نشریه پژوهش های آبخیزداری
پیاپی 90 (بهار 1390)

Compositing many spatial factors and constraints، management، planning and do right decision making in watersheds is very complicate and essentially need to apply computer، GIS and Multi Criteria Analysis (MCA). Hable Roud watershed was selected as study area that located in the north of Garmsar، and west of Firuzkouh. Numerous maps were used as spatial factors and constraints and a criteria tree model for compositing the natural spatial factors، economical spatial factors and spatial constraints were designed to determine suitable sites for gabion check dams construction. Factors were standardized Factors weighing were done by pairwise in analytic hierarchy process (AHP) and direct method. Factor layers were composited by spatial multi criteria evaluation (SMCE) in ILWIS. Outputs were composite index map (CIM) with continuous values from zero to one. This map was classified. By sensitivity analysis، the effect of changes in spatial factors weight was studied and more effectiveness factors were known. It was inferred the most effective factor are covering the basin vastly. Coincidence of implemented and recommended regions show suitability of this built system. Finally، recommended this scenario for gabion check dams building، watershed prioritizing and soil conservation planning. This scenario and model can make optimum program for watersheds accurately and fast.

Dracocephalum kotschyi is one of the medicinal and aromatic plant that find in natural site of mountainous and high lands. This plant incase has a lot essence is attend. In traditional medicine، this plant use for fever reduction، joints pain، rheumatism، inflammation against and sore recovery. Present study was carried out to know of ecological characteristic of this species for introduce and dense cultivation of this plant on farm land and then use in medical industries. Such as this plant natural sites were controlled of destroying. This study was carried out in range land of Bojnourd in 2008. In the site، the studies were climatically characteristic، geology، stand type، codominant plant and vegetable variation، physical and chemical analyses of the soil. Results showed that Dracocephalum kotschyi could be adapted for regions with semiarid- cold climate، annual rainfall average of 320 mm and annual temperature average of 10. 22 c. Dracocephalum kotschyi have dispersed in northern and north- west slope and altitude 1600- 1800 m of sea level in rocky area. The soils physical and chemical analyses showed that the soil is very shallow with loomy texture، pH= 7. 57- 7. 6، Ec=. 555 ds/m، CEC= 11. 14- 11. 9 Cmol/kg. The stand type was Stachys inflata- Festuca ovina and the codominant plants were over 58 species. Average of canopy covers and density were 0. 122%، 361 shrubs in hectare respectively.

For implementation of soil conservation and sediment control plans in drainage basins، the recognition of the main sediment sources and erodible area is necessary. In this research the relationship between sediments of small dams which are constructed on drainages of Ebrahim-Abad and Royan Catchments in Semnan Province، with the upland sources was determined using composite and quantitative Tracing Method. The aim of research has been the differentiation of sediment sources and determination the contribution and the relative importance of each source in sediment production. By field investigation، the combination of both surface areas under different lithology and sub surface sources (gully walls) were selected as sediment sources and source differentiation was evaluated using 15 fingerprinting properties and by Kruskal Walis and Diffraction Function Analyses. Finaly the contribution of each sediment source was determined by calculating multivariate mixing models. The results have shown good differentiation of sediment sources، so that in Ebrahim-Abad Catchment، an optimal composition of illite، Mg and Organic Carbon with 95. 8% and in Royan Catchment، Cholorit، XFD، N and Organic Carbon with 92. 9% differentiation power could differentiate sediment sources. The results of calculation using composite multi-variate statistical methods have show that Quaternary units and Shemshak، Dalichay، Hezar-Dareh، Karaj and Lar Formations in Ebrahim-Abad Catchment and Quaternary units، gully erosion and Karaj، Shemshak، Upper Red and Lar formations in Royan Catchment are the most important sources of sediments، respectively.

Homogeneity of soil particles is the potent factor which affects soil spectral signatures and known as the Geometric Standard Deviation of soil particles (σg). This study presents the influence of σg on spectral studying of soil texture using four spectral data sets of LISSIII-P6 and was coincident sampling operations. Subsequent to satellite data preprocessing، some operations were done such as: Normalized Difference Vegetation Index، Principal Component Analysis، Soil Line Euclidean Distance and Unsupervised Classification on acquired data. By stratified randomized sampling method and according to the false color composite and photomorphic units of the main image of the study area، 95 sample points were eventually selected and gathered from 0-5cm of soil surface. Afterwards، geometric standard deviation (σg) and texture fragments were determined for each sample point in the soil lab. Samples were accordingly divided into two parts، on the basis of the computed geometric standard deviation: the first، σg <10 (homogeneous soil) and the second، σg ≥10 (heterogeneous soil). Subsequently via correlation operations for both group، it was expressly displayed which in the first group (σg <10)، clay and sand had about 0. 7-0. 8 correlations with the remotely sensed data، whereas the second group (σg ≥10) had about 0-3-0. 4. Hence، the geometric standard deviation (σg) of the study region can powerfully impress soil spectral reflectance.

Desertification is the consequence of a series of important processes which two factors of climate changes and human activities are the most important ones. Arid and semi-arid regions occupy the vast area of Iran. Sistan region is one typical sample of desert regions of Iran and wind erosion is the most important factor of land degradation and soil deterioration in this region. Hence two models of ICD and ESAs are used to evaluate desertification danger zoning. For this purpose، at first، factors affecting desertification are identified by noting the region conditions and evaluated by using the relevant tables. By noting the region conditions، it became known that four factors of vegetation، soil، and climate and land use management are the primary factors affecting desertification process. The results obtained from these two models indicate ICD model classify desertification intensity in four classes of mild، and medium، high، and intensive totally occupied 13% (625. 6 ha)، 32% (1502. 7 ha)، 40. 7% (1962. 3 ha)، and 15. 2% (730 ha)، respectively. In addition، ESAs model classifies the region in critical class only، so that 68% of the region is placed in intensive critical sub-class (C3)، less than 1% in medium critical sub-class (C2)، and 31% in low critical sub-class. By noting the region conditions، the obtained results from ICD model، do not have conformity with reality، because the limits of the region have been classified in insensitive or mild classes. But as it is known and observable in the study area، in the map prepared by ESAs model، the region is completely classified in critical sub-classes that have absolute conformity with the natural conditions of the region.

The goal of this study is to assess the effects of plantation-exclusion project on vegetation properties. For sampling in both sites (grazed and project area) selected 3 transects، then sampling was done with random-systematic method and in both site (grazed and project area) three 300 meter transects were established and used 15 quadrates (4 m2) along each transect. In each quadrates recorded species list، canopy cover and density. T-test was employed to compare the data obtained from vegetation characteristics. Results indicate that used project caused an significant increased in cover percentage، production. Also in survey cover percentages abundance of planted species Stipagrostis plumosa، Salsola nitaria and Cratocarpus arenarius show that abundance all of species was an significant in both site (grazed and project area) and used project caused species abundance increased significantly، also cover percentage of S. plumosa changes in both of site were significant different the percentage of canopy cover of S. plumosa increased (٪2. 48) with plantation-exclusion project، but there was no significant differences between percentage of canopy cover، S. nitaria and C. arenarius. Study of condition and range trend condition indicates than project sites have good condition with positive trend and grazed areas have weak condition with negative trend.

In this study the seed susceptibility of Poa annua L.، Oxalis curniculatum، Medicago sativa and Rubus caesius L. species to wash or loss from slope surface was investigated. So، at first the mass، area، volume، density، surface to mass ratio، flatness index and eccentricity index of seeds was measured. 100 seeds from each species were distributed on sample plot with slope angle of 25، 45 and 65 degree and then rainfall simulation experiments were conducted on this plot during 40 minutes. Results showed that more seeds of Rubus caesius L. and Oxalis curniculatum have washed from surfaces with angles of 25، 45 and 65 degree at the first 10 minutes of rainfall simulation. During the rainfall simulation، Oxalis curniculatum seeds were more unstable than other seeds except for last 10 minutes on slope angle of 45 and 65 minutes. In this status the seed loss rate for Rubus caesius L. was more than other species. It seems that the reason of this issue be higher flatness index of Rubus caesius L. Poa annua L. was the most stable seed which had lowest loss rate during the rainfall simulation on slopes of 25، 45 and 65 degree. The seed loss rate increased with increasing slope angle. The most and least seed loss rate was occurred in slope angle of 65 and 25 degree، respectively.

An optimal planning system for managing the range and maintaining its vegetation is highly influenced by the humidity and rainfall of the range. In this research، the reactions of the Cornulaca monocanta species to the fluctuation of precipitation were studied at Ebrahim-Abad in Mehriz – Yazd. For this purpose three dominant Species were selected and their canopy cover and production were monitored every year along permanent line transect in random plots. Precipitation data were collected from nearby stations. According to data of precipitation، amount of cumulative rain was determined at various periods. Relationships between variables of plant parameters and amount of cumulative rain analyzed by Back ward and stepwise regression method. The Results indicate that plants species are affected by precipitation fluctuation. The Total vegetation cover has negative and significant correlation with winter Precipitation as well as canopy cover of Cornolaca monocanta. Whereas Precipitation in January-April and winter exhibited a high correlation with canopy cover of Launaea acantodes and Artemisia sieberi. The forage production was also influenced by seasonal precipitation. According to this result، annual yield of dominant plant species and annuals production can be estimated by precipitation in winter and January-April period. In the final، Result of curve estimation show that yield and canopy cover response of Cornolaca monocanta are in two forms of power and linear، respectively.

the type and intensity of soil erosion in a region generally subject to climatic conditions، ups and downs، soil and land use. That in between these، land use compared to other factors is more attention. Land use and erosion close relation with each other. In this investigation in order to investigate sensitivity to yield sediment and erosion the various land uses of gachsaran formation، part of gachsaran catchment in izeh city is selected to 1202 hectares area. This investigation to determine the relationship between the sediment produced by rain simulator with some soil physicochemical characteristics like percent very tiny sand، sand، clay، silt، pH، Ec، moisture، Calcium Carbonate and organic material in different land uses in gachsaran formation to do. Then sediment samples in 6 points and with repeated three times in the intensities of various 0. 75، 1 and 1. 25 millimeter in minute in three land use pastures، the residential and agricultural lands to help the rain simulator. In order to investigate factors in sediment opportunities and erosion vulnerability، samples of soil layers in 0-20 cm meters in the same number of sampling sediment. In order to do all the analysis of statistical methods used EXCEL and SPSS 11. 5 softwares. Then the most important factors in sediment yield is diagnosed by several factors regression. The results showed that sediment yield and erodibility in land uses، in the precipitation various intensities meaningful difference have. These regression models have showed that in the production of sediment in various land uses from between measured factors of the indexes have been quantities like silt، very tiny sand، lime، Ec، organic materials and pH have the largest role in the production of sediment. Then other parameter like run off threshold، percolation rate، sediment density in three land uses calculated. In the total the amount of runoff in residential land use in the highest and agriculture land use is lowest. The amount of sediment also agriculture land use is the highest and residential area is lowest. Run off threshold time، percolation rate، sediment density in agriculture land use is more than other land uses.

Determination of row spacing and amount of harvest in Atriplex canescens are essential، for shrub cultivating in desert areas. For studying the spaces and pruning treatments، a site about 4. 5 ha was chosen and planted by the species in the Kavir-e- Siah koh of Yazd province، in 1993. A split split-plot design applied for analyzing of treatments. The row spaces (2،4 and 6 m) were main treatments while durations of pruning (annual، biennial، triennial) and heights of pruning (0، 20، 40، 60 cm) were sub-treatments. The pruning and weighing of forage in treatments initiated in fall 1995 and extended until 2003. Results showed that there were no significant differences between the cumulated forage of row spacing treatments. There were not any differences between the durations of pruning (annual، biennial، triennial) treatments،too. There were significant differences between the cumulated forages of pruning heights treatments (P<0. 05). Result of together treatments effects showed that، the most 9-year cumulated forage yield attained in 2 m row spacing، 60 cm height and annual duration treatment.