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The Role of Topographic and Edaphic Factors in Mortality of Trees in Middle Zagros Persian Oak (Quercus brantii) Forests
Ahmad Hossieni , Syyed Mohsen Hossieni ,
Volume 3, Issue 1 (9-2016)
Abstract

Oak decline is a complex phenomenon that oak forests are faced with it across the world and Iran. Shalam forested area located in north of Ilam province was selectedto determine the role of topographicand some edaphic factors in tree mortality happened in Persian oak forests. The study region was divided into 20 homogeneous topographic units. Within each homogeneousunit,three 0.1-haplots  were randomly-systematically established for measuring the rate of tree mortality and oneprofile was prepared for characterization ofsome  physical and chemical soil characteristics (texture, moisture content, TNV%, OC% and N for each soil layer, and soil depth). In each plot,diameter at breast height (DBH), maximum and minimum crown diameters, crown dieback percent, origination and form of trees and shrubs for all species and site variables weremeasured. Results showed that 15.7% of forest stock had reduced while 97.65% of it belonged to Persian oak species. The results of multiple linear regression and RDA showed that tree mortality was significantly affected by elevation and aspect, but not by slope. The highestrate of tree mortality was observedin high elevation and south and west aspects. Also the results of multiple linear regression and RDA showed that tree mortality was significantly affected by soil depth and texture. So, the highestrate of tree mortality was observed in soils with less depth, less sand% and more silt%. It was concluded that topography and soil have effective role in tree mortality and its expansion across Zagros forests. Identifying the critical conditions in terms of topography and soil in these forests can help and be useful in the management of tree dieback.


Analysis of Soil Characteristics of Wild Pistachio (Pistacia atlantica sub sp mutica) Forests in Fars Province
Masoud Nejabat, Mohammadreza Negahdarsaber,
Volume 3, Issue 2 (3-2017)
Abstract
Background and objectives: Familiarity with the appropriate soil conditions for Pistacia atlantica leads to improve and develop forest vegetation cover in Zagros zone. The main aim of this research was investigate suitable soil characteristics ranges for natural growth of this species in Fars province.Materials and Methods: Field studies and soil sampling was done based on network sampling (20×20 km grid) in wild pistachio forests of Fars province with crucified pattern. The filed study showed mountain and hilly land are the main land types that pistachio species have placed on them. These land types include the displacement of rock, stone and gravel as high and low soil depth with moderate to severe water erosion.Results: Main physical and chemical properties measurement of soil samples showed that the only limiting growth factor has been the low soil depth. The low effective soil depth and light soil texture are the most important limiting factor on soil moisture storage ability (from rain). This deficiency, transition from drought or very dry periods (resulting from an undesirable distribution of rain) makes it difficult. Statistical analysis methods based on principal component analysis (PCA) and cluster analysis (CA) shows that wide ranges in soil characters, even up to about 40% differentiation in the measured properties do not make restrictions for pistachio Natural growth. Ecologically, Pistacia atlantica is a drought-tolerant plant. Wild pistachio (Pistacia atlantica) is one of the high resistance species in wide range of soil condition (soil characteristics) and this feature (desirable survival) make it favorite for Zagros forest rehabilitation.Conclusion: Land and grazing management (land use planning), along with watershed management practices can conserve and improve soil and environment of wild pistachio habitats of the Zagros forests.

Effect of Rhyzobacteria Inoculation on Improvement of Growth Characteristics of Mediterranean Cypress Seedling under Water Deficit Stress
Morteza Rooki , Masoud Tabari Kouchaksaraei , Seyed Ehsan Sadati ,
Volume 3, Issue 2 (3-2017)
Abstract
Background and objectives: Mediterranean Cypress (Cupressus sempervirens var. fastigiata) is a native, evergreen species. Due to its various merits, particularly its wide use in parks and urban green spaces, it is of interest in most climatic regions of Iran, including Zagros provinces. Due to the poverty of soil and limitation in water sources, the production of seedlings of this species has become particularly problematic in some of these regions. By using rhizobacteria Pseudomonas fluorescens inoculation in soil, for the first time, the present study aims to determine the resistance and variations of growth characteristics of seedlings under water deficit conditions.Materials and methods: The experiment was conducted as a factorial, using a completely randomized design with two treatments (i.e., with rhizobacteria and without rhizobacteria), different watering levels (3, 6, 9 and 12 days) in three replicates. After 5 months, growth characteristics of seedlings were measured.Results: Increasing the watering period (water deficit) caused to significantly decrease the survival, diameter, shoot biomass and total biomass, so that all seedlings were died under 12-day watering level. In watering period of 9 days, survival was reduced to 49.83 percent. There was no significant difference in collar diameter, root length, root volume and root/shoot biomass with water deficit intensity. However, the survival rate, height growth, shoot biomass, root biomass, total biomass and seedling quality index were greater in seedlings inoculated with rhizobacteria, compared with those of non-inoculated seedlings.Conclusion: The seedlings of Mediterranean Cypress inoculated with Pseudomonas fluorescens rhizobacteria are able to tolerate the water deficit stress and increase their growth performance; however, under optimal conditions, the rhizobacteria inoculation has no positive effect on survival rate of the seedlings.
 

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