total tree regeneration with altitude from sea level. The maximum and minimum number of regeneration were observed at the classes of "tree height

In recent years, one of the most important occurred events in Zagros is dieback of forest trees; which every day become more critical. To estimate the dieback severity of trees and determination of the relation between physiographic factors including: slope, direction and elevation from sea level with the dieback severity of forest trees, an area of 400 ha were selected and surveyed in the Ilam forests. Inventory was done by a systematic random sampling, and 80 rectangular sample plots with area of 0.1 ha (40 m × 25 m) were measured. Evaluated parameters into each sample plot were including: species name, diameter at breast height (DBH), severity of dieback, and topographic factors. The results showed that there is a significant relation between severity of dieback and slope (p = 0.008) and direction (p = 0.00001). Dieback of trees was increased with increasing of slope gradients. Severity of dieback was observed in west and south directions more than others. On the base of results, dieback percent of coppice trees was more than high trees. That's means; coppice trees relative to their abundance were damaged more than high trees. Also, there was a significant relation between DBH and severity of dieback (P=0.042) and dieback of trees was increased with increasing of DBH. The most number of withered trees were observed in diametric classes of equal & higher than 40 cm (DBH ≥ 40 cm). About 50% of the total trees were wizen or have had a signs of dieback.

The present investigation was aimed to study the qualitative and quantitative characteristics of Lebanon Oak (Quercus libani Olive.) in Marivan city-kordistan. To investigate the effect of altitude on the qualitative and quantitative characteristics of Lebanon Oak, 108 circular plots of 1000 m2 on three elevation classes of 1400-1600, 1600-1800 and 1800-2000 m were designated. Within each plot, the desired characteristics include: trees diameter at the breast height, height of trees, basal area, crown coverage, quality of trunks, crown symmetry and the status of regeneration were studied. Results showed that DBH quantitative and qualitative characteristics of Lebanon oak trees within the altitude of 1600-1800 m above sea level were significantly different compared with trees located in the altitude of 1400-1600 m. The highest mean diameter at breast height (20.77 cm), trees height (6 meters), basal area (3.75 square meters per hectare) were located in the altitudes of 1600-1800 meters above sea level. The average number of trees per hectare and average crown coverage were 92 and 12% in this altitude, respectively. 37.9% of the trees had a symmetrical crown. Also, about 48% and 52% of the tree regeneration were with the coppice and seed origin in this altitude, respectively. The results also showed that no significantly difference was found between the elevation range for 1600-1800 and 1800-2000 and the suitable elevation range of Lebanon Oak trees regarding to the quantitative and qualitative characteristics was 1800-1600 m.

The main aim of this study was to investigate cluster sampling method and random sampling method with one hundred percent of the estimated inventory features of density and canopy cover in protected forest occupied by Chartagh Ardal forest area for this purpose, 50 hectares of forest of the study area 100% survey with rectangular plots (20×50 m) were measured. In each clustering methods20 clusters were measured with 100 × 250 m demotions. In each cluster, characteristics the number of trees and canopy trees (both large and small diameter of the crown) were measured. In random systematic sampling methods 100 plots were selected in grid inventory with 50×100 m Dimension. The results this study showed a significant difference between the mean estimates of sampling methods with the actual 100% survey. The results of statistical error showed the cluster sampling method with inequality sampling units (5.59% and 9.64%)had more accurate than the cluster sampling method with equality units (6.46% and 10.69% ) and random systematic sampling (8.9 and 11.02% ). The basis of the criterion of authenticity and accuracy of cluster sampling with inequality members had more accurate than the cluster sampling method with equality units. Therefore, the cluster sampling method with inequality sampling units was suitable sampling method in the Chartagh Ardal forest area.

Acer velutinum is one of the most important forest species which forms a pure stand in the Asalem region (Guilan province). In this research, four untouched habitats or with less anthropogenic impacts were selected for A. velutinum in Asalem forest watershed catchment No.7. Then, the most important quantitative and qualitative trees characteristics and also some soils’ physico-chemical factors and geomorphological factors including the height from the sea level, altitude, percent slope and aspect were examined. The number of individual trees per hectare, diameter, total height of trees, grade quality, and symmetry of the crown were determined for all individuals in order to examine the growing stock condition of the species in each natural site (the mean was considered for these factors). The obtained results showed that there was a significant difference between the diameter, height and volume of the standing trees (per hectare), while there was no a significant difference between the symmetry of the crown and tree quality grades in the study area. The results of soil surveys demonstrated that the available phosphorus of soil and soil texture were two important variability factors in the study area. Based on the obtained results, the growing stock of A. velutinum has an optimal condition towards northern direction with low slope areas and height around 800 m.

The effect of forest management was investigated on natural forest stands at district 7- Shenrood (Siahkal). Parcel 2 of the given district (81 ha) was selected as an unmanaged region while parcels 3 and 4 (in total 80 ha) were considered as managed ones. Inventory was based on a systematic method. However، the starting sampling point was based on a randomized method. The dimensions of inventory were 200 × 150 m with circular plots 0. 1 ha. At each sample plot، we measured the kind of species، diameter at breast height، the height of two witness trees and the quality condition of trees. We also recorded all tree regenerations with diameter at breast less than 12. 5 cm. The obtain results showed that there are no significant differences between the average of basal area، volume per hectare and the degree of tree quality in managed and unmanaged parcels. There were also no significant differences between numbers and standing volume per hectare، mean Lorry’s height and regeneration in the managed and unmanaged forest stands at 0. 05 confidence levels. The number of beech species was respectively obtained 83. 87% and 97. 15% in managed and unmanaged parcels. Management practices in forest stands caused an important change from the gross beech forest stands to the pure beech forest stands and it also increased regeneration abundance of beech. The result also showed that the range of the altitudes is suitable for establishment of beech species.

In order to study the effect of elevation on quantitative and qualitative characteristics of the humid forests of Guilan Shafaroud، series 17، 16 and 7 were selected that fall in to three height classes; class 1 (less than 500 m)، class 2 (500 – 1000 m) and class 3 (1000 – 1600 m). In height class 1، 2 and 3 sample plots were determined as 4، 15 and 20 respectively and each sample plot was 0. 1 ha and characteristics of species، total height، crown symmetry، crown diameter، canopy cover، and diameter at breast height، regeneration status of the species and percent of species mixture in each site were calculated. The results showed that there are maximum density of lime in the elevation range of 600 - 1000 m from Height above sea level and extends to the northern and eastern slopes. Also، symmetry of the crown، regeneration status and canopy cover survey of trees showed that broad and symmetrical crowns ranged from 400 - 800 m، utmost regeneration density belong to height class 1، 2 and the height class 2 with %85 have maximum canopy cover. The distribution of trees in diameter classes revealed that forest under study has irregular uneven-aged structure and the irregularity of the curve also shows the ravages during different stages of growth. The overall، habitat of class 1 in Shafaroud forests، determine the most suitable habitat for lime trees.

The western forests of Iran have high value regarding conservation، economy، society، recreational capabilities and ground water resources. These forests are gradually degraded and exchanged into the coppice forests. The present study aims to compare the regeneration status of undisturbed and disturbed oak stands. Based on this، four cemeteries were chosen in the Marivan town namely Gomarelang‚ Ebrahim abad، Kanisanan and Naie. These areas were considered as «less disturbed stands». Besides the area surrounding the given places was considered as «disturbed stands». The systematic random sampling method was used with the sample plots of 0. 15 ha. The data were analyzed using t-test in order to compare the means. The obtained results showed that there are significant differences between mean numbers of regeneration in the “less disturbed” and “disturbed” areas at 0. 05 confidence level. The obtained results also showed that conservation can play a key role for restoration of degraded areas.