فصلنامه تحقیقات مرتع و بیابان ایران
سال نوزدهم شماره 2 (پیاپی 47، تابستان 1391)

Distinguishing of protected areas is one of the range management methods for improvement, sustainable development and richness of plant composition. This research was carried out to study the effects of conservation on some vegetative factors in some parts of Varjin located in Tehran province and protected since 1982. For this purpose, two vegetation types were selected in protected area as well as unprotected area. Four transects of 300 m length were then established in key areas of each vegetation type and 10 plots of 1m2 were sampled along each transect with 30-m intervals. In each plot, list of species was recorded and vegetative factors including density, composition and yield (cut and weighting method) were measured. All samples were weighted in wet and dry condition. Normality of data was tested and then measured parameters were compared by t test. Results showed that mean difference for all measured parameters in vegetation type of (Me Pe – As br) except vegetation composition of class III species and density of class II and III species were significant. Also in vegetation type of (Fe ov – As br), all parameters were significant except density of class I and class III species.

Rangeland assessment and recognizing changes in vegetation, yield and their affecting factors are of important issues for planning and optimum utilization management. Firstly in 2000, main habitats of Mazandaran province were determined and then a site was selected in each reference area for collecting statistical data. Vegetative factors (vegetation cover and yield) were measured in 10 sites along six transects of 200 meter length in sixty plots of one square meter. According to the results, maximum average percentage of vegetation cover (50.22) and maximum yield (417.87) were recorded for 2003. Minimum average percentage of vegetation cover (47.38) was obtained in 2001 and average yields of 391.46 and 391.63 were obtained in 2001 and 2002, respectively. Consequently, a relationship was found between vegetation cover percentage and yield with precipitation. Most of the sites in which average rainfall especially in late winter and spring of 2003 was more than that of the other years, higher average of canopy cover percentage and yield were recorded in the mentioned year. Also, livestock grazing management was effective on amount of yield and vegetation cover. The sites located in highlands showed a better condition due to the cool Mediterranean climate and higher precipitation and proper grazing management in rangelands. The condition of class I and class II species of these sites was better than that of downstream rangelands. In the sites located in lower regions with a cold semi-arid climate especially in sagebrush lands, range condition was lower than that of the highlands due to semi-arid climatic conditions and the use of rangeland in Spring and Autumn. Class III species were dominant in these sites. Precipitation affected all vegetative forms and for perennial grasses vegetation cover percentage and yield were affected. Since cushion plants were not considered in yield calculation, the increment of vegetation cover percentage had no effect on yield. Annual plants also affected the yield due to increased spring rainfall in some sites.

With attention to importance of range condition for correct management of range ecosystems and relationship among biodiversity, canopy cover percentage and the importance degree of dominant species with range condition and health, this research was conducted with comparison of three methods including pastoral value, six factors and four factors methods in summer rangelands of Lasem, Haraz. Plant types was separated with use of aerial photos (1:20000) and field control on topographic maps (1:50000).The sampling was done by quadrat and transects using random-systematic method in key areas. In this points Shanon, Sympson indices, importance degree of dominant species, canopy cover percent and scores of range condition methods has calculated for determination of relation among them. In order to Pearson correlation test, liner regression and analysis of variance were run with Mini tab 13.3. The results showed that Shanon diversity index had significant relation with six factors, four factors and pastoral value but rate of this relationship to six factors was more than other methods. Sympson index had not correlation with them. The comparison of canopy cover index and importance degree showed that these factors had not significant relation to pastoral value and four factors methods while six factors method had high correlation with them. Thus in this research, the best suitable method of range condition is recognized six factors method.

Salinity is one of the main expanding constraints in lands under cultivation. Therefore, the ability of plants to survive under such a condition is important for ecological distribution of the species and agricultural development. Despite extensive research in this area, there are still many issues associated with salt tolerance of plants. In this research, germination and seedling growth of two native species of Salicornia herbacea and Alhagi persarum were evaluated under different salinity levels. Seeds of these species were treated by different concentrations of NaCl and Na2SO4 in a growth chamber for 45 days. According to the results, germination and seedling growth of both species showed significant differences at in different salinity levels. Up to 200 mM and 150 mM NaCl, no significant differences were recorded for Salicornia herbacea and Alhagi persarum, respectively. In contrast, increment of sodium sulphate up to 100-150 m M, increased seedling growth and germination of Salicornia herbacea. While, a drastic decrease of germination was recorded for Alhagi persarum at 50 mM sodium sulphate. In general, it could be stated that Salicornia herbacea was more resistant to salinity.

Differences in particle size through downstream is a proper tool to understand evolution steps and river channel morphological changes, including sediment transport, channel migration context, the risk of floods and human activities. The present study investigated sediment deposits in upper rangelands of Tehran- Qazvin highway located in Khur-Sefidarak Basin, Tehran Province. Two main channels with Gravelly- sand bed as the main drainage channels were studied. The aim of this study was to investigate changes in particle size based upon sedimentology and its correlation with textural parameters including sorting, skewness, and kurtosis and calculating the approximate volume of sediments behind dams. These parameters were analyzed by sampling 66 samples from upstream to the downstream side of the Khor-Sefidarak channels. All natural factors (secondary branches and sediment sources) and non-natural factors (such as small dams) were effective in tissue changes on this system and the results indicated the continuity of sediment along the channels due to regular gradient of channel bed. Sediment particles through these two channels had a medium sorting. Sorting decreased toward downstream, because of facing secondary branches and increment of shared formation number and totally increased diversity in sediments. Results of bed sediment volume showed that the amounts of bed load sediment through Khor and Sefidarak branches were 271.6 and 246.3 cubic meters per year, respectively.

In this research relationship between vegetation and salt soil in Qom province was studied. The study area situated in central Iranian which is about 14631 km2 with Salt Lake. In this study, first considered region condition including the geographical position, geological history, pedology and climate. The aim of this study was assessment of plant communities of area and their relationship with soil. Primarily the vegetation types were distinguished at the field with physiognomic-floristic-ecologic method. The species data were gathered with stratifield random sampling method using the 10m by 10m quadrats recording the species covers, litter, bare soil, stone and gravel cover in the quadrat. In this study were considered 11 soil factors in 48 types of rangeland. Using cluster analysis was separated 13 plant communities in the region. To determine the effect of environmental factors on the establishment of vegetation was used CCA ordination method using software CANOCO. Ordination results showed that environmental factors such as electrical conductivity (EC), lime, sodium (Na), potassium (K) and calcium(Ca), are studied the most important role in the establishment and expansion of areas plant communities. Also plants of Chenopodiceae family compared with plants of Poaceae family have efficient mechanisms of salt tolerance. In salt lands gradual change of soil moisture, zoning of different species and vegetation types to come in parallel strips. Thus topography of the ground, although small, are the main factors of soil chemical and physical changes, and naturally caused the formation of specific habitat for various plant species.

This study was performed in order to determine spatial variations of drought in Kerman province by Standard Precipitation Index (SPI) and comparing interpolation methods of Kriging and inverse distance weight with powers of 1 to 5, over a thirty-year period (1970-71 to 2000-2001). According to the results during the study period (10-year intervals), maximum and minimum average amounts of SPI were respectively recorded for 1990-91 and 2000-2001. In all studied years, exponential model was determined to be the best variogram fitted to the spatial structure of data and the effective range of each station was a distance of almost 18.03 kilometers for all years except 1990-91 with an effective range of 5, 02 km. Cross validation techniques introduced Kriging as the best interpolation method for all years except 1990-91 in which IDW to the power of 5 was the best interpolation method. Spatial zoning map of SPI showed that moderate drought was recorded for southern parts of Kerman province such as Anbarabad and Jiroft in 1970-71 while in other parts of the province slight drought was observed except Rafsanjan. In 1980-81, slight drought was observed for most parts of the province while in Bam, Bardsir and east of Jiroft slight moisture was observed. In 1990-91, there was a slight drought was recorded for Kerman, Baft, Kahnooj and east of Jiroft. In 2000-2001, all parts of the province were at risk of drought as in the southern half of the province (Baft, Anbarabad and Kahnoj) moderate drought and in the northern half of the province(Kerman, Rafsanjan and Bardsir) slight drought were observed. Error maps showed considerable accuracy of interpolation, especially near the stations.

The aim of this study was to investigate allelopathic activity of aerial and underground organs of mountain sagebrush (Artemisia aucheri) on seed germination features, root length, shoot length and seed vigor of Festuca ovina.For this purpose, species of mountain sagebrush were collected from Taleghan rangelands in Tehran Province and then were dried in direct sunlight and grinded.Powder derived from aerial and underground organs to the amounts of 3, 6 and 9 grams were separately mixed with 900 grams of sand in completely randomized blocks with four replications. In each pot, 10 seeds were planted at a depth of 2-3 cm. Germination percentage, germination velocity, seed vigor, root length, and shoot length were measured. Data analysis was performed using MSTATC software and mean comparisons were carried out using Duncan's test. Results showed that there were no significant differences among measured factors. Also, the shoot and root lengths showed significant differences at probability levels of 5% and 1%, respectively. According to the results, Artemisia aucheri caused a reduction of root length in Festuca ovina.

Livestock grazing is one of the most influencing factors on the rangeland community structure and composition, which can also change the vegetation diversity. The main aim of this research was to survey the flora and plant biodiversity at three rangeland sites, being used under different grazing intensities, Baharkish, Quchan, Iran. Three sites were systematically selected along a spatial gradient of low, moderate and high grazing intensity, and 20 quadrates were randomly established within each site. Species composition, abundance and canopy cover were recorded within the quadrates. Simpson and Shannon diversity and Carmago and Smith & Wilson evenness indices were measured for each site. Floristic studies led to the identification of 156 plant species belonging to 34 families. The floristic composition of the area was strongly dominated by the Irano-Touranian elements. Shannon and Simpson diversity indices were significantly higher under the moderate than the low and heavy grazing intensity sites and the lowest diversity was significantly recorded for the heavy grazing site. Evenness indices did not significantly differ between the low and moderate grazing sites, but it was significantly lower under the high grazing site. In conclusion, proper livestock grazing is necessary for preservation of species diversity in the semiarid rangelands; Moderate grazing maintained the species diversity while light and sever grazing reduced or even eliminated some sensitive plant species.

In range management, appropriate time for utilization is set based upon plant life stages. Accordingly, phenology of Stipa hohenackeriana was studied in three research sites of Roudshor, Hasaan Abad and Khojir. This study was performed during three growth stages in 3 years. Twenty species were selected and was regularly visited from mid-March 2005. Vegetative, flowering, seeding and winter dormancy were considered as phonological stages. Collected data were interpreted using climatic data (temperature and precipitation) and for each stage, growth degree days were calculated. Results showed that start and end of growth differed in different years and these changes were affected by climatic conditions especially temperature and soil moisture. St.ho had a longer growth period in cool and humid years compared to warm and dry years. But required cumulative temperatures were almost the same in different years. Results indicated that plant growth was affected by growth degree days (GDD) and cumulative rainfall during growth season. Also, the analysis of variance showed that differences in plant height at different sites and also in different years were statistically significant (P<0.05).

Recognition of ecological factors affecting the establishment and distribution of plants is necessary and the use of multivariate analysis could be useful to achieve this purpose. In the current research, relationship among the most effective environmental parameters on distribution and establishment of vegetation types of Kachik Watershed was studied by multivariate analysis method. After providing land unit maps, density and canopy cover percentage were measured in reference areas of each land unit. Random-systematic method was used and sampling was performed on 53 quadrates established on 19 transects with intervals of 150 m. Soil samples were taken from the depth of 0-30 cm and pH, EC and percentage of clay, silt and sand were measured. Six separate ecological groups were identified by cluster analysis. Results of principal component analysis revealed that aspect, slope, pH, EC, soil texture and Ca had the most effect on distribution of ecological groups with correlation coefficients of 0.98, 0.96, 0.93, 0.89, 0.82 and 0.81, respectively.

In order to find some phenological phenomena of Atriplex griffithii with climate properties such as as temperature and precipitation, this study was carried out in the north-east of Semnan province from 2001 to 2004. In this survey, 10 Atriplex griffithii were selected and marked. Phonological stages (germination, vegetative, flowering, seeding, and regrowth) were measured in 15-day periods while reproductive traits were measured in 7-10 day intervals. Analysis of climatic data and recorded phonological stages showed that the growth of Atriplex griffithii varied with the fluctuations of drought and temperature in different seasons and two distinctive stages (vegetative and seeding) were recognized for each year. The first growth stage started from late winter and continued to mid-August and the second growth stage started from second half of August and ended in second half of December. Flowering started from May and seeds matured in June. Phonological stages also differed among geographical directions due to differences in rainfall, temperature and evaporation rate as flowering and seeding stages in southern slopes occurred in May and June and in northern slopes were in October and November, respectively. Obtained results can help range managers to set a time calendar for livestock entry and exit and also grazing season.

In this study, sustainability of forage production in some rangeland species of mountainous rangelands of Alamut Qazvin was investigated. These mountainous rangelands are located in the highlands of North-Eastern city of Qazvin as a part of south basin of central Alborz Mountains. The rainfall of these natural environments is 400 mm per year. Long dry season is considered as the main characteristics of the natural environments of these ecosystems. Production per hectare of 24 species was studied during four years. Combined analysis of variance for dry forage production (kg/ha) showed significant differences (p>0.01) among species and the years. According to the results of mean comparisons (Duncan’s multiple test) and cluster analysis (Ward method), Eryngium billardieri, Cousinia esfandiari, Artemisia aucheri, Verbascum speciosum, Agropyron intermedium, and Cirsium haussknechtii had higher forage production. Interaction effect of species * year was significant at 1% probability level and sustainability parameters were calculated based upon average forage production. Parameters of CVi, S2di and R2 had similar trends in introduction of sustainable species and most of them showed low forage production based upon these parameters. Parameters of Bi, W2i and S2i also showed the same trend in expression of sustainability and on the basis of these three parameters, an average forage production was recorded for most of sustainable species. In general, Cousinia esfandiari and Artemisia aucheri showed appropriate production sustainability based upon most sustainability parameters. Agropyron intermedium and Cirsium haussknechtii were not sensitive to adverse conditions while Verbascum speciosum and Eryngium billardieri were sensitive to adverse conditions. Therefore, Agropyron intermedium and Artemisia aucheri could be introduced for range improvement programs.