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During the last decade, oak decline has caused critical health issues within the Zagros forests in west Iran, which is currently approaching a threatening level with effects on stand structure and stability. Identifying the influential factors on the spread of this phenomenon can thus help forest planners and administrating units to control the crisis. This study aimed to assess different aspects influencing deterioration of oak trees with respect to stands environmental characteristics in the southern part of Zagros forests. For this purpose, 12 declined stand dominated by Brant`s oak (Quercus brantii) at different conditions in both the North and South aspects as well as two altitudes and three replications were chosen within Meleh-Siah forest site in Ilam province. A transect line was randomly assigned to each of the stands, along each or which three square plots (2500 square meter) were laid. Within the plots, all individual trees were inventoried. By using a randomized complete block and factorial design, methods were used to compare the mean values of the inventoried parameters. Although the results showed no significant difference between diameter, height, crown length and basal area of the stands along gradients of aspect and altitude, significant effect of aspect on decline rate in seed based trees as well as altitude on coppice trees were observed. The degree of decline in south aspect was greater than in north aspect. In addition, lower elevations showed larger effects than higher elevations. The interaction between two factors was also significant on the decline rate.

In this study, vegetative, climate, geology and soil properties of a Caucasian wingnut (Pterocarya Fraxiinfolia (Lam.) spach.) forest reserve in Dareh-shahr of Ilam Province were investigated. The Emberje method showed semi-humid climate. Soil texture was loam to loamy-sand, and the soil was shown to be alkaline ranging from neutral to slightly alkalin. A full callipering of the entire study site showed that the stand is composed of Fraxinus rotundifolia and Pterocaria fraxinifolia, accompanied by Wych elm and Caucasian Hackberry. All trees were seedling-initiated with the mean DBH, height and crown area of 64.3 cm, 13.8 m and 89.7 m2, respectively. The forest reserve was consisted of 53.8 % healthy, 38 % fractioned or crown-dried and 8.3 % dead trees. Most healthy trees were Hackberry, whereas the Ash trees were the least. The elm and wingnut mostly regenerated in basal shoot and coppice forms, while hackberry trees mostly produced seedlings. Despite the relatively small area, the forest reserve includes large trees, proper soil with enough organic matter which makes it of major ecological value to be more investigated. Provided with enough control and preservation, the regeneration and further growth of trees will be guaranteed, which in turn ensures the sustainability of this forest reserve.

Forest management and planning require a proper level of quantitative and qualitative information on forest stands. Such data is usually collected by means of different sampling methods e.g. transect method. This study aims at exploring the most appropriate sampling method for estimating basal area incorporating their on precision and cost in a case study of Dalab forests of Ilam province. To this aim, a representative area encompassing 37.2 hectares of forests was selected and surveyed by a 100% inventory. Three sampling methods (transect based on probability theory, transect with fixed 50 m length and transect with fixed number of 5 trees) were applied. Based on a regular random sampling pattern, 37 samples were selected for each sampling method in a 100 × 100m grid. The results showed significant difference between the measured basal area and those estimated by any of the three sampling methods. The E%2×T criteria was additionally applied for a better evaluation of the applied sampling methods .These cost and precision criteria turned out the transect method with fixed number of 5 trees to be the superior to other tested methods, which can be further suggested for estimation of basal area of trees in Dalab Forests of Ilam province.

Understanding the phenological characteristics of the semi-parasitic continental mistletoe (Loranthus europaeus Jacq.) is an essential step for a timely control management of its expansion. To this aim, a portion of oak stands of the southern slope of the Manesht mountain located in Hyanan region in the North East of Ilam was investigated. Three test sites located in altitudes of 1800-1600, 2000-1800 and 2200-2000 m above sea level were considered, in each of which five mistletoe-infested Persian oak trees were selected. The phenological traits were monitored over five years. The results showed that phenological traits are affected by elevation, i.e. the phenological events at lower altitudes occur a few days earlier than the higher elevations. In addition, the appearance time of phenological events was different during successive years. According to the results of our phenological analysis at different altitudes and in different years, it is concluded that the optimal time span for removing mistletoe is prior to its fruit ripening until August. In order to avoid the problems of collecting and dispersing of mistletoes seeds, we can remove the mistletoes on the Brant`s oak trees before the ripening of fruits in the proper time of cutting.

In order to investigate the reaction of biodiversity and richness of plant species in relation to physiography and physico-chemical properties of soil, Arasht catchment (approximately 500 ha) from Kabirkoh protected area in Ilam province was selected. After determining transects in different aspects, 67 sample plots (20m×20m) in a grid of 150m×150m were established (northern aspect 24 plots, western aspect 20 plots and southern aspect 23 plots). The environmental factors and vegetation in each sample plot were recorded. Results from correlation analysis showed that the biodiversity of herbaceous species in southern aspect has a negative relation with clay and sand and has a positive relation with silt and lime. The biodiversity of herbaceous species in northern aspect has a positive relation with soil saturation percentage, organic matter and nitrogen and has a negative relation with altitude. The biodiversity of herbaceous speciesin western aspect has a negative relation with EC and altitude and has a positive relation with lime. Based on the results, it can be stated that for ecological evaluations in Zagros region, physico-chemical factors are more suitable for herbaceous species and physiographic factors and land form are more suitable for shrub and tree species.

In this research tentative model was determined by GIS for evaluation of the ecological capability in Zagros forests. The study was carried out in Masbei area [Oak (Quercus brantii Lindl.) forests] located in south aspects of Kabirkooh in Ilam province. This model was designed in five different classes and forest evaluation process was done in quantitative form using the model. In order to ecological evaluation in the study area, some factors including altitude, aspect, slope, climate, land form and soil depth were applied. The results obtained from this model showed that there are 425 different ecological situation in 7436 ecological final unit within the study site. Coefficient of determination (R2=0.56) between potency gradations of ecological potential and mean height of trees in 64 field plots (0.15 ha) showed that this model is fairly suitable efficient for ecological potency evaluation in Zagros forests.

In order to study the effect of canopy and stand density on natural regeneration, 460 ha from oak forests of southern aspect of Manesht mountain in north of Ilam province was selected. Forty six sample plots, each 2000 m2 for recording stands characteristics and 46 micro plots, each 400 m2 for recording regeneration characteristics were established by random systematic sampling method. Variables in macro-plots included dbh, maximum and minimum crown diameter of all tree species. Number, height and quality of seedlings were studied in the micro-plots. The collected data were analyzed by Excel and Spss softwares (ANOVA test) and then compared using of Dancan test and correlation. Results showed that the abundance of seedlings in this area were low. The number of Quercus brantii and Pistacia atlantica seedlings has a positive correlation with canopy density, whereas Lonicera nummularifolia and Amygdalus orientalis had negative correlation. The maximum height of Quercus brantii seedlings (160 cm) found in denser canopy, while it was 88 cm in stands with open canopy. The maximum seedling height (154 cm) of Lonicera nummularifolia and Amygdalus orientalis were measured in the stands with open canopy. The mean height of seedling, the ratio of tall seedlings to whole seedlings and their vitality in denser canopy (located in northern aspect and medium elevation) were more than those in the stands with open canopy (located in southern aspect and higher elevation). These results indicate the best growth condition in northern aspect and medium elevation due to the richer canopy.

The aim of this study was to survey vegetation in relation to some edaphic and physiographic conditions in Arasht catchment (approximately 510 ha) of Kabirkuh protected area in Ilam province. For this purpose, 67 sample plots (20m×20m) in a systematic grid established in the study area. Some factors, including tree and shrub species type, number and canopy coverage were recorded by measuring their small/large crown diameters in each sample plot. In order to record the herbaceous species, cover percentage for each herbaceous species were recorded in four micro–plots (1.5m²) that were defined with Domin criterion. The Canonical Correspondence Analysis (CCA) and TWINSPAN methods used for the site classification and definition of ecological species groups, respectively. Results showed that there are six ecological species groups in the study area. Some soil physicochemical properties and physiographic factors play an important role in recognizing of ecological species groups. The most important factors affecting the establishment and distribution of ecological species groups were soil texture, lime, nitrogen, organic carbon, elevation and slope.

This study was carried out in Melehgavan protected area (app.160 ha) located in northwestern of Ilam city. The main objective of the study was to survey the ecological species groups in relation to some physiographic attributes and soil physico-chemical properties. The field data were obtained using 67 sample plots (20m×20m) in a systematic random grid. The attributes including tree and shrub species type, number of each species and canopy coverage, which were recorded by measuring their small / large crown diameters in each sample plot. In order to record the herbaceous species, the Whitaker’s snail plot method was applied, which resulted in 81 m2 of the minimum plot area. The Canonical Correspondence Analysis (CCA), Principal Components Analysis (PCA) and TWINSPAN methods were used for the site classification, determining of the relationship between species composition and environmental properties and also definition of ecological species groups, respectively. Results indicated that there were three ecological species groups in the study area. The first group had a positive correlation with the soil pH. There was no indicator tree species in this group but Stipa capensis, Fibigia macrocarpa and Medicago rigidula could be detected as indicator herbaceous species. The second group was established in the higher elevation and its site had more moisture and mineral nutrients than the sites of other groups in the area. Quercus brantii and Bromus tectorum were identified as the indicator species for this group. Daphne mucronata and Euphorbia macroclada species were defined as the indicator species for the third group, which was established in the low elevation above sea level. The mineral nutrients of this group were less than the second group.

The aim of this study was ecological survey and site classification of Arghavan valley, north of Ilam, Iran. For this study, vegetation (tree, bush, shrub and herbaceous species), soil and physiographic factors were investigated in 57 plots. Multivariate analysis recognized four sites. Amygdalus scoparia group had positive correlation with elevation and had low species diversity. Cerasus microcarpa group had positive correlation with organic matter and negative correlation with elevation. This group had high diversity and richness. Ficus carica group was in rocky site, while Quercus brantii was in compacted soil with high clay ratio. Results showed that elevation from sea level, stone proportion of soil, soil texture and organic matter were the most important factors influencing vegetation.